View Full Version : Solution for fuel pump at or near maximum capacity?


ArKay99
05-23-2008, 06:55 PM
I'm running a 99 vette (single fuel supply line), LPE 403 with a bunch of other go-fast parts. I was recently on a dyno and ran 514rwhp on an MAF only pull. The AFR went to 11:1 and stayed there until around 5000 rpm and then climbed steadily to 12.1 @6800 rpm's. I know there is more to be had. I don't think that the limiting factor is the fuel pump, I'm wondering if I should be prudent and make sure the fuel system is up to it. Also, I'm running flow-matched 42 lb/hr injectors. I'm thinking my fuel pump is nearing or is at it's rated capacity. Is there a solution to up the output some to guarantee 58psi at the injector using the stock fuel pump? Or would it be better to just put in a 255 gph Walbro?

onfire
05-23-2008, 08:00 PM
Go with the new Walbro for cheap insurance.

Old Geezer
05-24-2008, 07:35 AM
Go with the new Walbro for cheap insurance.
I agree, it's new pump time.

An N/A tune at 11:1??:confused:
From the numbers you posted, it sounds like you can lean it below 5000, and leave it at 12:1, above, and be good to go?? Maybe, even a bit leaner above 5K?? Say 12.5??

ArKay99
05-24-2008, 08:47 AM
I agree, it's new pump time.

An N/A tune at 11:1??:confused:
From the numbers you posted, it sounds like you can lean it below 5000, and leave it at 12:1, above, and be good to go?? Maybe, even a bit leaner above 5K?? Say 12.5??
No doubt. I didn't get to finish the tune. I was getting the MAF dialed in and had to come off the dyno, so we did one last pull where it was at. I saw the AFR dive from 14.6 to 11 and stay there until around 5k. Then it started to go leaner. That's what got me thinking my fuel pump was done. I want to get the fueling straight, put on some 3" exhaust, and go back and shoot for 12.9 PE. I should pick up some torque and a lot of power.

CamaroSS19
05-25-2008, 06:42 AM
Well it seems you are running wahy to rich down low witch is the reason the pump is running out of steam if you were running say 12.1 the whole rpm range you would probably not see the spike upward cause it would be using less fuel . and you make more power .

You got a 403 you may as well upgrade the pump to at least a walboro or a racetronics and not worry about it . but your curent setup if leaned out should be fine ,actualy its still fine cause your not going dangerously lean but to rich isnt good either