trouble starting

so i got a 90 xj given to me because it didint run at first thaught it was bad spark because it was really weak so i changed the cps and now its got a strong spark but still not starting and now where the fuel line joins into the fuel rail threw the fuel regulater i belive is what it is it pukes fuel out now could that be the problem not enuf fuel pressure to start?

Sounds like the O rings are bad in the fuel line coupler. Get a new coupler from the dealer.

Is the leaky connection at the front or at the rear of the fuel rail?

the front its where the hard line connets to i belive what is the fuel regulator and it has like a plastic connecter in it? no o rings

What do you mean "pukes fuel out"? Is it an actual fuel leak or do you mean that when you presss in on the fuel schrader valve, the fuel pressure is low?

Yes, you need to attain a certain fuel pressure for the engine to start.

Place a fuel pressure gauge on the schrader valve (looks like a tire inflation valve) on the fuel rail to verify. I believe you're looking for around 31 psi with your XJ.

A quick and dirty test is to spray a bit of starting fluid into the throttle body. If the engine starts and runs momentarily, you have confirmed that you have a fuel delivery problem.

For spark, you are looking for a strong, blue, snapping spark. Orange or yellow spark = weak spark which may not be strong enough to start the engine. Testing of coil and ignition control module are also in play here.

If you have verified strong spark and good fuel pressure, test the compression on all cylinders with a good quality screw in compression gauge. Fuel + spark + compression = spark. Compression is often overlooked and should be checked, especially on an older vehicle with unknown history. For the Jeep 4.0 you're looking for 120-150 psi in each cylinder with no more than a 30 psi variation between cylinders.

Check compression and spark plugs first. Well, I mean after you fix the fuel leak.

did a test today dont kno if it was my tester or not but it read 75 lbs then i change the hose on the tester and went to 90 so im kinda stumped

forgot to add what had happend was the guy who gave it to me had it running one night shut it off and the next day wouldnt start so????

You might want to try another fuel pressure gauge to confirm as your numbers are extremely high.

If the pressure truly exceeds 45 psi, check the fuel return line for kinks or obstructions.

Renix through 1995 OBDI XJs fuel pressure:

31 psi with vacuum applied to the pressure regulator; 39 psi with no vacuum applied to the pressure regulator.

If you pinch off the fuel return line on the Renix-1995 XJs the fuel pressure will shoot as high as 95 psi--if you pinch off the return line ONLY DO SO FOR A QUICK TEST--you can damage the system and cause injury to yourself.

DEFAULT condition of a failed pressure regulator is TOO HIGH PRESSURE.

If the fuel return line is not damaged then the pressure regulator needs to be replaced.

Yah you should see around 35psi normally. Yes there are O-rings in the pressure regulator connection (the seal replacement kit Richard is talking about is part # 83502745 which is still available and it includes the 2 O-rings, spacer, and the installer). The connection can leak if not aligned right or seals damaged.

gonna try another tester when i have the chance also did a compression test and all cylinders read 50 psi :s now my dads thought to that was maybe it jumped a tooth and the cam is outta wack so the valves are slightly open during the compression cycle could that be a possibility if so how do i go about fixing it take apart the front end and re do the timeing? any other possibilities please feel free to comment would gladly like to hear and try everything befor i do a engine swap

CromeY90 said:

gonna try another tester when i have the chance also did a compression test and all cylinders read 50 psi :s now my dads thought to that was maybe it jumped a tooth and the cam is outta wack so the valves are slightly open during the compression cycle could that be a possibility if so how do i go about fixing it take apart the front end and re do the timeing? any other possibilities please feel free to comment would gladly like to hear and try everything befor i do a engine swap

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Re-index the distributor first before you go pulling the engine apart.

the distributor can lower compression?

If the distributor is firing the sparkplug at the wrong time it won't start.

If the timing chain has jumped then the compression will be off as the valves may not be fully seated on the compression stroke.

So, no the distributor won't effect compression, I was thinking of the no start issue. Why you would have 50 psi across the board makes me think you have a gauge problem, as the engine wouldn't have been running at all much below 110 psi, so it would be weird to have all at 50 at the same time. A blown headgasket doesn't let go straight across the board, the rings don't all wear the same amount at the same time.

CromeY90 said:

gonna try another tester when i have the chance also did a compression test and all cylinders read 50 psi :s now my dads thought to that was maybe it jumped a tooth and the cam is outta wack so the valves are slightly open during the compression cycle could that be a possibility if so how do i go about fixing it take apart the front end and re do the timeing? any other possibilities please feel free to comment would gladly like to hear and try everything befor i do a engine swap

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I think you are going way out there. Not likely the timing chain moved even if it sucked water in.

I've seen it suggested here that if the cylinder walls have been washed because of too much fuel it can lead to low compression/leakdown and to put a little oil (not much) in the spark plug hole.

i thaught it was the guage as well and tested it on my other jeep wich got 125 psi so i am going to use a diffrent guage just to make sure but i am stumped here

CromeY90 said:

i thaught it was the guage as well and tested it on my other jeep wich got 125 psi so i am going to use a diffrent guage just to make sure but i am stumped here

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What "other" Jeep--is the "other" Jeep supposed to have 125 psi fuel pressure? Sounds like you need a different gauge.

joe_peters said:

What "other" Jeep--is the "other" Jeep supposed to have 125 psi fuel pressure? Sounds like you need a different gauge.

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I think he change subject. Compression.

yes srry it was 125 compression

and yea srry im bouncing around fuel psi and compression psi im just trying to figure any possible solution other then a engine swap