HeavyC

So I am having some problems with my jeep. It's been like this for a while but I am not sure what the problem is. If my jeep has been sitting for a while (30 min to a day or two) I have a tough time starting it. To get it to actually start I have to prime the fuel pump a few times, but even after that it runs really rough for a few minutes. I then have to let it warm up for a few seconds, turn it off, and then restart it to get it to run smooth. What's weird if my truck sits for around a week it'll start right up. Also it seems that sometimes it will stutter as I am driving down the road and even stall out. I changed out the fuel filter but that had no affect. I don't know if it could be the fuel pump (never had a fuel pump go out on me before).

troy fritz

I'm having the same problem with mine.My MAT sensor is bad.

HeavyC

Ah gotcha. How can you tell if it's bad? I still haven't figured out how to run codes (it's and 87 so I have no idea if I even can.

89Laredo

No codes on a 87, unless you buy a 1000$ snap-on scanner and run it while the jeep is running.

I would go to a parts store and rent a pressure gauge..

Jeff H

Sounds similar to something going on with my '98, but it's only been doing it for about three years so I didn't think it was that serious.

May be hocus poocus, but it works every time. I turn the key on and wait 'til the fuel pump pumps up, turn the key off and back on listening to the fuel pump two more times before turing the key to "start" and it fires immediately. It will idle ever so slightly roughly for about two seconds and level off. If I don't do that, I crank for several seconds before it lights and then it idles very roughly for ten or twenty seconds and sometimes stalls. Fires right up after the stall though.

My guess was that I was losing pressure in the fuel system while it sits (no leaks to atmosphere anywhere) and I had to make sure pressure was "up" before I had enough for a good start.

Maybe superstition, but it has been working like that.

89Laredo

There is a check valve known to go bad and bleed off fuel pressure.

HeavyC

Jeff h. That sounds a lot like mine but if I let it idle rough it won't smooth out. I also am wanting to figure it out because of stalling problems because that gets worse the more I drive it.

troy fritz

You check the ohms at the MAT harness.When its at operating temp it should be about 4000 then drop off steadily if its good.

Jeff H

Not the same thing then, I would bet. Once it starts (after I have failed to start it "correctly") and starts idling roughly, if I tromp the pedal once, it levels off and plays nice.