Jeep not starting... again

[thesupercroc]

Greetings all!

I'm having no/hard start issues. What it will do is crank well then what to fire up and get a couple of "fires" and then either nothing or it will run.


So far I have changed or replaced


crank shaft position sensor
coil
plugs
plug wires
cap
rotor
throttle position sensor


I had the battery checked and it was ok.

thoughts?

[LGrocks]

Have you checked fuel pressure?

[NW99XJ]

Hmm ... might be a fuel issue...
I would go to your local parts store and rent a fuel pressure gauge, and test the pressure at the rail.
I would also do a real good inspection of all the vacuum lines, a nasty vacuum leak could present some of these issues.
Another option could be something like a intake manifold leak.
An old-school method for finding a vacuum leak is by using some starting fluid, and spraying it around the intake manifold seal, and vacuum lines. When u hear the RPM's change, you know u found your leak.

[thesupercroc]

Have you checked fuel pressure?

do you {or any one} know what the specs are for the fuel pressure?

[LGrocks]

NW99xj or 4.3lxj might chime in to confirm but I think I'd be looking for 35-45psi at idle.

[bluedragon436]

Isn't the 97+ or maybe even a few years earlier, like 43-49psi?? I want to say it's supposed to be something like that IIRC.... Try turning your key to the on position, just before the start position a few times for just a few seconds, to let the pump prime and pressurize the fuel rail, and then try starting it, see if it starts fine then...

[NW99XJ]

Fuel pressure at idle should be between 44 & 52 PSI.
With engine off, fuel pressure should not drop to less than 24 psi over a 5 minute span.

[4.3LXJ]

43 psi is what my FSM says

[thesupercroc]

when cranking it waas at 45 PSI .

I have not had time to look for vac leaks yet so that is next up on the list of things to check.

[cantab27]

injectors all good.....

[thesupercroc]

injectors all good.....

How would I go about check them?

[bigjim350]

Have you scanned it to see if its throwing any codes?

[BlackYeti]

I have had an alternator go out on a 96 that I wasn't aware of. Changed a bunch of sensors and tested things here and there. Before I left that night, I got it to run "sort of" by holding the gas pedal down a bit. It ran only at 2000 rpms or higher. While I was sitting there the gauges light came on and I looked at my volts to figure out that there was not enough there to charge the battery, or keep the dam thing running at idle.

TL;DR, Try to start it with the gas pedal depressed and see if it will run. Regardless, check your alternator. Some of these engines require more than 12 volts to run properly.