Low fuel pressure

[rodstored-72]

i have a '86 C10 with dual tanks. i have a 5.3 GEN IV ('11 sub) for some reason I am averaging 53PSI at the rail. i have a AC DELCO EP380 fuel pumps. with the "Corvette style" regulator any ideas what could be causing low pressure. both tanks work - feeding fuel 7 there are no leaks.

thanks!!

[LS short box]

Does it run all right? I may be all wet but 53 psi should be fine. Not a gen 4 but the gen 3 LS6 in my 98 Wrangler runs great at 55 psi. I'm running a Walbro 255 in-tank pump.

[87chevy.com]

Originally Posted by rodstored-72

i have a '86 C10 with dual tanks. i have a 5.3 GEN IV ('11 sub) for some reason I am averaging 53PSI at the rail. i have a AC DELCO EP380 fuel pumps. with the "Corvette style" regulator any ideas what could be causing low pressure. both tanks work - feeding fuel 7 there are no leaks.

thanks!!

spec shows KOEO 55-61 PSI

I had a WIX brand fail within months, full fuel pump pressure at the rail.... toss it and machined down a bosch fuel fuel regulator and installed it to the stock BMW fuel filter (this was a BMW to LS swap)

https://www.bimmerforums.com/forum/s...sure+regulator

also get wayyyyy more filter media in there. only down side is inlet and outlet ports are 5/16


in all of my gen5 swaps, I use a Bosch adjustable fuel pressure regulator and a -6an regulator holder/adapter. dial it in exactly what I need.

clint

[rodstored-72]

thanks for the replies... the fuel press. gauge is reading 58 at idles and low rev driving. it "drops" to around 51-53 at hi revving instances. it runs really smooth and good in general.
clint: what does KOEO mean? thanks for your knowledge.

[AussieinNC]

KOEO Key On Engine Off

KOER Key On Engine Running

[rodstored-72]

aussie, thanks for the reply.

[truckdude239]

i run the ac delco ep381 pump in mine

[rodstored-72]

truckdude, i don't think it is related to the pump "type" as maybe a bad pump from the get go?? still not sure what is causing the "weak" pressure.... I feel 3 possibilities:
1) the corvette regulator/filter (just being set on the weak side)
2) 1 of the fuel pumps (dual tanks)
3) something up with the tank selector valve (not switching tanks completely)

all items are new & purchased from normal channels (amz, lmc, rockaauto)
just have to tackle 1 /time ... i guess
...just frustrating.. aarrggg

[87chevy.com]

I haven't done this myself yet, I've been putting this off for years, but when I get around to installing the passenger fuel tank I will set it up as a transfer pump, use the OEM switch, connector and new aftermarket selector valve, but will have that setup only as a transfer pump to the main tank. I would not trust the selector valve to operate at the higher pressures than intended...

with my setup, I might do one of 2 things..
1) run the aux tank to the valve in, valve out would go to the vent port on the main tank... and then when off, the valve would switch and then the vent line would be connected to charcoal canister, any fuel left in the line should drain back down past the roll over valve .. main and aux tank would need a Y fitting on the charcoal line so the tank does not build pressure.

2) Use the selector valve again to retain the fuel level sensor / gauge working and just have the aux tank pump the fuel into a new bung / -an bulkhead fitting ..


clint

[rodstored-72]

clint, thanks for the info. I am in the process of having the injectors cleaned/tested/checked to see if that helps the hi end "lean" condition the tuner told me about. I liked the idea of the dual tanks, but it makes it harder and more expensive to work with...