Fuel pump suggestions
Thread Starter
Heel & Toe
Joined: Dec 2008
Posts: 18
Likes: 0
From: Oakdale Ca
Fuel pump suggestions
Hey folks, I had my 87 dyno'd a couple weeks ago. It made 434rwhp, which I'm happy with at least till the end of the week. Anyways at around 5200rpm it started leaning out a bit. We had it at around 11.5 aft till that point and then it started climbing and by 6000rpm it was at 12.5afr. The Dyno guy is saying fuel pump. I have a walbro 255lph intank pump on it and 50lbhr holley injectors. The ecu is a sds programable unit. I increased the rpm and fuel maps up high but it made no difference. So either pump or injector I would guess. The fuel pressure gauge didn't drop at all like I would think it would if it were the pump. But I thought the injectors would also be good for more hp than I'm running. I didn't look at the duty cycle while it was on the Dyno so I'm not sure what it was running at. Any advice would be great. Ah and the motor is just a 350 8:1cr with a procharger d1 at 10psi
Melting Slicks
Joined: May 2001
Posts: 3,014
Likes: 18
From: Raleigh, NC
As long as the pump is healthy, and seeing alternator voltage (~14) the pump should support that kind of power pretty easily.
However, if you want to put a pump in it, I really like the fuel lab pumps. They are expensive, $400 or so, but it's the last one you'll have to buy.
Another option is the stock pump from a Toyota Supra Turbo. They are more powerful than the Walbro 255, quieter, are only marginally more expensive (I've seen them for $155 online) and have a much better track record when it comes reliability. That is what I would use if the fuel lab pump wasn't an option.
I've heard about a new pump from Bosch, but I don't know anything about it. It would be worth investigating if you are looking to replace the pump.
Good luck!
However, if you want to put a pump in it, I really like the fuel lab pumps. They are expensive, $400 or so, but it's the last one you'll have to buy.
Another option is the stock pump from a Toyota Supra Turbo. They are more powerful than the Walbro 255, quieter, are only marginally more expensive (I've seen them for $155 online) and have a much better track record when it comes reliability. That is what I would use if the fuel lab pump wasn't an option.
I've heard about a new pump from Bosch, but I don't know anything about it. It would be worth investigating if you are looking to replace the pump.
Good luck!
Supporting Vendor
Joined: Oct 2004
Posts: 761
Likes: 68
Hi B69, Couple of years ago I posted lots of pump tests including the Toyota. The Toyota does flow a little more but can pull up to 30 amps - yes 30 !!!
Fuel pressure should have continued to rise with boost - so it is a fuel delivery issue, BUT:
What fuel pressure regulator are you using? Aftermarket units like the SX and Fuelab "waste" a lot of fuel on the return and require monster pumps to deliver what you need.
If you have a stock regulator then install the Racetronix wiring harness and an in-line GSL-392. That'll be the end of your fuel delivery problems.
BR - greg
Fuel pressure should have continued to rise with boost - so it is a fuel delivery issue, BUT:
What fuel pressure regulator are you using? Aftermarket units like the SX and Fuelab "waste" a lot of fuel on the return and require monster pumps to deliver what you need.
If you have a stock regulator then install the Racetronix wiring harness and an in-line GSL-392. That'll be the end of your fuel delivery problems.
BR - greg
Thread Starter
Heel & Toe
Joined: Dec 2008
Posts: 18
Likes: 0
From: Oakdale Ca
Hey greg,
Thanks for the reply. I currently have a holley stealth ram intake and the fuel rail and regulator it came with. I'm not sure what kind it is. It is adjustible thou. How much power will the additional pump and wireing support horsepower wise. After doing the math the 50lb injectors are only good for about 700hp NA. And I was thinking I'm making around 500 at the crank and I'm still burning extra fuel to drive the blower. Which if I remember correctly takes nearly 100hp at 10psi on a 350. So that puts me at 600hp worth of fuel. And I'd like to up the boost to around 15psi shortly so I don't want to upgrade the fuel system another time after that.
Thanks
Chris
Thanks for the reply. I currently have a holley stealth ram intake and the fuel rail and regulator it came with. I'm not sure what kind it is. It is adjustible thou. How much power will the additional pump and wireing support horsepower wise. After doing the math the 50lb injectors are only good for about 700hp NA. And I was thinking I'm making around 500 at the crank and I'm still burning extra fuel to drive the blower. Which if I remember correctly takes nearly 100hp at 10psi on a 350. So that puts me at 600hp worth of fuel. And I'd like to up the boost to around 15psi shortly so I don't want to upgrade the fuel system another time after that.
Thanks
Chris
Supporting Vendor
Joined: Oct 2004
Posts: 761
Likes: 68
Hi Chris - with the 2 pumps in series you can easily support 850 HP @ 70 psig (you must use the Racetronix harness to power the 2 pumps). With the 2 pumps I think you'll find the Holly 50's are just fine.
BR - greg
BR - greg
Thread Starter
Heel & Toe
Joined: Dec 2008
Posts: 18
Likes: 0
From: Oakdale Ca
Thanks greg,
That sounds like just what the doctor ordered. Do you sell the pump and harness? I might be interested eventually in doing away with the IC and using one of your elbows and water/alk injections too.
Thanks
Chris
That sounds like just what the doctor ordered. Do you sell the pump and harness? I might be interested eventually in doing away with the IC and using one of your elbows and water/alk injections too.
Thanks
Chris
Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
As an FYI, I was running the twin Walbros on my '87 Vette combo up until I switched away from the 355. That combo went as far as 571WHP and no issues with the fuel pumps.
I have a monster in there now and can see no reason why I would ever need to upgrade.
I have a monster in there now and can see no reason why I would ever need to upgrade.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer