I have a 92 F350 that chugs/surges when going down the road at highway speeds, especially when going down a hill. When I look in the mirror I can see lots of bluish smoke puffing out when it does this. It also seems to loose its prime when it sits for an extended time (overnight). It turns over for an extended time before it starts. I replaced injectors hoping that would correct the problem, but no luck. I put new fuel lines and glow plugs in it about 10 months ago. Do you think it is the fuel pump? Thanks for the help.

 

Sounds like a pickup in the tank, thats what mine does

 

Have you fixed it before...is it an easy fix? What exactly is happening?

 

pickups in the tanks crack and suck some air. could be but the blue smoke throws me off. only blue smoke when it does this? need more info on truck. auto or man? miles?

 

When the truck starts it smokes a lot more than usual. You can hardly stand to be anywhere near it, strong smell and lots of smoke. The truck has 158,00 miles and is a manual. It puts out blue smoke when it is cold and idling, and also when driving at highway speeds, most noticably when going down a hill. It is not a constant output of blue smoke-it comes and goes. Almost seems like it is getting too much or not enough fuel. Not sure if the starting issues are related, but it seems like it started at the same time.

 

how old is the injection pump?
these pumps are only designed for around 100000-110000 miles.

also what letter injectors did you get. also where did you get them. some companies sell junk.


i am gona say probly injection pump.

 

I have never replaced the injection pump. A neighbor who has had a few 7.3's suggested it was probaly the pump also. Are they an expensive part and labor intensive-not a do-it yourself project? I got the injectors from Pensacola Diesel. Not sure what letter they are, didn't see anything about a letter when I ordered them. What is that?

 

the letter on them determins fuel rate. my stock 83 had letter "a" injectors.
a 94 idi with factory turbo will have letter "gg" injectors.

also the injectors could be bad. i would take them out and have them tested. find a injection shop near you and take them in. also they could do the pump.

 

I made an appoinment at local injection shop. The guy also thought it was probably the pump. Thanks a ton for your help, i really appreciate it!

 

What happened with your diagnosis? It sounds like simply air in the fuel lines. Just bought an 87 6.9L, played with the water sep (didn't know better) before I drove it home 500 miles and had surging on the freeway with problems starting when I stopped to refuel. After reading online extensively I found that those symptoms are indicative of AIR in the fuel lines. Most of the time air gets in via a bad water sep and or bad fuel pump. Both of which are easily cured. Here's the remedy.

First, BYPASS the stock water sep. Second, buy a water sep/fuel filter from RACOR part #BF811. Only problem is that you will be forever tied to Racor fuel filters.

Other option is buy a 1988-1993 7.3L fuel filter mount/manifold from a boneyard. The stock 7.3L fuel filter itself already has a water sep built-in. A little more costly ($40 v $15) than the 6.9L filter, but worth it. You WILL need the plastic bowl that screws onto the bottom of the filter. Bowl is $80 new from Ford, so I'm looking in the local junk yards first.