Caprinaholic

This is a bit of a project, with hopes of turning it into a work truck sooner than later....I'm no mechanic (I can change a tire and brakes...that's where my abilities end) but learning.
1994 F150 5.8L EFI with 150,000 miles. Had a motor rebuild at 130,000 supposedly by a dealership, and serviced there per manual recommendations under the first owner. Tranny is original. The second owner bought it last summer to learn how to work on the truck. This is what he's done:
New battery, fuel filter, spark plugs, oil change 100 miles ago, and he replaced the positive battery cable.

It cold started once from the rear tank after purchasing it (while messing around with it in the shop), but otherwise... you have to spray a little starting fluid or gasoline in the air intake, and then it starts right up and it'll run and start for the rest of the day. It also needs to be in 1st gear to get from 0 to ~20 MPH, after which it can be put in Drive and it'll stay at speed fine...unless you get to a steep hill...and then you go back in 1st or you'll be crawling...push the accelerator too hard while it crawls and it'll backfire. I live in the middle of steep hills...

Since purchase, It's had a fuel pressure test, and read at the correct levels. Just pulled all but two spark plugs...they're sooty. So's the inside of the tailpipe. One cylinder has had a compression check and read 140. Check engine light is on, but neither a OBD1 code reader nor the jump wire method could get a reading on codes. We might try the jump wire again. Dad (ex mechanic, still plays with his diesel) is beginning to think the ECU is bad. A Buyer inspection yielded a distributor suggestion.

Any other ideas?

raski

Fuel pressure test good,what was the pressure?? Why did you only check compression of one cylinder?? You seem to be all over the place with a lot of guess work. You need to gather more useful information and post it so we may help you.

Caprinaholic

I'm working on limited knowledge and my more knowledgeable helpers have limited time, so we pulled spark plugs and then ran out of time, and one cylinder was checked when someone had a second just to get an idea of what we're working with. We're intending to run all of them today, but one helper had a birthday today and my other one has a bum arm for a few more weeks (post shoulder surgery).
Fuel pressure was between 35-40.

Caprinaholic

Compression check as of today
Driver's side, bumper to cab: 135, 140, 135, 135
Passenger's side, bumper to cab: 140, 135, 140, 140

raski

Decent compression, you say no codes. Does that mean you got a pass code or no codes at all?

Caprinaholic

The check engine light is on steady, but neither an OBD1 reader nor the jump wire method yielded any codes. No codes whatsoever. We're going to try the jump wire method again just to make sure that wasn't operator error.
We're planning to check timing next.

raski

I wouldn't mess with the timing at this point. It will not change unless the timing chain jumped and I doubt that is your problem.. If you cannot retrieve any codes at all with the check engine light being on, I would look at the ECM. You should be able to retrieve codes with the reader. Some believe they don't work but the reader is doing the same as the jumper wire method.. The electrolytic capacitors inside the ECM may be bulging out.

raski

I am curious on your findings so far.

16IngotFX4

Another consideration cold be the O2 sensor or clogged CAT. The clogged CAT can rob power on those in no time!

If O2 sensor isn't reading correctly, it could run rich (right?).

Caprinaholic

Finally took it in to a shop...they originally wanted to work on the fuel system (I typed up a full history for them and handed it in with the truck...all the work that had been done...all the test results...all the function oddities...it isn't the fuel system!), but finally talked them into messing with the ECM. Yup, it was the ECM. Got a new one installed and it runs like new. Almost new.

Now there's a lot of tune up work since it apparently sat in the first owner's bushes for long enough to grow lichens. Changed out the sooty spark plugs, put a new throttle position sensor on (the code reader found a code for it once the new ECM was installed), ran some cleaners through both fuel tanks. I'll probably put a new fuel filter on it. Put a set of new tires on it as the old ones looked worse on closer inspection than either I or Dad thought originally. New brake line on the left side. New brake shoes in the rear drums. It still has a bit of a tranny leak and a coolant leak that I monitored the last couple weeks when I drove it on a trip from the Seattle area to Colorado, SD and back to the Seattle area. The tranny leak seems to have slowed considerably from when it was first noticed, it's holding oil well and the coolant leak seems to have slowed a bit on the trip (but still leaking). I checked fluids several times over the course of the trip. I did add one quart of oil at the beginning, and coolant twice during the trip (I hauled tools and fluids with me).

Now it's shaking when accelerating between 40-55 MPH (new as of a couple days ago). And the rear tank acts like it's out of fuel when I put a load on it (accelerating hard -especially up hills, or going up a steep grade). I played with it during the trip, and there were plenty of hills and mountain passes to test it. Coming home, it backfired while accelerating very hard...switching to the front tank solves the "out of fuel" problem, and then I can switch back to the rear when the road levels out or goes downhill and it works fine for that. The front tank works flawlessly. But there's stretches along those roads where I need that extra tank to get to the next fuel station. I never ran out of fuel, but I definitely made sure to factor in its issues to my driving and fuel stops. Almost there!