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Mazda Engine Performance \  Weber Carb Question?????/

Weber Carb Question?????/

Mazda Engine Performance Mazda Engine Mazda Tech
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replies 18
following 4
 
burtandurny101   +1y
A while ago i bought and fixed up an 83 b2000.
the carb sucked so i ripped out all the environmentally friendly stuff and put on a weber. she runs great!

BUUUT...... I noticed last week that the "return line" for the fuel that used to be hooked up to the old carb dribbles fuel......

What do i do with this line? i have had it just hanging out....somebody, i dont remember who told me that was fine.....

A mechanic told me to hook it up to a vacuum port on the intake. Should i??

Thankss ya'll!

-Burt
dan woodland   +1y
It sounds like the return line to the fuel tank? Here on my automatic you can see the return line. .

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On my return line is a one way valve to ensure the fuel flows up only one hose to the carb.

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Or it's a vent line for the 5 speed. I believe if you hook it to a vacuum source it will draw fuel and or fumes into the manifold and possibly mess up your mixture.
burtandurny101   +1y
I have a 5 speed manual.
And i am like 99% sure it is the return line.

IF... i was to connect the lines with a splitter should a put a check valve behind or in front of the Fuel pressure regulator?

also, should the connection between the lines be i front or behind the F.P.R.?
dan woodland   +1y
All of mine is after the FPR.

Tank (with internal FP) to FPR
FPR to splitter
Splitter to Carb
Splitter to one way valve
One way valve to tank (with internal FP)
burtandurny101   +1y
One thing though, i am 'purdy sure that the automatics have an internal electric fuel pump and the older models and all the manuals have a mechanical FP that is not in-tank.
When i did the carb swap some 2 years ago i remember lookin into it a bunch cause of the needle and float getting broken if you dont put the FPR on there...........and if i remember correctly you dont really need one for the elcric fuel pumps....maybe enot though...

I am still a bit confused as to what exactly you mean.
I would super appreciate a sketch of how you have stuff it all put together.
I hope that aint to much to ask; you have already helped me out a lot!

Thanks!

-Burt
Cusser   +1y
Use FPR if you have an electric fuel pump; not needed with the mechanical fuel pump.
dvsdev   +1y
I put a FPR on my recent weber install, I checked to see what the pressure from the factory mechanical pump was, mine was just over 6psi, weber recommends 2-2.5psi so I would run a reg regardless of being factory mechanical or electric fuel pump.
I also plugged the carb return line, option I did was pull the fitting out from carb, cut off barb, fill the whole thing with solder, refit fitting and re-sealed around the fitting with a fuel safe thread lock solution.
Depending on your setup, if you have a good inline filter you could just split the fuel inlet hose and fit to both carb fittings, looking at them they both hook-up before the needle anyway so it should be all good... Should be.
burtandurny101   +1y
Ok..... got tubing and a splitter today. could not for the life of me locate a fuel rated check valve: but a miracle happened and little metal nipal already stock on the return line turned out to be one! Great sucess.

Just making double sure, i was supposed to hook the check valve so fuel may only run down the return line?
So the fuel line goes to the FPR, FPR to splitter, splitter to (fuel filter then too) carb, splitter to check valve (set so that fuel will only flow into the return line).

I have notice that the tube going to the check valve from the splitter bulges a bit.... what gives??

Also! what is the most premium Fuel Pressure to run? my reg is adjustable to the .5 PSI (1-7 or something).

Thanks a bunch! I'll snap a photo right fast and throw em' on here.
burtandurny101   +1y
I have since added the fuel filter on the line headed to the carb, but this is my set-up.

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burtandurny101   +1y
One more thing!!!!

The vent line (which i had plugged for some reason) is now open and hanging out. i think it was the original cause of my return-line dribbles...... but oh well.

Should i leave it as is? or should i run a tube down and away from the heat of the engine?
I dont have a carbon can, which is i think where it used to go.

Thanks!

-Burt