Team MightyBoy

the mechanical fuel pump on my F8B has decided to spew fuel everywhere, and not from any of the hoses!

what i need to know is;
Are the F8B / F5A fuel pumps interchangable? same flow rates etc? because i have 2 spare f5a's i can scavange parts off if i can.

thanks in advance, cam.

I'm not sure of the technical side, but my mate and i did a f8b swap on his mighty boy, and when we put fuel thru the motor it split the pump, it had been previously damaged, so we put a F5A pump on it and it runs ok

I've tried to interchange pumps from an F8B Alto to an F5A MB and the pump lever was different and they weren't interchangeable.

Then again some people swear they are able to be swapped. Give it a go and see I guess, or install an electric fuel pump instead.

ah goody mixed replies lol.

well ive got both series of f5a's maybe only one of them are able to be swapped over, ill give it a crack.

ok good news and bad news.

good news;
the pump i used from the f5a looks identical, bolted up and ran perfectly

bad news;
its splattering oil out the breather hole :S

the one i originally removed, the FUEL looked to be leaking from the breather.


any ideas? i have one other pump i can try, but its been sitting with its engine unstarted for over 13 years haha

help!

i had to buy a new one for mine the other day. got it from repco for 100 bucks.

me217

were you having any of the problems above?

ive got a few vl's in my backyard may just pinch a pump from one of them.

If fuel is coming out of the breather then it means the diaphragm is stuffed. If your VL commos are EFI then there's no chance you can use the pump.

MightyBoy fuel pump = 3-6PSI
VL fuel pump = 38-42PSI

You'd have fuel spewing out every gasket in the carby!

haha fair enough! guess ill just have to buy a new one.

check out the solid state ones on ebay $30-$40 from memory. They look to be made in the same factory as the $100 repco solid state ones.

You just have to make a bracket and a blanking plate for the pump housing (or just leave your old pump in there) then splice off a power wire.

I used the wire that goes into the back of the carby that opens the idle solenoid when the ignition is on. You could go to the trouble and wire in the ground to your oil pressure switch so that the pump stops if there is no oil pressure (ie ignition on, but engine not running) but i'm lazy and don't mind the risk of squirting fuel over the engine if i'm in an accident that somehow ruptures the fuel line and I somehow miraculously survive that hefty impact in the MB's F1 inspired monocoque cabin

yeh i heard the lateset f1/indycars cabins where inspired by the MB ?

anywho are these the type you mean? 4-6psi
http://cgi.ebay.com.au/12-Volt-SOLID-ST ... 240%3A1318

yeah that's them...i've had one in mine for about 1 1/2 years no troubles at all.....

excellent. i will have to make a blank plate for the standard pump becuase its spraying oil everywhere now.

thanks!

have a read of this.....a much cheaper option for anyone needing a pump

http://www.tamon.org/forum/viewtopic.ph ... light=pump

i just fitted one of the pumps from ebay, works a treat. i also went to the trouble of wiring in a relay so if the motor stops so does the fuel pump.