Mattloz

Ok guys I have a 90 Cherokee renix 4.0 that I swapped a 91 4.0 into well long story short I bought new plugs, new icu, new coil, new cps, and now a used computer I tried to start is to see is the computer wold fix it ( mine had a short anyways) and nothing, the jeep did stuffer at one point and befor I got the new computer it turn on once and never turn back on

Do you think my fuel pressure is low or my pick up on my distributor is bad??

XJwonders

when u bought the new stuff. Was it for the renix or for the HO?

Mattloz

It was for the renix lol no worrys I'm a mechanic so i know the difference between the two I'm going to check my fuel pressure Tomorrow just want to see what some people would say

Ps I'm still going to school for mechanics I'm not a master tech

foxmxrcer

So, you replaced the renix with a h.o engine, and replaced the renix ecu with a h.o one or another renix? And you put renix parts on your h.o engine?

Mattloz

Everything is renix I just used the block and head of the h.o into the renix jeep EVERYTHING is renix also flywheel

I was able to turn the car on once after a few day of trying well I turn it on for about 10 seconds I turned it off for about a minute and tried to start and haven't started since. I bought a ecu because mine was fried (I had bypassed it ) well I got a new one hoping it will work but nothing it did spudder once as I'm like 1 cylinder did fire but stopped thinking it my fuel pressure because ot usually spudder after many cranks so I'm thinking not enough fuel is spraying and after many cranks later it finally get a good ratio and starts to spudder

XJwonders

Did u do the cruiser54 tips?

Mattloz

Yes I did even the distributor indexing

cruiser54

The gizmo in the distributor will not cause this problem.

Check your fuel pressure.

Mattloz

Yea that's what I'm going to check later today fuel pressure at the rail should be 39 psi right

Do I test while cranking or cycling ignition

Also how do I know if the fuel pump is causing low pressure or it's the fuel filter I do hear the pump prime and run when cranking so I think my pump is fine

When I bought the jeep the guy said it barely had any fuel in it so I added about 5 gallons and took the fule line and put it into a red gas tank and cycled the ignition to pump some old gass out you think the filter could be clogged? Jeep had 215,xxx miles and don't know if it has been changed

wauto

Fuel filter is cheap and easy to change. Check fuel psi key on, not cranking.

Mattloz

Thanks will post results

Mattloz

Ok my results are turn the ignition on ( not cranking) 39-40 psi dropped 5 psi in 2min and 20 seconds(35psi) dropped to 33psi in about 8 min dropped to 32psi in 12 minutes

Mattloz

What else can cause it a no start issue baeically everything is new electrical wise that tipically need for a car to run correctly

XJwonders

fuel pump

Mattloz

But what's is wrong it drops pressure to quick