[deanhaj300zx]

1971 240Z

OK, so last week i stalled and pulled over. after some diognosing i found it to be fuel starvation. i swaped the mech. fuel pump and filter with a klnown workable pump and a brand new filter. week later, SAME @!#$, fuel starvation . all this was on a half tank of gas by the way. to get home THIS time i bypassed the filter and got it home. i blew through filter, thier was like no resistance.

whats the deal?

should i drop the tank and clean out? get a new fuel line?

 

[johnh240]

I would start at the carbs and work back to the tank, clean fuel bowls and carb inlet screens, then replace the filter, blow out lines from carbs back to tank (both supply and return), make sure pump is good, and drain tank into a clean container and see what kind of crud there is. If you get lots of particles you would need to decide then whether you want to do the tank. If it were just a few fine particles I would just do a complete drain of tank and add another filter by the tank (2 total) and try it, and try to keep the tank as full as possible. Perhaps adding a can of fuel system dryer of some sort to assure no water in fuel system. If the problem continued, then I would pull tank for cleaning/ repair. From all I have seen and heard, I would go with the 'Gas Tank RENU' system. They are franchised nationwide I believe.

http://www.gastankrenu.com/

 

[JeffK]

I had the same problem for 2 years. I know it wasn't tank, lines , filters, or carbs 'cause I replaced or inspected each. What I did was block my return line and installed a FPR before carbs. Haven't had a problem since. Not sure what problem blocking the return line could cause, anyone with any input out there.
JeffK

 

[WoZZd]

Jeffk,
I think u replied to my topic as well about feul shortage. I've been having this problem as well and I check everything from carb back with zero improvements. So I decided one day to block off my return line and its fine now. I didn't do the FPR, just blocked it off with a plug and its running. Its just a band aide until I could figure the real problem out. Didn't help much but at least you'll know that your not the only one having these kinds of problems.

 

[johnh240]

If you have to block the return line, that would indicate a lack of pressure from the pump, OR possibly someone has reamed out the tiny little hole in the return pipe (where it comes off the head, near the mech fuel pump) and enlarged it. That can cause a high flow of fuel back to the tank and too little PRESSURE at the carbs. Or sometimes the floats are set too low and bumping the pressure up by blocking return compensates. Whatever system you use, it's always best to double check what the pressure is at the carbs. s/b ~ 3.5 to 4.25 psi.