mechanical fuel pump to electric fuel pump question

[benzo]

Just curious and wanted to confirm if my assumption is correct. I am using the stock Lseries fuel pump that is mechanically driven but considered swapping to a electric unit. If I did this would the benefit possibly be quicker starts as fuel would be sent to carbs faster as opposed to the mechanical one needing the engine to cycle to pump it? would there be any other benefit to warrant making the swap.

 

thanks in advance

 

Benzo

[HRH]

Your car, once turned off, should still hold pressure if the needle and seat are in good condition in the carburetor, and the mechanical pump is in good condition and not reversing after shut off due to a crappy diaphragm.

 

An electric vs. mechanical should make about .02% difference in the start up quality. The other problem is getting the correct low pressure fuel pump. Most SU, Webers, Hitachis only want 3-4 psi to run effectively. There are electric pumps that provide that pressure, although a little harder to find. I do know we have some at NAPA, part number 610-1051 I think, or maybe it's 1050. One's 1-5 psi, the other 5-9 psi.

 

The other thing you'll want to do is mount it back by the tank, otherwise it will overheat the cheaper pumps trying to suck that far, and/or be too much pressure and try to flood the bowl.

 

I still run a mechanical pump on my dual SU equipped rally car, and it works great. That's one of the reasons I never changed it. I had an electric on my previous 510 and really with carburetion, there's not a need for it unless you're running massive carbs.

 

So to answer your question: No, stick with the mechanical, it's not worth the hassle unless you're planning on going efi sometime in the near future. :)

[benzo]

thanks for the reply. my car is actually fine. it starts fine only time it takes a while to start is when I let the car sit for a week but that is normal. I was just curious if there were any other side benefits but it seems like there would not be. I hear you on the psi amount as I have mikuni's and at first the fuel psi was at 6 psi with stock pump but I got a regulator and dialed it down to 3 psi. I just seem to see a lot lately the use of the factory style nissan electric pump but wondered also if there was wiring set from factory near the tank for a electric pump ( I have a wagon) or would I have to run wires. I have not been under the car for a while and don't remember

 

thanks for the feedback.

[banzai510(hainz)]

the later fuse blocks will have a Airconditioning Blue wire wrap up under the fusebox with a round bullet type connector u could use a as switchable 12volts.

 

I have a electric Mallory pump on my yellow car and it if it sites it makes no different in starting. Still take awhile and with 44s I got to choke the shit out of it.

 

My Banzai beater. has 40s and I just pump a few times and start right up. NO CHOKE. stock pump

[ggzilla]

Yes, carbs are designed to use choking when starting. My Mikunis have no choke cable, so it takes a few pumps and run it at 2000 rpm for a while before it'll idle. With the choke/starters turned manually just a bit, it will start and immediately idle.

 

The 720 electric fuel pump is rated at 7 psi and I have no regulator. Maybe that's why I'm only getting 22 mpg from my Mikunis. Runs good otherwise.

[240ADAM]

I had triple webers on my Z and never used a choke and I used the stock mechanical pump. After a just a week your carbs should still have full bowls of fuel so the electric would make no difference. I think people wast there time hooking up mech fuel pumps the stock is just fine.

[RoadRace]

i have always ran electric pumps. i recently bought a vintage 710, really trick car, been neglected for 20 plus years. the guy had huge money in this car as he raced it nationally back in the day - i got pics of it from road america, brainerd, watkins glen and mosport with this car. the L18 it came with was full comp prep, 600 lift cam, titamium retainers, max compression - he threw the book at it, no expense spared. he ran the stock fuel pump with Weber dual 45's. if i didn't already have the electric pumps (i run a redundant system), i wouldn't have gone away from the oem unit.