Off Idle Stumble???

G

Gmoney

New member
So I just put in a new Walbro fuel pump, and after about a week I have this off idle stumble. When I'm at a light then give it gas to go it stumbles real bad then it catches and seems to run fine. Another thing too, I get a check engine light like two minutes after I start it, it stays on for a minute or two then goes away. I jumped the two ports on the ALDL to see what it might be, but all I get is code 12.

Today it won't even run....any ideas?
 
AUSyTyIN

AUSyTyIN

Unbusted $#it box
Re: Off Idle Stumble???

I've found that when you "fix" something, and something "else" goes wrong, 95% of the time it is what you "fixed." Worth checking in my book
 
It's just a six

It's just a six

Super Member
Re: Off Idle Stumble???

Yup, I agree, just because a part is new does not mean it could be a bad part.
I have put in $250,000 auto pilot computer new, & it was no good. Had to return it & get another new A/P computer.
And these parts are supposed to be much better than a car part, when a plane has a problem in the air..[flying] it can't just pull over to the side of the road like a car can.
 
bezerk

bezerk

New member
Re: Off Idle Stumble???

It's just a six said:
Yup, I agree, just because a part is new does not mean it could be a bad part.
I have put in $250,000 auto pilot computer new, & it was no good. Had to return it & get another new A/P computer.
And these parts are supposed to be much better than a car part, when a plane has a problem in the air..[flying] it can't just pull over to the side of the road like a car can.
Click to expand...

did you test drove it?:D
 
SpoolingTurbo6

SpoolingTurbo6

Donating Member
Re: Off Idle Stumble???

AFPR? or some junk in the filter or injectors.............try + - the fuel pressure, more fuel
might be getting in now
 
Don W.

Don W.

Stab it and steer it
Re: Off Idle Stumble???

Pull the ECM "a" & "b" fuses to reset the thing then do a test drive. Also the TPS comes to mind. If you didn't touch it would it choose now to fail? Does it stumble if you ease into it? What happens when you floor it from an idle?

As mentioned do you have an AFPR?
 
G

Gmoney

New member
Re: Off Idle Stumble???

I'm gonna get it scanned tomorrow to see what that check engine light was all about.

I do have a AFPR, what should the fuel pressure be set to, its a lightly modded truck; 20g, 3bar, custom chip, alky...
 
D

denny

Active member
Re: Off Idle Stumble???

Gmoney said:
I'm gonna get it scanned tomorrow to see what that check engine light was all about.

I do have a AFPR, what should the fuel pressure be set to, its a lightly modded truck; 20g, 3bar, custom chip, alky...
Click to expand...

If you have a custom chip then you will have to contact the chip vendor to see what the static FP should be.
 
G

Gmoney

New member
Re: Off Idle Stumble???

Hooked it up to a fuel pressure gauge and drove it today. The stumble off the line would come with a drop in fuel pressure. It didn't matter if the vacuum line was on the regulator or off and plugged, fuel pressure was all over the place.

I just replaced my pump because racetronix said there was rust in the pump and fuel sock, would rust be causeing the new pump to have problems??

If so why do I have rust in my tank, and how do I get it out?
 
Don W.

Don W.

Stab it and steer it
Re: Off Idle Stumble???

Gmoney said:
If so why do I have rust in my tank, and how do I get it out?
Click to expand...

Well your got some water somehow, it's that simple.

Fuel tanks can usually be cleaned and leaks repaired at a radiator shop. Call around for estimates.
 
sy2675

sy2675

He Saved the Pimp'n Game!
Re: Off Idle Stumble???

I am having this same stumble. If i ease into it it stumbles, but if i nail it it seems to run fine. Any suggestions? I have sent some datamaster files to my tuner but havent heard back yet.
 
AUSyTyIN

AUSyTyIN

Unbusted $#it box
Re: Off Idle Stumble???

sy2675 said:
I am having this same stumble. If i ease into it it stumbles, but if i nail it it seems to run fine. Any suggestions? I have sent some datamaster files to my tuner but havent heard back yet.
Click to expand...

Find a different tuner :D His seems like a rare case, yours might be a fuel issue, and ignition issue, or a few other things. Recent tune up?
 
G

Gmoney

New member
Re: Off Idle Stumble???

So that day I tried to start it and it would barely run was because of the MAP sensor. I have razor's alky kit and it gets its readings from the MAP sensor. That day I tried starting it the stock boost gauge was pegged at full boost as soon as I turned the key on, therefore telling the alky pump to spray. I had a full tank of methanol in there that day and it sprayed all of it into the motor resulting in the hard start. I replaced the MAP senor today, drove it and the stumble seems to be gone. I'm going to drive it to work tonight and see if there is any stumble.
 
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