Engine/Transmission (1994 - 1998) No fuel at WOT!!!!

[JAmos]

hmmmmm

I'm gonna do some investigating now. My 97 seems to run better at partial throttle than flat to the floor. It has new filters and a plate similar to a 100 but maybe not quite as aggressive. The plate is far enough back to keep the gov. lever from hanging up underneath, star wheel turned all the way, afc full forward, and gov. springs tweaked. In second it jumps to 3000 rpms, and it sounds clean. No missing/popping.



Jordan

 

[Highfinance97]

If it is leaking from the return line, whould that give me my "WOT" problem???

And why??



Michael

 

[Joe G.]

I've been reading this thread. I don't think anyone has a clue. If the thing starts good and has plenty of power at part throttle than any of the replies so far don't address the problem. I certainly don't know. However, it appears to be some sort of rack position or governor problem better tackled by a pump shop. You might want to check the linkage really close to make sure something is not wrong there.



A return line leak will make a mess and can cause a hard start, but once you have it running it should respond properly at WOT.



Michael,



Do you have a fuel pressure gauge? If not you might want to put one on and take it for a drive to see what it says at WOT when the engine is showing the symptoms. If the fuel pressure is ok, then you probably have an injection pump problem. If fuel pressure dies then look at your fuel supply system.

 

[Highfinance97]

Joe. about the linkage,

since i had everything off the pump when i removed the pump could the linkage be being "overthrown" or Past fuel fuel??



as for a fuel pressure gauge, i have one on but its hooked right into the fass and the fuel line is going straight to the inlet on the 7100. Is the a "T" fitting that i could put inline or would it be better to read the fuel pressure from the overflow valve???



Michael

 

[Joe G.]

First of all, I think putting a FASS on a 12 valve is a mistake. The mechanical pump increases full flow with RPM. Electrical pumps don't. The stock pump is almost bullet proof. Electrical pumps aren't. No cavitation with the mechanial pump. That might happen with an electrical pump.



The fuel pressure you want to know about is at the input to the P7100 pump. That eliminates all problems between the tank and the injection pump. If you have good pressure at the injection pump then look at the injection pump. If not then look at whatever you have between the tank and the injection pump. The pressure at the overflow valve is on the return output of the injection pump. It should be the same, but with an odd problem like this it's better to know what the input side is.



I would look at what the linkage is doing at WOT. Make sure that the fuel solenoid is up when you check the linkage. Turn the key on and lift the fuel solenoid rod to do that. There are a couple of small screws (8 mm socket I think) that attach the linkage lever to the pump lever. Make sure they are tight and both are there. There is an over center point that you will notice when the pedal is pushed. That is because of the way the governor is when the engine is not running. That is ok.



Sorry I can't be of more help, but I have not run into this problem before.

 

[Highfinance97]

Update

I Replaced the return line from the injectors and the pump return line so that fixed my leak, The truck stats better now BUT... ...



I still have a problem at full throttle could it be that the the arm is going under the plate like MLEE said??







Michael

 

[Highfinance97]

Found The Problem

The high idle stop screw is missing so it IS going past full "throttle"



I dont remember removeing or it even being missing



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Michael

 

[JAmos]

With the high idle screw gone, wouldn't that allow even more fueling? Or does it move past the point of max fuel and start to defuel?



Jordan

 

[Highfinance97]

With the high idle screw gone, wouldn't that allow even more fueling? Or does it move past the point of max fuel and start to defuel?



Jordan

yes it will "defuel" actually there is no fuel what so ever





Michael

 

[seriousdiesel]

Hmm, imagine that. did you get the new screw in yet?