Dumb Question-Electric Fuel Pump

[Anonymous]

I'm just thinking it through before I start spending money but, with the key on and the engine off, what would stop it from just flooding everything out if left on for long? I know on EFI systems, it will just run for a second, then cut off.

 

[StrangeRanger]

You need a pressure regulator and a return line plumbed back to the tank with an electric pump

 

[Anonymous]

Thanks I feel stupid now so I take it I couldnt use a non-return style regulator?

 

[addo]

Don't. Just don't. I've been there and it was a whole 'nother pain in the ring. The return style is dearer to buy and install, but worth every cent.

 

[Anonymous]

Yeah I'll take it that its a bad idea, so return system it is.. Thanks again

 

[LaGrasta]

Oh oh! Have I done my mine wrong? I just have the electric plumbed in with a filter in place of the mechanical. When I switch the ignition, I'm just sure to not let it pump and pump witout actually starting the car. But why would I do htat anyway? I haven't had any trouble.

 

[Anonymous]

just god forbid the carbs start leaking... bad things man, bad things

 

[Mustang Boy]

ok here it is the previous owner installed an electric fuel pump with no return cause none of the parts stores had a stock one he kept it from flooding by installing a flick switch that turned the pump on and off boy was a that a PITA and if the lines ever went dry u would never get any gas
i remember after i was done rebuilding it and putting the t5 in the gas gauge said i had half a tank and i couldnt get it to start for anything and we figured out that the electric pump was a style for newer cars where it just pushes fuel instead of sucking fuel on one stroke and then pushing it on the other stroke and it was a bastard cause we couldnt firgure out wut was wrong for like 4-days

 

[addo]

A return line pump runs cooler and strains the pump motor less. I destroyed two Holley Blues by not using a return line. Expensive lesson.

Electro-mechanical diaphragm pumps like the Carter, Facit and SU types (Holley used to sell a small one also) load up the "motor" less and the internal valves cause the pump to not push against excess reistance when the fuel bowl needle valve is shut.

Linc scored an expensive bypass type fuel regulator on Evilbay for about $20 IIRC. So - they're out there!

Regards, Adam.

 

[LaGrasta]

Crud, I thought I was done with that mod. And it was working so well too.

So I need a "Bypass Fuel Regulator?"

 

[MustangSix]

It depends on the type of pump you use.

The rotary vane pumps work better with a bypass regulator. On EFI systems the ECU usually only allows them to run for a few seconds when you first turn the key, then afterwards as long as there is an crank signal. On carbed engines they usually run continuously. They are cooled and lubricated with fuel, so they last longer with a bypass.

The lower pressure diaphragm style electric pumps like the little Facet and SU pumps are fine with just a single line. They only pump when needed and stop when they reach a cutoff pressure. You can hear them ticking away when you turn them on and they stop when the bowls are filled.

 

[Anonymous]

I'm just thinking it through before I start spending money but, with the key on and the engine off, what would stop it from just flooding everything out if left on for long? I know on EFI systems, it will just run for a second, then cut off.

A typical low pressure electric pump is regulated by the same thing that regulates the stock mechanical pump-- the float valve. The pump does not have enough pressure to pump past a properly working float, If the float never sticks or the needle never gets trash in it theoretically it will not cause a problem.Many EFI pumps are high pressure and have an internal switch to keep strain off fittings and hoses etc- these will pump past even a perfectly working carb float.. I have used the cheap electric pumps with good success- but have always wired them to a separate switch so that a stuck float won't strand me, also eases refilling carb if tank is run dry. Similar to a gravity fed carb on a motorcycle, if the float sticks, you switch off the petcock and ride till it sputters, flip it on for a while then off again. You may go years or forever without a float sticking--BUT when one does you need a contingency plan or a big fire extinguisher!!

 

[thinman56]

okay, shopping through some old posts before buying an electric fuel pump. my problem is only 4 psi of pressure (at idle) from the mechanical, even though it's brand new, and the car runs awesome until i open it up, then it runs out of fuel in seconds. so, if i just want a couple pounds of boost to the regular fuel pump, and for more fuel flow when i need it, sounds like the cheapest and safest option is one of these diaphragm pumps from facet or SU? is everyone out there using an electric pump removing the stock mechanical pump, or are some of y'all boosting with electric?

by the way, it's not the choke flap slamming shut, the vacuum goes to zero when i go WOT, last year i got some good advice that said it's likely fuel supply, bowl going dry to soon. raised the float level, little or no change.

thanks....

 

[addo]

Can you plumb a fuel gauge into the car, even if temporarily?

Looks like the Triumph Stag fuel pumps are the largest readily available electric diaphragm units. Not sure who to contact in the US.

 

[thinman56]

wow, they're $280 USD, ouch. i guess that's the next thing, addo, take my fuel pressure gage and move it where i can see it while driving. try it this weekend before shelling out for another part.

thanks

 

[addo]

Scott, there's cheaper sources. Rimmer Bros have the newer version for USD$106 + S/H, the old style one is $16% +... It may have BSP fittings (be warned).