Engine/Transmission (1994 - 1998) Pump problem's, motor won't shut-off

[jpearson]

I think something has come loose or broke in the fuel pump, here's the problem. The motor died when I slowed down to make a turn and did't want to start back up, after I stopped I finally got it started and it was hung wide open and would not shut off, I immediately pulled it in gear and held the brake and finally got it to shut down by holding the brake pulling the mystery switch to bogg it down. I checked the shutdown solenoid and it is working, (it was replaced not that long ago). I am going to tear into the pump in the morning and try to see whats wrong. All the throttle linkage looks ok and appears to be working fine. Any advice and suggestions will be appreciated.

 

[JohnE]

Sounds to be another governor lever screw dropping loose and screwing (pun intended) with a spring stack.

Start with governor spring inspection.



edit

Awesome what a Goerend TC can do isn't it?

 

[Joe G.]

If the fuel shut off solenoid was working where was it getting fuel to run away? The fuel shut off solenoid stops fuel from going to the pump. If there is no fuel it has to stop regardless of what the governor is doing.

 

[jpearson]

Joe G. correct me if I am wrong but with the shutdown being spring loaded it makes it fail safe. It takes power to the sv to make truck run. I think the only problem you can have from the shutdown SV is not starting unless it were to hang closed somehow. The shutdown sv is pulling in and out like its supposed to, something is making the motor go wide open as soon as it starts. The pump looks ok looking thru the side plug and governor lever looks to be working ok. I'm still stumped.

 

[HoleshotHolset]

The shutdown solenoid/lever pulls the rack back to a point where the engine usually dies. If the governor (or something else) is preventing the shutdown lever from pulling the rack back... . then it'll run free.



I have a pump taken apart on my kitchen table and can visualize some scenarios in the governor section that would/could cause this to happen.



98Rammer's pump did something similar to this from a governor lever (or something else contacting the governor spring pack... and bending it). His truck idled at like 1800rpm... but it would still shutdown via the normal routine.



Matt

 

[JohnE]

Maybe it isn't the pump.

Are you drawing oil from a blown turbo seal and causing the runaway?



98rammer and Chillydog both had the governor lever adjusting screw drop into the governor which jammed against a spring stack to bend the rod. That causes a poor running and very high idle but not a runaway situation.

 

[wsmalley]

That's what I was going to add guys... . we are missing the other point here... . the engine was performing a runaway. Realize that our fuel pumps hold a LOT of fuel inside themselves. That would explain why shutting the key off doesn't kill the engine right away. So his shutdown solenoid very likely DOES work just fine. There is bound to be something else feeding his engine (blown turbo seal, etc). During every runaway situation, cutting the key does nothing due to the massive fuel reserve in the pump.



So with that in mind? Why don't we start suggesting causes of runaways. You can start by doing a Search for runaway engines and what causes the different engines to do it. Then apply it to your own truck and look to see if you have that problem. Just MHO of course

 

[jpearson]

You guys might be on to something I spent yesterday looking the fuel pump over and can't see anything loose, I looked at everything I have done to the pump thinking something had come loose but its all OK. I just did a search on runaways, my situation sounds about like what happened to HALLAS and his runaway, but I was lucky I was able to stall my truck out. Thanks for all your help.

 

[jpearson]

Can,t find any signs of turbo problems,the turbo and all the air ways coming into the motor are clean and dry which puts me back to the pump. Does anyone know where any pump schematics can be found

 

[jpearson]

Can,t find any signs of turbo problems,the turbo and all the air ways coming into the motor are clean and dry which puts me back to the pump. Does anyone know where any pump schematics can be found

 

[jpearson]

The cause of the runaway was the pump, it had a plunger cease up. I still don't understand why the shutdown sv would not shut the motor down. I got the pump back today and hope to have my truck back on the road tomorrow.

 

[Deezul1]

I must be missing something here. The shutoff solinoid is what kills the engine when the key is turned of as far as I know. If that is so then the massive amounts fuel in the P pump must not be available to the injectors or the engine would continue to run after the key was turned off. I would think that even though there may be a bunch of fuel in the pump it isnt getting sent to the injectors due to no fuel being added to the P pump and no fuel pressure pushing it there.

Glad you found the problem and we can learn from it.

 

[jstarnes]

the plungers in the pump turn to add/take away fuel (speed up/ slow down the engine) if they cannot return to the zero delivery state of twist (engine shut down,via the solinoid lever pulling the rack back in turn twisting the plungers to "the kill position")



if some thing jambs the rack open the engine can run away



if some thing jambs the rack closed the engine will not start



the rack position is controled by the governer

 

[Deezul1]

jstarnes

Thank you for teaching me something new. I had always thought the solinoid shutoff was like a solinoid valve and it controled fuel flow rather than moving a lever. Its good to know how it really works.

John

 

[HoleshotHolset]

Stuck plunger = no shutdown.



I'll have to keep that in mind. Good info!



Matt