electric fuel pump problems on sbf weiand 671
hi all . been a while for me . been back on my car and looking at getting it on the road in 4 weeks . so i have a problem i need help with . i had contamination withinn my fuel- being water - yuk - isnt good for carbs - so i have cleaned out the tank . lines , overhauled carbs , and have fitted a new holley pressure reg and have replaced my mechinacal high flow eldebrock fuel pump for a electric one . the main reason is so i can set up my carbs before cranking the engine but also if the car was stood for a while it took alot out of the battery to re pressurise and crank this engine being supercharged .
ok . i bought from ebay a bosch electric fuel pump . fitted a filter before it and have fitted the regulator after it. the regulator is brand new and i havent tried to change it from the factory set . i have over 12psi on my guage near the carbs . my needle valves are passing by and filling the engine with fuel .
so my question is . have i bought the wrong fuel pump ? ie the one i have on another v8 ticks fast and then starts to slow down then stops . this fuel pump is noisey and doesnt seem to shut off ?
are some pumps constantly pushing ? ie one for a fuel inj system meaning it pushes huge pressure for a common rail type engine . or regardless should it stop if my regulator doesnt allow any more flow ?
again lots of questions and i maybe barking up the wrong tree . can a fuel pump push past a regulator ?
was thinking of changing it for another one if its not correct ? if so what ?
i have a 351w now bored to 5.9 and have a 6/71 weiand with 2x 600 vac sec carbs .
You cannot use the Bosch pumps in a dead head configuration.
The need a return line and a bypass style fuel pressure regulator.
A Carter P4601 pump and holley fuel repssure regulaotor would have been a better choice.
1/2" fuel line.
A pair of Carter P4070 pumps thru (two) twin 3/8" fuel lines (1 for each carb) needs no regulator at all.
The pair will feed that motor with room to spare. Just needs fuel filters inline before the pumps and twin fuel pickups in the tank. (will support over 800HP)
The bosch pumps are more for EFI. You need to dynamicaly flow test your fuel system with bypass and return line to ensure it can feed the motor enough at WOT high rpm. Flow test it thru a test orrifice that is equal area to the combined 4 needle seats. Test for working flow volume and pressure thru the orrifice.
4psi flowing fuel pressure is fine.
If the fuel system cannot keep up to motor demand at WOT the supercharged motor will leanout and burndown.
A 600 horsepower motor needs a fuel system that can flow 60 GPH (US) @WOT max power output.
This is the real flow, thru a test orifice, @ the working pressure and supply voltage. not the advertised GPH rating "free flow". Not the same thing.
.5 (1 half) pound per Horsepower per hour. You want 6 to 7psi at idle and not less than 2.5psi at max flow demand WOT/max power.
cheers f bird . its been awhile . hope your well and good. i was wondering about what to do on my fueling , thinking i need to speak to a specialist over here ? or do you reckon i could achieve it myself ? will speak to "real steal" in the morning and see what holley pumps they can provide with your figures in mind . i have a copper 3/8" of inch fuel line from tank to engine . i was told it would be enough . whats your thoughts ? . no fitings on it . have bent it all nicely.
I strongly recommend the carter electric fuel pumps over holley.
not big on copper fuel lines on a car. Tends to crack with chassis vibration.
Use steel or aluminum fuel lines.
1 3/8" single line is not enough for a 600hp supercharged motor.
1 1/2" or two 3/8" lines.
if you are going to attempt to run it with just a single 3/8" fuel line you'd best dynamically flow test the system
to ensure enough flow. You cantalk to all the experts you want but untill you flow test the system on the car
you do not know the flow capacity.
Basic errors like this are unforgiving on a supercharged car.
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