I've always read that electric fuel pumps should be mounted near the tank because they are better at pushing fuel than pulling but just how bad are they at pulling?
I've got a 350 Chevy that's probably about 350hp that doesn't have provision for a mechanical fuel pump. I'd like to put it in my '66 El Camino as a temporary upgrade before I get my big block built for it (which will have a mechanical fuel pump). Since I'll ultimately be running a mechanical fuel pump I'd rather not mess with the fuel lines and running wires to the back of the car that I'll have to change back later. How bad would it be to mount an electric fuel pump up front so I can keep the fuel lines the same and just run some short wiring in the engine bay?
I used to have a Morris Minor that came with an SU pump mounted on the firewall so I know that worked but obviously much lower hp/fuel requirements than the El Camino.
Short answer, no. Long answer, no they don't.
There are some pumps that pull fuel better than others, but none of them are good. I had a Holley gerotor pump of some sort years ago on a car that had a similar need and no space to mount the pump close enough to the tank. Still needed to modify the plumbing though, because you need a vent line from the pump back to the tank return. Pumps set up to do this have an inlet, an outlet, and a vent/purge line because the pump can't pull against pressure, so when moving air, the air goes through this small diameter port until fuel reaches the pump, and the restriction of fuel vs. air then results in the majority of flow volume going to the fuel rails.
It's not a great solution, and the pump still needs to be fairly close to the tank and/or mounted as low as possible so there's some head pressure there to prevent back siphon on shutdown.
I'm not sure about the SU pump. It could have been a gerotor or diaphragm pump like the one I am referring to, or there may have been a low pressure feed pump in the tank.
In reply to gearheadE30 :
I believe the SU pump is a diaphragm type. There is no other pump on the vehicle.
This is for a carbed application running about 5-6 psi.
Noddaz
PowerDork
12/7/23 5:55 p.m.
It won't take much to hook a pump up in the engine compartment to try it.
And if it doesn't work out, you know what you hve to do.
Noddaz said:
It won't take much to hook a pump up in the engine compartment to try it.
And if it doesn't work out, you know what you hve to do.
Yeah, I think I'll try running an electric pump on the current engine and if that works I'll swap the 350 in.
Some are bad, some are really bad. Depends what flow and pressure you need.
The electric pumps with good suction are generally way more expensive than any other solution.
There is a safety thought if replacing a mechanical pump with an electric one. Look into wiring in a safety switch that will turn the pump off if the car crashes, turns over or the engine stops for some other reason. Think about it. If the car crashes and there's a fuel leak with the pump still running, that's an inferno waiting to happen.
Google "electric fuel pump safety shut off switch" and you'll get lots of hits.
In the Jeep world I ran one on the firewall of my CJ for years. A generic parts store 'Purolator' it was the only fuel pump I had. All it had to do was keep the bowl full and it had no problem with that. But I eventually moved it to near the tank and I was glad I did. The reason? Mounted to the firewall or anywhere under the hood and they can get annoyingly loud. Put it back at the tank and you'll never hear it.
Paul_VR6 (Forum Supporter) said:
Some are bad, some are really bad. Depends what flow and pressure you need.
The electric pumps with good suction are generally way more expensive than any other solution.
Everything is expensive these days. The Purolators that I had such good luck with, and I just rigged up one to pump out a boat tank a week or so ago, were purchased for around $25 back in the late '90s 
This guy will run a carbureted street engine just fine. Even mounted way upstream of the tank
An oil pressure switch makes a serviceable fuel pump safety switch. If the engine stops, the fuel pump stops.
It's nice to have an inertia or roll over switch because the motor won't necessarily stop running in a crash.
i'm glad someone mentioned those though / I just remembered I put one in our old bronco and hid the switch a little to where if it got tripped I might not remember!
I ran one on the firewall on my Mini for years, it worked just fine but, I was only trying to fill the bowl on a tiny Su carb, and it only wanted about 2 psi.
I still think it would work, OK. Mine was a cheap generic but the even cheaper "Mr. Gasket" ones I bought at Autozone were terrible if they worked at all.
A 401 CJ said:
Paul_VR6 (Forum Supporter) said:
Some are bad, some are really bad. Depends what flow and pressure you need.
The electric pumps with good suction are generally way more expensive than any other solution.
Everything is expensive these days. The Purolators that I had such good luck with, and I just rigged up one to pump out a boat tank a week or so ago, were purchased for around $25 back in the late '90s
Big difference between carb pressure and efi. The pumps I use that can actually pull fuel and flow good volume at pressure start just under a grand.
Paul_VR6 (Forum Supporter) said:
A 401 CJ said:
Paul_VR6 (Forum Supporter) said:
Some are bad, some are really bad. Depends what flow and pressure you need.
The electric pumps with good suction are generally way more expensive than any other solution.
Everything is expensive these days. The Purolators that I had such good luck with, and I just rigged up one to pump out a boat tank a week or so ago, were purchased for around $25 back in the late '90s
Big difference between carb pressure and efi. The pumps I use that can actually pull fuel and flow good volume at pressure start just under a grand.
Uh...roger. Did the OP indicate he was going to run EFI on the engine he was ultimately going to replace the mechanical fuel pump on?
It sure sounded to me like he's asking if an electric pump will work to suck fuel in lieu of pushing fuel to a small block Chevrolet in a '66 El Camino. I don't get all of the comments here acting like that's a heavy lift.
Scrooge face off.
A 401 CJ said:
Paul_VR6 (Forum Supporter) said:
Some are bad, some are really bad. Depends what flow and pressure you need.
The electric pumps with good suction are generally way more expensive than any other solution.
Everything is expensive these days. The Purolators that I had such good luck with, and I just rigged up one to pump out a boat tank a week or so ago, were purchased for around $25 back in the late '90s
This guy will run a carbureted street engine just fine. Even mounted way upstream of the tank
Thanks for info with real world experience. Sounds like I wouldn't have any problems. It's actually academic now as I have a different engine lined up that has a mechanical fuel pump.
