Stalling when Hot, ~Urgent

K

KETCH-UP

New member
Just in time for the extravaganza meet Typhoon trouble! It shuts down when hot. Had this problem also in May 08. In "May" the fuel pressure would drop to zero when hot. The pump was a 2 year old walboro 255. Thought it was odd to fail a pump so soon, but replaced it along with the filter. The problem seemed fixed. Today the problem came back and I was able to troubleshoot while hot. The truck starts after a cool down, runs ok, starts to stumble, shuts off. While stumble starts to happen, timing light on ignition continues ok and blinks some after shutdown of course till engine stops turning.=Normal
The fuel pressure slowly drops when stumble starts, and goes slowly to zero, then shut off. The 12 volt wire at the fuel pump has solid 12 volts until ~ 5 seconds after shutdown. = Normal. I really can not believe another fuel pump is bad. I am thinking the Kenn Bell adjustable FP regulator is somehow crapping out? It shows no signs of trouble... The truck runs good , cold ,under boost. Sorry to ramble, but please help!
 
K

KETCH-UP

New member
Re: Stalling when Hot, ~Urgent

fp relay going bad?

Thanks for the input. I am measuring directly at the wire harness to the fuel pump and getting 12 volts. So i think the relay must be ok.
 
NecroWolf

NecroWolf

lost marbles member
Re: Stalling when Hot, ~Urgent

are you measuring it after it stalled while its hot or when its cold?
 
N

NOWAY55

New member
Re: Stalling when Hot, ~Urgent

Not that this is it, but ...... I was having a similar issue would stall when in gear and stopped or off gas. Reset the IAC and all has been well since. I did check FP and other things 1st though.
 
turbodig

turbodig

Active member
Re: Stalling when Hot, ~Urgent

KETCH-UP said:
Just in time for the extravaganza meet Typhoon trouble! It shuts down when hot. Had this problem also in May 08. In "May" the fuel pressure would drop to zero when hot. The pump was a 2 year old walboro 255. Thought it was odd to fail a pump so soon, but replaced it along with the filter. The problem seemed fixed. Today the problem came back and I was able to troubleshoot while hot. The truck starts after a cool down, runs ok, starts to stumble, shuts off. While stumble starts to happen, timing light on ignition continues ok and blinks some after shutdown of course till engine stops turning.=Normal
The fuel pressure slowly drops when stumble starts, and goes slowly to zero, then shut off. The 12 volt wire at the fuel pump has solid 12 volts until ~ 5 seconds after shutdown. = Normal. I really can not believe another fuel pump is bad. I am thinking the Kenn Bell adjustable FP regulator is somehow crapping out? It shows no signs of trouble... The truck runs good , cold ,under boost. Sorry to ramble, but please help!
Click to expand...

Replace ignition module.

Check your fuel pressure when hot.

Stock chip, or ?
 
K

KETCH-UP

New member
Re: Stalling when Hot, ~Urgent

__________________
Dig

"Replace ignition module."
I put a timing light on the coil wire, and had steady blinks even after the engine stalled out and was spinning down.


"Check your fuel pressure when hot."

My fuel pressure is 52 and solid when cool or warm. When hot the fuel pressure slowly drops to zero. The 12 volt source directly at the pump is solid 12v even when fuel pressure drops to zero.

"Stock chip, or ?"
I have the ultimate 3 bar, it seems to be a good match for my lightly modded truck. Have had in for ~4 years.

Thanks for the input!
 
SY2932

SY2932

Administrator
Re: Stalling when Hot, ~Urgent

turbodig said:
Replace ignition module.

Check your fuel pressure when hot.

Stock chip, or ?
Click to expand...

X2 on the ignition module. Heat will make them act up if they on their way out. GM part #1048-2827. Most of the major chain stores can check it for you to see if it is bad or not. They also have non OEM replacements as well. Have one in my truck at the moment as a matter of fact, a Duralast DR140 (Autozone). Hope to see you in PA this weekend, truck or no truck
icon_smile.gif
!
 
Tooky

Tooky

Serious about performance
Re: Stalling when Hot, ~Urgent

I would try replacing the fuel pump relay regardless, just to see what happens. Relays are only a couple bucks. It sounded like your fuel pump was losing power.
 
SY2455

SY2455

70's Veteran
Re: Stalling when Hot, ~Urgent

Check your EGR valve, If it should stay open all of the time the engine will start to stumble and the other components will try and make adjustments for it until the engine stalls. Are there any codes present?
 
kentuc

kentuc

Member
Re: Stalling when Hot, ~Urgent

You have 12 volts + at the tank,but do you you have a good ground at the tank?
 
K

KETCH-UP

New member
Re: Stalling when Hot, ~Urgent

Thanks for all the good input. I made it to the meet with a few pull over cooldowns.I am going to drop the tank and inspect carefully. I am going to redo the electrical connections in the tank for sure. I may also replace the regulator because it may be bypassing. I am going to try to get it hot and "messing up" tomorrow. I am going to measure the current to the pump to try to prove the inside tank connections are going open. And pinch the fuel return line to see if pressure comes back up to test regulator.
 
AutoVation

AutoVation

Member
Re: Stalling when Hot, ~Urgent

Any news?

I'm having a similar issue. Truck just died on me (2nd time in 2 weeks). First time I replaced the FP with a Walbro 255. The truck ran 100x better than before... until it died on me again on the highway today. I'm going to try the relay and then hope I don't have to start chasing an electrical gremlin...argh.
 
AutoVation

AutoVation

Member
Re: Stalling when Hot, ~Urgent

After reading your post again and comparing with the information from my mechanic, this is the same thing that is happening to my Sy. I just replaced the pump a week ago. It's reading 12V and slowly starts dying as it heats up.

From my other thread:
My question is... how does a fuel pump warming up cause it to go bad? Does a fuel pump actually warm up? It shut down after 15 minutes of driving. Does it take 15 minutes to warm up a fuel pump? Wouldn't either work or not work? I'm not understanding the mechanism of failure here.
 
AutoVation

AutoVation

Member
Re: Stalling when Hot, ~Urgent

KETCH-UP said:
I am set up to catch it, but problem is temporarly gone. Go figure.
Click to expand...

I had the pump replaced (again). Truck is running fine now. Please post if this problem comes up again.

I think I my replacement pump may have been a defective pump. I'm going to check a couple other things first.
 
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