GT-ER

Hi, I don't own a mustang but my friend does and I installed a Saleen supercharger kit on his car but we are having fueling issues.

The mods are as follows:

Free flowing exhaust with no cats.
Saleen Series VI supercharger kit w/ 3.4" pulley.
Ford Motorsports 47lb fuel injectors.
CAI w/95mm maf housing.
KB Boot a pump.

The issue is fuel starvation above 5000rpm. It goes way lean ( high 12's ). The tuner says he thinks it's the pump because fuel pressure drops from 7xpsi to 5xpsi at those rpm. He also says the maf needs more room as it's topping 4.6V.

Thoughts?

hammeron

my only thought is to verify the part number of the injectors to make sure the correct injector values are entered in the tune.

GT-ER

Already did that. He also stated that the injectors were near 100% duty cycle which would make sense if the pump is weak.

Is the 2010 fuel pump that weak? With a boost a pump?

BTW- the car put down 415whp on a mustang dyno.

GT-ER

It would also explain the fuel pressure drop.

GT-ER

Wow...no info.

moosestang

How much boost is the car making? I'd make sure the boost-a-pump is working correctly, sounds like it's not. Do you have the boost a pump turned all the way up?

You should not be making enough boost/power to max out a stock pump + boost a pump. Data log the pump voltage at WOT, but not at 5k rpms, because that **** could blow.

Also, your tuner doesn't sound like he knows what he's doing. You should not be maxing out the MAF with a 95mm housing. I'm pretty sure that's the same size as the whipple MAF housing. I'm at 4.53v at 6k making 10-11psi.

bigstick

my guess is either you have a bad fuel pump, or the BAP isn't cranked up all the way.

The stock pump isn't weak at all. I have the stock pump, 39lb injectors and a BAP and am running 449rwhp with plenty of room to spare.

GT-ER

BAP is working, already checked and it's at 17V. As for the maf, the values seen are similar to yours ( 4.6V @ 6K making 10psi ) so I guess we are good there.

Does anyone know if perhaps the issue is with the 2010 pump? The pump seems to be exclusive to 2010's. I'm also be told by others that the oem pump sucks, there seems to be some discrepancies with what the pump can or cannot do.

GT-ER

I would just hate to swap in another pump and still have the same problem. Fuel pressure drops from 7xpsi to 5xpsi...is this normal behavior for these cars?

moosestang

70 psi is not normal. It maybe normal for a stock pump and boostapump, but dropping off isn't. The only time mine spikes to 70+ is when I let off to shift. With 47lb injectors, i would expect to see 50psi or less at WOT. Mine runs 60psi above 4k, but that's because the whipple comes with smaller injectors and it needs the higher pressure to flow the same amount as a larger injector. How are you reading the fuel pressure?

Be sure all your vacuum lines are routed correctly. Wasn't there some problem with saleens vacuum line instructions? I remember reading something about it years ago.

Are you sure you aren't getting spark blow out? Are your plugs gapped correctly? Just because it's reading lean, doesn't mean it's a lean mixture. You could have 1 plug not firring.

So it jumps to 70psi at WOT, then drops to 50 closer to red line? That's not normal. it should hold 40psi and increase to 50 by red line. This is with dual gt500 pumps, but even with a stock pump + boostapump, it shouldn't start high and then drop.

There are a few tuners over at modularfords.com that post in the tuning/diagnostic forum. I'd try posting your problem there. They may have run into the same problem before.