Electric Fuel Pump

[dodj]

The link provided above to the 4110 is probably the most popular one as it does not require a return line or a regulator.

I thought Holley carbs need the fuel pressure regulated down to 5psi. Can they handle 7 psi ok?

[ireland383]

My Holley manual for my 3310 states between 5 and 7 PSI. I'm using the smaller Summit pump and getting 8 PSI. So far so good.

[MEK-Dangerfield]

I thought Holley carbs need the fuel pressure regulated down to 5psi. Can they handle 7 psi ok?

I would strongly suggest using a regulator. I used an electric Mallory fuel pump for one season, and that baby was putting out 11 PSI of pressure.     Even the hi-volume mechanical  Carter pump I am using now puts out 8 PSI, so I have that regulated down to 6 PSI.

[the_engineers]

I have a Mallory 110 and have it regulated at the carb at 6 psi.  It's tied into a MP low pressure switch.  Should I ever wreck and become incapacitated, the pump will shut off if the the motor dies.  If not, I guess it's adios.  It's not meant as an anti-theft device, there are better ways to do that.

On the 110, if you idle for a period, it'll start to whine as the pressure behind the regulator builds.  Best scenario would be a regulated bypass that feeds excess fuel back to the tank.

[Strawdawg]

It will actually shut off when the fuel bowls are dry unlike a fi set up where it will kill it immediately

The real advantage of the oil pressure switch in this case is to allow the pump to be off until you turn the key to start...rather than immediately start running when the key is turned to the run position

[high perf mopar]

im using the mallory comp 110 also. i went with this pump because,1, u dont have to have to have gravity feed like so many electric pumps do,2,its a dead head pump,which means u dont have to have a return line,and its quiet.i cannot hear it with the engine running,,3" system with dynomax super turbos.barely hear it without the motor running,,but according to mallory the best way to plumb it is by taking off the filter in tank and using a 100 micron filter before the pump which is what im doing so u dont have fuel starvation. and using a regulator at the carbs set to 5 1/2 psi...its wired into one of the aux connectors in the dash harness key operated and i have a 20 amp toggle switch wired in so i can shut it off manually.. 

[dodj]

It will actually shut off when the fuel bowls are dry unlike a fi set up where it will kill it immediately

I was kind of thinking from a different angle. As in, if I get in an accident and the engine is dead but the fuel pump keeps on pumping, flooding the area with gas. If it is tied in to oil pressure, it would shut off when/if the engine dies.

[Strawdawg]

yep, you are correct

[Talkwrench]

dodj its a good idea to have it with the oil pressure cut off. Those old Holley style pumps need a return line or they stuff up. The regulator can be used to do this if you know how. Holley have a new type I think its called a GP 125 no need for a reg . Dont put much more than 6 psi on the pressure. they are very noisy and old fashioned..

[JoltinJoe]

dodj its a good idea to have it with the oil pressure cut off. Those old Holley style pumps need a return line or they stuff up. The regulator can be used to do this if you know how. Holley have a new type I think its called a GP 125 no need for a reg . Dont put much more than 6 psi on the pressure. they are very noisy and old fashioned..

I'm considering adding a regulated bypass to return excess fuel back to the tank at an extended idle period.  How do I do this with an Oil Pressure Cutoff Switch in place?

[Talkwrench]

If you have the holley reg you have one line in to the reg, one to the carb and the other you need to get a holley main jet and drill it out to about .050" [if not the right size] Start at that size and watch your pressure. Solder it in the last outlet attach your return line to that back to your tank. I cant see how that would effect your cut off switch.

[Strawdawg]

If you use the Mallory 4110 pump, it has an internal bypass valve that recirculates within the pump which eliminates the need for an external regulator.  There is an adjustment screw on the pump to set the bypass pressure if need be.  7 psi at the pump is not 7 psi at the carb in most cases...would need pretty big fuel line to obtain that...irc, the instructions say do not use an external regulator with this particular pump.

[JoltinJoe]

If you use the Mallory 4110 pump, it has an internal bypass valve that recirculates within the pump which eliminates the need for an external regulator.  There is an adjustment screw on the pump to set the bypass pressure if need be.  7 psi at the pump is not 7 psi at the carb in most cases...would need pretty big fuel line to obtain that...irc, the instructions say do not use an external regulator with this particular pump.

So no external regulator at the carb area?  I guess that if the Mallory pump is set at 7psi, then I should somehow check the pressure at the carb (as 7psi is too high at the carb)? 

[Chryco Psycho]

7 psi at the carb semms to work but is on the upper limit , I would not run more than 7 

[Strawdawg]

So no external regulator at the carb area?  I guess that if the Mallory pump is set at 7psi, then I should somehow check the pressure at the carb (as 7psi is too high at the carb)? 

If you have 7 at the pump, you will have less than 7 at the carb.     The plumbing between the carb and the pump exacts its toll