surging issue

[sht2kll]

Howdy all: I have an M1008. Lately, while driving on level road at 55 mph, my truck will accelerate a couple of hundred rpm by itself (almost like a dead cylinder that all of a sudden comes back to life. In the last few days i noticed while driving uphill, with my foot mashed to the floor to accelerate, it is surging pretty good. I can't say that it is losing power, because this truck will only do 35mph going up the hill as it is (5800' AGL). I am going to change my fuel filter, but was wondering if maybe the IP is headed South.? I also thought maybe an injector,but the truck seems to idle ok and accelerates fairly smooth. There is no injection services where I live and the closest place would probably be Twin Falls, Idaho.I would hate to just throw parts at it, but that may be the only option in my case.

[Robyn]

Do check out the filter first.

If this does not do it, or you then have troubles priming the filter, look at the lift pump.

A system with a failed/failing lift pump will still function fairly well but under a hard pull the transfer pump in the IP can't pull enough fuel to get the job done and the engine will/can surge.

Unplug the power wire (usually large Pink) from the IP when repriming the filter.

You can unhook the line from the lift pump (engine mounted on the 6.2) and run a line into a can.

Spin the engine and see how well it pumps fuel .

Never do this with the IP power connected as the engine will fire and you will suck the system full of air :(

Check this stuff out and see what shakes.

Missy

[sht2kll]

I removed the stock fuel filter assembly and put a Stanadyne FM100 head assembly on it. It accelerates going up the hill now. Funny how when it loses power gradually over time you forget how well it did when it was healthy. Thanks for the help

[Subzilla]

And don't forget to keep a spare filter with you. I've had to replace mine a couple of times while away from home. It seems like the surging/lost of power symptoms come on suddenly and you never know when they will come. A bad tank of fuel from a shotty gas station can contibute to this condition even though you may have just installed a new filter. Poor running? Always change the filter first.