It cranks fine ,wont stay running

[Patman1901]

Hi, Just bought my first Jeep, 2003 liberty limited. its just getting to 140,000. It ran fine for 2 weeks then as im driving it just dies,like the key is turned off. so the first time i kept trying to get it started again and it acted like it was out of gas...even though it was 1/2 full,the guage does work.After about 30 minutes it started and i got backon the road, it drove fine for a couple miles then died again,Its an automatic so i coasted to a stop and same thing,this time it didnt seemtowant to idle but if i kept therpm's up ( 2,500+)it would stay running enough to get into drive and run down the road for another couple mile,.All the way home..
So i figured fuel pump...So i got a new one from autozone,the cheaper one,not delphi, cuz im cheap..
Anyways it was identical to the original and went in just fine,. the fuel line connectors fought me to release from the pvc fittings on the top of the tank,but i won,now i also had replaced the fuel filter assembly before this because i heard that might be the problem and i figured at 140,000 it was due,. i got that through amazon.it too was exactly the same as the first one,
so after all that it still is doing the same thing,
Ive checked the pressure at the fuel rail test port on the passanger side,by the way it the v6 4.3l, and i dont get gas of any real pressure,and that was true before i replace the pump/filter and still now
ive double checked the quick connectors at the fuel rail in and the two coming out of the top of the pump assembly,when i turn on the ignition the isnt 12 vdc at the electrical connector above the tank but when i turn the engine over its getting 12 vdc ,ive even unhooked the quick connectors at the tank end and fuel rail input then turn it over for a sec and im getting gas coming out so so the pump is moving gas but its like not strong enough
the engine is back to cranking over then almost starting to starting then only running at high rpm but wont stay running on its own.Ive had a shop check it out and paid $140.00 for him to tell me what i already knew!So its been sitting for over a month now and im really frustrated

can i put an electric fuel pump on in line? and also what about cutting out the quick connectors and sw?itching to hose clamps

 

[DadOSix]

Couple ideas:

Check the grounds in the back near the fp wiring.

Do you hear the pump pressurize when you turn the key to run (not start). Should be able to hear it priming thevsystem.

Borrow / rent a fp gauge and getva real reading. We are dealing with fuel injection here, so the pressure must be spot on.

You see 12v at the pump - is it enough to run the pump? If using a digital meter, don't. Add a load like a brake light or headlight.

Could be many things. Let's eliminate and go with what we can test.

 

[lfhoward]

I would suspect the idle air controller (IAC), located near the throttle body. If it is gummed up with carbon it might not open enough to let air in at idle, and so the jeep just dies. Had this happen to my XJ many years back. It would stay running as long as my foot held the throttle open, but die at idle. Cleaned the IAC with a soft toothbrush and throttle body cleaner and the problem went away.

 

[daves06lrenegade]

Low fuel pressure may be caused by a vacuum being created in the gas tank... Remember drinking pop out of a bottle? When you pull out so much you have to let air back into the bottle before being able to pull more pop out... Emission controls keep the gas fumes captured by not allowing the tank to vent and there are solenoids that can stick open or closed... You may have problems with the engine drawing gas UNTIL there is so much vacuum in the tank it can't draw anymore... Try removing the gas cap and starting the car... The tank will not be able to create a vacuum... If it runs OK you need to address an emissions problem like a plugged carbon canister, purge valve, vent valve...
Keep us posted on what you try and found...
Dave

 

[Patman1901]

Thank You- thats some good advice.

 

[Patman1901]

I would suspect the idle air controller (IAC), located near the throttle body. If it is gummed up with carbon it might not open enough to let air in at idle, and so the jeep just dies. Had this happen to my XJ many years back. It would stay running as long as my foot held the throttle open, but die at idle. Cleaned the IAC with a soft toothbrush and throttle body cleaner and the problem went away.

Great Idea- Ill do that ,thanks so much

 

[Patman1901]

Low fuel pressure may be caused by a vacuum being created in the gas tank... Remember drinking pop out of a bottle? When you pull out so much you have to let air back into the bottle before being able to pull more pop out... Emission controls keep the gas fumes captured by not allowing the tank to vent and there are solenoids that can stick open or closed... You may have problems with the engine drawing gas UNTIL there is so much vacuum in the tank it can't draw anymore... Try removing the gas cap and starting the car... The tank will not be able to create a vacuum... If it runs OK you need to address an emissions problem like a plugged carbon canister, purge valve, vent valve...
Keep us posted on what you try and found...
Dave

i tried the gas cap trick,i was thinking along those line also-thank you ..ive noticed the air tube going onto the tank at the top of the pump assembly.what is the round bodied mechanism that that goes to ,it says "filter" on it but its not showing up on any filter i can see ,it sits next to the filter i reolaced that shows fuel filter.
i even disconnected it at the top where it enters the tank/pump opening,is it a vacuum breaker
or breather?
Youve been very helpful,thank you

 

[Patman1901]

I would suspect the idle air controller (IAC), located near the throttle body. If it is gummed up with carbon it might not open enough to let air in at idle, and so the jeep just dies. Had this happen to my XJ many years back. It would stay running as long as my foot held the throttle open, but die at idle. Cleaned the IAC with a soft toothbrush and throttle body cleaner and the problem went away.

Thanks for your help,thats something i didn't try ,or know..

 

[Yetiboy01]

If it starts & runs ok when it is cold then dies when hot it could be a faulty crank sensor, a common problem easily fixed

 

[Patman1901]

it starts butdoesn't stay running for more than a few seconds, ive actually hooked the pump up to a spare battery so i can hear the motor in the pump run, im not getting juice to the pump with the key on to the acc spot,,yet if i pull the line off to the fuel rail and bump he key to start it will push some gas out

 

[Patman1901]

If it starts & runs ok when it is cold then dies when hot it could be a faulty crank sensor, a common problem easily fixed

thanks,i bought the service manual,finally, and its great because it list the actions by the pcm and the sensors, it list the crank-shaft sensor as one of the first things to check,im putting it in now..i'll find out soon,since i've replaced all the sensors now the only thing leaft is the pcm itself i guess.
good news is i can buy one on-line pre-programmed to the VIN for a good price. so im learning thanks to you and the other jeep owners,

 

[Maxdestruction04]

Turn your key on and off 3 times quickly and then 3rd time leave it in on but not start and it will show your codes in odometer. If you see P0340 or P1391 its most likely cam or crank sensor.

 

[DadOSix]

thanks,i bought the service manual,finally, and its great because it list the actions by the pcm and the sensors, it list the crank-shaft sensor as one of the first things to check,im putting it in now..i'll find out soon,since i've replaced all the sensors now the only thing leaft is the pcm itself i guess.
good news is i can buy one on-line pre-programmed to the VIN for a good price. so im learning thanks to you and the other jeep owners,

You know, i recall upthread that you went cheap on the fuel pump. Did you get a loaner gauge and check pressure at the rail? Still could be marginal pump. Pressures key off, key on, engine cold, engine hot. Might go a long way to solving this. I know a new pump 'should' be good, but the quality control on some of the parts these days leaves much to be desired.

 

[69BahamaYellow]

Having just gone through this starts but dies problem on my 2002, My problem turned out to be a faulty MAP sensor. I initially ruled it out because it was brand new, along with all other sensors, the MAP sensor was China made from Amazon and after checking everything else, like it sounds like you did, I replaced the MAP with a USA made one from Autozone, and it has run great ever since. I don’t ever buy China made anything unless it’s a last resort, and this is why. Had an overheating problem recently also and replaced the thermostat with a China made one in a pinch. Solved my overheating problem, but added a P1281 engine warm up too long check engine code. Replaced thermostat with USA made one and code went away.

 

[Patman1901]

Having just gone through this starts but dies problem on my 2002, My problem turned out to be a faulty MAP sensor. I initially ruled it out because it was brand new, along with all other sensors, the MAP sensor was China made from Amazon and after checking everything else, like it sounds like you did, I replaced the MAP with a USA made one from Autozone, and it has run great ever since. I don’t ever buy China made anything unless it’s a last resort, and this is why. Had an overheating problem recently also and replaced the thermostat with a China made one in a pinch. Solved my overheating problem, but added a P1281 engine warm up too long check engine code. Replaced thermostat with USA made one and code went away.

thank you! i ordered a new PCM for ir after it did the coils and plugs,and realized i didnt change that yet because everything shows the air temp
but not the MAP,,, whats the part number? do you have it?

 

[Patman1901]

You know, i recall upthread that you went cheap on the fuel pump. Did you get a loaner gauge and check pressure at the rail? Still could be marginal pump. Pressures key off, key on, engine cold, engine hot. Might go a long way to solving this. I know a new pump 'should' be good, but the quality control on some of the parts these days leaves much to be desired.

i want to say thanks, i replaced everything but the PCM, allmost.
i ordered a new PCM thats programmed and it was alot less than
ive already put in

 

[Ksat]

I wouldn't replace the PCM just yet. You should only get power for several seconds at the pump when key is turned to the "on" position.

I would try disconnecting the connector at the pump and directly wiring in another battery to power it continuously, then check fuel pressure at the rail. If it reads OK, try and start the engine. If pressure doesn't read OK, you may have a restriction in the lines somewhere, a vacuum created by a venting issue (as mentioned), a faulty pump, fuel pressure regulator problem, something clogging the pickup line or possibly wiring problem.

 

[DadOSix]

I wouldn't replace the PCM just yet. You should only get power for several seconds at the pump when key is turned to the "on" position.

I would try disconnecting the connector at the pump and directly wiring in another battery to power it continuously, then check fuel pressure at the rail. If it reads OK, try and start the engine. If pressure doesn't read OK, you may have a restriction in the lines somewhere, a vacuum created by a venting issue (as mentioned), a faulty pump, fuel pressure regulator problem, something clogging the pickup line or possibly wiring problem.

OP states a new 'cheaper' fuel pump was already installed. No update as far as getting actual fuel pressures that I recall.

 

[69BahamaYellow]

Duralast MAP Sensor SU3239. This one is made in USA. OEM one isn’t available at my dealership​

 

[Patman1901]

I wouldn't replace the PCM just yet. You should only get power for several seconds at the pump when key is turned to the "on" position.

I would try disconnecting the connector at the pump and directly wiring in another battery to power it continuously, then check fuel pressure at the rail. If it reads OK, try and start the engine. If pressure doesn't read OK, you may have a restriction in the lines somewhere, a vacuum created by a venting issue (as mentioned), a faulty pump, fuel pressure regulator problem, something clogging the pickup line or possibly wiring problem.

iv'e tried that, the pump runs and the gas pressure was 49 +-2 psi
waiting on a pcm.thank you