Carburettor fuel pressure question.

[Screamn_Sleeka]

are you sure?

the return line usually comes from the top of the fuel inlet.. ie, above the float needle and seat.

having the retun line shouldn't have any effect on the fuel that is already sitting in the fuel bowl...

or am i missing something?

Yeah i am sure, however i did simplify it. As its usually the pressurised lines that boil, so they are on the return line, you are right, the return does not come from the bowl because you cant physically return fuel from the float bowl. However, circulating the lines insures the fuel is at its highest desity when entering the bowl, effectly making the fuel in the bowl cooler to start with.

It was a big problem with all V8's (early 1960's), fuel was vapourising in the lines at idle on go hot days and the gas pressureised the bowl and carby didnt work, i dont know a car build after mid 80's without a return line. (although they also changed over to EFI around that time )

[Talasas]

My dad uses a small lightweight electric fuel pump from a Subaru EA82 (I think anyway) on his plane engine. It was the best option and also happened to be the cheapest

[Screamn_Sleeka]

Best option is a Carter lower pressure pump.

If thats for a real plane, i hope he has more than one.

[o_man_ra23]

Hmm... boiling fuel?? why do 18Rs have the return coming from the pump??. The pressure of the EFI pump will damage your float valve. A facet, or clakker type pump will happily suck fuel through an EFI centrifugal pump, so no need to remove the EFI pump... just put the facet inline.

Sounds like the greatest feat of reverse evolution since politicians were invented.

Cheers, Owen

[oldcorollas]

there is a pressure relief in the mechanical pumps... well. KE10 didnt but KE30 etc did

are the stocker pumps centrifugal? the Walbros i have are gerotor(sp?) and ain't gonna get sucked thru.

[o_man_ra23]

Pretty sure Toyota just used cheapo centrifugals like everyone else stu... at least for low grade M series cars

Cheers, Owen

[haison]

Ahh crap! NOW i find out you can draw fuel thru the efi pump.. I've just dropped the tank and pulled it out.
BAH!

[o_man_ra23]

Try sucking through it (vacuum pump or something) and let us know how it goes.

Cheers, Owen