Upgraded fuel pump wiring, pressure increase. Slight issue

eg6auto · Post by **eg6auto** » Fri Oct 19, 2012 1:54 pm

I have a Aeromotive 340lp in a 92 Si hatch. I installed a relay, running 10awg from the battery to relay then inside gas tank, I also did 10awg inside tank for power and ground. I grounded the (-) outside of the tank where the factory wiring runs. I also put a new main relay in, because I beleive I fried the previous due to fuel pump demand. I had the beginning tune for [email protected], however I've been getting a slight stumble when at idle, cruising, or decel- never when increasing throttle. My Lc-1 wideband went bad so I thought that was the problem, bought a new one and swapped it out, along with plugs (NGK 7E gap .022). Problem still existed so I swapped out NGK wires, along with cap and rotor. Motor felt much better, but stumbling still exists. I looked over it thursday morning and noticed the fuel pressure was around 70psi (wow! how did that happen?). Should I be usisng a fuse inline with the 10awg going to pump to restrict amps? Why didn't factory FPR keep pressure at 43.5? I changed out stock regulator for a decent aftermarket, pressure will increase from 60psi, but not go lower than that. Is this just a tuning issue, or do I need to go back over my wiring?

eg6auto · Post by **eg6auto** » Fri Oct 19, 2012 2:14 pm

Just spoke with a tech at aeromotive (Brett), he told me that now since pump is getting proper current demand, it isn't being restricted. He said it sounds like pressures sre building up inside tank and in return line. How hard is it to upgrade these two lines?

Bindegal · Post by **Bindegal** » Mon Oct 22, 2012 9:40 am

My $0.02: You might be seeing the result of flow restriction in the fuel-return line. As the new pump is likely pushing through much more fuel than the stock one, that means your return line needs to flow much more fuel than it did before. If the fuel return line flow is insufficient, that would result in a higher fuel pressure at the manifold. This would be evident mostly at low duty cycles such as idling. /Allan

Post by **Gaskleppie** » Wed Oct 24, 2012 12:53 am

Bindegal is right. Ive seen it on a S2K with 2 pumps and a starvation tank. Both pumps had to pump it through the old single return line. The pressure went to the moon!

eg6auto · Post by **eg6auto** » Tue Nov 06, 2012 12:44 pm

I'm going to change out the return line with the new black nylon Earls hose, it is steel braided under the nylon to hold most pressure while costing the same. I will also cut off the factory return arm from hanger top, and make hole bigger so I can weld a AN fitting to it. I'm going to use -6AN. Thanks for your help guys, this will allow my pump to last much longer and also I will be able to drop the pressure when and If I need more fuel flow, Allowing me to utilize the feature of the pump- that's why I bought it.