500 EFI Procharged lean #7
 

I have a 2000 Cat with 500 EFI with a Procharger (motor has 10 hours on it). I have the 50lb injectors in it from Procharger, but am having problems with cylindar #7 running lean. I have set the fuel pressure to 42lbs at idle which allows #7 to run "not lean" but the other 7 holes are rich and the boat wont run well. This condition existed when I had the stock injectors as well. The computer is a mefi3 and has a stock program, but in the next 2 weeks I will have Pfaff custom tune it. Before that, I need to find out why #7 wants to run lean. Any ideas? I heard that the fuel rail may need to be drilled out to a certain size, but want to get your advise. Thanks.

The fuel rail restriction deal was on the mefi-1 and 2 502 mpi fuel rails (pre-99 or even older). You might have a lean spot in your tune at a certain rpm and 7 is the most affected,your custom tune on the water is the best bet,mount a couple of 02 sensors on it first,one near #7 and one near #6 or 8 and see how they compare. You might end up setting bpw a little rich in a certain rpm band to get #7 safe but you probably won't have to pour fuel to the whole motor all the time just to make it safe,Smitty

Related boost reference
 

Thanks for the advice Smitty. Do you have any opinion on using the Procharger boost reference line for the custom tune or should I switch to a 2 bar map sensor? Or, from reading other posts, I'm thinking that the regulator may not need to transition if the injector pulses will possibly compensate for the current pressure transition. Would you suggest setting a constant fuel pressure rather than a transition?

2 bar map sensor

#7 is notorious for running lean. 42# injectors seem small for this build. ProCharger recommends 60# injectors on their LS2 builds.

Both,you should definately run a 2 bar map sensor and custom programming but a 50 lb injector at 42.5 psi will only support 533 hp at .6 bsfc so you will still need to raise fuel pressure under boost
http://www.injector.com/injectorsele...10270102c35ac6
you can play with the numbers and see what I mean,but change the bsfc to .6 when you do your calculations,Smitty