Hypgnosis77

Hey Guys,

New to the forum. Did an extensive search on my problem and didn't turn anything up. I drive a '93 Jeep Cherokee Sport 4x4 with a 4.0 L straight six with multi-port fuel injection (MPI). Here goes:

So I just about ran her dry of gas. Fueled up again and hit the highway. About 10 miles later I'm cruising along fine and all of the sudden she dies.

I pull off to the shoulder. She's never done anything like this before. I start her up and away we go again. 2 miles later she dies again. Starts up again fine, idles fine, revs up all the way till the governer kicks in, stays up there fine till I let off. Idles down and purrs like a kitten. I go to pull away and as soon as I get out on the road she dies again.

The damn thing runs fine. It'll idle and/or rev for as long as I want. It runs until I put her in drive. As soon as I get moving again she dies.

My best friend is a pretty good backyard mechanic, and he figures either the engine is blown (i.e. bad pistons / heads / valves / seals / head gasket) or - more likely - fuel problems. Since I just about ran her dry before fueling up, maybe I picked up some dirt from the bottom of the tank. Or bought some bad gas.

Towed her back to the yard and tried a few things. Tried taking the fuel filter off and blew through it, then finally punched a hole through to see if there's a blockage. That didn't change anything.

Tried dumping some fuel injector cleaner and gas-line anti-freeze (I live up in Alberta, Canada) in the gas tank. No dice.

Did a compression test to rule out the blown engine theory - compression is fine. One piston is a little lower than the others, but within the normal range (112 psi, with highest one coming in at just under 140. The rest are in the 125 - 135 range).

Back to the fuel system, I've replaced the filter and narrowed it down to the fuel pump, fuel rail or fuel pressure regulator. I bought the fuel pressure tester, but it was gettin close to dark as I was about to take it out of the package so I decided to take a look at the fuel rail just to make sure I could find everything.

As I'm lookin at the regulator I notice the vacuum line attached to it is loose AND worn / cracked right at the connector. I can't tell if it's actually got a hole or not, but I'll be checkin it out tomorrow.

Anyone know if a leaking vacuum line from the fuel pressure regulator could account for my experience?

Let me know.

Trev

solderjunkie

Buy a fuel pressure gauge.

Go right now.

You can watch the fuel pressure with the gauge taped to the windshield.

You need to figure out exactly what is being lost to cause the engine to stop. Everything your buddy has suggested so far has really been a waste of time and money.

Hypgnosis77

Hey folks. Just lettin ya'll know I got the problem licked. Turns out it was, indeed, the vacuum line to the pressure regulator. Replaced it and she runs like a little princess again.

Thanks anyway.

Trev