engine surges

[jason lott]

anyone reconize this? When I'm cruising at about mid throttle in my m1008 it surges. This seems like the fuel is restricted and then clears up. Major power surge! I want it to run like this constantly. A friend said it might be the fuel injector pump. I thought maybe a bad injector. By the way it starts, idles and runs good other wise. has a new fuel filter and was primed properly. Any help. I wouldn't be able to keep this truck if it weren't for this forum!!

 

[T_F_E]

Could be a dying lift pump or clogged sock in tank. You could also be getting air in your system somewhere.

 

[Keith_J]

Could be a dying lift pump or clogged sock in tank. You could also be getting air in your system somewhere.

Certainly the above. The engine-driven pump would be my last guess since it is running fast at the conditions of the surge. If the fuel filter purge gives good fuel flow at idle, it isn't likely to be the pump.

Filter? Definitely possible. Pickup sock? Also a good possibility although cleaning it can be a pain since the flexible lines are just long enough. The fuel tank is installed before the bed, reinstalling with bed on means you need to be a contortionist to get all three on with clamps installed. Been there, done it.

The sock is a Nylon affair with a brass screen "window" on the bottom about 3/4" in diameter. The Nylon wets fully, allowing full flow even if there is only 1/2" of fuel in the tank. It can get clogged with bacterial slime. It can be cleaned with compressed air. Clean the tank while you are at it.

 

[skark_burmer]

Once warm, at constant engine speed and load...

If the surge you are feeling is a power boost you have an air leak.
If the surge is a lack of power you have a clogged filter or kinked line.

Air leaks in order of likelihood
filter housing
lift pump
lines at the filter housing
jumper lines between injectors
cracked internal tank line

 

[Fred431]

Had the same problem. I replaced the fuel filter. It was running prior to changing the filter when I tried to purge the new filter no fuel comming out of the filter. It was the lift pump must have been dying all along and the filter change did it in. Anyway I drove the truck from New Hampshire to Florida 1600 miles and it ran fine. This may not be your problem but it cured mine. Fuel pumps are cheap . If yours is the original it might be worth your while to change it

 

[skateabrock]

not likely but, if you are living in NY, and not using this as a daily driver, old diesel can gel up, in the winter months they use a (winter) diesel as opposed to the summer diesel. the summer diesel gels up A LOT if it gets cold and sits for a period of time. Just curious if you don't use your rig as a daily driver, did you last fill up in the summer?

 

[jason lott]

engine surge

It's got a winter blend fuel in it. The surging has occured before and after the filter change. I was hoping the filter was the problem. Based on you info it sounds like a air leak. I'm noticing a little fuel around the fuel filter housing. If fuel is leaking out than air will get drawn in...right? Waiting for the woodstove in the garage to warm up so I can have a better look. (5degrees today!!!) Also, where can I find the Tech manuals for the m1008? Thank you guys for the help!! I've never used a better site.

 

[p3amea6]

It's got a winter blend fuel in it. The surging has occured before and after the filter change. I was hoping the filter was the problem. Based on you info it sounds like a air leak. I'm noticing a little fuel around the fuel filter housing. If fuel is leaking out than air will get drawn in...right? Waiting for the woodstove in the garage to warm up so I can have a better look. (5degrees today!!!) Also, where can I find the Tech manuals for the m1008? Thank you guys for the help!! I've never used a better site.

5 degrees that is why I live on the out bank of NC .No block heater .