fuel pumps- electric or mechanical

M

mrscullini

Member
on my '79 sII, 345, the po installed an electric pump. i'm not having any issues, just curious. i like the simplicity of a mechanical pump. what is the advantage (or disadvantage) of the electric pump over the mechanical?
 
One advantage of electric is if the vehicle has sat for a while it is likely to start quickly instead of needing a bunch of cranking to prime the mechanical pump and fill the carb.

Have a friend with an IH fire engine that he wanted to start right up when the key was turned. Installing an electric pump achieved this.
 
FDChappie said:
One advantage of electric is if the vehicle has sat for a while it is likely to start quickly instead of needing a bunch of cranking to prime the mechanical pump and fill the carb.

Have a friend with an IH fire engine that he wanted to start right up when the key was turned. Installing an electric pump achieved this.
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thanks, makes sense. mine does sit for a while between drives. it really is just a joy rider.
 
There is an upside to using an oem mechanical pump. All that cranking to prime the fuel system also primes the oil system too.
 
FDChappie said:
There is an upside to using an oem mechanical pump. All that cranking to prime the fuel system also primes the oil system too.
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that's a good point. especially in my case where it sits, all the oil settles. i think i'll look at swapping back to a mechanical pump. thanks.
 
I have a 72 Scout that only gets started about once a month. I just pull off the top of the air cleaner and pour about a 1/4 shot of gas down the carb, and it always fires off pretty much instantly.
 
One caveat with electric pumps and carbed IH engines is fuel pressure. The mech pumps are calibrated to deliver between 5 & 7 psi. You want the same from an electric pump. This is easily achieved with a pressure regulator and verified with a pressure gauge.
 
Scoutboy74 said:
One caveat with electric pumps and carbed IH engines is fuel pressure. The mech pumps are calibrated to deliver between 5 & 7 psi. You want the same from an electric pump. This is easily achieved with a pressure regulator and verified with a pressure gauge.
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interesting. the po had it installed. i've never checked the fuel pressure. it seems to run fine. i haven't seen a regulator, granted i haven't looked that hard. there aren't too many places for it to hide without being noticed. what would be symptoms of high fuel pressure?
 
Fuel overflow at the carb, flooding out and poor overall performance. You'd know that something wasn't right.
 
Scoutboy74 said:
Fuel overflow at the carb, flooding out and poor overall performance. You'd know that something wasn't right.
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thanks. definitely don't have that. the thing runs pretty damn well.

i got if from the original owner a little more than 2 years ago. under the hood it is all original with a 345 other than the carb. last year i put a pertronix ignition module in. the original speedo was swapped a number of years ago. near as i can tell it has about 120k original miles.
 
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