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post #1 of (permalink) Old 06-10-2004, 01:53 AM Thread Starter
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Hard starting TJ

When my tj sits for 6+hours when I start it, it acts like it is not getting gas. Stop cranking and then hit it again and it starts. Wondering if anyone else has experienced this problem. It could not have come at a worse time. I want to say it is probably the fuel pump but I do not have a guage to test it.
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post #2 of (permalink) Old 06-10-2004, 11:26 PM
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Re: Hard starting TJ

My 4 banger does that too. Basically when I first crank the key it starts then dies if i don't feather the gas or i try to drive off. Usually after i start it the second time it stays running. I am not sure what causes it but it might be the way the computer controls the gas/air flow to the engine while cold. I would have thought it was a bad sensor but the dummy light doesn't come on and I know it works cause I had a bad O2 sensor a while back.
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post #3 of (permalink) Old 06-11-2004, 05:52 PM
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Re: Hard starting TJ

If that is an electric fuel pump try turning the key on (but not to start) and waiting a few seconds. If it then fires up quickly the fuel is returning to the tank and you have to wait for pressure to build up enough for the injection.

I have had several GM trucks like that but never bothered to fix them... or even try to figure it out... so now I turn the key to on and wait just out of habit.

Dale
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post #4 of (permalink) Old 06-11-2004, 10:09 PM Thread Starter
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Re: Hard starting TJ

Dale that actualy works, my issue is, if there is a small problem with it I want to go ahead and fix it so it does not leave me sitting somewhere. I just hate the thought of taking down the tank.
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post #5 of (permalink) Old 06-11-2004, 10:52 PM
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Re: Hard starting TJ

I understand but like I said.... I don't know.... put thousands of miles on those trucks.

Would have to think that it's a simple air leak into the fuel system. Fittings, hoses, lines and maybe even the filter.

But I trade out the work truck about the time it's worthless... over and over.

Someone else has been here....

Dale
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post #6 of (permalink) Old 06-12-2004, 04:40 AM
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Re: Hard starting TJ

[img]images/graemlins/tongue.gif[/img] Our 4.0 ZJ has done this for years. We just flip the key on and wait a few seconds, then crank up. [img]images/graemlins/crazy.gif[/img] You DO KNOW that most fuelies have a start sequence whereby the electric fuel pump runs for three seconds initially, and then drops out and waits to see if the engine actually starts before delivering more fuel.......you do know that, right? [img]images/graemlins/crazy.gif[/img] Fuel injected GM stuff is that way. [img]images/graemlins/tongue.gif[/img]
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post #7 of (permalink) Old 06-12-2004, 05:25 AM Thread Starter
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Re: Hard starting TJ

I understand what you are saying Dave, but for 7 years the thing started as soon as you hit the switch. That concerns me.
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post #8 of (permalink) Old 06-12-2004, 08:42 AM
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Re: Hard starting TJ

Check for a leak down. It is probably the residual pressure check valve in the pump. See related TSB

NO: 14-06-97
SUBJECT: Fuel Pump Diagnosis
DATE: Jul. 3, 1997
SYMPTOM/CONDITION:
Symptoms may include no start, rough idle, long crank times, driveway die outs or erratic fuel pressure. A new fuel pump has been released which delivers improved performance. This pump should be used whenever fuel pump failures are encountered.

DIAGNOSIS:
Basic fuel system diagnostics should be used as outlined in the appropriate service manual. A brief recap of the basic diagnostics follows:

Fuel pressure specification - 49 psi - plus or minus 5 psi.

High fuel pressure indicates problems with the fuel pressure regulator. Refer to the service manual for regulator diagnosis. Do not replace the fuel pump for high pressure.
Low fuel pressure - Low pressure could indicate a pump problem or it could indicate a plugged fuel filter or restricted fuel line or no fuel in the tank. Be sure to check these items before replacing the fuel pump.
Fuel System Leak down - When checking fuel pressure be sure to check the integrity of the system after shut down. With the fuel pressure gauge connected, shut the engine off and observe the pressure gauge. The system should maintain at least 24 psi for five minutes after shut down. If the pressure bleeds off quicker, it could indicate that an injector is leaking down or that the pressure regulator is leaking. This can lead to driveablitiy problems and require further diagnosis.
NOTE:IN RARE CASES WHERE MULTIPLE FUEL PUMP FAILURES HAVE OCCURRED ON THE SAME VEHICLE, A BUILD UP OF RESIDUE MAY HAVE ACCUMULATED ON THE INSIDE OF THE FUEL TANK. THE PRESENCE OF THIS RESIDUE IS NOT EASILY IDENTIFIABLE. THE RESIDUE CAN PASS THROUGH THE IN TANK FILTER AND CONTAMINATED THE PUMP ROTOR. IF MULTIPLE FAILURES HAVE OCCURRED WITH NO OBVIOUS INDICATION OF THE CAUSE, CONSIDERATION SHOULD BE MADE TO REPLACING THE FUEL TANK TO AVOID FUTURE PROBLEMS.

PARTS REQUIRED:
Quanity Part No. Description
1 04762964 Pump Module - 1994-1995 XJ
1 04798941 Pump Module - 1996 XJ
1 04883261 Pump Module - 1996 ZJ
1 04897754AB Pump Module - 1997 TJ - 15 gallon tank
1 04897755AB Pump Module - 1997 TJ - 19 gallon tank



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post #9 of (permalink) Old 06-13-2004, 10:40 PM
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Re: Hard starting TJ

</font><blockquote><font class="small">In reply to:</font><hr />
You DO KNOW that most fuelies have a start sequence whereby the electric fuel pump runs for three seconds initially, and then drops out and waits to see if the engine actually starts before delivering more fuel.......

[/ QUOTE ]

While I have not driven a "Cryslerfornicated jeep" with more than 100 miles on it (and not for more that a couple of miles), I have driven lots and lots and lots of miles in GM - Jimmy, Blazer, Pickup, Van... not to mention the wife's GTP, most of them I could hear the fuel pump as I turned on the key (noisey little suckers (pun intended)).

My point is simple and ends in a question. I have always assumed (yes that word) the fuel pump was running until some sensor shut it off because a particular pressure was reached in the fuel system (rail or TBI) at the delivery point.

Have I been a fool to ASSume that? It just turns off even if the fuel pressure is still low at "three seconds"?

D'oh I feel used (or just misinformed).

BTW: Jeff dropping the tank on a Jeep isn't really very hard. I think we used velcro on the Yellow Jeep last time. [img]images/graemlins/smirk.gif[/img] But it needs to come down again [img]images/graemlins/blush.gif[/img] there's a rock shaped dent in the tank skid plate (now how did that happen?).

Dale
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post #10 of (permalink) Old 06-18-2004, 12:52 AM
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Re: Hard starting TJ

My 97 does the same thing. The previous owner had the fuel pump replaced. It didn't help in this case.
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