F150 Farm Truck Help

1986 Ford F150 half ton pick-up Just after I bought it ,it used to stop running but would not restart , It happened once in a parking lot , got it towed they replaced a part they said on the side of the distributor???, The next time some months later it stopped in the middle of the road , towed to workshop and they said she's jake !!!, About two weeks later stopped again outside my house , The same tow scratched his head, and said it was the fuel pump , they replaced the timimg chain , it slipped a cog ???, Yesterday I was driving to town and it started to chug along as if it was running out of gas or it was trying to change gear erratically, I moved the gear lever to O/drive and was able to steer it into a fuel stop nearby. Checked the trans oil level down a bit and topped up , Restarted engine it ran for about 10 sec, then stopped , did that a couple of times , rev the engine in park no sign of miss, because the engine revs and speed shift the gears up and down is there something out of wack that makes trans shift even though the truck is not under load or pulling any additional weight .When in use it shifts at about 35 and about 45 , The truck has about a little over 100K since new , I bought it about 93K . Its a V/8 and likes the taste of fuel ,although driven at around 50mph . Is there anyone out there who has had experience with this model , I would be extremely grateful.

If yours is fuel injected I would suggest checking the wires connected to the TPS(throttle position sensor) located on the throttle body. My 91 had similar problems and it turned out a couple of wires were shorting there and causing it to miss,die,shift erratically and just plain run goofy. I spent months "dealing with it" and checking everything over and over trying to get it fixed. If yours isn't fuel injected it would have to be something else though. Good luck.

check your coil resistance and look for vacuum leaks

To check fuel pump,,turn key on,lift hood,up top near firewall should be small fitting on fuel line with tire valve cap,remove cap and push valve in,lots of fuel under high pressure will come out,also good way to burn you and truck up if you are smoking!I had one like yours and boosted another vehicle and screwed up computer located behind left kickpanel in front of door,may want to replace it.Very common,junkyards are full of em,er was till recently.Good luck, Hoss

Those models were rough on ignition modules.They are located on the outside of the distributor housing.Use a genuine Motorcraft replacement module when replacing.They cost more but the aftermarket brands don't last long.I would also service the gasoline filter on the truck.Usually a bad module won't let the truck start.This problem does sound as though its fuel related.

Does the truck have dual tanks?If so,the dual tank switching valve on frame is probably junk.Replaced a few of them havin' same problem you described.

First one really had me scratching my head.

check oil pressure sender unit I think on that model it also has low oil presure shut down My 87 had both oil shutdown and fuel selector problem interemently. Talk about hard to isolate!!!!!!!! I had full head of hair before figuring that both would interemently have open circuit Low oil is easy to jump for testing at sender located neat distributor, well truefully its still jumped.

Bradk , no only one tank , but thanks for suggestion

I had a Ford station wagon years ago that had similar symptoms. Mechanic finally traced it to a double wall exhaust pipe with the inner wall collapsed. This made back pressure high and vacuum erratic that caused the engine to lose power and the transmission to shift unpredictably. Just a thought.

Thanks OFM , I have thought for some time about fuel flow ,although I couldn't pin it down , I think the fuel filter may be time for replacement

Elijah , yes fuel injected , and the similar problem is a good match , Now to find the Throttle Position Sender , in addition to what I wrote this thing stops some time when I pullup in the yard , so the shorting of wires at that point is a definite look and see.

Thanks everyone , you are a great bunch , I will be trying all suggestions and I think it will solve the problem . only wish the local mech had the same enthusiasm

The tps is on the throttlebody. It has a clip with wires going to it and is on the left or passenger side. You can tell the tps by the fact that the mounting holes are slotted for adjustment. The wires were shorting just at the clip junction on mine.

You should try and measure the fuel pressure when running the truck to see if its drops off. I had that problem on a GM vehicle and after installing a fuel pressure gauge I noticed the pressure dropping off. Pulled the gas tank and it was full of rust and dirt. Replaced the pump in the tank and cleaning the tank solved the problem. Hal