VP pump crapping out?

J

jgsturbo

caveman
Joined
Dec 26, 2011
Messages
483
VP truck (S475, 150s, stg2 cam) bucks like crazy after its on the road for 30min towing. Tran Temp is 150s, bucks on any edge setting except for 0/0 (stock). Add timing, things go south.
Noticing some hazing on start up etc.

New pump time? its been run dry a bunch of times do to boost and the damn sump coming uncovered.
 
What am I looking for ? It's connected.
Its been slowly getting worse and worse, only happens after going down the road for 10-15miles. It gets worse the higher levels.

I think I'm ready to try a new SOVP.
Does it on cruise control so APPS is pretty much out.
Aerated fuel? Should happen at all times.
 
The damn edge posi-lock, I might try soldering but not much faith.
Runs normal unloaded even on 6.
 
11-14psi @ the injection pump. Seems pretty steady.

Took it for a drive unloaded and it does chug some if you hit a good hill.
Towing it just gets stupid.
 
Watching, sounds similar to how mine has been acting. Any other oddities, egt, smoke?

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Just a stupid thought but I've seen it affect a couple different vehicles but the fuel tank isn't vapor locking is it? Clogged vent on the top of the tank
 
DISTURBED said:
Just a stupid thought but I've seen it affect a couple different vehicles but the fuel tank isn't vapor locking is it? Clogged vent on the top of the tank
Click to expand...
Can't speak for the OP, but I don't think so with mine, it's only under light throttle, push it harder and it smooths out and seams to run great. Just hot and smokey. That's what sucks, if I drive like a 17yr old douche, it seems fine.

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soo..its along shot but when my fp went bad it plugged my filter with chit and it would run fine like that sometimes and then sometimes it would do the bucking thing....
replace it and rip it apart to see whats in it
 
jgsturbo said:
Wouldn't vapor lock knock down the lift pressure?
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Depends on how much fuel it is letting pass the OFV. Pressure could stay the same and flow be brought down. It was just a thought. Maybe leave the cap off or loose to see if it changes anything. The thing that gets me is it doesn't do it all the time and only does it after being driven for a while. If the Inj pump was going bad you would think it would run like crap all the time unless something is being effected by say heat soak. My personal truck did the bucking while towing real bad when the apps went bad but would do it pretty much all the time but very faint while just driving.
 
jgsturbo said:
The damn edge posi-lock, I might try soldering but not much faith.
Runs normal unloaded even on 6.
Click to expand...

Damn I was hoping you were gonna say stealth plate. I know you said it seems to do it when you add timing. Pull the wire tap and crank the edge back up.
 
Try dumping cool water on the pump when it acts up to see if it goes away.

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Had a pump guy tell me the vp's computer don't get replaced when they are rebuilt. Age and heat seems to be taking a toll on them. I've been threw several vp's. You could feel the timing vary on a couple then bang, they were dead. One would shut off for a millisecond or so then one day it just quit. It's a shame they didn't make the computer a standalone somewhere it could live in a decent environment. I'm guessing no one makes a replacement computer.
 
they wear out. electronics just do..like anything else does

idk if they repl the comp or not but some rebuilds are better than others..
 
IDK, might be tank vacuum. Cracked cap with a load the other day couldn't get it to happen . The lift is fd up with parts right now so might be a minute before I can really check.
 
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