[1farmgirl]

I have a '91 F250 diesel pickup. It has a couple of problems that I would like to fix. First-when you press on the accelerator to go uphill, it has slight surge almost like a hiccup? just quick and slight but it will keep doing that until you let up on the accelerator. This is even more pronounced when you have a load. We had the injectors replaced, and hoses, and injector pump rebuilt. I think it has something to do with the transmission. (automatic) Our local diesel mechanic said he can't think what else it would be (after he charged us $1200 for the injector repairs). My hubby isn't real mechanically inclined, but if we could get some ideas, maybe some suggestions, that would help give us a starting point. My dad can work on gas engines, but has had no experience with diesel. Our chilton hasn't been real helpful with IDing this problem, either.

Another thing we would like to figure out with this truck is the headlight switch. We have to pull it all the way out, then slowly push it back in until we get taillights. Too far out or in you don't have headlights or taillights- one or the other.

Any help or suggestions would be greatly appreciated.

Kathy

 

[Unregistered-1427815803]

It sounds like the transmission to me to. First thing you may want to do is to check your transmission fluid. It could be low due to a leak. How old is the truck? How many miles do you have on it?

 

[agmantoo]

The headlight switch has dirt in it and the contacts are dirty or corroded. A replacement of the switch is in order. You might try spraying some electronic contact cleaner into the switch if you can manage to get some into it.
If you put the auto transmission into low will the engine still have the same symptoms as you accelerate?

 

[flaswampratt]

My first thought was the tranny also, and I beleive agmantoo is right on the money.

Sounds like the tranny is shifting back and forth between over-drive and third gear. Drop the tranny into a lower gear before throttleing up and see if the problem dissapears.

Buy a new headlight switch. Just isn't worth the trouble of your head lights failing halfway thru a curve.

Best Regards........<+><

 

[greg273]

There are a few sensors that could be a fault, if it is indeed a transmission problem. Check out 'thedieselstop.com', thats a very informative website.
I've had tranny problems with mine, and even replaced a few sensors, but what seemed to cure the ills was a quart of Transmission Gasket sealer.
greg

 

[fordy]

...............The Absolute BEST website for help with your Ford truck is...FTE....Ford truck Enthuasists........more help than you will ever need......fordy...

 

[Beeman]

It does sound like a trans problem. That trans should be a 4spd. electronic shift trans. You might have something as simple as an out of adjustment throttle position sensor or a loose wire/bad connection.
As for the headlamp switch that is a very common problem with Fords. First problem is the switch is junk and so will the replacement. They just can't handle the amperage draw and it is easily compoundes by towing a trailer with lights. When you remove the switch for replacement there is a very good chance the plastic block connector is melted as this is also very common on Fords. This block should be available at a good parts house or the Ford dealer.
If you tow a trailer with lights it is a good idea to run the trailer lights off of a relay that is triggered by the headlamp switch. This will take the amperage load away from the switch and put it on the relay.

 

[1farmgirl]

I appreciate the advice and suggestions. I would like to fix this because it seems to be a pretty solid farm truck otherwise.

The engine has 191,000 miles on it. It has done this shifting thing since we bought it four years ago. Sometimes it's hardly noticeable--more noticeable when you're hauling something in the back or pulling a trailer. I just don't like it when I have to drive it. Oh, and one other thing it does, is a pretty loud click when you put it in gear or in park. We never could figure that out, either. We even replaced the U-joint? I think it was, because that seemed more where the sound was. That didn't fix it. I don't know if these are related.

The headlight switch has been replaced and yes, it looked like it had been hot. Beeman, thanks for the suggestion, and I will relay it because we do use this vehicle to pull trailers.

If you put the auto transmission into low will the engine still have the same symptoms as you accelerate?

I will check this out. I do know that if you push the overdrive button, it seems to make it quit doing the shifting thing.

 

[fordy]

..................About that "click"....try this..while idiling, put your foot on the brake ....then put the truck in gear and see if it clicks, iF Yes, then you Need new....U-Joints.....fordy....

 

[Don Armstrong]

Look, I know this is silly/simple, but check all the mechanical links in your throttle connection. It might be that you are getting stickage because the throttle connections are rough, and they're just plain sticking. Rub them with some fine emery cloth or steel wool or both. I don't think it would cause what you're seeing, but it could cause some problems which could confuse the symptoms you're seeing.

 

[moopups]

Conserning the loud clicking, there is a possiability that the differinal has worn enought that there is slack between the ring and pinion gears. This is cured by resetting clearances by adding shims to reduce the loose space, a job for a compent mechanic. Check the fluid level first, could be that simple.