fuel problem?

[hi_c]

1059746

Ok, had trouble starting the Jeep this morning. I believe that the fuel system is not maintaining pressure when the Jeep is turned off. The engine would turn and turn but not start. Finally, I barely ignited and with a stomp of the pedal, it rolled over. The fuel works fine when driving, not a single problem there. So after I got here to work, I cut it off and then started it up again. It started on the first try. But maybe that's because it still had some good fumes and left over fuel in the cylinders.

Does this sound like the fuel pump or sending unit? If so, is it possible that it works fine when the motor is running, but not before? I have an 89 YJ. Anyone had this problem before? I believe the pump and sending unit are in the tank, so it would require a drop to replace it, and I just filled the tank last night! Thanks for any help.

:-? :-? [addsig]

 

[jps4jeep]

1059749

Not sure were you are hailing from, But up here in the northeast, we have had months of below 0 temps and in real cold weather fuel can do some wierd sh*t. Try putting some fuel stabilizer and some dry gas in. I had a problem couple of years back when I bought my first jeep. It was doing the same thing and mine is a Fuel Injected 94. Turns out it had sat on the lot so long that moisture had built up in the tank and froze.
How it helps.[addsig]

 

[Bounty__Hunter]

1059752

Which engine do you have?

I think the carb'd 4.2L has the mechanical fuel pump on the engine block, and the TBI 2.5L should have an electric pump, probably in the tank.[addsig]

 

[hi_c]

1059753

It's the fuel injected 2.5L. It's the TBI, and yes, the pump is in the tank. Is the pump the same thing as a sending unit? I'm here in Charleston, South Carolina. Weather didn't get below 20 this winter and the Jeep is garage kept. Haven't had a problem until just this morning. It's been running great. <knock on wood>. It still runs great, once started, but it's the starting that's troubling me.

c
[addsig]

 

[jps4jeep]

1059760

still could be moisture in the tank. The only thing with a fuel pump is, in my experiences, they either work or don't work. I have not personally come across a pump that was sometimes working. Check the fuel filter as well. Might have a clog. And this may be a strech but check you plugs! A bad plug can make starting a chore, but you said it ran OK so maybe not, wouldn't hurt though[addsig]

 

[dingus]

1059762

my jeep did that in its early stages of the CPS (crankshaft position sensor) dying on me. it would sometimes take a few MINUTES of cranking to get it to start up. keep an eye on that, and be careful not to get yourself stranded.[addsig]

 

[west747]

1059767

i had the same problem with my inline 258....all it took to fix those long starts was a 5 dollar fuel filter....[addsig]

 

[Bounty__Hunter]

1059769

Replace the fuel filter, along the driver's side frame rail.

Yes, the pump and sending unit are one piece.[addsig]

 

[idrthrbfishing]

1059838

sound like a fuel filter I dont think any fuel is kept pressurized when the engine is off, also check you egr lines to ensure they are not cracked as this can also cause "strange things" to happen but usually when running or on real hot days in the sun. As for your pump its good or bad not inbetween unless its a loose wire. then your pump would be good and power for it would be erratic at all times while driving. [addsig]

 

[Tug-n-pull]

1059876

When I seen the name of the post I figured it was the price of gas that had you all up in the air! hehehe Tug[addsig]

 

[bluebelle]

1059890

hi c - have you resolved this starting problem yet? My 4l had a starting and stalling problem. There are several problems that may occur with injection systems but most are easily diagnosed.

Does your engine ever just stall for no apparent reason?
Does your engine chug (like you're switching the ignition key off then back on real fast)?
How many miles on the motor and how many miles/time on the filters?

By the way, the sending unit is the source of the fuel gauge signal and wouldn't be a part of what you describe in your problem.

Fuel injection systems have residual pressure when the engine is off. There is a check valve built into the fuel pump that keeps around 35 psi in the lines to ease starting. If your system doesn't stay pressurized restarting would be tough.

Here’s a quick check, when you turn on your key to the on position, but not to the start position (don't engage your starter) does your pump run for a few seconds then stop?

If you can hear it (you may need to have someone get their ear by the tank as you do this) and it cycles each time you turn the key on/off then there's a possibility that that check valve may be allowing fuel back into the tank and therefore not keeping the system pressurized.

If your pump only runs once or twice when you cycle the key, your check valve is probably operating.

There’s a series of fuel pressure checks that you can do to really find out what you're pump is doing before you go through the trouble of pulling the tank and spending around $400 for the pump/sending unit.

Let me know if this helps.
[addsig]

 

[GreenReaper93]

1059993

I'm sorry to kinda break the train of thought, but does anyone know if the sending unit and the fuel pump for a 93 YJ are in one piece? :-? [addsig]

 

[mujaman]

1059998

i have a 97 cherokee and had the same problem a few months ago. once it was started... it was fine, but i'd have to crank it forever to get it to start. all it took to fix it was a fuel filter. unfortunately on the cherokee you have to drop the tank to get to it... so hopefully the TJ isn't the same. [addsig]

 

[joeycj5]

1060004

Possible fuel filter, but an electric fuel pump has a check-valve in it so the fuel does not run back into the tank. These go bad, and cause hard starting, its main cause of fuel pump replacement. Next to complete pump failure.

edited by: joeycj5, Mar 16, 2003 - 02:19 PM[addsig]

 

[jeepster]

1060097

maybe you just need to run some injection cleaner thru the system. the injector tips might be clogged up and when you are under acceleration you have more pressure to force the fuel thru . not a bad idea to change the fuel filter ifn its been a while.[addsig]

 

[Snitty]

1060133

its strange that this topic came up... I spent an hour under the jeep today replacing the fuel filter because it wouldn't start.... after I replaced it... vroom vroom[addsig]

 

[hi_c]

1060183

Sorry for the delay. I spoke with a service manager at the Dealership who is a member of my jeep club. He said that there is an O-ring between the tank and the fuel pump that breaks, quite often. The gas in the tank should stay pressurized so that the fuel gets to the cylinder before cranking. Well, when the O-ring is busted, it loses it's pressure. He said to turn the key almost all the way but don't crank. You should hear the pump pressurize. Do this several times, kind of like priming the bulb on your lawn mower. This works for me everytime. He said they replace this O-ring on Jeeps at least 5 times a week. So when the tank gets almost empty, i'm going to replace it.

;-) [addsig]