My grandson recently bought a 1988 F-150 with a 5.0 liter V-8 with two gas tanks. It has been a farm truck, and I suspect it hasn’t had a lot of regular maintenance. It was very dirty when he got it and he has been cleaning it up and trying to get it to run properly. He is 17, and this is his first vehicle, so he needs some help. I’ve helped him with some problems, but he lives 2-1/2 hours from me, and he needs help more often than my trips there provide. Diagnosing problems at a distant is difficult.

He’s replaced a lot of things like fluids, spark plugs, battery and cables (corroded badly), dimmer switch, etc.

The truck runs pretty good now, but it will start to run badly after running well for several miles. It jerks and sometimes dies. Then won’t start right away. Then it will run okay for some time. They had a local “mechanic” look at it, and of course, he couldn’t get it to run badly while he had it.

I have been searching the forum for similar problems. I believe that it is a fuel related problem. I understand that there are two fuel pumps. I see problems relating to fuel pumps, fuel filter, and selector switches and related relays. I’ve also seen mention of diagnosing the computer light blinks to determine the error codes.
I will actually see the truck next week and would like some direction as to how to proceed.
Apparently there is a plug to access the computer. Can someone direct me what to look for?
Also I did some searching for code readers. I found one on amazon that claims to work on most Fords from 1982 to 1995. It is a “INNOVA 3145 Ford Digital Code Reader”.


The reviews sound impressive. Or should I just go with the jumper and count the light blinks?

Thanks for any help you can give,
Les

 

The code reader is the bees knees. I tried the whole counting flash thing, which in a pinch is cool, but the code reader is the way to go. I do suggest the extension cable as well that way you can sit in the cab with the reader in your lap. Makes it easier when yer by yerself.

 

Here is the location of test port, drivers side:

 

I have that same code reader for my 94 F150 and it works great. theHead406 is right about the extension cable. Otherwise, you have to run back and forth from reader to cab to do the brake test, overdrive on/off toggle, and then the WOT test. Unless of course you have a helper. The book that comes with the reader is well detailed.

 

On your recommendations, my son-in-law and grandson purchased the code reader referenced above.

They received the reader yesterday and plugged it in.
Here are the results:

23: Throttle position sensor signal our of range

10: Cylinder 1

41: HEGO sensor

53: Throttle position sensor

32: EGR pressure feedback

I hope someone can help decipher these. I will be there this weekend, so will try to get as much info as possible. It the meantime, does anything jump out as the possible cause of the problem? Please let me know if there is more or different info needed.
Thanks for your help, Les

 

I have a little better idea of how the truck runs now. When cold it will start OK, but will not keep running without keeping your foot on the gas. After warming up for about 10 minutes it will run OK and can be driven. It will drive fine, but periodically it will hesitate and almost die. Then will be OK for a time. It seems to do that randomly while driving.

There are a couple error codes relating to the exhaust gas O2 sensor and EGR. That looks like a good place to start. Any suggestions as to the most likely culprit?
What does the 10 code indicate? All I see is the #1 cylinder is not contributing. Low compression? bad ignition wire?

There are also a couple of throttle position codes. What does that mean?
Thanks,

 

No, start by inspecting the wiring to the TPS sensor and replace it if that looks OK, then clear codes with the code reader or by disconnecting the battery for 15+ minutes and do a test drive.

Code 10 is just a separator between KOEO(real time) and CM(stored) codes.

Codes 32 and 41 are less significant which means they won't affect engine operation as much as a bad TPS sensor.

Code 32 suggests a problem with the EGR position sensor but it's not totally dead and won't be a significant contributor to your problems.

Code 41 is simply telling you that the engine isn't running correctly, it is not telling you there is an O2 sensor fault.

 

OK, they got new TPS sensor installed. Tried to start it and the starter wouldn't engage. They have had issues with the starter before, worn teeth on the drive, etc so they decided to replace the starter. They got that in today, and the truck started right up and ran OK.

My grandson took it out for a test drive and it was running great. He drove several miles and then while slowing down it died. He pulled off the road and tried to start in. It cranked, but would not start. After several tries apparently the battery couldn't handle it and then it wouldn't turn the engine. I suspect it hasn't been driven it enough recently to properly charge the battery.
His dad came over with his Honda and brought jumper cables and gas, in case the gauge is not accurate. They got it to start once. It ran about 15 seconds and died again. After that, they couldn't get it to turn the engine even with the jumper cables attached.
I don't know if the Honda alternator has enough power to crank the V-8 or not.

Besides the problem of running badly, we now have an issue with it cranking the engine.

Where do we go from here?
Thanks, Les

 

I decided it was time for a hands-on visit. At that point it wouldn’t crank, start or even consider running. I suspected a dead battery by now, so connected it to a battery charger overnight. It started charging at 6 amps, and by morning it was down to 1 amp. Voltage was just a shade over 13 volts. Installed freshly charged battery and tried to start. Just clicking from the solenoid, no cranking. Measured output at solenoid, 0 volts. Touched starter cable to input side of solenoid and immediately got cranking. Off to Napa for a new solenoid. BTW, this solenoid was only about 3 months old. Also from NAPA. Installed new solenoid and got cranking. After a few seconds, the engine fired and ran at a high idle. After a few minutes the RPMs came down and it was idling normal.

We connected the code reader, cleared the codes, then read the codes again. This time we got 11, 32 and 41.

Decided it was time for a test drive. Drove about 15 - 20 miles. During that time we got a few stumbles, but it always recovered and ran well most of the time. We filled both gas tanks and I noticed that the gas gauge doesn’t work. On one tank it floats to the full mark, while on the other tank it floats to the empty mark. The amount of gas in the tanks doesn’t seem to affect the position of the gauge

My conclusion is that while doing the first test drive after replacing the TPS, My grandson ran out of gas. He tried starting it enough to seriously weaken the battery. The added gas got it running briefly. Then the solenoid finally lost all contact and ended up with a no crank situation.
I believe the key to getting it running was the new TPS. There still are some problems relating to the EGR and O2 sensor. Also the gas gauge is a little bothersome. I’m back home now and the truck is running, but I still would like to get the other issues solved.
Thanks, for all the help. Especially the tip on the TPS. Any suggestions on how to proceed now?


PS: Took the solenoid apart expecting to see burned contacts. What I found was one of the contacts was pushed back out through the case far enough to lose contact. Appeared to be a manufacturing defect, but hard to tell since it was destroyed in disassembly.