andy74

on my 86 camaro,that was swapped to a carb before i got it,i am still having a problem that acts like the car is running out of gas when driving-sometimes i can go 10 or 12 miles,then it stalls and will restart when i put it in neutral-other times it will run for only a minute or 2.never causes any issues at idle in the drive way,and has always started right back up-i put on a new holley by pass fuel regulator,hooked up the lines from the tank,return line to tank using factory lines,and put a bolt in the carbon canister line- my question is would the blocked canister line cause the issues im describing?any other ideas? when i had this problem at first,and i posted a few months ago,i jumped the wiring to the fuel pump,and it filled a 5 gallon gas can in a few minutes,so i think the pump is okay-i plan to eventually drop the tank and remove the factory pump,but thats at least a month away-does any one have any ideas on what i should do or check?

five7kid

iTrader: (14)

The vapor canister provides the vent for the fuel tank. You might be building up a vacuum in the tank.

andy74

should i put a fuel filter or something on the line where the vapor canister was?

naf

iTrader: (7)

Try running it with the cap loose first. Gas cap that is. I doubt this is your problem but the charcoal canister is generally a good thing to keep.

When you restart it, does it run another 10-12 miles before stalling again or is it good once it warms up?

andy74

when it restarts sometimes it will run for another 10 or so miles,sometimes it quits after a mile or so-my other thought was that the fuel was vapor locking,but i m not sure how to check?the fuel lines are pretty close to my exhaust pipes,so i think ill get some insulation and run it on them just to be safe-ill try to drive it tonight with the cap loose and see what happens

andy74

i tried running her last night with no cap/loose cap,seemed a little better,it took about 20 miles to stall this time-my tought is i ll have to drop the tank,and remove the factory pump,then use a holley blue pump off my parts car-cant think of anything else

naf

iTrader: (7)

Try putting a fuel pressure guage in-line with your carb. See what the fuel pressure is WHEN it is misbehaving. Don't drop the tank just yet.

andy74

i did that already, the fuel pressure drops right to zero, then when i restart it it runs back to 6 1/2,right where i have the regulator set-i actually drove around the block with no hood and a helper watching the guage-still doing the same thing! im usually not a parts changer,and id rather figure out the problem before tossing parts at it,but im at a loss,new regulator,new carb and good fuel lines-what else could it be?

Ozz1967

iTrader: (4)

Could be vapor lock...but running with the cap loose should solve that problem. Are you running the in-tank pump or a mechanical pump on the block?

andy74

factory tpi intank pump,holley by pass regulator,useing factory lines,and hooked up to a holley 650 carb,wouldnt vapor lock take more than a few seconds to go away? or would the factory pump pushing gas to the regulator clear that up?my lines are close to the exhaust,which i ll be also swapping soon,as soon as i get the rear end out of my parts car

Ozz1967

iTrader: (4)

Vapor lock happens when the fuel gets hot and bubbles putting air in the line, usually from running too close to the exhaust though any sufficiently hot day can suffice. This causes a vacuum lock in the line where the mechanical pump can't pull fuel through because it's literally "Sucking air". The pusher pump was added to keep the fuel flowing from the tank even if the mechanical pump was unable to pull the fuel through the line. And yes, it normally takes some time for it to go away. Anywhere from 30 min to 3 hours depending on how hot it is outside.

naf

iTrader: (7)

Make sure the pump's getting power. Maybe run a remote test light to it to see that power's still going there when it conks out. Could be a bad oil pressure switch/relay/wiring/etc.

andy74

ill check that out tonight and get back with you, the wiring is all goofy from the previous owners genius ideas,so ill chase all the wiring down,and see what gives-i m also going to pull the return line off and stick it in the gas can,see how the flow on it is with the car running-thinking maybe i got a wrong boxed regulator?holley stuff has always worked for me in the past,so im just going to start eliminating variables

andy74

i had a fuel relay in my box,so i switched it to eliminate a variable,wiring is all good to the pump and oild pressure switch,still acting the same-i drive 6 miles to work and it quit 4 times this am-i usually dont drive it everyday,but i need it to be reliable when i need to-i am going to pull the return line off and check that tommorow night after work,and i am more than open to any other ideas,thanks for your help everyone

five7kid

iTrader: (14)

Just to be clear, you have monitored fuel pressure when this is happening - it is fine at first, and then drops to zero after a few minutes before the engine dies?

That's not long enough to create a vacuum in the tank. But, your pump may be dieing.

As far as venting goes, the white valve above the axle is supposed to let air in as the fuel level goes down (or temperature drops). I didn't check the cracking pressure of the valve, but it is pretty low. Guess I could hook my MityVac to it and see.

andy74

yes, thats exactly what happens with the fuel pressure,it drops to zero,then the car dies after about 45 seconds or so,i ran the car with no gas cap to see if venting was an issue,didnt change a bit-so im guessing that the vent/cap situation is okay,and i put an old fuel filter in the carbon canister line instead of a bolt like the po had,still nothing has changed other than my beer bill getting higher!

naf

iTrader: (7)

Sounds more and more like a failing fuel pump. I'd encourage you to check everything else before dropping that tank though. But you may have to bite that bullet.

andy74

i cant see anything left to check-i still am wondering,will a tbi pump fit right in,and is the wiring the same?im thinking a lower pressure pump will be easier for the regulator to step down the pressure,or i have a holley pump that i can use,just not sure how to wire it in,and i dont want a toggle switch or anything like that -can i use the factory wiring/relay?

naf

iTrader: (7)

Should be able use the factory wiring and relay. Those pumps don't draw much power.