Trying to solve air intrusion on 92 4x4?

[blowre1]

A few months back I was driving my IDI late in the afternoon when I had the first episode. I stood on the throttle in 2nd gear and just before I would normally shift to 3rd, at I guess 2300 rpm or so, the truck had a surge of power and then started "missing" like a gasoline engine, but I had plenty of fuel in the tank. So I clutched it and she idled okay and the fuel filter light came on. In the dark, I drained the filter. Later that week I changed the filter too.

Then it did okay for a few days but had another episode early one morning on my way downtown. I read some stuff on here and talked to my paw and he diagnosed it was the lift pump. He had a 6.9 for years until it was totalled by a drunk school bus driver.

I'm making this thread to list the sympotoms I saw in the days before I was able to make it to my farm to change the lift pump.

- No problems while the engine is cold or right after coming up to temp. Plenty power and no surging for the first couple miles from my house.
- Hard starting after the truck has gotten warm and then sat for a few minutes. Maybe takes 3-5 seconds of cranking to run. I also need batteries so take that how you want. Starter just rebuilt though.
- When I took off my old filter, it wasn't full of fuel. Filled the new one and put it on. This lead me to believe it was the lift pump, and I bought a new one at autozone.
- I struck out for my farm one saturday (to go change the lift pump and work) and just before I got to the Mississippi River bridge, I "ran out of fuel' and coasted into a service station. The filter was not full when I checked it. I refilled the rear tank (which was 1/2 full) and the fuel filter, got her fired up, and narrowly crossed the river. I was running out of fuel at the top and clutched to cost down.
- When I got on the highway the fastest I could go without surging and carrying on was about 45 mph. I drove that way with the windows down, still smiling because I was in a ford diesel, for 30 miles.
- I stopped for lunch and when I was parking in a place I could easily get her on a trailer just in case, the truck killed. Just idling and shifting to reverse and before I could let out the clutch, she died. Wouldn't start again so I got lunch and called my parents to come get me. 45 minutes later I checked the fuel filter and it was full! Oil level was good too. I tried the key and wham cranked right off so I took off with my mom following.
- I made it about 10 miles before I couldn't even maintain 35 mph, without surging and carrying on, and I was approaching a spillway bridge. I left it at a service station.
- After Texas A&M beat Bama, me and my dad went back to get her and I managed to make the rest of the trip without having to tow it in the dark and surging persisted in an unpredictable manner.

The next day we changed the lift pump, pulled it off, and I drove it around pretty hard and no problems! Or so it appeared...

Thanksgiving day I went to see my GF and her family. I was crusing at 65 or so with a big smile coming around a turn and when I got on it and....the surging returned with a violent shaking of the truck.

Her uncle has a 94 NA E40D that is doing some of the same stuff. He told me if he hits a hard bump in the field, the truck will kill and won't start. And he ALREADY changed the lift pump. If he switches to the other tank and cranks, his truck will start again. He told me that maybe the valve for switching tanks had a recall and he's getting in air there.

My plan: Rebuild the fuel system from the tanks to the filter. I know both pickups are broken off, so I'll start there. I'll let you guys know what I find, and maybe we can help people get their fuel problems figured out faster. I don't want anyone to be stranded in a 9,000+ lb truck on the side of the road.

One more thing. I fell like there's a connection between turning the wheel and the surging starting. Could be a total coincidence. But the time she killed when I was parking, I turned the wheel just before it killed.

Sorry if that was too wordy for you. Let me know if you guys have any input, wild ideas, or insight.

- Brooks

 

[riotwarrior]

I'm wondering if the wheel turning is flexing a wire that may or may not cause the FSS to click intermittently and cause that stumble and stall.

I'd consider that FSV too that could be problematic.

How old/miles on IP? there could be a correlation between heat and the IP getting weaker as it's older.

That's about all I got for now

Al

 

[Fordsandguns]

You could rule out the steering moving a damaged or loose wire by running a jumper wire between the battery and the FSS on the ip. Put the jumper in and start the truck and take it for a spin. If it still surges then you know that isn't the cause. Or maybe it fixes it so you know that was the problem.

 

[Tim4]

- When I got on the highway the fastest I could go without surging and carrying on was about 45 mph. I drove that way with the windows down, still smiling because I was in a ford diesel, for 30 miles.

- Brooks

I can't help with your problem, but I thought that line was indeed worth quoting.

Actually, we've got a squeezey bulb and fuel line from the boat store. If I had such issues as you describe, I would set me up a tank in the passengers seat, tie the line in at the fuel filter and see if a completely independent fuel source cured my ills. For a longer test, strap the tank on top of the tool box and hammer down.

Just keep in mind that the fuel will still return to the frame mounted tank so you'll run out of test fuel quicker than you think.

 

[Kalashnikov]

I would say it sounds like air intrusion at the slectector vavle as well. I get some surging when switching tanks sometimes. I also have a broken pickup tube in the rear tank.