The Stovebolt Site Forums The Parking Lot '60-'66 Trucks 1966 Chevy C10 250 Electric Fuel Pump

Some time ago I replaced my stock gas tank with the tank mounted in the back of the frame near the rear bumper. Now, after the truck sits a few days, it takes a while to start because fuel drains back to the tank. I've thought about an electric fuel pump and am not sure what pressure is appropriate. Also, I was wondering if there was some form of back flow prevention device that could be installed. Your comments and thoughts please about sizing the appropriate electric fuel pump for a carburated engine. Thanks - Tim-o

Tim,
I had a 250 engine in my 1963 C10. Factory tank too. For some reason the carb would be starved for fuel at highway speeds after 10 minutes of driving. A new electric fuel pump from eBay cured the problem.
You want a simple electric pump that delivers 4-6 psi. No return line is required. If the carb float is set properly and working then the pump will not flood the carb or intake with fuel.
I hooked mine up so it bypasses the mechanical pump.

If you turn the pump on manually then make sure it doesn’t stay running when the engine is off. It’s possible to flood the crankcase with fuel if the carb float isn’t working properly and THAT’S DANGEROUS. The same risk can occur if the pump turns on via the ignition switch. If the engine stalls, the fuel pump could continue pumping fuel past a faulty float valve and flood the crankcase with fuel.

I hooked mine up to a separate switch on the dash. Worked fine. Cheap pumps are noisy. Spend your money wisely.

Thanks for the great advice. I was thinking about a Holley pump. The one I saw indicated it was 3 - 7 PSI. It's interesting that you used a separate switch. I envisioned switched by the ignition, but I could see if you had the ignition switch on without the truck running, flooding could occur. I could also see, at my advanced age... that I could leave a separate switch on.. and cause the same issue. Did you use a block off plate to remove the old mechanical pump?

If you do a search on "electric fuel pump run through oil pressure switch" you will get a number of hits. Usually in the 20-40 dollar range. We wire all of ours this way so if oil pressure drops to zero for any reason the pump shuts off.

Tim,
Coilover has given great advice about using an oil pressure switch to control the fuel pump.
My fuel pump stayed in the engine but didn’t do anything. I bought a blocker plate but never used it. Partly because it still worked and if the electric pump failed I could swap lines back to the mechanical, but I just couldn’t go at highway speeds.

I have purchased a Holley 12-427 Mighty Mite electric fuel pump for the ‘66 250. Taking “Coilover’s” advice, I also purchased a Holley 12-810 pressure switch. I’m looking at the wiring diagram for the pressure switch and it is simple enough - but I’m wondering... there has to be ignition switch “on”power to the pressure switch. Instead of wiring it from the fuse panel, it there a “on” power source available under the hood, and if so, it is advisable to splice into the power source for this purpose? I was wondering about splicing into the existing pressure switch lead.

Thanks -
Tim-o

I have been using electric fuel pumps, mostly as a backup system to the manual pump for over 50 years. Through the years I have found that a rotary pump works best because the manual pump can pull fuel through the pump where as other pumps can't.
An electric pump should be placed as close to the fuel tank as possible because by nature they push better than they pull.
Most vehicle made since the mid '60's have a fuse block generally mounted on the inner portion of the cowl. Generally there will be at least one AUX/Access terminal that is hooked to the ignition switch.
I always install a switch in the line going to the pump, that way I can control when I want the electric pump to run.
If the electric pump is going to be used as the primary pump it is a good idea to install an oil pressure switch in the line. However if the pump is only used to prime the fuel system the oil pressure switch will negate the electric pump.
In theory the oil pump pressure switch will trigger at a low pressure, however, by the time the engine has been cranked over many times the oil pressure might not be enough to trigger the fuel pump.
If the electric pump is being used to avoid a vapor lock, the dead engine will loose oil pressure and there-bye not trigger the electric fuel pump... Been there done that.
I use to have a fleet of trucks that had aux-fuel tanks, usually one on each side under the flat bed, (50 gal per tank) We would run an aux tank til it was out of fuel, then hit the tank valve, either mechanical or electric to switch to the other aux tank, at the same time we switched tanks we would turn on the electric pump to get the fuel moving in lieu of waiting for the engine pump to pick up the fuel. The main tank was the last tank because it was the only one to have gauge in it.
I have had three motor homes that that similar fuel systems, the modern engines with fuel injection changed the game, dual feed systems are now the common application on multiple fuel tanks.

Thank you, Wm L, for sharing your years of experience with electric fuel pumps. I’ve completed the project using your helpful hints and the instructions that came with the Holley pump and oil pressure switch. I mounted the pump on the passenger’s side frame and grounded it by wire brushing a spot on the frame and attaching the ground wire to one of the mounting bolts. All near the gas tank that I moved to the rear of the truck. The fuel line ran down the passenger side of the truck so that mounting position made quick work of mounting the pump and cutting the fuel line to insert the pump inline. I, too, bypassed the mechanical pump and left it in place and used brass plugs in the inlet and outlet ports. I ran the power line from the pump across to the driver’s side of the truck and up toward the cab following the gas gauge line. I took the time to make a wiring cover incorporating the fuel gauge line and the pump power line so that it looks neat entering the firewall. The power line from the pump went to one of the terminals on the Holley oil pressure switch.

I removed the existing oil pressure sender and I utilized a 1/8’’ pipe thread brass nipple inserted into the engine block where the old sender initially was, and a brass “T” to allow for the existing oil pressure switch and the new Holley oil pressure switch to be installed. With the diameter of the Holley pressure switch — it was good that I bought a standard and not a “close” nipple to insert into the block. The tolerances were really close — but I did get both senders installed into the “T”. A minor problem — when reattaching the original wire end to the existing oil sender — the wire broke — so I had to do a little splicing to make that work.

The other wiring was fairly simple — I made a short “jumper” wire from the starter solenoid starter wire to a terminal on the Holley oil pressure switch. Additionally, I utilized one of the “ignition on” terminals at the fuse block to deliver power to the remaining terminal of the Holley oil pressure switch. The way I understand this wiring configuration works, the power from the starter circuit allows the pump to run and move fuel until the oil pressure reaches a desirable level — then the “ignition on” circuit provides operating power for the pump. Still takes a while before starting due to changing the pump location but pressure wise, it appears to be exactly what I needed. I may consider a separate power switch instead of the starter circuit — to get fuel to the carburetor before engaging the starter.