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My '78 with 400 engine with factory duel fuel tanks is having trouble keeping the fuel line primed (i do not drive it every day) and in the high-altitude hot summer it vapor locks. I am looking at installing an aftermarket universal electric fuel pump on a switch, running it only before start up or when it is trying to vapor lock.
Any lessons learned or advice from those that know more then i do? I was leaning towards one of the $15 ones on ebay, and installing it right after the tank switch. I saw something about it having to be at an angle, but I am not sure why? Will my mechanical fuel pump have any trouble sucking gas through it when the pump is turned off? Any advice, or links to previous threads would be much appreciated. thanks!
I was having the same issue on my 75. I daily drive my 76, so my 75 sits for 3 weeks or so between drives. The "GREAT" fuel with lots of ethanol doesn't sit in the carb long and evaporates. So it results in crank and crank with a lot of throttle pumping. I was against running electric only fuel pumps, but cost and effectiveness overcame. I put a Summit "red" pump near my fuel tank. It runs better, it starts better. AND the option of mechanical pump is always there. Just in case TEOTWAWKI happens
Sorry for the double post, BUT....I'm against running electric and mechanical pumps together. There is a risk of failed mechanical pump diaphragm and filling engine with fuel. Not worth it in my worry wart mind.
I have made that conversion on my dent and a '47 power wagon for the same reasons. In terms of pump, the Mr Gasket mini pump works with a stockish engine. The Carter pump would have more capacity. It made a huge improvement on both.
Either pump needs a pre-filter for durability. Normally best is a coarse mesh (100 micron) or course mesh followed by a standard filter if the fuel tank is older.
The pump and filter will act as a restriction with electric pump turned off. Vapor lock issues will be worse w/o the electric pump running. Installing a bypass check valve reduces this problem. On the PW I installed the bypass valve and on my dent I run the electric pump all the time on a relay.
In terms of safety, a low oil pressure cutoff switch can shut down the electric pump if the engine is not running. There is a really good "how to" post in FTE on setting this up. A push button switch to bypass the low OP safety device would be needed for priming.
Here is my two cents. I use a carter electric fuel pump in my 78 F250 and it works great. I bought a check valve and installed it by the fuel filter as well as a small cooler for my fuel line and all problems solved.
The pump and filter will act as a restriction with electric pump turned off. Vapor lock issues will be worse w/o the electric pump running. Installing a bypass check valve reduces this problem.
My mechanical pump runs great except at start ups after sitting, switching tanks when i run one dry (gauge is not working), and when I am in the high country in the summertime, so it is an occasional use thing. I am interested in how the bypass check valve is set up so that I can run both. do I just run a line in parallel to the pump with a check valve?
And can I do the whole thing with 3/8" rubber fuel hose, or is better trying to make use of the factory metal line?
I was having vapor lock problems in the summer time in New Mexico. I went with the electric carter pump and found an electronic fuel pump controller that runs off the tach signal off my distributor. It primes for 2-3 seconds when you turn the key on and shuts off if the motor stalls. No oil pressure switch involved. LMC advertises it.
That pump controller is slick! Thanks for the idea, will get one ordered. I'm solidly in the electric pump fan group, I have several of these that sit for weeks at a time (sometimes months), so when you go to use them, the battery is weak plus the carb is dry - so you end up wanting to crank the snot out of it on a weak battery to fill the carb. The oil pressure switch means the same problem, the pump isn't running unless the engine is spinning, so I have farm trucks that are hooked up keyed-direct (gulp - don't tell anybody), and 2 pickups with the pumps on relays triggered off oil pressure switches, and then a little momentary button under the dash that bypasses it - not the most user-friendly setup (my family and hired help say all my stuff is "owner-operator" - only the owner can operate it ). That little pump controller will make it the best of both worlds! Thanks!!
My mechanical pump runs great except at start ups after sitting, switching tanks when i run one dry (gauge is not working), and when I am in the high country in the summertime, so it is an occasional use thing. I am interested in how the bypass check valve is set up so that I can run both. do I just run a line in parallel to the pump with a check valve?
And can I do the whole thing with 3/8" rubber fuel hose, or is better trying to make use of the factory metal line?
The bypass is plumbed around the electric pump/filter combo. It "T's" into the main line on the tank side of the electric pump and "T's" back into the main line on the engine side.
You should be able to use all the factory hard lines and locate the pump just forward of the selector switch. The check valve is installed to let the engine pump pull fuel from the tank but stop back flow when the electric pump is running. I used a 3/8" brass check valve from the hardware store. Summit and other places would have other valve options. It can be a pretty compact affair. You use rubber hose, including a loop back to the factory line, to plumb up the rest. I did bent up a short length of 3/8" steel line on my dent to help make the loop tighter so it would fit in the frame rail without kinking for neat packaging.
Here is a pic of the pump/bypass setup on the PW. I set it up so the main fuel pump on the engine had a straight shot for minimum restriction. The pump in the picture is one I had laying around. It is electric diaphragm and ideal for this application but not readily available that I know of. The mini pump should work fine. It probably has 5/16" connections so need to plan for correct fittings. I put a dash mounted toggle switch to operate it. Power is key switched.
This pump solved 3 problems 1) vapor lock on hot re-start 2) vapor lock on a steady run in hot weather 3) extreme long cranking after sitting.
Here is a pic of the pump/bypass setup on the PW. I set it up so the main fuel pump on the engine had a straight shot for minimum restriction. The pump in the picture is one I had laying around. It is electric diaphragm and ideal for this application but not readily available that I know of. The mini pump should work fine. It probably has 5/16" connections so need to plan for correct fittings. I put a dash mounted toggle switch to operate it. Power is key switched.
This pump solved 3 problems 1) vapor lock on hot re-start 2) vapor lock on a steady run in hot weather 3) extreme long cranking after sitting.
Thanks, that is really helpful. I like how you kept the run straight for the mechanical fuel pump.
As far as the check valves, this one looks much more robust then the 3/8" fuel check valves (all aluminum) I am seeing on ebay. Is this just a brass plumbing one from the local hardware store? that seems like it would be the weak link in the system
Yes, the check valve is a 3/8" brass plumbing valve from ACE hardware. An automotive design check valve would be more compact and lighter. As far as flow and flow restriction I guess it depends on the particular valve. The brass one is a bit overkill. That said, it works pretty well. After start in moderate weather the truck runs fine with electric pump off.
PS: ditto on the steel T's. If you are ordering parts, you can probably find something lighter and more compact if you want.
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). That little pump controller will make it the best of both worlds! Thanks!!
