Mower

I am new here. I have a 90 jeep cherokee 4.0. It cranks a long time before starting. I have replaced fuel filter and fuel regulator, distributor cap and rotor. When it does finally start the idle is erractic, 500-1200 rpm. When I step on accelerator it wants to die. What are the possibilities?

tjwalker

You need some hard data. Start with testing your fuel pressure.

For your 90, you need 31 psi of fuel pressure to start and run your 4.0 engine. Disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi.

Certainly there are other possibilities, but you haven't replaced the fuel pump yet, so testing fuel delivery is job #1.

Also, search out CRUISER54 for his tips. He is a Renix guru. And a heck of a Hank Hill kind of propane guy

bad_idea

You have a Renix era jeep. Read cruiser's tips on his website: http://cruiser54.com. His tips will get it running decent. It will likely always take a while to start up though. My 90 is running good, completed most all of his tips. Still takes a while to crank up. From what I understand, the Renix jeeps just take a while to crank up.

While testing the fuel pump, do a flow rate test also. It may show the correct pressure, but not flowing enough fuel. The FSM has a procedure for testing the fuel pump.

Programbo

Try some of the things suggested. A long crank time is often a symptom of a fuel injector that is "leaking down" or stuck partly open. After you turn the Jeep off the fuel continues to leak out the injector tip and when you try starting it you have to burn off the wetness in the chamber. Of course in most cases the Jeep then runs fairly ok. Unless it's just stuck partly open and not functioning otherwise

Mower

I was thinking fuel pump but wasnt looking forward to replacing it. After replacing fuel filter and regulator it cranked several times but didnt start so I pulled the plugs and they were dry. So I knew it had to be a fuel issue. I thought maybe there was a fuel pump relay or maybe crank sensor. Its pushing fuel but I am guessing it's not pushing enough. Thanks again.

bad_idea

The fuel pump on the 90 looks easy to get to. I haven't had to pull mine, but looked at it. The pump can be pulled without dropping the tank.

BillyBoy

Try just turning the key forward to acc. , wait 2 seconds, then off, then acc. and wait 2 seconds, then crank it.

Essentially, you're double.priming the pump. When mine was going out that bought me another 3 months till the weather was nicer to change mine out.
Good luck.

67 GMC

The Renix Jeeps do crank longer than a modern vehicle. I'm not sure if there's a post on the site that compares what the actual crank time is typically but my '87 cranks for a few seconds whereas my Toyotas are already started way earlier.

The most important thing is that it starts and runs!!