tmeff429

Heres what I got. Driving and the motor just dies. Try to start it the motor turns over, but wont start. The fuel pump isn't priming. I bought a new fuel pump relay and a new pump the new pump isn't priming either. I pulled the fuse to make sure it wasn't blown, and it's not. I lifted the float on the sending unit gas hand moves. What should I check next? Sometimes it will act like it's gonna start, but wont. It's got a V8 AND 4X4 if that helps. Any help would be great. Thanks

ol"blue

You need 3 things to run: fuel, spark, and air. We know you're getting air. You can check for spark, and then chase down fuel issues.
But I'd remove the air horn to TB elbow and pour a little gas, or starting fluid into the TB and see if it fires. If it fires up you know it's fuel related, so look for the problem in a fuel pump fuse, relay, ground, clogged filter, or a problem with the pump/pick-up. JMO
And Welcome to CF!
Dan

tmeff429

I'll give it a shot. I'm assumin that the TB is the throttle body right.

ol"blue

That's correct.
Dan

tmeff429

OK I replaced the fuel filter, the fuel pump relay, and checked the fuse. All checked good. I pulled the fuel line from the outlet of the fuel filter gas squirted every where. So I have gas that far. I pulled the plug, got spark. I squirted starter fluid in the TB still not starting.

What should I try now?

tmeff429

Anybody got any ideas? What would keep it from starting?

rivercrazy

Do you hear the pump come on when you turn the key without turning the motor?

Have you tested your fuel pressure at the rail? You can rent a tester from Autozone.

Are you sure you have spark? How did you test that?

trucker

Actually there is 4 "things" you need to start: fuel, air, spark and compression.
The timing my be off. If you have compression gauge then check all cylinders. It should not have less that 100 lbs and no more that 20lbs difference. If the spark plugs are black then you have too much fuel going in. Check the oil cap for signs of oil - blown head gasket. Milky oil. There is more that just fuel,air and spark to have engine running and you have those three basics.
Time to "dig in". Mark the 1st cylinder plug and have firing order ready. Pull plugs and spin engine. With some carton at cylinder hole look for signs of water or oil. Then check compression. Did you overheat the engine?. The electrical gauges are not correct and when the temp shows high or engine lights come on most of the time it is too late. I have manual gauges added.

Willys55

There is one thing you can try. Don't laugh because this was an issue for 93-95 GC. The rear tailgate latch completes the circuit for the vehicle security system and when it fails it sometimes causes the seurity system to arm, when it arms with the driver door unlocked you end up having no injector pulse and a weak spark at the coil because the ignition circuit has a voltage drop while cranking. (about 6 volts) Check to see if you have a good blue spark from the distributor cap to the plugs and using a test light you can see if you have injector pulse while cranking. If not try locking and unlocking the car from the drivers side using the key not the transponder

jeepfan93

Interesting, how to check that rear latch circuit is good?

trucker

If the dome lights go out then the latch is closed. My will start with the back door open. You have fuel, spark and air. Check if the firing order is correct. Distributor my be loose and out of time. Does the engine spin very fast?

tmeff429

yeah the engine spins good. the spark does look weak though.if the security relay is bad would it cause similar problems.

tmeff429

Can you by-pass the tailgate circiut for the security system? If so how? Also the fuel pump is priming, but it is not as loud as it used to be. You can barely hear it priming.

trucker

The reason I asked about engine spinning fast is that you my not have compression. I would check the compression.

tmeff429

Engine is turning over fast. It just wont start up. The battery is starting to drain. I'm gonna charge it back up, but other than that. IDK?