engine won't start. i'm thinking fuel pump

my jeep died on me the other day and hasn't ran since. i can spray starter fluid in the tb and it'll run until the fuel is burnt, but as soon as i open the tb at all it dies. tried changing out the cps which didn't work, tried changing fuel pump relay out, tried by-passing the ballast, none of which did anything helpful.

i haven't been able to check the rail for pressure yet (hopefully tomorrow) but i know fuel is getting to it. i can prime it and press the schrader valve, but the gas doesn't shoot out, it just trickles. i also took the injectors out of the head while they were still hooked up and had a friend crank it, all injectors fired, but i'm not sure what that means.

wondering what all control fuel delivery and if anyone has any ideas on what i should be looking for. thanks in advance

First the formal A** chewing: always provide year/engine/trans/tc and any mods repairs done recently that could have an effect. Now, with the pleasantries over:

You shouldn't have fuel trickling out of the Schrader valve, it should have some force to it.

Hook up a pressure gauge and see what you are getting. 87-95 30/39 psi; 96+ 49 psi.

joe_peters said:

First the formal A** chewing: always provide year/engine/trans/tc and any mods repairs done recently that could have an effect. Now, with the pleasantries over:

You shouldn't have fuel trickling out of the Schrader valve, it should have some force to it.

Hook up a pressure gauge and see what you are getting. 87-95 30/39 psi; 96+ 49 psi.

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yeah, i apologize. it's a '92 with no mods. did go through a huge puddle shortly before it crapped out though...

try the resistor on the driver side inner fender. it is white with two wires plugged in at each end. mine had the same problem. after swapping in a known good fuel pump still did the same thing as you describe. got out the FSM and traced wires. the resistor was cracked and corroded. hope this helps.

The ballast resistor can just be jumped around. You say the injectors fired....does that mean that they sprayed gas, or that they clicked and did not spray gas?

Could also be the fuel pressure regulator. I have gone through a few of those things.

winterbeater said:

The ballast resistor can just be jumped around. You say the injectors fired....does that mean that they sprayed gas, or that they clicked and did not spray gas?

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i already tried the ballast resistor, the injectors sprayed gas

I'm thinking one of the othernasty c-sensors...

Crank Position Sensor (On the bell-housing of the tranny)
Cam Position Sensor (In the distributor cap)
Throttle Position Sensor (Yeah, I know there's no C in it, but I suck at math.)

Have you tried checking computer codes?

If it runs with starter fluid in it, It's got to be fuel pressure; but if there's any fuel coming out, then it'd probably run, just run badly. (Or almost start.)

XJPhoenix said:

I'm thinking one of the othernasty c-sensors...

Crank Position Sensor (On the bell-housing of the tranny)
Cam Position Sensor (In the distributor cap)
Throttle Position Sensor (Yeah, I know there's no C in it, but I suck at math.)

Have you tried checking computer codes?

If it runs with starter fluid in it, It's got to be fuel pressure; but if there's any fuel coming out, then it'd probably run, just run badly. (Or almost start.)

Click to expand...

i've already changed the cps and tried swapping the tps and ias from another engine. it will start occasionally, but dies immediately.

checked fuel pressure and it barely even reads 5psi. haynes manual says if it's lower than 20psi to change fuel pump... is there anything else (electronic) that could cause low pressure?

As stated above you MUST have 30 psi w/vacuum attached, 39 psi w/o vacuum attached.

rc_mx5 said:

checked fuel pressure and it barely even reads 5psi. haynes manual says if it's lower than 20psi to change fuel pump... is there anything else (electronic) that could cause low pressure?

Click to expand...

A pinched hose on the ID, or bent or crushed fuel line (tube) would do it, plugged fuel filter. Low voltage to the pump, bad relay, bad connectors.

Had same thing happen to my 90 just last month, thought it was fuel pump too, decided to try new fuel filter, been running fine ever since.