Hard Start. What to replace?

I have read hundreds of posts about this exact problem, but have yet to see what the solution is:

My 93 Jeep Wrangler Sahara (4.0 Inline 6) will not start until I leave the ignition "on" for anywhere from 20 to 90 seconds and hear the pump or fuel system engage for a few seconds. Then it starts right up and runs fine.

I notice that the "check engine" light fails to light until this fuel pump sound is heard.

I have replaced the fuel pump relay and the filter.

I am not sure what else to replace:

The Fuel Pump? (I have read that failed to fix the problem)
The CPS (Crankshaft Position Sensor) ?
Some other fuse or relay?
Maybe the computer?

Any help would be MUCH appreciated. Thanks!

You should be able to hear the pump when u 1st put the key in On positon for about 2/3 secs then quit. This is the initial priming in the fuel system. The Brain activates the Relay and then to the pump.also to include a reference signal from the the Ignition

Another thread in GC seems to point to the computer. http://www.automotiveforums.com/vbulletin/showthread.php?t=273382

I had the exact same problem with my 1995 I-6. I replaced the fuel pump and nothing changed. Eventually the Jeep wouldn't start no matter how long I left the ignition on. I ordered a new computer and the Jeep fired right up, but then the problem persisted. The last thing I replaced was the fuel pump relay and I haven't had a problem since. If you have a fuel pressure gauge you might want to check the pressure when the problem happens.

Well I will have to spring $170 Plus $70 Core for the computer I think.

Could be worse I guess :)

I don't think computer is going to do it. The computer is doing nothing during to time you say but waiting on you. You need to check fuel pressure, but even then the wait time has nothing to do with that. The pump will only run for a few seconds after the key is turn on. It kinda sound like you are having a time building up fuel pressure. You can cycle key on and off 3 times leaving it on then and read codes from flashing check engine light.

You can cycle key on and off 3 times leaving it on then and read codes from flashing check engine light.

That is good information. I will check that.

As far as the computer goes, I am going by what nart86 in the other thread mentioned above. He had the same symptoms and finally replaced the computer as a solution. (page 3 of that thread).

The thing starts right up after the pump finally kicks in.

Thanks for your help.

That is good information. I will check that.
The thing starts right up after the pump finally kicks in.


It was the computer!

$130 (plus core) from Schucks for the one I needed. Starts right up every time now. The installation was easy. (4 screws, 5 counting the windshield washer reservoir removal)

Well good to hear. I would not have thought computor yet. Oh well.

Seems there is an increasing number of these jeeps with computer failure. When I had my problem Jeep said they don't make that computer and that it shouldn't fail. I own a 1995 and my issue happened in 2001.

It seems to have fixed some alarm problems as well. :)