I've been battling various issues with my pump lately and I've concluded that its just plain worn out and tired. A $700 rebuilt pump is not feasible right now though. The biggest issue I'm having now is when I romp on it my fuel gets cut off and I have to let off the throttle and then roll back into it. The engine doesn't die it just returns to idle. I haven't changed anything in the pump, which leads me to believe that something is failing internally. I'm running the stock fuel pin which I ground on a little, my star wheel is backed out so far that its past the locking mechanism. Fuel screw is in a bit but I don't know how far. And fuel pressure remains the same about 12 psi. Any of this make sense? Thanks.

 

Check the power wire at the fss. Very common symptoms of a bad connection there.

 

I've been down that road before. I know its not that. Its every time I give it full throttle in any gear. It lasts about 5 seconds pulling hard and then its like hitting a brick wall. It just cuts out and returns to idle.

 

I dunno, but it seems like you did make several changes to the pump with a ground fuel pin, star wheel backed way out, fuel screw turned in an unknown amount? Possibly you meant that none of those changes were recent, before problem started.

Regardless, it might be worth a try to reverse the last change you made before problems started? Also to double check everything inside the AFC housing too.

Sometimes a #366 spring install can mess up the indexing on throttle linkage, happened to me and a couple of buddies. Had to get the 3 throttle lever pieces back one notch on shaft for things to work right - loosened it up and moved lever back while pushing down till it 'clicked' down into place. My friends had the same experience correcting that problem on their's.

Can you get ahold of a stock fuel pin to try instead of the ground one? Just some ideas, I'm by no means any kind of diesel expert!

 

Sorry I didn't mention when I made those changes. When I made changes it was running great afterwards. I did all that about a year ago. The way its acting has been recent. I have rotated the pin back to the stock side and it didn't make a difference. The previous owner turned the fuel screw in, but I don't know how much. I'm guessing about 1-1/2 turns and I've gone in another 3/4 of a turn with no hint of runaway. I backed it out 1 turn but it still cuts out on fuel. I've also played with my timing anywhere from stock to 1/8" bump and it doesn't change the way its acting. All this has led me to believe that my pump is just worn out. Its got 330k on it and that last 40k its been cranked up.

 

Sorry to hear that but sorta what I suspected. Hopefully some of the guys can suggest some temporary fix to get you running pretty good, at least long enough for you to save up for a rebuild!

 

Did you turn your starwheel clockwise from stock? If not you may be loosing spring pressure.

 

No I turned it counterclockwise. It's up much higher than stock and has lots of tension. I have to compress the spring when I put the top back on. Every truck is different and that's just what mine likes for better low end power.

 

This tells me you are:
not supplying enough fuel
or
sucking in air at high fuel demands
or
your fuel tank is pulling a vacuum restricting fuel supply

I had a similar deal with my 91. A low pressure piston lift pump fixed that problem.

 

I don't see how I can be running out of fuel. With a high pressure piston pump, 3/8" lines and a 1/2" draw straw I think I'll always have enough fuel supply with a stock pump and stock injectors.

 

Does it do it with a plumb smooth full tank of fuel?

 

Yes. Doesn't seem to matter if the tank is full or empty.

 

Is there any chance that your exhaust system is restricted, like a collapsed muffler or pipe?
I have repared gassers with clogged cats do the same thing, idles fine but would not run past a quick rev.
Jim

 

There's no muffler to be collapsed and the rest of the exhaust is fine. It's got to be something in my pump. It runs great until I hit the very top end of the throttle and then it cuts out. As long as I stay below that point it's ok.