Fuel line check valve- draining issue

There's a BIG difference between an open cup of gasoline and a closed carburetor bowl with a small vent hole. And no, my '86 Bronco with a 460 and aftermarket carb did no have an EVAP system. I don't see how the EVAP would have any impact on the issue. The fumes are captured by the charcoal canister, and then reintroduced into the engine when it's running. The volume of fumes from the canister are not sufficient to start the engine, not even close. It's just a way of keeping the raw gas from venting to the atmosphere... instead it vents to a canister. Either way, it's evaporating out of the bowls at the same rate, the only difference is whether or not you're storing the fumes.

Three weeks ago I tore down my engine to port the heads. I pulled the carb (holley 4bbl) off the engine and set it on the bench without spilling the fuel out. It sat in open air, on the bench, in my carport, for a week and a half before I reassembled the engine. When I put the carb back on the engine, it still had more than plenty of fuel in the bowls to start the engine, it fired on the first crank. You're trying to say that a similarly vented carburetor, sitting on an engine with an air filter in place (slows evaporation because of trapped fumes) will completely drain the bowls in 3 days? I think maybe you had a different problem such as a slow leak or major boiling on a very hot shut-off.

And the Edelbrock carb has to have plugs below fuel level, doesn't it? The secondary jets screw into the floor of the bowl, the primary jets are at the bottom of the metering rod well, how did they drill the fuel passages down at those levels? The passages can't all be cast in, they have to be drilled, which means they had to plug the hole that they drilled from. The Edelbrock/Carter carb may not have any gaskets below fuel level, but I think it has to have plugs, and those plugs can leak.

But my motor/carb has done this since new - Not saying the carb couldn't be bad from the factory, but at leas now you've steered me into another test - I'll have to yank it and bench test it to check for slow leaks. (just like checking a motorcycle carb).

I've got an even easier test. Next time you park it, stick a wadded up paper towel or piece of gum in the carb vent. Then wait a few days, come back, DON'T FORGET TO REMOVE THE GUM, and crank it over. If it starts, it was an evaporation problem. If it just cranks, it must've leaked out somewhere.

thanks for all the replies, this is awesome!! I waited 2 days to start it again. I got in, pumped the gas twice, heavy choke, cranked 2 seconds. Engine started and ran at 2000 rpm for 2 seconds, and quit. I pumped again 3 times and it started after about 5 seconds of cranking then ran. I kept my foot on it at 2k where it smoothed out. No smoke. Choke position didn't seem to matter.

After 30 seconds, I took my foot off of it, and it went to 250 rpm, loping and either flooding or starving for fuel, I cant tell. I managed to save it and kept my foot on it until I could fiddle with the manual choke to keep it running at 1100 rpm. It stayed smooth at 1100 for the next 2-3 minutes until it could finally idle on its own at 800 with a slight lope (cam).

Keep in mind I have set the carb for lean best idle mixture when hot, and I don't have any exhaust heat crossover (rpm heads), 10* initial timing.


I got lucky when it started this time after a few seconds, normally it takes much longer. It seems that if it doesn't start right away, it takes forever with no inbetween.

I still need to move the filter up the line on the pressure side of the pump, and route the hose with a loop in it near the firewall as sort of an anti drain back feature.

I'd hate to think I was flooding it when starting, but I don't smell any raw gas during the cranking process when it takes a long time to start. The engine doesn't try to fire, catch, make any noise, backfire, etc. Nothing until at one point, it just springs to life!

I will try some of the ideas here like the bubble gum, paper towel thing, taking it off with gas in it and putting it over a tupperware ( I'm not telling the wife I borrowed it)

I run my filter right off the tank. Its a filter like you would see at the gas pump, long canister with changeable element. Never had an issue. Our dirt Late Models are set up the same exact way, filter before the pump, no issues what so ever

You know...

A flooded engine will crank and crank with NO reaction of sound until that one fateful moment when the spark overcomes the saturated chamber and electrode, then Vroooom, it will start like nothing was amiss....

FE

Originally Posted by Bailey28

I waited 2 days to start it again. I got in, pumped the gas twice, heavy choke, cranked 2 seconds. Engine started and ran at 2000 rpm for 2 seconds, and quit. I pumped again 3 times and it started after about 5 seconds of cranking then ran. I kept my foot on it at 2k where it smoothed out. No smoke. Choke position didn't seem to matter.

After 30 seconds, I took my foot off of it, and it went to 250 rpm, loping and either flooding or starving for fuel, I cant tell. I managed to save it and kept my foot on it until I could fiddle with the manual choke to keep it running at 1100 rpm. It stayed smooth at 1100 for the next 2-3 minutes until it could finally idle on its own at 800 with a slight lope (cam).

You may have a choke problem.

Next time it sits, lift off the air cleaner lid and work the accelerator linkage once and observe for a shot of fuel. If you see a shot, no matter what duration, you have fuel in the bowl(s).

Being a manual choke makes starting it a little more difficult.

Pull the choke closed...

Depress the accelerator once and release it...

Crank the engine...

If it starts, immediately open the choke just a hair (this initiates the choke pull-off feature). The fast idle should be in the choke mechanisn, so there should be no reason to touch the fuel. As it warms, open the choke slowly to allow the mixture to warm and blend in the plenum. You may have to drive off with the choke partially closed for proper cold air operation.

Having no heat crossover or choke stove will make cold operation more difficult. Having to pump the fuel continually or hitting it twice before starting causes carbon fouling in the cylinders and further hard starting/poor performance.

Why no automatic choke?