1991 F-350 Dually Crew Cab 7.3 (not power stroke). 82500 miles
Runs good most of the time but a bit sluggish then occasionally it will have a smoothe and powerfull surge this will last for a few miles. It then returns to it's usual sluggish self.
I change oil, filter every 2500 and fuel & air filters every
3000-5000. MPG 10-12. Any help is appreciated.

 

Injection pump maybe?

Les

 

I agree with Les. The injection pump was the weak link on that engine. They usually needed to be rebuilt (you can buy a rebuild kit for them just like a carburator) about every 70,000 to 100,000 miles.

 

Who offers a rebuild kit?What about internal calibrations in the
pump?

 

 

put a bottle of mystery oil in the fuel tank. It sounds to me like the injectors are clogged up. Or try higher quality diesel or cetane booster. Try the easy stuff before the harder stuff.

 

I say to put a bottle of mystery oil in the fuel tank because it helps to unclog the injectors and also clean out the injector pump. Many truckers I know use the stuff and it works.

 

Do you mean something like Berryman B-12?

My wife and I are testdriving a '95 F-350 (7.3L powerstroke), and it seems to almost stall at times. It has actually died a couple of times at intersections, etc. Mostly I'm concerned with the loss of power on the road. It is hard to describe, but it is like the injectors stop working for a couple of seconds.

Any thoughts on that?

The truck appears to be in great shape and it only has 52000 miles. According to the dealership, a couple used it as a ranch truck, but decided to trade it in for a Dodge.

 

Stanadyne Performance formula works great. The stalling is from the diesel fuel being so dry ( poor quality ). Dump a bottle in both tanks each, and it will work wonders... The performance formula will also boost the cetane rating, and lower the gel point. I can't really say enough good things about it.

1991 F350 CC Dually 7.3l, E40D, Soup bowl removed, K&N