candipogo

got a 383 chevy with 2 1406 edlebrock carbs on edlebrock performer rpm manifold. manual fuel pump. if i let it sit for a few weeks at a time, engine will lose prime, i guess. all of fuel drains back out of carbs and past fuel pump. i have cranked it seven or eight times in multiples and no start. if i remove one of the fittings at the carb and crank the engine with help then i see fuel after a few moments. then, after i reconnect and crank engine will fire immediately. fuel tank is vented and ok. i wonder if this is check valve in fuel pump? or? it has been suggested to me to get a check valve installed in line or possibly replace fuel pump. any ideas appreciated.
phil

Bud2

OK, i'll have a go here. I'm far from an expert and I use carter single carbs (no choke) so I don't know **** about your setup. I would expect my car to lose the petrol from the carb after a few weeks too. But I wouldn't stress the starter/battery either. I'd squirt a bit of petrol down the vent, work the linkage to see if it inturn squirts fuel down the throat of the carb. THEN I'd turn the key.

Cheers! Bud.

tuxnharley

After my 67 has set for a while the fuel bowls on the Holley are pretty much empty. I like to crank it in two sessions of maybe 5 - 7 seconds each until the oil pressure comes up above 30 psi.

By then the fuel bowls are full again and, with 2 or 3 pumps of the gas pedal (no choke on this one) the car fires right up.

Zoomin

This sure seems to happen more now than in years past. Anyone else notice this?

tuxnharley

Ethanol evaporating faster than gasoline?

Vette5311

RatDog

That’s what works for me, too.

Steve

Frankie the Fink

Look, I've overhauled 10-12 carbs in the past decade, I put them on the car bone dry, bowls empty, fuel filter empty. It takes 5-7 seconds for the car to start and idle, on a very few rare occasions it might take two tries...not usually.

I'd check my fuel pump pressure and flow....check BOTH, they are two different things...

Pop Chevy

There is a check valve in the fuel pump. I have a Holley pump that had the valve actually came loose. It was just crimped in, I put the valve back in with JB Weld 2 yrs ago and now it starts right up after setting couple weeks..Yours could be leaking , I had the same symptoms as you.

65tripleblack

There are 2 poppet valves in a mechanical pump: one for intake and the other for exhaust. I have had one come loose as well and destroyed the main pump housing. They are not check valves.

Frankie the Fink

Yes, poppet valves should be staked in but some rebuilders neglect doing it.....
You can't diagnose a fuel delivery problem properly though until you've done the checks I indicated above first.
Just my opinion...

DansYellow66

Edelbrocks have pretty large vents into the fuel bowl right beside the primary metering rod wells. It's not much wonder the volatile fuel we now have evaporates out of them pretty quickly.

Mr D.

Same here, 427 with Holley.

GTOguy

Lessee here....I'm a guy who used to tune cars for a living, and did it for many many years, starting in the '70's. So I've dealt with a LOT of carbureted cars. I currently own 5 carbureted vehicles. The Corvette has 2 WCFB 4 barrels, the '65 GTO has triple Rochesters, the '67 GTO has a Quadrajet 4bbl, the '15 Ford has a Holly G updraft, and the '83 Toyota has an Aisan 2bbl. ALLLLLLL of these vehicles EXCEPT the 103 year old Ford with a brass updraft oem Holley carb 'lose prime' (gas evaporates) if left 'for a few weeks'. It's simply the way it is, particularly with ethanol in the fuel.

65tripleblack

It's not so much due to the 10% ethanol content in gasoline as it is with internal/external carb leaks and/or heat soak after the engine is shut down. Vintage carbs are prone to internal leaks where fuel drains out of the bowl(s) and into the intake after shutdown. In some cases this can be exacerbated by heat soak, whereby the fuel boils in the bowls and backs out the vent stacks and down the carb throat. The fact that vintage carbs are made from pot metal makes them more susceptible to heat soak than aluminum.

For the life of me, I couldn't get my old Holley 2818 to stop running dry after a couple of days. Since I replaced it with an all aluminum Quick Fuel about 6 years ago, I can lay up the car for weeks and it fires up in less than 1 full crank. Longest I have not started it (during the driving season) was 5 weeks, and it fired right away.

Oh, yeah, I use E10 93 octane gas.

John McGraw

The fuel from the float bowls is not flowing back through the pump to the tank. Once the fuel goes through the float needle, it is air-gapped and can not siphon back out of the bowls. While the check valves can leak in the pump, it will only let the short section of vertical line drain back to the pump. The pump is at a lower elevation than the inlet in the tank, so the fuel will not drain the main fuel line back. We have just gotten spoiled by EFI cars where fuel is instantly available as soon as you crank it! This is how carburetor type engines have always been in warm weather. When you park the car, the fuel just evaporates from the float bowls. None of my LS3 powered cars have this problem


Regards, John McGraw

MikeM

All true!

MikeM

All true as well. Glad to see you posting, John.

candipogo

frank, my pressure is at 6.5lbs. normal. i have been told there is supposed to be a check valve in the fuel pump to prevent this. may be faulty. i have to take one of the lines to the carbs loose and crank the engine till i see fuel. then re attach and it will start. i also understand they make in line check valves that help with this.
thanks,phil

candipogo

[QUOTE=65tripleblack;1597399264]It's not so much due to the 10% ethanol content in gasoline as it is with internal/external carb leaks and/or heat soak after the engine is shut down. Vintage carbs are prone to internal leaks where fuel drains out of the bowl(s) and into the intake after shutdown. In some cases this can be exacerbated by heat soak, whereby the fuel boils in the bowls and backs out the vent stacks and down the carb throat. The fact that vintage carbs are made from pot metal makes them more susceptible to heat soak than aluminum.

For the life of me, I couldn't get my old Holley 2818 to stop running dry after a couple of days. Since I replaced it with an all aluminum Quick Fuel about 6 years ago, I can lay up the car for weeks and it fires up in less than 1 full crank. Longest I have not started it (during the driving season) was 5 weeks, and it fired right away. these are current gen edlebrocks...maybe 5-6 years old. but after a few weeks it has no fuel to crank. i am going to check fuel flow. beginning to sound like i may have a fuel pump issue.
thanks,phil