MPI Fuel System Problems? - JeepForum.com

 
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post #1 of 6 Old 07-30-2005, 06:56 PM Thread Starter
Yoink
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MPI Fuel System Problems?

I'm looking for a little advice before I purchase a new fuel pump.

Symptoms:
Currently the Jeep won't start. Before it stopped starting it was acting like it was running out of fuel despite a full fuel tank, just filled it up yesterday. Last week it did a very similar thing cranks, tries to start and then sputters and dies. I replaced the fuel filter. THe problem disppeared until today. When it runs, if you push the gas the tries to die and smells real bad. The exhaust pops and the engine generally runs like ***. Before it got to the point where it died, it was drivable if you slowly pushed on the gas, if you tried to give it any more throttle though it would bog down and act like it was running out of gas. This is an I6 Fuel Injected. I've replaced the fuel filter, spark plugs, checked the distributor cap (it was a little dirty so I cleaned it. I've also cleaned the air filter. I think it sounds like a bad fuel pump or mebbe I've got some junk in my gas tank that's clogging my filter again.

Question:
Am I on the right track? Should I buy a new fuel pump? Should I be looking at other things? Aside from taking it to a mechanic what are some tests I can do to narrow down the actual problem.

Thanks for the future use of your brains.


'95 YJ SE - I6 4.0L, 2" BDS, 1" Shackle Lift, 2.5" BL, 31X10.50 A/T's, Herculined (Work In Progress)

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post #2 of 6 Old 07-30-2005, 09:07 PM
sentinal02
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Quote:
Originally Posted by Yoink
what are some tests I can do to narrow down the actual problem.

Thanks for the future use of your brains.
check your fuel pressure. if it's jumping around it's probably the pump. does sound like it could be the pump though. you might try some injector cleaner as well

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post #3 of 6 Old 07-30-2005, 11:17 PM
kg6mti
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I second the check of the fuel pressure. Check your fuel lines also the system needs to hold pressure. You mentioned that it smells real bad. Does it smell like fuel?

Experience is what you get when you get what you didnít want.
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post #4 of 6 Old 07-31-2005, 04:03 PM Thread Starter
Yoink
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Continued

Okay, so today I bought a fuel pressure tester from Autozone. I plugged it in and ran the test in the FSM. I'm getting about 39 PSI no matter what. FSM says that with the vacuum hose plugged into the fuel pressure regulator I should get about 31 PSI, I get 39. With the Hose UNPLUGGED it's supposed to be 39, I get 39. So this indicates to me that there is something wiggy with the fuel pressure regulator but everything in the book says that if the regulator is bum the pressure should stay at 31... not stay at 39. WTF? We also through there were some ignition problems so we switched out the ignition coil after some tests that determined that it was an issue. Directly after the coil was replaced the motor cranked right up and ran nice and smooth for a good 10 minutes and then started into the same crap. If it's the fule pump shouldn't that mean my pressure should be super low, not more or less normal? Advice? Help? Please.

'95 YJ SE - I6 4.0L, 2" BDS, 1" Shackle Lift, 2.5" BL, 31X10.50 A/T's, Herculined (Work In Progress)

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post #5 of 6 Old 08-05-2005, 12:22 AM Thread Starter
Yoink
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Oddly Enough

This ended up being a spark issue. Turns out the coil inside the distributor was dying. Just thought I'd post some closure in case anyone else comes across this problem in the future. Thanks for the suggestions guys.

'95 YJ SE - I6 4.0L, 2" BDS, 1" Shackle Lift, 2.5" BL, 31X10.50 A/T's, Herculined (Work In Progress)

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post #6 of 6 Old 08-05-2005, 04:54 AM
kimvansa
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Quote:
Originally Posted by Yoink
This ended up being a spark issue. Turns out the coil inside the distributor was dying. Just thought I'd post some closure in case anyone else comes across this problem in the future. Thanks for the suggestions guys.
So what did you replace, the coil or the distributor or did you mean condenser?
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