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Re: 96 Grand Cherokee Stalling
philthy wrote: > did u replace the cap and rotor too? I replaced the cap today. It didn't help. I have not replaced the rotor. Doug B. |
Re: 96 Grand Cherokee Stalling
philthy wrote: > did u replace the cap and rotor too? I replaced the cap today. It didn't help. I have not replaced the rotor. Doug B. |
Re: 96 Grand Cherokee Stalling
From the '96 FSM
DIAGNOSIS AND TESTING FUEL PUMP PRESSURE TEST-4.0L ENGINE NOTE: The fuel pressure test port is used on certain engines only. If equipped, the test port will be located on the fuel rail (Fig. 8). A sealing cap is screwed onto the test port. All fuel systems are equipped with a fuel tank module mounted, fuel pressure regulator. The fuel pressure regulator is not controlled by engine vacuum. With engine at idle speed, system fuel pressure should be 338 kPa 6 14 kPa (49.0 psi 6 2 psi). WARNING: DO NOT ALLOW FUEL TO SPILL ONTO THE ENGINE INTAKE OR EXHAUST MANIFOLDS. PLACE SHOP TOWELS UNDER AND AROUND THE PRESSURE PORT TO ABSORB FUEL. WARNING: WEAR PROPER EYE PROTECTION WHEN TESTING FUEL SYSTEM PRESSURE. (1) Remove the protective cap at the fuel rail test port. Connect the 0-414 kPa (0-60 psi) fuel pressure gauge (from gauge set 5069) to the test port pressure fitting on the fuel rail. (2) Start the engine and note pressure gauge reading. Fuel pressure should be 338 kPa 6 14 kPa (49.0 psi +/- 2 psi) at idle. (3) If pressure is at O psi, connect DRB scan tool and refer to operating instructions in the appropriate Powertrain Diagnostics Procedures service manual. (4) If operating pressure is above 51.0 psi, fuel pump is OK but pressure regulator is defective. Regulator is not serviced separately. Replace fuel pump module assembly. FUEL PRESSURE LEAK DOWN TEST Abnormally long periods of cranking to restart a hot engine that has been shut down for a short period of time may be caused by: ² Fuel pressure bleeding past a fuel injector(s). ² Fuel pressure bleeding past the check valve in the fuel pump module. (1) Disconnect the fuel inlet line at fuel rail. Refer to Fuel Tubes/Lines/Hoses and Clamps in this section of the group for procedures. On some engines, air cleaner housing removal may be necessary before fuel line disconnection. (2) Connect the appropriate Fuel Line Pressure Test Adapter Tool (number 6539, 6631, 6541 or 6923) between the disconnected fuel line and fuel rail (Fig. 11) or (Fig. 12). (3) Connect the 0-414 kPa (0-60 psi) fuel pressure test gauge (from Gauge Set 5069) to the test port on the appropriate Adaptor Tool. The fittings on both tools must be in good condition and free from any small leaks before performing the proceeding test. (4) Start engine and bring to normal operating temperature. (5) Observe test gauge. Normal operating pressure should be 338 kPa 6 14 kPa (49 psi 6 2 psi). (6) Shut engine off. (7) Pressure should not fall below 24 psi for five minutes. (8) If pressure falls below 24 psi, it must determined if a fuel injector, the fuel pressure regulator or a fuel tube/line is leaking. (9) Again, start engine and bring to normal operating temperature. (10) Shut engine off. (11) Checking for fuel injector leakage: Clamp off the rubber hose portion of Adaptor Tool between the fuel rail and the test port "T" on Adapter Tool. If pressure now holds at or above 24 psi, a fuel injector or the fuel rail is leaking. (12) Checking for fuel pump module or fuel tube/line leakage: Clamp off the rubber hose portion of Adaptor Tool between the vehicle fuel line and test port "T" on Adapter Tool. If pressure now holds at or above 24 psi, a leak can be found at a fuel tube/ line. If no leaks are found at fuel tubes or lines, replace the fuel pump module. "DougW" <post.replies@invalid.address> wrote in message news:hGpah.43$DF6.28@newsfe24.lga... > dougguitar@yahoo.com wrote: >> DougW wrote: >>> It should hold pressure for over 4-5 hours. Given this and your >>> 45psi for fuel pressure I'm starting to think the regulator might be >>> shot. When you take the vac line off see if there is gas dribbling >>> out. >>> >>> -- >>> DougW >> >> OK, I timed it. After 4 minutes, the pressure had dropped from around >> 49 psi to about 35 psi. After 12 minutes, it had dropped to 20 psi. To >> add to my fun, the 96 GC does not have the fuel pressure regulator >> attached to the fuel rail: it's built into the fuel pump. @#$% >> There's just a direct connect fuel line going to the fuel rail. >> >> Will a regulator fail in this intermittent way? If that's the case, >> then I have to pony up the $300 plus for a new fuel pump. Sure wish I >> could be sure before I make the financial plunge. > > Hard to tell, the 96 made a lot of changes and my books are only good > up to the 95. 49 psi might be normal. Still though I thought pressure > was supposed to be maintained longer than that. I'd suggest calling a > dealership and asking if a mechanic could look that up for you. It's > worth a shot. > > I don't think it is your fuel pump. Pumps and pressure regulators > usually fail to the low pressure side and what you get is a lack of > power at wide-open-trottle or even pinging. > > -- > DougW > > > |
Re: 96 Grand Cherokee Stalling
From the '96 FSM
DIAGNOSIS AND TESTING FUEL PUMP PRESSURE TEST-4.0L ENGINE NOTE: The fuel pressure test port is used on certain engines only. If equipped, the test port will be located on the fuel rail (Fig. 8). A sealing cap is screwed onto the test port. All fuel systems are equipped with a fuel tank module mounted, fuel pressure regulator. The fuel pressure regulator is not controlled by engine vacuum. With engine at idle speed, system fuel pressure should be 338 kPa 6 14 kPa (49.0 psi 6 2 psi). WARNING: DO NOT ALLOW FUEL TO SPILL ONTO THE ENGINE INTAKE OR EXHAUST MANIFOLDS. PLACE SHOP TOWELS UNDER AND AROUND THE PRESSURE PORT TO ABSORB FUEL. WARNING: WEAR PROPER EYE PROTECTION WHEN TESTING FUEL SYSTEM PRESSURE. (1) Remove the protective cap at the fuel rail test port. Connect the 0-414 kPa (0-60 psi) fuel pressure gauge (from gauge set 5069) to the test port pressure fitting on the fuel rail. (2) Start the engine and note pressure gauge reading. Fuel pressure should be 338 kPa 6 14 kPa (49.0 psi +/- 2 psi) at idle. (3) If pressure is at O psi, connect DRB scan tool and refer to operating instructions in the appropriate Powertrain Diagnostics Procedures service manual. (4) If operating pressure is above 51.0 psi, fuel pump is OK but pressure regulator is defective. Regulator is not serviced separately. Replace fuel pump module assembly. FUEL PRESSURE LEAK DOWN TEST Abnormally long periods of cranking to restart a hot engine that has been shut down for a short period of time may be caused by: ² Fuel pressure bleeding past a fuel injector(s). ² Fuel pressure bleeding past the check valve in the fuel pump module. (1) Disconnect the fuel inlet line at fuel rail. Refer to Fuel Tubes/Lines/Hoses and Clamps in this section of the group for procedures. On some engines, air cleaner housing removal may be necessary before fuel line disconnection. (2) Connect the appropriate Fuel Line Pressure Test Adapter Tool (number 6539, 6631, 6541 or 6923) between the disconnected fuel line and fuel rail (Fig. 11) or (Fig. 12). (3) Connect the 0-414 kPa (0-60 psi) fuel pressure test gauge (from Gauge Set 5069) to the test port on the appropriate Adaptor Tool. The fittings on both tools must be in good condition and free from any small leaks before performing the proceeding test. (4) Start engine and bring to normal operating temperature. (5) Observe test gauge. Normal operating pressure should be 338 kPa 6 14 kPa (49 psi 6 2 psi). (6) Shut engine off. (7) Pressure should not fall below 24 psi for five minutes. (8) If pressure falls below 24 psi, it must determined if a fuel injector, the fuel pressure regulator or a fuel tube/line is leaking. (9) Again, start engine and bring to normal operating temperature. (10) Shut engine off. (11) Checking for fuel injector leakage: Clamp off the rubber hose portion of Adaptor Tool between the fuel rail and the test port "T" on Adapter Tool. If pressure now holds at or above 24 psi, a fuel injector or the fuel rail is leaking. (12) Checking for fuel pump module or fuel tube/line leakage: Clamp off the rubber hose portion of Adaptor Tool between the vehicle fuel line and test port "T" on Adapter Tool. If pressure now holds at or above 24 psi, a leak can be found at a fuel tube/ line. If no leaks are found at fuel tubes or lines, replace the fuel pump module. "DougW" <post.replies@invalid.address> wrote in message news:hGpah.43$DF6.28@newsfe24.lga... > dougguitar@yahoo.com wrote: >> DougW wrote: >>> It should hold pressure for over 4-5 hours. Given this and your >>> 45psi for fuel pressure I'm starting to think the regulator might be >>> shot. When you take the vac line off see if there is gas dribbling >>> out. >>> >>> -- >>> DougW >> >> OK, I timed it. After 4 minutes, the pressure had dropped from around >> 49 psi to about 35 psi. After 12 minutes, it had dropped to 20 psi. To >> add to my fun, the 96 GC does not have the fuel pressure regulator >> attached to the fuel rail: it's built into the fuel pump. @#$% >> There's just a direct connect fuel line going to the fuel rail. >> >> Will a regulator fail in this intermittent way? If that's the case, >> then I have to pony up the $300 plus for a new fuel pump. Sure wish I >> could be sure before I make the financial plunge. > > Hard to tell, the 96 made a lot of changes and my books are only good > up to the 95. 49 psi might be normal. Still though I thought pressure > was supposed to be maintained longer than that. I'd suggest calling a > dealership and asking if a mechanic could look that up for you. It's > worth a shot. > > I don't think it is your fuel pump. Pumps and pressure regulators > usually fail to the low pressure side and what you get is a lack of > power at wide-open-trottle or even pinging. > > -- > DougW > > > |
Re: 96 Grand Cherokee Stalling
From the '96 FSM
DIAGNOSIS AND TESTING FUEL PUMP PRESSURE TEST-4.0L ENGINE NOTE: The fuel pressure test port is used on certain engines only. If equipped, the test port will be located on the fuel rail (Fig. 8). A sealing cap is screwed onto the test port. All fuel systems are equipped with a fuel tank module mounted, fuel pressure regulator. The fuel pressure regulator is not controlled by engine vacuum. With engine at idle speed, system fuel pressure should be 338 kPa 6 14 kPa (49.0 psi 6 2 psi). WARNING: DO NOT ALLOW FUEL TO SPILL ONTO THE ENGINE INTAKE OR EXHAUST MANIFOLDS. PLACE SHOP TOWELS UNDER AND AROUND THE PRESSURE PORT TO ABSORB FUEL. WARNING: WEAR PROPER EYE PROTECTION WHEN TESTING FUEL SYSTEM PRESSURE. (1) Remove the protective cap at the fuel rail test port. Connect the 0-414 kPa (0-60 psi) fuel pressure gauge (from gauge set 5069) to the test port pressure fitting on the fuel rail. (2) Start the engine and note pressure gauge reading. Fuel pressure should be 338 kPa 6 14 kPa (49.0 psi +/- 2 psi) at idle. (3) If pressure is at O psi, connect DRB scan tool and refer to operating instructions in the appropriate Powertrain Diagnostics Procedures service manual. (4) If operating pressure is above 51.0 psi, fuel pump is OK but pressure regulator is defective. Regulator is not serviced separately. Replace fuel pump module assembly. FUEL PRESSURE LEAK DOWN TEST Abnormally long periods of cranking to restart a hot engine that has been shut down for a short period of time may be caused by: ² Fuel pressure bleeding past a fuel injector(s). ² Fuel pressure bleeding past the check valve in the fuel pump module. (1) Disconnect the fuel inlet line at fuel rail. Refer to Fuel Tubes/Lines/Hoses and Clamps in this section of the group for procedures. On some engines, air cleaner housing removal may be necessary before fuel line disconnection. (2) Connect the appropriate Fuel Line Pressure Test Adapter Tool (number 6539, 6631, 6541 or 6923) between the disconnected fuel line and fuel rail (Fig. 11) or (Fig. 12). (3) Connect the 0-414 kPa (0-60 psi) fuel pressure test gauge (from Gauge Set 5069) to the test port on the appropriate Adaptor Tool. The fittings on both tools must be in good condition and free from any small leaks before performing the proceeding test. (4) Start engine and bring to normal operating temperature. (5) Observe test gauge. Normal operating pressure should be 338 kPa 6 14 kPa (49 psi 6 2 psi). (6) Shut engine off. (7) Pressure should not fall below 24 psi for five minutes. (8) If pressure falls below 24 psi, it must determined if a fuel injector, the fuel pressure regulator or a fuel tube/line is leaking. (9) Again, start engine and bring to normal operating temperature. (10) Shut engine off. (11) Checking for fuel injector leakage: Clamp off the rubber hose portion of Adaptor Tool between the fuel rail and the test port "T" on Adapter Tool. If pressure now holds at or above 24 psi, a fuel injector or the fuel rail is leaking. (12) Checking for fuel pump module or fuel tube/line leakage: Clamp off the rubber hose portion of Adaptor Tool between the vehicle fuel line and test port "T" on Adapter Tool. If pressure now holds at or above 24 psi, a leak can be found at a fuel tube/ line. If no leaks are found at fuel tubes or lines, replace the fuel pump module. "DougW" <post.replies@invalid.address> wrote in message news:hGpah.43$DF6.28@newsfe24.lga... > dougguitar@yahoo.com wrote: >> DougW wrote: >>> It should hold pressure for over 4-5 hours. Given this and your >>> 45psi for fuel pressure I'm starting to think the regulator might be >>> shot. When you take the vac line off see if there is gas dribbling >>> out. >>> >>> -- >>> DougW >> >> OK, I timed it. After 4 minutes, the pressure had dropped from around >> 49 psi to about 35 psi. After 12 minutes, it had dropped to 20 psi. To >> add to my fun, the 96 GC does not have the fuel pressure regulator >> attached to the fuel rail: it's built into the fuel pump. @#$% >> There's just a direct connect fuel line going to the fuel rail. >> >> Will a regulator fail in this intermittent way? If that's the case, >> then I have to pony up the $300 plus for a new fuel pump. Sure wish I >> could be sure before I make the financial plunge. > > Hard to tell, the 96 made a lot of changes and my books are only good > up to the 95. 49 psi might be normal. Still though I thought pressure > was supposed to be maintained longer than that. I'd suggest calling a > dealership and asking if a mechanic could look that up for you. It's > worth a shot. > > I don't think it is your fuel pump. Pumps and pressure regulators > usually fail to the low pressure side and what you get is a lack of > power at wide-open-trottle or even pinging. > > -- > DougW > > > |
Re: 96 Grand Cherokee Stalling
billy ray wrote: > From the '96 FSM > > DIAGNOSIS AND TESTING > > FUEL PUMP PRESSURE TEST-4.0L ENGINE Wow, thanks. At least I now know that 49 psi fuel pressure is correct for my vehicle. I'll double check it, but I'm pretty sure the pressure stayed above 24 psi for at least five minutes after shutting off the engine. Doug B. |
Re: 96 Grand Cherokee Stalling
billy ray wrote: > From the '96 FSM > > DIAGNOSIS AND TESTING > > FUEL PUMP PRESSURE TEST-4.0L ENGINE Wow, thanks. At least I now know that 49 psi fuel pressure is correct for my vehicle. I'll double check it, but I'm pretty sure the pressure stayed above 24 psi for at least five minutes after shutting off the engine. Doug B. |
Re: 96 Grand Cherokee Stalling
billy ray wrote: > From the '96 FSM > > DIAGNOSIS AND TESTING > > FUEL PUMP PRESSURE TEST-4.0L ENGINE Wow, thanks. At least I now know that 49 psi fuel pressure is correct for my vehicle. I'll double check it, but I'm pretty sure the pressure stayed above 24 psi for at least five minutes after shutting off the engine. Doug B. |
Re: 96 Grand Cherokee Stalling
DougW wrote: > When I was having problems in my 93 I found out the napa part with harness was needed. This was the same coil Jeep installed to > solve an earlier idle problem. The harness has an internal resistor. > > The coil gets 12v from the ASD relay, make sure it's pins are clean. Actually you might swap that relay with the AC or Fog relay > just to make sure. > DougW Doug, What is the "harness" you're referring to with the coil? The wiring harness? I'll try swapping out the ASD relay with something harmless, too. Thanks again, Doug B. |
Re: 96 Grand Cherokee Stalling
DougW wrote: > When I was having problems in my 93 I found out the napa part with harness was needed. This was the same coil Jeep installed to > solve an earlier idle problem. The harness has an internal resistor. > > The coil gets 12v from the ASD relay, make sure it's pins are clean. Actually you might swap that relay with the AC or Fog relay > just to make sure. > DougW Doug, What is the "harness" you're referring to with the coil? The wiring harness? I'll try swapping out the ASD relay with something harmless, too. Thanks again, Doug B. |
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