I have a 1994 F-250 7.3idi non-turbo 2wd. It has a 5spd & 3.55 ratio with 198,000 miles. When i got the truck, it smoked white smoke badly when i eased off the accelerater. It would stop if i let all the way off or if i got back on the pedal. During this period it would feel as if it was studdering,skipping, or hesitating. It would stop that as well if i got back on the gas. I changed the fuel filter on top of engine & the white smoke cleared up but the studdering did not. Some days are worse than others & have also noticed that if i'm on the pedal hard, it seems to have a dead miss in it every so often. Sometimes the miss would be every 2-3sec & sometimes it would be longer before it missed again. But thats only if i'm on it hard. Just driving normal on the back roads, it runs like a top. I also noticed that it does not blow any black smoke at all, at least not enough that i can see in the mirrors. Just with in the last week i've noticed it being harder to start. Normally i just touch the key & it fires off. Now it seems to want to roll over a few times before it starts, especially when the motor is still hot. Also at idle it smokes a little whitish blue smoke but gets progressivly worse the longer it idles. Sorry for such a long tread, but i just wanted to cover all bases. So would all this be caused by the IP or timing?

 

Also, the trucks averages 16.5mpg. It's a regular cab long bed 2wd 5spd. Shouldn't it be better?

 

Thats not long post, more info is good. And welcome to the forum!

Most likely an issue with the injector pump and you were on the right track to put a new filter on. Under good conditions that truck should get better MPGs but considering the issues, its doing pretty good.

Sluggish hot start is also a symptom of a worn out pump. Internal clearances increase as things age and hot fuel can leak past loose components more easily than cold fuel. Do you know if the pump is factory original? Generally they start to wear out around the 100k mile mark along with the injectors but many are able to beat the odds depending on the quality of fuel they ran and if any supplement was used.

Stalling when you let off the pedal is a sticky governor or fuel metering valve (or both). In theory it might also be affecting the hot start problem. Simple trick is to dump some diesel fuel cleaner in the tank. I run Stanadyne Lubricity supplement, while other guys prefer diesel kleen. For a more aggressive dose, remove the filter, drain it out and refill it with the additive only. Now start and run the engine for maybe 20 seconds and shut it off allowing it to sit over night. Then

For cases like this however, I would use Dex 3 automatic transmission fluid. I had this happen to me and I tossed about 1L in the tank and drove it. 1-2 hours of driving later and it all cleared up, but it really depends on how far gone the pump is. I also have to say that some guys are concerned about using ATF in the tank because its red and you might get busted for that (off road fuel is also "red"). On closer research I found that marked fuel has its own specific dye that can be tested for so legally there shouldn't be an issue.

The reason I suggest ATF is nothing worked so well for me including the purpose bought store lubricants.

 

I've ran seafoam thru the tanks before & it did average better mpgs on that tank but it did not solve the studdering when i ease off the gas pedal. Also, will a worn IP cause the idling smoke to get worse & worse the longer it idles?? Thanks for the welcome, I really hope i can get this resolved.