Starving for fuel? Please help!

[wynschevytruck]

I have a 1968 Chevy c-10 pick up with a stock Chevy 350 with a carter quadra jet carburetor. I recently had upgraded the exhaust with a true 2 1/2" dual exhaust with a crossover from Flow master. The problem that I am having is when the truck is idling for about five minutes it shuts off with no warning. I have adjusted the idle fuel screws to four full turns and still have the problem. Do I need to upsize the jets on the carb or maybe replace the carb with a bigger one.

[geezer#99]

Look in the carb while it's idling. You shouldn't see any fuel at all.
It could be flooding.

[litew8]

Replacing the exhaust shouldn't have anything to due with an issue like that. Just coincidence.

[geezer#99]

Originally Posted by litew8

Replacing the exhaust shouldn't have anything to due with an issue like that. Just coincidence.

Depending on what exhaust set up he originally had it could.
So, what exhaust set up did you have?
Post some pics.

[cdowns]

first thing i'd do would b to change the fuel filter

[litew8]

Originally Posted by geezer#99

Depending on what exhaust set up he originally had it could.
So, what exhaust set up did you have?
Post some pics.

How about you explain that for everyone.

[swamp rat]

I think what he's getting at is that if the exhaust was super restrictive then a new system could require a bit of re jetting and air/fuel ratio adjustment? But at idle i cant see that being a cause for it to just shut off unless its so rich it chokes itself out, or so lean if finally stumbles and dies.

I'm thinking he has some debre floating around in the carb that blocks the idle circuit randomly or crud that is blocking the needle and seat.

[wynschevytruck]

geezer#99, I was messing with the truck for a little yesterday. I found that when it was starting to stall the carb was bone dry and it wasn't flooding out. Also before I upgraded the exhaust the previous setup had a 1 1/2 single exhaust with a cherry bomb muffler. I noticed major restriction around the starter.

[wynschevytruck]

swamp rat, after I checked the fuel filters and blew out the lines I pulled the carb apart to check inside the carb thinking it maybe dirty and found the inside was pretty dam clean.

[wynschevytruck]

cdowns, that was the first thing I checked, fuel filter in the carb is new and clean also the sock filter in the tank is clear

[wynschevytruck]

also found that after the truck stalled yesterday, that it would not restart. I sprayed some 2+2 down the carb and ran until it burned the 2+2 off than shut off. it was probably a good half hour before it would start again

[cdowns]

checked the fuel filter not changed the fuel filter two different things

[wynschevytruck]

True! Going out today for parts for my other car. I will add fuel filter to my list

[geezer#99]

If it's bone dry and won't start right back up, I'd suspect the fuel pump. If you're changing out the filter on the carb, put the end of the fuel line in a small bucket and crank it over. Should fill the bucket real quick with strong jets of fuel.

[wynschevytruck]

ok, I changed the fuel filter and still having the same problem. as soon as I get a second body I will check the fuel pump operation

[luvbowties]

Often, there is a short section of flex fuel line connecting the hard line from the tank to the fuel pump that intermittently closes upon itself. Being under a vacuum/suction condition from the pump, it can close up & starve the pump AND the carb from fuel. When this happens, it can be a nightmare to visually "catch it" in the 'squashed' condition. You might replace it just to be safe.
Sam

[wynschevytruck]

Sam, their is a short piece of rubber hose from the tank going to the steel hose that runs along inside the frame to the fuel pump, also their is another small piece before in enters the fuel pump. old truck, probably old hose. I will replace the two pieces of hose.

[luvbowties]

Originally Posted by wynschevytruck

Sam, their is a short piece of rubber hose from the tank going to the steel hose that runs along inside the frame to the fuel pump, also their is another small piece before in enters the fuel pump. old truck, probably old hose. I will replace the two pieces of hose.

Good idea--prolly old and flimsy and without enough body-strength to remain open & flowing while under vacuum for a few minutes. Good part of this upgrade is that both pieces are easily accessible.
Sam

[littlechub]

my guess would be either one of the rubber lines is dry rotted and is sucking air, or the new exhaust is close enough to one of the lines its getting the line hot and vapor locking. I had a similar problem on a 73-87 truck, took several weeks to finally find the dryrotted rubber line was sucking air.

[wynschevytruck]

the cross over pipe section is right below the rubber hose at the tank. I had a temp. of 190 degrees at the top of the exhaust pipe and the rubber hose was at 90 degrees. I thought of the same thing that it maybe vapor locking

[Boog]

Have you recently changed the fuel filler cap? Is it vented or non vented? The next time it stalls remove that cap and see if it helps.