i'm curious if anyone knows the specs of the early style electric in tank assist pump for early third gens that also have a mechanical fuel pump? What PSI it puts out, flow, did it use a regulator?

more specifically, could this pickup and pump set up be used as an in tank method of reproducing the "holley red or carter street" electric pump/mechanical pump configuration?

406 is running out of gas halfway through 3rd gear when shifted at 6500.

traps 107mph when shifted at 5500 to prevent running out of gas..

need more fuel and don't like the noise of external inline electric pumps.

 

well, I was able to find out that the current P/N is 25115461 and cross references to AC Delco EP171 ... (87 LG4 in tank pump). At napa this in turn cross referenes to:
Doesn't seem like it has enough GPH rating.. ??

 

The in-tank pump the factory added in '86 was merely put there to prevent vapor lock by giving the fuel a little added "push." It was not intended to be an alleviation to fuel depravation. At least, that was GM's reasoning behind its addition. I don't think I would trust it to help feed a 406.

What pump do you have now? For the price, I would just stick a good mechanical pump on there, if you have a fuel pump eccentric.

 

already have one of those holley 110gph mechanical deals. it seems to be not quite enough - or more accurately, it can't pull the fuel up from the tank without some help. When I searched, there were some guys running helper electric pumps (carter, holley red, etc.) at the rear to help get the fuel up to the mechanical.

since I don't like the noise of the external electrics, I was trying to find an in-tank electric helper.

but if I'm going to go through the work to put an in-tank electric in where none existed (sump, wiring, etc.), I might as well do a walbro 255lph and a good bypass regulator, and ditch the mechanical altogether.

 

I would think there's something else wrong with your fuel system besides the pump if a 110 gph pump can't keep it fed. The Walbro pump has less capacity than that, 255 lph is only 67.3 gph.

 

right. and if you do the math, this 406 probably won't ever even need 50gph (from the math I found online, 50gph = 475HP).

from what i've read doing searches, the problem is not the pump capacity, but rather it's inability to pull fuel forward from the tank under heavy acceleration. on the second run when I wasn't short shifting, the car probably would have ran 110+ had it not been for the fuel problem...which is solid 12 second territory, traction permitting.

That's why there are people running the helper pumps (holley reds, carter street pump, etc.) in the rear....so the mechanical doesn't have to suck the gas forward.

at least - that's my understanding of it.

 

Should that really be a problem on a 12 second car, though?

 

myself and other cars from our shop have run cars well into the 10s on mechanical pumps alone, so the problem lies elsewhere.

 

alright, i tend to be in agreement now.

i did some more searching and it looks like most folks can successfully run 12's on a mechanical alone. so, i'll go over the system and see whats up.