BigRich954RR

iTrader: (1)

Ok stock short block engine running 14 psi of boost (procharger). Has been running great at a A/F ratio of 10.8 . With a walbro fuel pumps and meth injection for last few months.

While on a run it felt a little slower I looked over saw a A/F of 13.2 i let off right away.

Before i went home i added alot of fuel to the tune and drove the car home. Driving home car felt fine got on it till 10 psi of boost felt good/strong power a/f staying at 11.5. idle is good no misses so far.

When home i pulled all plugs They looked clean no oil or anything? Put them under a 40X microscope. saw a little bit of alum preping on all, mostly on 7 and 8 plugs saw more alum specks on the white center part. started testing the meth system. Seems ok more tests needed as of now.
Switching meth pump with new one when it comes in. but all tess seem to show the meth system is good

1 Whats things could cause my a/f ratio to change so much looking for all things ?

2 Friend said he heard of the walbro pumps having issues any truths to that?

3 What are the chances the motor is toast even if its running pretty good?

4 Whats engine parts did i mostly likely started to melt ?pistons or heads?

5 What other tests should i do ?

KMS.1320

iTrader: (1)

Could have started collapsing the ringlands preventing the rings from spinning. What you are seeing on the plugs might be from the rings/cylinder wall if that's the case. You'd notice if you detonated a hole into a piston. Start with a compression and leakdown.

Grimes

iTrader: (3)

if you're running 14lbs on a stock shortblock, you were definitely running on borrowed time. Also, if you're seeing Al specks, then start saving for a forged bottom end now.

BigRich954RR

iTrader: (1)

I know I'm pushing the stock block like a mother fker. I have weber racing sleeving a ls2 block right now that's going to be forged.Ordered that the day I upped the boost But like to try getting a little more time out of it.

Still need to find out why the engine went lean in the first place. Reason I have a few questions.

Grimes

iTrader: (3)

what kind of fuel system and injectors are you running?

BigRich954RR

iTrader: (1)

walbro pump with 60 lb injectors meth system thats flowing about 285 lbs per hour of fuel at 15 psi of boost. Been running strong for last few months. just leaned out this weekend

1.8t

Fuel pump could be failing. I know they get spotty before they fail and Walbros seem to have a hell of a rep for failure around here.

koolrayz

iTrader: (26)

I had one do the same thing to me this year. Changed the fuel pump and was good to go

BigRich954RR

iTrader: (1)

Dam i bet its the walbro that screwing me then. how to tell if its the walbro?

koolrayz

iTrader: (26)

I logged a run. The same tune i ran all year. A/F was fine at bottom RPM as the rpm climbed the A/F rose with it. Injector duty cyle was the same as my old logs that had good A/F. I figured it had to be the pump. It was 2 years old so i changed it.
I dont have an in car fuel pressure gauge. This year I will have one and log the pressure from now on.