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Discussion Starter · #1 ·
I noticed yesterday that my fuel pressure dropped quite a bit. Is this normal for the twin walbros to get heated and lose capacity when outside temperature is up or the fuel tank is below half full? this would not be too good if I was to run someone with a low tank of gas.
 

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Discussion Starter · #7 ·
jaynite said:
how big of a drop are were talking here? i had an issue with one of my rubber lines in the tank after installing my 2 pumps and could'nt get more then 33psi...one of the lines was split..replaced both lines to be safe and now its solid at 43psi... i also only run one pump at anything under 2psi i believe, once over that the other one turns on..

jay
I think about 7lbs of fuel pressure drop. When the tank is full I do not see this problem. I think the pumps are heating up and not as efficient as cold. BTW, this is twin walbro into a -8 braided line.
 

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Discussion Starter · #8 ·
supra400hptt said:
I'm the only one that I've seen with this problem, but when I ran my pumps off of the battery my fuel pressure would drop after starting the car. It would go down around 8 psi after a few minutes of running. I ended up hooking the walbros back up to the stock fuel pressure ecu and with regulated voltage my fuel pressure is stable now. Try it if you don't find another solution.
I ran the pumps off the batery since I thought the ECU did not provide enough power for 2 pumps.
 

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Discussion Starter · #11 ·
silvino said:
How did you wire that? Almost everyone I know running dual pumps triggers relays off of the fuel ECU, and direct power to the relays which power the pumps directly.
I used the ecu to trigger the two relays also.
 

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Discussion Starter · #12 ·
supra400hptt said:
Dual walbros and -8 here also. My pressure would be in the low 30s at start up, a few minutes latter start to drop a psi or two at a time until it ended up in the low to mid 20s. Drove me nuts. I changed pumps, regulator, put in a fuel cooler and finally rewired the pumps to the stock fuel ecu. Problem solved.

There have been several discussions on running two pumps on the stock fuel ecu. Don't do it with MKIV pumps. Ok in my experience with two walbros. Search for those threads if you want to read more.

It is interesting that you are powering both pumps with the stock ecu power. I would like to resolve this problem too. May be I will monitor the fuel pressure when the tank is full and see if this problem exist there. Thanks.
 

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Discussion Starter · #21 ·
sully said:
i run my dual walboros on the stock fuel ecu.. I ran new wire inside the tank to the stock connector and ran new wire outside the tank using the stock connecters (depinning). I grounded my pumps on the pump hanger and used the old +/- at +/+ for the 2 new pumps.
I did the same for my set up. It might have to do with the Aeromotive FPR when it is hot. However, I noticed this problem with the SARD FPR I was using too.

I have been monitor my fuel pressure the last couple of days and I noticed that the pressure does not drop as much if the tank is full or more than 1/3 full. I guess I just have to keep more fuel in the tank from now on.
 

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Discussion Starter · #23 ·
Chucky Doll said:
I’m running the dual pump/line set-up myself. Both pumps are running full-time at 12v. I’m not seeing the problems some of you are experiencing. I’m curious to whether or not you guys are insulating your pump?
I think I used a rubber sock that came with it.
 
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