Electric fuel pump function.

[seeking]

Gents, I recently installed an electric fuel pump as a replacement to my old mechanical pump on my 440B bobcat skid-steer. Can someone please explain how an electric fuel pump functions without a return line to the gas tank. Is there internal designs which restrict pumping after a preset pressure is met. If so how does that work. I have a pressure regulator in-line between the pump and Carburetor. but I don't understand how a pump can function without a return line.

 

[antfarmer2]

Mine has a return line and I think your does too

 

[seeking]

Mine has a return line and I think your does too

Antfarmer2, no my mechanical pump did not and neither did the electric pump. I read somewhere that 7psi and below it is OK without a return, but I still vision that pump running behind that regulator, I know it cannot back-feed on the same supply line because there is a one-way valve on the pick-up and there is only that one line coming from the fuel tank. The electric pump is rated for 2-7 Psi, and I believe the demand of the 440 is around 2.5 psi. given this rating on the pump 2-7 psi, seems to say it will gear down to minimum of 2 psi and gear up to a max of 7 PSI ??. Without a return line in the design I don't understand the mechanics. Know if a relay required on these small fuel pumps?.. Thanks for the reply..

 

[Tazza]

Antfarmer2, no my mechanical pump did not and neither did the electric pump. I read somewhere that 7psi and below it is OK without a return, but I still vision that pump running behind that regulator, I know it cannot back-feed on the same supply line because there is a one-way valve on the pick-up and there is only that one line coming from the fuel tank. The electric pump is rated for 2-7 Psi, and I believe the demand of the 440 is around 2.5 psi. given this rating on the pump 2-7 psi, seems to say it will gear down to minimum of 2 psi and gear up to a max of 7 PSI ??. Without a return line in the design I don't understand the mechanics. Know if a relay required on these small fuel pumps?.. Thanks for the reply..

The way i understand how an inline fuel pump works is it has a plunger and non return valves, so it just vibrates, so even if it's not moving fluid it causes it no harm, it doesn't stall like a rotary pump would and burn out, so a return line isn't really needed.

 

[Rodger]

The way i understand how an inline fuel pump works is it has a plunger and non return valves, so it just vibrates, so even if it's not moving fluid it causes it no harm, it doesn't stall like a rotary pump would and burn out, so a return line isn't really needed.

With carb engines , as long as the fuel pressure does not over-ride the needle and seat , no problem . Some electric fuel pumps stop when they hit the preset pressure , some keep running though generally slower . I add an electric anytime I work on a fuel system . I add a pump bulb anytime I get a chance to make it easier to bleed filters . Advance Auto sells diesel electric pumps fpr $68 and gas pumps about $10 cheaper .

 

[davim]

With carb engines , as long as the fuel pressure does not over-ride the needle and seat , no problem . Some electric fuel pumps stop when they hit the preset pressure , some keep running though generally slower . I add an electric anytime I work on a fuel system . I add a pump bulb anytime I get a chance to make it easier to bleed filters . Advance Auto sells diesel electric pumps fpr $68 and gas pumps about $10 cheaper .

Aloha Rodger, I have a similar issue,, its hot here and the mechanical fuel pump vapor locks, want to install an electric, plan to use pressure reducer, question ? best place to locate the electric fuel pump,( it gets pretty warm around the engine and its cowlings and do i need a bleeder valve past pump back to tank to allow pump to prime? any suggestions would be of great help,, im in the dark over here....Mahalo for your time,,, [email protected] ps what is a pump bulb? similar to what is used on small boat motors?

 

[davim]

With carb engines , as long as the fuel pressure does not over-ride the needle and seat , no problem . Some electric fuel pumps stop when they hit the preset pressure , some keep running though generally slower . I add an electric anytime I work on a fuel system . I add a pump bulb anytime I get a chance to make it easier to bleed filters . Advance Auto sells diesel electric pumps fpr $68 and gas pumps about $10 cheaper .

ooooops,, my previous post is in reference to a 440B - 18MQS Mahalo