I had my ears and 'seat of the pants' on full alert today on the way to and from work, but couldn't feel so much as a hick-up. So far so good. I'll probably go for a >100 mile trip this weekend to really test it, but (at the risk of jinxing myself) I think the ol' truck just might be fixed.

And if nothing else, those capacitors really needed replacing.

 

The aluminum electrolytic 'can' capacitors dry out (or leak out) over a decade or two (or faster in a hot environment). In the guitar/tube-amp world, the first thing you do when you get a [new] old amp is recap it.

 

I don't know if the same applies to automotive ECU's, but a few years back the PC industry had a rash of faulty capacitors. Seems most were traced back to chineese manufacturers.

 

Well, the computer wasn't the cause. It did the same thing just now on the way into work. Cruising along at 70 and suddenly feels like it runs out of gas but there's 1/3 tank still in it. I actually poured a couple of gallons from a can to try to eliminate the posibility that fuel level could have something to do with it (I'll try filling it up after work, too) but after a couple of miles, the same thing happened. The good news is that it showed a cel, so maybe there'll be a code or two that will help shed some light on the problem.

This is getting really old. If I had the place to do it I swear I'd rip everything associated with the engine and fuel system out and swap in a cummins 4bt.

 

I think you have (or had) more than one problem that needed addressing.
Don't give up just yet !!!!!

When your truck is "running" it runs great......sounds like the computer issue is resolved.
Now you're gonna' be chasing the cutting out problem.......

Post your code(s) that the computer has stored.

At one time my truck cut out and missed for several weeks and was throwing a code for "system lean" before it finally died on the side of the road one night.
It turned out to be the dual tank selector switch in the dash that was failing and eventually totally failed.

We'll get you through this !!!

Bob

 

KOEO codes:

522 Not in P or N during test (it was)

Cont. Memory codes:

72 Power interruption detected or Message Center Control Assembly circuit failed.

172 HEGO sensor circuit indicates system lean (right side) (this is a KOER code according to Fordfuelinjection.com and I haven't done one of those since the last time the battery was disconnected. Will it collect and store this code during normal operation?)


I think I read somewhere that I'm only supposed to get all three digit or all two digit codes, but I checked it three times and this is what I counted. Could the lean condition code be due to an interruption in the fuel supply? I'm going to fill up the tank and see how she does on the drive home. If it doesn't misbehave, I'll drop the tank and see if something's come loose. And I'll try to trace down every connection I can to clean it and apply dielectric grease.

 

You'd think a fuel supply problem would affect both banks of cylinders, but it's a complex system so...

Do you have dual tanks? Does the problem happen on both tanks, or just a particular one?

The fuel tank selectors are notorious for failure (if you have dual tanks). I believe you may also have a secondary/booster fuel pump on the frame rail, as an additional failure point. Early on the in-tank pump was a low-pressure unit (maybe from the carburetor days), and the high pressure (maybe 45psi) pump was mounted on the left frame rail after the tank selector. Later model trucks (not sure when) had only high-pressure pumps in the tanks.

At the age of your truck, if the O2 sensors haven't been replaced, I'd suspect the right bank sensor had failed. I also believe that each bank of fuel injectors is on a separate circuit. Common positive, I think, and each ground is switched independently by the computer.

522 and 72 both sound like continued computer connector problems, or possibly wiring harness. (intermittent ground somewhere?) I forget exactly what it is, but there's a procedure to clear codes. Pulling the battery might have done it, but I'm not sure. Properly clearing codes on the OBD-1 EECIV involves shorting a pin to ground, IIRC.

 

Just the one bank of cylinders on the ol' 300. I think I remember reading that the 'right bank' codes were used for the inlines.

Unfortunately, my truck only came with the one 17 gal tank from the factory. A little over three years ago I swapped it for a new poly 32 gal Bronco tank but used a salvage yard sending/pickup unit and reused the original pump from '92. I am beginning to suspect that there's something going on back there. I put another 10 gal in it today after work bringing the level up to 3/4 tank (indicated by the gauge) and didn't have any problems on the drive back home. The next step in testing this hypothesis will be to siphon off those ten gallons and see if the problem comes back.

The O2 sensor was replaced last summer when I was getting it in shape to pass emissions to register the truck up here in Anchorage.

I think you're right. I'm going to spend some quality time with the truck and try to clean up all the connections and grounds I can find. As far as I know, disconnecting the neg side of the battery for more than ten or twenty minutes is supposed to clear the codes. I'll do some more research on the grounding a pin thing, though.

 

If the issue is only occuring with low(ish) fuel level in the tank, it could be the pump going bad. Follow my thinking here: If the pump is getting old, it could be running a bit warm. With the tank fairly full, the pump is totally submerged, but as the fuel level drops, the pump is no longer submerged. Being totally submerged, the fuel acts as a coolant for the pump, preventing overheating. Once the pump is no longer submerged, it can get hot and not be able to supply correct pressure and/or volume of fuel.
The same scenario could also be playing out if the pre-filter is partially plugged, or the fuel line is restricted. Even a slightly loose ground for the pump can cause this same type issue.

Moral of the story, if it is fuel level related, check everything before just assuming it's the pump dying. While the pump *may* be the problem, it could also be caused by something that costs next to nothing to repair, and we all love finding those simple-free fixes........

 

Right- there's only one O2 sensor. I think the fuel injectors are divided into two banks, though.

No problem with the selectors, then. They're a major pain on the dual-tank trucks. 32gal tank FTW. Doubt there's any problems with debris plugging the pickup, either, on your new tank. Unless some piece of rubber fell off the old pump/sender...

Solid.


Therangerstation.com has a great writeup on EEC-IV stuff, from what I recall, including reset procedures. I liked it better than fordfuelinjection.com.

I don't know off the top of my head, but there might be a Schrader valve on the fuel rail you can use to check fuel pressure, or maybe a line you could T-into.

Also see if you can check the pump voltage when it's running bad. That and the pressure (before and after the regulator, if possible) would tell you a lot about what's going on. If the pump voltage and fuel pressures are good/correct, then you've got a computer issue.

Not sure if there's a limp mode on the EEC-IV trucks. If anything, I think it would idle fast, with severely retarded timing and run stinking rich.

Your 18 year old fuel-pressure regulator might be flaky, too. There's a common mod to replace the non-adjustable factory 4.9 regulator with an adjustable 5.0 regulator. Just have to fabricate a collar (ring of steel w/ 3 screw holes) to mount the thing with.

While these engines are cold-blooded, I'd expect the radiator to be dang hot in a Georgia summer. (heck, I just blew the old pinhole-leak radiator on my '76 on a 100+ F day last month). Spit might be able to sizzle on the head under normal circumstances. Factory t-stat is 195F, I think, and different parts of the engine are going to run hotter and cooler. Lean running produces combustion over-temperatures, so the head would run even hotter.