02 Chevy 2500HD 8.1L PO171

[Arc Burn]

Idles fine get on the gas a little and it just stumbles trys to quit,code is po 171 lean on bank one.
I did regap these plugs lower a few weeks ago as per JohhnyD's specs,gonna check them again,maybe i was off a bit.

[mrl16]

check fuel pressure

[Arc Burn]

Ran fine for a few hours now both banks are lean and PO506,idle controll/rpm low?

[Arc Burn]

Gonna look for a fuel pressure gauge tomorrow,filter is 6 months old,i cleaned the mass air sensor,just got in from plowing,42" here and this stumbling truck was not happy:(

[wyldman]

Sure sounds like a weak fuel pump. Also check for air leaks !

[John DiMartino]

This is not from the plug regap...this is a proven mod....check for air leak in intake boots,between TB and MAF,and fuel pressure....the 8100 trucks go thru filters fast...orobably because they go thru a lot of fuel :D.Did you post for help on the dieselplace? I would if you didnt already.

[Arc Burn]

Dumb question,just took the truck out for 10 minutes,brought it in to change the fuel filter,both convertors are to hot to touch after 10 minutes of driving yet the muffler and all pipes before and after the convertors are relativley cool,should they heat up that fast?

[John DiMartino]

10 minutes is plenty of time to heat up the convertors especially if your driving it.....

[Arc Burn]

Alright.Just changed the filter,same thing,just took the chains off today so i was able to try and bring it up to speed,hit the gas full throttle and nothing,just a huge bog,spit and carry on,looking for a fuel pressure gauge still....

[Arc Burn]

Have a gauge coming in the morning.....

[motormouse]

I'm just throwing this out there:


We were talking about 8.1 motors yesterday and a friend of mine says their town has 8 or 10 trucks with this motor and 100k plus on each one. The only problem they had were some kind of sensors that went bad causing truck to run poorly.

[John DiMartino]

I'm just throwing this out there:


We were talking about 8.1 motors yesterday and a friend of mine says their town has 8 or 10 trucks with this motor and 100k plus on each one. The only problem they had were some kind of sensors that went bad causing truck to run poorly.

Crank sensor...thats all that goes wrong with them usually,along with exhaust studds if they are worked pretty hard...

[Arc Burn]

20psi at idle:(Guess it's pump time:rolleyes:

[John DiMartino]

20psi at idle:(Guess it's pump time:rolleyes:

Your lucky it even ran....and got you home...It is possible,(but not likely) it could be the fuel pressure regulator as well.Just wanted to put that out there.I know mine is adjustable...57psi (with vac hose off) seems to be the sweet spot for my truck..On the old school EFI i used to slowly pinch the fuel return line with needle nose vise grips with the pressure guage on it when its running,and watch the guage to see if it climbs up....most new trucks have plastic lines....or the regulator is in or near the tank
im willing to bet the pumps been weak for a while,when you replace it the truck will probably run like a raped ape..esp with your tightened plug gaps...

[Arc Burn]

So is your regulator on the fuel rail or in the tank?The guy that just took the rreading said it wasn't adjustable?

[John DiMartino]

The regulator on my 01 is on the fuel rail.........mines got a small allen head screw under a rubber cap,not sure if they are all that way.i didnt know mine was adjustable,I found out from thedieselplace....

[Arc Burn]

Driver side towards the rear,i see something that resembles it with a small vacum line but this unit is not removable,it's part of the rail,looks like a snap ring on the top of it though?
I'd be pissed if i replaced the pump and it was something stupid like a contaminated regulator.

[John DiMartino]

Arc,chances are 99.9% it is the fuel pump......

[Arc Burn]

Yeah,gonna bite the bullet,now i'm seeing 3 or 4 different pumps:scramble,why can't things be simple;)

[Arc Burn]

New fuel pump,much better now;)Thanks to all who helped