Alot of marinas have switched to ethanol gas now also. Real issue for marine fuel systems

Fuel Injectors all checked out good.

Now that you guys mention injectors going bad I think I will set up my Holley EFI to run close loop with about 30 percent correction allowed. If I have 1 injector go bad I would hope it would richen up the remaining 7 enough to alert me to a problem.

Hadleycat, heres some math, lets say you have a target afr in your auto tune set for 12.0, a injector starts to falter and flows 30% less (happened to gimmefuel), and lets assume your running batch fire 2 and 2 on each side with a 02 sensor on both pipes. So your 30% less cylinder spikes to 15.6 afr, the other 7 are at 12.0, your overall average is 12.44, so when your computer "autotunes" it back to the 12.0 target youll have 7 cylinders that are 11.5 and one thats 15.0-1, not good. Now if it tunes each batch individually and you ran bothh batches down odd and even sides of motor it would be more like the 3 cylinders would be 11.0-1 and lean cy;linder would be 14.5 but still if boosted would melt piston or tulip valve, fwiw, Smitty

put a 02 bung in that tube and see what you have, bet its lean

Question.... Several years ago had 502 MPIs rebuilt as 540s 500hp by a big name shop. #7 leaned out twice on one motor and once on the other causing the piston to fail with first 6-10hrs. These were Dyno tuned and no corners cut anywhere. The "fix" by the builder later on (he did stand behind his work) was a larger injector in #7.

Just curious what your guys thoughts are? Sold the power after it was last fixed disclosing all info as faith was lost in it.

In a batch fire scenario how will one larger injector help 1 cylinder ?? my understanding is its all mixed in the plenum and the firing hole takes what it needs, at least that's how it was explained to me. It would help in a direct port injection intake

a 502 mag has one injector per cylinder,no mixing in the intake manifold.

are you running merc intake ? single planes will also be better at equalization from what I've seen, smitty is testing a lot of this as we speak..

Oopps, ya I was thinking of the 500 EFI my bad

Yes stock MPI intake with modified fuel rail