Vacuum, wiring, bad gas, and rust.

[Myron]

So my truck was running out of fuel around a gallon below completely full. By completely full I mean gas running out of the fill neck, not the second click at the pump at the gas station. The problem started as the truck running out of fuel at around a half tank, and progressively got worse. Then the truck wouldn't run at all, no matter how much fuel was in the tank. I was not getting fuel, not even to the filter. I dropped my tank, drained it, found a fair amount of rust, the strainer, and a large magnet inside. I thought the sending unit might have a hole in it, so I filled a small bucket with fresh gas and the truck ran with the sending unit in the bucket, no matter if the pump was submerged just enough to pick up fuel or submerged all the way to where it seals at the tank??? After weeks of troubleshooting, I traced the vacuum line from the top of the tank and found that it was broken right behind the valve cover, on it's way to the canister. Replaced it and the truck ran better than it ever has since I've owned it, with the pump in the tank and only a gallon or so of fuel in it (And I no longer have to turn the pump on with a toggle switch, it comes on with the ignition). I put the tank back in the truck and it ran amazing for about a half mile, then died. Now it won't start unless I use starting fluid, and even then won't stay running. I have fuel both before and after the filter, and at the injector. Doesn't make sense to me. Strainer is back in place, and fuel filter was replaced with a WIX as the old one was clogged, also has new vented gas cap. :hmm: Any ideas?

[Myron]

Any ideas on why a motor that's getting fuel and spark wouldn't run?

[jimoshel]

Is gas getting into the cylinder? The fact that it will start says the ignition is good. Grind the starter for 10 seconds. Then pull a couple plugs. If it's getting gas the tips should be wet. If they're dry, no getting gas. Check for voltage at the injectors. It's not likely all 6,4 injectors go bad at the same time. Possible but not likely. If no voltage check the circuit back to the ECM. If there is voltage take a hose, or metal rod and hold one end to your ear. Place the other end on each injector. You should hear a clicking as the inj work. No clicky, no worky. Upon rereading your post I'm not sure if you have MPI or TBI. If it's MPI the above paragraph applies. If TBI then you should see fuel spraying from the injector.

[Myron]

I guess I should have clarified 88 2.5 TBI. After looking again today I now only have fuel dripping from the injector, not spraying. I can only think of three possibilities. 1)I drained my battery down trying to figure out what's wrong with it. 2) My strainer is clogged with rust. 3) All or most of the plugs undone underneath my hood need to be plugged in. I can't find where they go or anything that says where they go and if I don't soon I'm thinking about posting pictures of them on here if you guys think it would help. There's quite a few.

[jimoshel]

Nothing like having all the details before making a diagnosis. If there is fuel dribbling out of the injector then it should start and maybe run, Not right , but still start. There should be a very visible spray from the injector. First thing to do is hook up all and every loose hose and connection. They could be affecting all kinds of things, Vacuum, signals, etc.. If after hooking everything up and it still doesn't run, then replace the injector. There should be a diagram on the radiator support showing hose hook ups. If thats gone or obliterated then get a Haynes Or Chilton. They do have emission control diagrams in them. If your going to be doing a lot of the work needed on your Jeep then get a FSM. They pop up on EBay a lot.

If it was really rusty then there is the possibility you didn't get it all out and some got loose and worked into the filter, lines, injector. Check and clean if needed.

 

 

:wrench: