mechanical lift pump to fuel pump
 

hey guys i got my 93 12 valve cummins i put in my chevy and im just getting ready to fire it for the first time. i keep hearing bad things about these mechanical lift pumps though so i got a question about it.

the chevy came with an aftermarket electric in line fuel pump that is about 2 feet from the motor. can i use that with my mechanical fuel pump or can i replace my mechanical fuel pump with the electric one? or will it damage something if i add the extra fuel pressure? it would also help me a ton in priming the fuel lines. any input is greatly appreciated. thanks

it only needs 9 to 12 psi to run now if you plan on bumping up the power you will need more volume an airdog or a fass will do the job

more then 12 psi will blow the seals in a ve pump.You can use the electric pump with a regulator,but theres nothing wrong with the factrory lift pumps if theyre in good shape.The piston type pumps(mechanical) are a good conversion,but there are 2 types,a low pressure (for ve pumps) and a high pressure(for p pumps)

im just not a huge fan of the mechanical pumps and since i already have a nice mechanical i think ill just use that and use a regulator on it as well to keep it around 10 or 11 psi with a nice fuel filter. i just didnt know if it was bad for the engine or something to use an electric pump

The stock lift pump is fine for a stock engine, producing 5-7psi. The only problem with them is being a diaphragm design they are liable to fill the crankcase with diesel if they fail with a bad diaphragm. The VE will only take somewhere around 20psi max input pressure before you run the risk of blowing out the front seal on that which BTW, will also fill the crankcase with fuel.

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They will take more than that. The piston pump puts out 15psi and mines been running like that for three years, overrunning up to 16-18 all the time..

well i got the regulator that will run 5-10 psi so i believe that will work out. and i picked up a nice fuel pressure gauge so i can keep it monitored as well. is there any downside to leaving the mechanical pump on the side of the motor just not hooked up and run the electric fuel pump right into the fuel filter port, or do i need to take it out and plate it off

I would take it off just to save the cam lobe if you are not using it. But no real downside. It might come in handy someday when the electric quits for some reason if you keep the pieces to hook it back up again in the toolbox..

Set it to 15psi, The VE pump uses inlet pressure to help advance teh timing, it will like the extra psi.

Thats what I did.
https://www.dieselbombers.com/5-9l-r...e-install.html

What kind of electric pump is it? If everything is left stock then it probably doesn't matter. If you're looking for some power then you should find the specs for the pump. The gallons per hour is as important as the psi. Of coarse with the small factory pickup in the tank and the restrictive fuel filter and heater you can't flow but so much anyway. Its more work, but you'll be better off to mount your regulator and gauge after the filter. You lose a little pressure through the filter.

i dont know who made the elctric pump to be honest i know its internally regulated though from 5.5-10 psi. i did mount everything right after the fuel filter for that exact reason. i got it all running and bled today it runs like a beast