electric fuel pump switch
11-12-2004, 11:10 AM
#21
Guest
Posts: n/a
Re: electric fuel pump switch
> Yep. Different system with the fuel pump controlled by the engine
computer
> on a fuel injected application. They pressurize the rail first by running
> for 2-4 seconds then shut down. When the key is moved to Start, they pump
> runs from that point till when the key is moved to Off. On some vehicles
> there is an interlock with oil pressure. As long as there is oil pressure
> the fuel pump relay gets power. There are also impact/rollover switches.
Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
of an electronic fuel pump. It's still carbureted however. So I'm not sure
about using a pressure interlock. The jeep doesn't get used all that often
and it seems the float eventually runs dry (it's been needing a rebuild for
ages...). So the pump has to run a bit into order to refill the carb and
start running. There wouldn't be any oil pressure yet.
That said, it's a little annoying to hear the pump rumble when the engine's
off but in the run position. It'd be nice to either have a quieter pump or
some sort of cut-off like you mention. Any idea about one suited for a carb
setup? One with some sort of shut-off timer with a pressure sensor override
would seem like the right idea.
> You could put in a cutoff switch or safety interlock like race cars use.
> Just a simple safety switch that cuts power to the pump. Better to use
> a relay for that type of application though.
Agreed, no sense running the full current of what a pump might draw through
a switch. They tend to overheat. Granted a beefier switch would handle it
better. It'd be a toss-up between spending more on the switch or the cost
and the wiring up of a relay circuit.
-Bill Kearney
computer
> on a fuel injected application. They pressurize the rail first by running
> for 2-4 seconds then shut down. When the key is moved to Start, they pump
> runs from that point till when the key is moved to Off. On some vehicles
> there is an interlock with oil pressure. As long as there is oil pressure
> the fuel pump relay gets power. There are also impact/rollover switches.
Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
of an electronic fuel pump. It's still carbureted however. So I'm not sure
about using a pressure interlock. The jeep doesn't get used all that often
and it seems the float eventually runs dry (it's been needing a rebuild for
ages...). So the pump has to run a bit into order to refill the carb and
start running. There wouldn't be any oil pressure yet.
That said, it's a little annoying to hear the pump rumble when the engine's
off but in the run position. It'd be nice to either have a quieter pump or
some sort of cut-off like you mention. Any idea about one suited for a carb
setup? One with some sort of shut-off timer with a pressure sensor override
would seem like the right idea.
> You could put in a cutoff switch or safety interlock like race cars use.
> Just a simple safety switch that cuts power to the pump. Better to use
> a relay for that type of application though.
Agreed, no sense running the full current of what a pump might draw through
a switch. They tend to overheat. Granted a beefier switch would handle it
better. It'd be a toss-up between spending more on the switch or the cost
and the wiring up of a relay circuit.
-Bill Kearney
11-12-2004, 11:10 AM
#22
Guest
Posts: n/a
Re: electric fuel pump switch
> Yep. Different system with the fuel pump controlled by the engine
computer
> on a fuel injected application. They pressurize the rail first by running
> for 2-4 seconds then shut down. When the key is moved to Start, they pump
> runs from that point till when the key is moved to Off. On some vehicles
> there is an interlock with oil pressure. As long as there is oil pressure
> the fuel pump relay gets power. There are also impact/rollover switches.
Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
of an electronic fuel pump. It's still carbureted however. So I'm not sure
about using a pressure interlock. The jeep doesn't get used all that often
and it seems the float eventually runs dry (it's been needing a rebuild for
ages...). So the pump has to run a bit into order to refill the carb and
start running. There wouldn't be any oil pressure yet.
That said, it's a little annoying to hear the pump rumble when the engine's
off but in the run position. It'd be nice to either have a quieter pump or
some sort of cut-off like you mention. Any idea about one suited for a carb
setup? One with some sort of shut-off timer with a pressure sensor override
would seem like the right idea.
> You could put in a cutoff switch or safety interlock like race cars use.
> Just a simple safety switch that cuts power to the pump. Better to use
> a relay for that type of application though.
Agreed, no sense running the full current of what a pump might draw through
a switch. They tend to overheat. Granted a beefier switch would handle it
better. It'd be a toss-up between spending more on the switch or the cost
and the wiring up of a relay circuit.
-Bill Kearney
computer
> on a fuel injected application. They pressurize the rail first by running
> for 2-4 seconds then shut down. When the key is moved to Start, they pump
> runs from that point till when the key is moved to Off. On some vehicles
> there is an interlock with oil pressure. As long as there is oil pressure
> the fuel pump relay gets power. There are also impact/rollover switches.
Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
of an electronic fuel pump. It's still carbureted however. So I'm not sure
about using a pressure interlock. The jeep doesn't get used all that often
and it seems the float eventually runs dry (it's been needing a rebuild for
ages...). So the pump has to run a bit into order to refill the carb and
start running. There wouldn't be any oil pressure yet.
That said, it's a little annoying to hear the pump rumble when the engine's
off but in the run position. It'd be nice to either have a quieter pump or
some sort of cut-off like you mention. Any idea about one suited for a carb
setup? One with some sort of shut-off timer with a pressure sensor override
would seem like the right idea.
> You could put in a cutoff switch or safety interlock like race cars use.
> Just a simple safety switch that cuts power to the pump. Better to use
> a relay for that type of application though.
Agreed, no sense running the full current of what a pump might draw through
a switch. They tend to overheat. Granted a beefier switch would handle it
better. It'd be a toss-up between spending more on the switch or the cost
and the wiring up of a relay circuit.
-Bill Kearney
11-12-2004, 01:53 PM
#23
Guest
Posts: n/a
Re: electric fuel pump switch
wkearney99 did pass the time by typing:
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
It's also a lot easier to wire a relay. At about 8-9$ for a relay it's cheap.
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
It's also a lot easier to wire a relay. At about 8-9$ for a relay it's cheap.
11-12-2004, 01:53 PM
#24
Guest
Posts: n/a
Re: electric fuel pump switch
wkearney99 did pass the time by typing:
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
It's also a lot easier to wire a relay. At about 8-9$ for a relay it's cheap.
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
It's also a lot easier to wire a relay. At about 8-9$ for a relay it's cheap.
11-12-2004, 01:53 PM
#25
Guest
Posts: n/a
Re: electric fuel pump switch
wkearney99 did pass the time by typing:
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
It's also a lot easier to wire a relay. At about 8-9$ for a relay it's cheap.
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
It's also a lot easier to wire a relay. At about 8-9$ for a relay it's cheap.
11-12-2004, 03:01 PM
#26
Guest
Posts: n/a
Re: electric fuel pump switch
wkearney99 did pass the time by typing:
>> Yep. Different system with the fuel pump controlled by the engine computer
>> on a fuel injected application. They pressurize the rail first by running
>> for 2-4 seconds then shut down. When the key is moved to Start, they pump
>> runs from that point till when the key is moved to Off. On some vehicles
>> there is an interlock with oil pressure. As long as there is oil pressure
>> the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
Good article on the oil interlock:
http://www.streetrodstuff.com/Articl...mp_Conversion/
The cutoff switch is commonly called an "Inertial Cut-Off Switch" and can
be had from just about any auto vendor (or maby even NAPA). It's just an
impact switch similar to an airbag sensor that cuts the power to your
pump should it get whacked hard enough. And by hard, I mean enough to
bend metal or set off the air bags, not bouncing on a trail. Fairly sure
the new Jeeps have them.
A timer circuit would have to be made, not sure of any commercial sources.
I could give some suggestions if your handy with electronics.
--
DougW
>> Yep. Different system with the fuel pump controlled by the engine computer
>> on a fuel injected application. They pressurize the rail first by running
>> for 2-4 seconds then shut down. When the key is moved to Start, they pump
>> runs from that point till when the key is moved to Off. On some vehicles
>> there is an interlock with oil pressure. As long as there is oil pressure
>> the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
Good article on the oil interlock:
http://www.streetrodstuff.com/Articl...mp_Conversion/
The cutoff switch is commonly called an "Inertial Cut-Off Switch" and can
be had from just about any auto vendor (or maby even NAPA). It's just an
impact switch similar to an airbag sensor that cuts the power to your
pump should it get whacked hard enough. And by hard, I mean enough to
bend metal or set off the air bags, not bouncing on a trail. Fairly sure
the new Jeeps have them.
A timer circuit would have to be made, not sure of any commercial sources.
I could give some suggestions if your handy with electronics.
--
DougW
11-12-2004, 03:01 PM
#27
Guest
Posts: n/a
Re: electric fuel pump switch
wkearney99 did pass the time by typing:
>> Yep. Different system with the fuel pump controlled by the engine computer
>> on a fuel injected application. They pressurize the rail first by running
>> for 2-4 seconds then shut down. When the key is moved to Start, they pump
>> runs from that point till when the key is moved to Off. On some vehicles
>> there is an interlock with oil pressure. As long as there is oil pressure
>> the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
Good article on the oil interlock:
http://www.streetrodstuff.com/Articl...mp_Conversion/
The cutoff switch is commonly called an "Inertial Cut-Off Switch" and can
be had from just about any auto vendor (or maby even NAPA). It's just an
impact switch similar to an airbag sensor that cuts the power to your
pump should it get whacked hard enough. And by hard, I mean enough to
bend metal or set off the air bags, not bouncing on a trail. Fairly sure
the new Jeeps have them.
A timer circuit would have to be made, not sure of any commercial sources.
I could give some suggestions if your handy with electronics.
--
DougW
>> Yep. Different system with the fuel pump controlled by the engine computer
>> on a fuel injected application. They pressurize the rail first by running
>> for 2-4 seconds then shut down. When the key is moved to Start, they pump
>> runs from that point till when the key is moved to Off. On some vehicles
>> there is an interlock with oil pressure. As long as there is oil pressure
>> the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
Good article on the oil interlock:
http://www.streetrodstuff.com/Articl...mp_Conversion/
The cutoff switch is commonly called an "Inertial Cut-Off Switch" and can
be had from just about any auto vendor (or maby even NAPA). It's just an
impact switch similar to an airbag sensor that cuts the power to your
pump should it get whacked hard enough. And by hard, I mean enough to
bend metal or set off the air bags, not bouncing on a trail. Fairly sure
the new Jeeps have them.
A timer circuit would have to be made, not sure of any commercial sources.
I could give some suggestions if your handy with electronics.
--
DougW
11-12-2004, 03:01 PM
#28
Guest
Posts: n/a
Re: electric fuel pump switch
wkearney99 did pass the time by typing:
>> Yep. Different system with the fuel pump controlled by the engine computer
>> on a fuel injected application. They pressurize the rail first by running
>> for 2-4 seconds then shut down. When the key is moved to Start, they pump
>> runs from that point till when the key is moved to Off. On some vehicles
>> there is an interlock with oil pressure. As long as there is oil pressure
>> the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
Good article on the oil interlock:
http://www.streetrodstuff.com/Articl...mp_Conversion/
The cutoff switch is commonly called an "Inertial Cut-Off Switch" and can
be had from just about any auto vendor (or maby even NAPA). It's just an
impact switch similar to an airbag sensor that cuts the power to your
pump should it get whacked hard enough. And by hard, I mean enough to
bend metal or set off the air bags, not bouncing on a trail. Fairly sure
the new Jeeps have them.
A timer circuit would have to be made, not sure of any commercial sources.
I could give some suggestions if your handy with electronics.
--
DougW
>> Yep. Different system with the fuel pump controlled by the engine computer
>> on a fuel injected application. They pressurize the rail first by running
>> for 2-4 seconds then shut down. When the key is moved to Start, they pump
>> runs from that point till when the key is moved to Off. On some vehicles
>> there is an interlock with oil pressure. As long as there is oil pressure
>> the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
Good article on the oil interlock:
http://www.streetrodstuff.com/Articl...mp_Conversion/
The cutoff switch is commonly called an "Inertial Cut-Off Switch" and can
be had from just about any auto vendor (or maby even NAPA). It's just an
impact switch similar to an airbag sensor that cuts the power to your
pump should it get whacked hard enough. And by hard, I mean enough to
bend metal or set off the air bags, not bouncing on a trail. Fairly sure
the new Jeeps have them.
A timer circuit would have to be made, not sure of any commercial sources.
I could give some suggestions if your handy with electronics.
--
DougW
11-12-2004, 05:23 PM
#29
Guest
Posts: n/a
Re: electric fuel pump switch
The Jeep engines have an oil pressure switch on the sender unit. This
can be used for the pump on in the run position with a relay. Stock,
the switch runs the manifold heater with a relay on the 258 and the
choke.
For starting, you feed the pump power from the starter solenoid.
This way the pump runs direct with the starter and only with oil
pressure when the key is in run.
You can put your safety cutoff on the relay circuit if you want one in
easy enough. It would just need to cut the power.
The carb emptying out when it sits normally means you have the gas
filter in upside down by the way. The filter has two outlets, the
center one goes to the carb and the top one goes to the return line. If
the return line isn't at the top the gas will syphon back to the tank
when it sits. A pinhole leak in the suction side line from the pump can
also let air in when sitting and only leave a small stain because it is
on the suction side.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
wkearney99 wrote:
>
> > Yep. Different system with the fuel pump controlled by the engine
> computer
> > on a fuel injected application. They pressurize the rail first by running
> > for 2-4 seconds then shut down. When the key is moved to Start, they pump
> > runs from that point till when the key is moved to Off. On some vehicles
> > there is an interlock with oil pressure. As long as there is oil pressure
> > the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
>
> > You could put in a cutoff switch or safety interlock like race cars use.
> > Just a simple safety switch that cuts power to the pump. Better to use
> > a relay for that type of application though.
>
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
>
> -Bill Kearney
can be used for the pump on in the run position with a relay. Stock,
the switch runs the manifold heater with a relay on the 258 and the
choke.
For starting, you feed the pump power from the starter solenoid.
This way the pump runs direct with the starter and only with oil
pressure when the key is in run.
You can put your safety cutoff on the relay circuit if you want one in
easy enough. It would just need to cut the power.
The carb emptying out when it sits normally means you have the gas
filter in upside down by the way. The filter has two outlets, the
center one goes to the carb and the top one goes to the return line. If
the return line isn't at the top the gas will syphon back to the tank
when it sits. A pinhole leak in the suction side line from the pump can
also let air in when sitting and only leave a small stain because it is
on the suction side.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
wkearney99 wrote:
>
> > Yep. Different system with the fuel pump controlled by the engine
> computer
> > on a fuel injected application. They pressurize the rail first by running
> > for 2-4 seconds then shut down. When the key is moved to Start, they pump
> > runs from that point till when the key is moved to Off. On some vehicles
> > there is an interlock with oil pressure. As long as there is oil pressure
> > the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
>
> > You could put in a cutoff switch or safety interlock like race cars use.
> > Just a simple safety switch that cuts power to the pump. Better to use
> > a relay for that type of application though.
>
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
>
> -Bill Kearney
11-12-2004, 05:23 PM
#30
Guest
Posts: n/a
Re: electric fuel pump switch
The Jeep engines have an oil pressure switch on the sender unit. This
can be used for the pump on in the run position with a relay. Stock,
the switch runs the manifold heater with a relay on the 258 and the
choke.
For starting, you feed the pump power from the starter solenoid.
This way the pump runs direct with the starter and only with oil
pressure when the key is in run.
You can put your safety cutoff on the relay circuit if you want one in
easy enough. It would just need to cut the power.
The carb emptying out when it sits normally means you have the gas
filter in upside down by the way. The filter has two outlets, the
center one goes to the carb and the top one goes to the return line. If
the return line isn't at the top the gas will syphon back to the tank
when it sits. A pinhole leak in the suction side line from the pump can
also let air in when sitting and only leave a small stain because it is
on the suction side.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
wkearney99 wrote:
>
> > Yep. Different system with the fuel pump controlled by the engine
> computer
> > on a fuel injected application. They pressurize the rail first by running
> > for 2-4 seconds then shut down. When the key is moved to Start, they pump
> > runs from that point till when the key is moved to Off. On some vehicles
> > there is an interlock with oil pressure. As long as there is oil pressure
> > the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
>
> > You could put in a cutoff switch or safety interlock like race cars use.
> > Just a simple safety switch that cuts power to the pump. Better to use
> > a relay for that type of application though.
>
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
>
> -Bill Kearney
can be used for the pump on in the run position with a relay. Stock,
the switch runs the manifold heater with a relay on the 258 and the
choke.
For starting, you feed the pump power from the starter solenoid.
This way the pump runs direct with the starter and only with oil
pressure when the key is in run.
You can put your safety cutoff on the relay circuit if you want one in
easy enough. It would just need to cut the power.
The carb emptying out when it sits normally means you have the gas
filter in upside down by the way. The filter has two outlets, the
center one goes to the carb and the top one goes to the return line. If
the return line isn't at the top the gas will syphon back to the tank
when it sits. A pinhole leak in the suction side line from the pump can
also let air in when sitting and only leave a small stain because it is
on the suction side.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
wkearney99 wrote:
>
> > Yep. Different system with the fuel pump controlled by the engine
> computer
> > on a fuel injected application. They pressurize the rail first by running
> > for 2-4 seconds then shut down. When the key is moved to Start, they pump
> > runs from that point till when the key is moved to Off. On some vehicles
> > there is an interlock with oil pressure. As long as there is oil pressure
> > the fuel pump relay gets power. There are also impact/rollover switches.
>
> Good to know. I put a 3.4L in my Cherokee some time ago and it requires use
> of an electronic fuel pump. It's still carbureted however. So I'm not sure
> about using a pressure interlock. The jeep doesn't get used all that often
> and it seems the float eventually runs dry (it's been needing a rebuild for
> ages...). So the pump has to run a bit into order to refill the carb and
> start running. There wouldn't be any oil pressure yet.
>
> That said, it's a little annoying to hear the pump rumble when the engine's
> off but in the run position. It'd be nice to either have a quieter pump or
> some sort of cut-off like you mention. Any idea about one suited for a carb
> setup? One with some sort of shut-off timer with a pressure sensor override
> would seem like the right idea.
>
> > You could put in a cutoff switch or safety interlock like race cars use.
> > Just a simple safety switch that cuts power to the pump. Better to use
> > a relay for that type of application though.
>
> Agreed, no sense running the full current of what a pump might draw through
> a switch. They tend to overheat. Granted a beefier switch would handle it
> better. It'd be a toss-up between spending more on the switch or the cost
> and the wiring up of a relay circuit.
>
> -Bill Kearney