Starts then dies...Vacuum Line Hell

Morning. Having trouble keeping my Jeep running.
1990 Cherokee 4.0 Auto
I can start it, but then it high idles then dies. If I gas it it dies immediately.

It cranks for a longer than normal time (while fuel pressure tester on it, the pressure slowly builds up), then finally fires, high idles then falls flat on its face. The fuel pressure plateaus at 15 PSI if I have the vacuum assist on or not. But as noted before, the fuel pressure builds, peaks and drops. I can keep it running with ether ( I know its bad to do but I wanted to make sure it was not another problem). Also if you can see from the pictures that the vacuum lines are a NIGHTMARE!!!! I got this Jeep from a kid that used it as a mud runner so most of everything non-essential was removed (including vacuum lines), which could be causing or adding to the problem. From what I have read so far that the starting then dying may be a vacuum problem. The fuel pressure tester booklet and my Haynes manual were less than helpful on how to hook the unit up so here are the pictures of how I did it. Let me know if I left something out. Thanks in advance!

http://s1232.photobucket.com/albums/ff363/imwoodhouse/

Your fuel pressure is too low. You're looking for about 35 running at idle and 39 when you pull the hose off the fuel pressure regulator.

Probably stupid to ask but that would be replace fuel pump then?

imwoodhouse said:

Probably stupid to ask but that would be replace fuel pump then?

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Probably...........

imwoodhouse said:

Probably stupid to ask but that would be replace fuel pump then?

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cruiser54 said:

Probably...........

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Other possibles: crap in tank; hose in tank between pump and tank flange is cracked/split/loose clamps; clogged fuel filter; damaged fuel line; bad FPR.

Wearing safety glasses you can squeeze the FPR return hose and see what the pressure does--DO NOT DO THIS FOR MORE THAN A SECOND OR TWO--pressure can exceed 95 psi with a correctly operating pump.

I would start at the tank. Pull the pump assembly, inspect the condition of the fuel tank, the pickup sock, the rubber lines from the top of the pump to the mounting flange.

Clean up any mess/problems. If you need to replace the fuel pump--recommend Bosch 69302--and the fuel filter.

You should use a new mounting flange gasket.

Sounds like a plan.....Thanks!

I would check the fuel pressure regulator (FPR) before I messed with the gas tank and fuel pump. Pull the vacuum line off the FPR and see if you smell gasoline leaking while cranking. Then check the fuel line rubber for age, fuel filter next, and check the ballast resistor!!!!!!!

Ecomike said:

and check the ballast resistor!!!!!!!

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Forgive my ignorance, but what is that, what does it look like and how would one check it?

imwoodhouse said:

Forgive my ignorance, but what is that, what does it look like and how would one check it?

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White ceramic part with two one wire connectors, under the hood, front drivers side, on the side in front of and next too the EGR solenoid, and a lone relay. It drops the run voltage to the fuel pump. The ECU bypasses it while cranking to get more voltage to the fuel pump.

What is the static fuel pressure with ignition switch on but not starting? FP should run about 5 seconds when you switch from off to run only, do not start. Should reach and hold 29 psi IIRC.

Ecomike said:

What is the static fuel pressure with ignition switch on but not starting? FP should run about 5 seconds when you switch from off to run only, do not start. Should reach and hold 29 psi IIRC.

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Maybe 5 PSI ....it never got anywhere close to the 29 PSI it needs

Then check the voltage to the fuel pump at the fuel pump, check the fuel hoses, fuel filter, and carefully run the "brief" return line hose squeeze test Joe described in detail below to try and find the weak link(s). Does not sound like the B resistor. My 87 and 89 both died on no fuel once, different years in the last 3 years, and turned out to be old dirty quick connect pins and a dirty ground at the fuel pump / gas tank!

Ecomike said:

Then check the voltage to the fuel pump at the fuel pump, check the fuel hoses, fuel filter, and carefully run the "brief" return line hose squeeze test Joe described in detail below to try and find the weak link(s). Does not sound like the B resistor. My 87 and 89 both died on no fuel once, different years in the last 3 years, and turned out to be old dirty quick connect pins and a dirty ground at the fuel pump / gas tank!

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I like the sound of that better than the $100 fuel pump.... :spin1:

Yes I am cheap!

As Mike suggests: RCBRC. Refresh Connections Before Replacing Components.

Hey everybody dvlfsh9 here, new to . Recently purchased an 89 and had the same problem about 1/4 mile from the purchase point. I was wondering if woodhouse had any success repairing his problem and where he found his success. Any advice would be great. Thanks

sounds like a ballast resistor problem. the connections on my 90 are increadably loose for something that never gets unplugged

90xj06 said:

sounds like a ballast resistor problem. the connections on my 90 are increadably loose for something that never gets unplugged

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If you suspect the ballast resistor, bypass it. Just connect the two wires together. Only thing is your fuel pump may be noisier.