fuel pump questions

[dleach1407]

So I think I am still dealing with my fuel pump overheating my fuel. Its better than it was before because I dont have boiling issues but I get a pretty big swing in my fuel trims if I drive the car for a few hours vs 30 minutes. I currently have a on3 triple hat with dual 340lph pumps and an 03 cobra tank. The first pump runs off the computer, the second is activated by a Hobbs switch set at 3psi. I was thinking of switching out my main pump for a 190 or even 155lph pump and leave the secondary 340lph in there for when it goes into boost. I ultimately want to switch back to e85 so I need some overhead but I thought switching to a small main pump will help with the heating issues since I wouldnt be recirculating the fuel nearly as much. As a refresher, I completely rebuilt the fuel system last year. The regulator is in the rear. I have a 8an supply and a 6an return with 8an behind bars rails. the supply line from the rear to the front is wrapped in fiberglass insulation and reflective tape to reduce heat absorption. Will I have any issues running mismatched pumps or should I replace both pumps with 190s?

[dleach1407]

Anybody?

[jcbryant]

Have you thought about running the return fuel through a cooler before returning to the tank. Couldn't a simple power steering cooler from a car help?
you could put it under the car where is could get some air flow.

[wwhite]

Not enough information.
Are your pumps in series or parallel?
Why is your regulator at the rear?

[m-barans]

You could hit the pumps with less voltage and trigger 12V power with a switched relay. A concept similar to factory gen 2 Lighting trucks fuel systems. Just a thought “spin the pumps less until you need them”

[dleach1407]

Have you thought about running the return fuel through a cooler before returning to the tank. Couldn't a simple power steering cooler from a car help?
you could put it under the car where is could get some air flow.

Yes i have. I found a 6an cooler but I really don't have enough room under the car. The car sits pretty low too so under car options are limited

[dleach1407]

You could hit the pumps with less voltage and trigger 12V power with a switched relay. A concept similar to factory gen 2 Lighting trucks fuel systems. Just a thought “spin the pumps less until you need them”

I don't need 680lph. I'm only making 560whp. My car is 99% street car so streetability is the most important thing. I have thought about what you mentioned which could be done with a 5 pole relay and a resistor but i feel using a small pump or pumps is a better option in the long run.

A 155+340 or dual 190s will both meet my needs. I really like the idea of running a 155 and 340. It should solve all my fuel heat issues

[red5.0fogger]

Can you somehow take a temperature measurement of the actual fuel in the tank? Or even use infared thermometer on the bottom of the tank. If the skin of the tank is near ambient i would think the temp is not a problem. It could just be adding air bubbles somehow. I think I saw a video about the cavitation problem.

[dleach1407]

Can you somehow take a temperature measurement of the actual fuel in the tank? Or even use infared thermometer on the bottom of the tank. If the skin of the tank is near ambient i would think the temp is not a problem. It could just be adding air bubbles somehow. I think I saw a video about the cavitation problem.

I think cavitation is unlikely. The return line goes all the way to the bottom of the tank. It doesnt seem to matter if its full or half a tank. If I drive for a few hours, the fuel error is adding 8-10%. If I check them 30 minutes after warmup, they are 0 to 2% off. Im gonna get a gauge to monitor the fuel temps to verify. I dont have a infared thermometer.

[Fasterthangas]

It's my opinion that you don't need 2 pumps. I'm willing to bet one 340lph pump will be fine for your hp. Did you run new wiring to the pumps and what gauge?
I had a similar issue until I went to heavier gauge wiring from the battery to the pump. I now get a good 14v at the pump.
As an example; I ran a 190lph pump on a 400hp 347 with 34lb injectors. I never ran out of fuel.