My Truck is possessed! Crazy Surging Idle HELP [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: My Truck is possessed! Crazy Surging Idle HELP


stevenrossi
11-22-2007, 01:48 PM
Hey fella's!

I don't normally post here because my 6.2L has been great to me, but just recently it decided to start giving me problems! and this one i can't figure out. I've searched the forum and its not giving me the exact answer i need!

Long story Short

Woke up in the morning, fired up the truck...drove to work no problems...nothing out of the ordinary. Stopped at the bank, got my coffee and parked at my shop everything was A-OK. This is where it got wierd...i shut off the truck and went inside...my delivery driver came in for work and his delivery had shown up...so he went outside and started up the truck ( i use the truck as a daily driver and a delivery try ). I heard all of this from inside...it started up just fine...then as he just got in the door, letting it warm up again and to pickup his paperwork...i hear the truck SURGE waaay up...come down...shut off...end of story.

Ever since it just surged up and died, its been nearly impossible to start back up...i turned it over for about 45 seconds total and it finally started...and BOY did it run rough. The idle hunts up and down...and it'll either die or just run rough and surge like crazy.

A) It continues to surge - this surging will not go away warm or cold
B) My fuel pump (frame mounted) is working
C) I changed my fuel filter 5 minutes after it started doing this - didn't fix the problem
D) New fuel tank
E) All belt accessories seem ok and not siezed
F) There is power to the IP
G) I've never changed anything on the motor except for the alternator since i've had it - so the IP does have some mileage on it
H) When the truck is running, i opened the bleeder valve on the thermostat housing and fuel did come out at a steady rate and the truck didnt shut off after about 10 seconds, there wasn't any air in the stream that i could see.

I have my fuel driver working permanantly - its wired up so its always running when the ignition is on...so i turned the key ahead to have the pump run and looked around for leaks as it built up pressure...and i didnt see anything dripping or leaking. I cracked the front 3 injector lines on both sides and each of them had fuel, some more than others (it seemed) but fuel, none the less.

The local diesel mechanic told me that its the IP - but i mean this just happened out of the blue, the truck never smoked or had a hard time starting...it was perfect up untill that happened, nothing wierd what-so-ever.

I may have missed a few details so please ask me any questions, and don'r be shy, i've worked with diesels before so i know more than the average guy, but not EVERYTHING.

P L E A S E H E L P!!!

email me directy with any tips!!!

stevenrossi49@hotmail.com

jdemaris
11-22-2007, 02:43 PM
I may of missed it somewhere - but I don't see where you've described exactly what your vehicle is - as to year, truck -Suburban, Blazer, Van, etc.?

It would help to know what you have - and especially if it's older than mid-1985.
From what you describe, it sounds like the injection-pump housing is over-pressurized - perhaps from a clogged outlet. Try removing the return-fuel fitting completely from the pump and check it to see if there's anything stuck in it.

stevenrossi
11-22-2007, 03:08 PM
I may of missed it somewhere - but I don't see where you've described exactly what your vehicle is - as to year, truck -Suburban, Blazer, Van, etc.?

It would help to know what you have - and especially if it's older than mid-1985.
From what you describe, it sounds like the injection-pump housing is over-pressurized - perhaps from a clogged outlet. Try removing the return-fuel fitting completely from the pump and check it to see if there's anything stuck in it.


Its a 1991 Chevrolet K1500 6.2L

How does one get to the return line? Must i remove the intake?

P.S - its impossible to start. Do you think the supply pump is getting weak?

stevenrossi
11-22-2007, 03:15 PM
Update - within 10 seconds of disconnecting power to the lift pump, the truck studders and dies.

roblrobl
11-22-2007, 04:12 PM
Sounds like a sticking or worn out shut off solenoid in the injection pump. Try tapping on the pump after turning the key on.

stevenrossi
11-22-2007, 04:46 PM
Another UPDATE!!!

Pinhole leak behind the lift pump!! Im fixing it right now and we'll see if this fixes the problem!

Keep your fingers crossed fella's