Gumby

I need some fast tech help fuel system related.

I never see a fuel pump like that. Do I need them both, the main feed and the small line? What does it do? some sort of over flow or pressure relief bypass???

Looks strange on a mechanical pump. My first thought is to just block it off but will I over pressure the system? Ive replaced line and pump on cars before but they had one the main fed and a vent.

I got a 12-16psi electrical pump I was gonna put on at some time with a 7psi oil pressure switch and It would not have a line for that small return anyways. Strange to see a return on a carbed car.

Its a Buick 350 though but same family.

Stekman

It has 3 holes on the mech. pump? If so, the third is to the return line. If that truly is the case, its a fuel system "safety" issue. Vapor lock yada yada. Sends excess fuel back to the tank after peak pressure has been reached, that good stuff.

ede

i think you've skipped over some background info, or i'm a dumbass and missed it. you have a mechanical pump with 3 lines right? inlet, outlet, and bypass. it's not uncommon to see 3 lines on a mechanical pump. not all have them but some do. if there is provisions for the return to the tank i'd use all 3 lines.

TechSmurf

Man, why are you PMing me this thread? I hate carbs! I hate mechanical fuel pumps! And everyone else is right anyway!

Gumby

Anyone have any idea how that vapor thing works? what pressure it is set at or what ever?

I wonder if I still went with an electric pump but ran it through the mech pump, would it still act like a bypass and return fuel like it should? I would pull the pin or cut the arm so the stock pump did not work. would fuel still flow and be returned like stock?

good idea?


The vent goes into my "empty" canister. [Who knows where all the crap inside went? maybe PO sucked it into carb.] I was thinking of getting one of the old type filter vac things for the air cleaner lid, so any vented fums goes into the engine, instead of the air.

good idea?

Gumby

Maybe you should consider a name change to FITechSmurf

dankhound

Anybody else here think this guy shouldnt touch the fuel system due to the safety hazard?

Gumby

Let me guess, your so concerned for my life that I should pay some shop $60hr to have some high school flunky work on it for me???

no thank you.

dankhound

I just think you may be in over your head. The fuel system is one place you dont want to try to rig stuff up.

Just ditch the mechanical fuel pump all together if you get an electrical pump. Then buy an adjustable fuel pressure regulator.

Vapor lock is a condition where the fuel in the line turns to gas. The pumps cant pump the gas to the engine so it will die. Its caused by the lines being routed to close to a heat source or sharpe bends in lines. While it happens almost entirely in cars with mechanical fuel pumps it can still happen in an electrically pumped car. Althou it usually doesnt get to the point of lock. Usually it just causes bubbles in the fuel line.

Gumby

I had a 79 duster that got vapor lock bad but it was their fault from running steel lines around the engine block 3 times. I ended up fixing it by putting an electric pump in the trunk. But it was hard wired and not very safe in a crash. I figure for the same price, I can get the v6 7 psi oil pressure switch or 20 feet of return line and use a mech pump.

Would like to ditch the mech pump. Install the electric in the rear, 7psi safety switch and forget about it for a long long while. Everything else on the car has been fixed. The fuel is the last thing. [ its an 80 with 77,000 miles so it sat allot] I hardly drive the thing but like driving it when I can. Its a pig on gas compared to my 2.8 Bird. But once in a while it nice to snap open the Qjet and smoke some tires. And float like a boat instead of the go cart like ride of my Bird.

I still gotta flip $150 for insurance n plates. And I just can't go hog wild on the fuel system when I have a new feed n vent, a nice elec pump collecting dust and a $8 oil switch at AutoZone waiting for me.

Confuzed1

iTrader: (4)

I just went through the same thing. Here:
https://www.thirdgen.org/techbb2/sho...hreadid=234479