When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
68 Olds 455 edlebrock 600cfm with the original mechanical fuel pump.
The problem I’m having is when the car is hot and you shut it off and let it sit for 5+ minutes it doesn’t want to start easy. Everytime it turns over a few times almost starts but doesn’t then you gotta crank it over a bunch more times and pump the gas and eventually it fires but it’s always a little fight.
what’s weird though is if you shut it off wait maybe 30 seconds then start it again it fires right up without even touching the gas at all .
I bought a new fuel pump thinking maybe that’s the issue and the pumps letting the fuel drain back. Fuel filter is clean .
Replacing the fuel pump would have been the last thing I'd consider to be the issue. You mention no hesitation while driving, fuel is being delivered once the vehicle starts, the engine runs - unclear to me why you'd suspect the fuel pump and change it - none-the-less, you did but it didn't change anything.
It sounds like ignition (from your description) - it doesn't sound like fuel starvation and I'd wager it isn't related to the carburetor. Again, it sounds like ignition. Contact points ignition or electronic ignition?
No first cold start of the day I pump the pedal 3 times and it fires right up on the electric chokes and runs great. I have not replaced the pump yet . And I have an HEI distributer.
The problem I’m having is when the car is hot and you shut it off and let it sit for 5+ minutes it doesn’t want to start easy. Everytime it turns over a few times almost starts but doesn’t then you gotta crank it over a bunch more times and pump the gas and eventually it fires but it’s always a little fight.
Have you tried depressing the gas pedal, holding it to the floor, and then cranking the engine? This is the procedure for starting an flooded engine. Try it and see what happens, as in if it's any different than what you have described above.
I was referring to the old fuel pump being potentially bad by letting the fuel drain back down the lines to the tank and not keeping it up to the carb ? Hence the difficulty starting . And no I have not tried depressing the pedal all the way down , I didn’t think i needed to do that when the engine is hot
My money's on ethanol fuel blend. The stuff that passes for gasoline now is designed for fuel injected engines.
Just curious why you put that Edelbrock on there. The worst QuadraJet is better than the best Edelbrock AFB clone. If you still have the original QJet clean and rebuild it and reinstall it.
I was referring to the old fuel pump being potentially bad by letting the fuel drain back down the lines to the tank and not keeping it up to the carb ?
There have been numerous discussions about this, with focus on exactly how the fuel bowl would drain.
OK, So…..you start the cold engine on any day with 3 pumps of gas & it fires right off and continues running is what I believe you stated.
You drive the car for X number of miles, the engine gets to operating temperature and if it sits ~30” it fires back up but if it sits 5’+ it won’t start for some time unless you continue to pump the accelerator an inordinate number of times I think you stated.
Try this. Take car for drive to operating temperature. Turn off car let set 5’+. Remove air cleaner, look into carburetor - pump accelerator linkage. Do you see fuel flowing into carburetor via nozzles as you pump linkage?
Hot engine causes fuel percolation, which results in flooding.
I thought the OP was referring to fuel draining back down the fuel line but what you're saying is a vapor lock (percolation) condition I guess. Hmmmm....interesting. I read some on this and evidently as Glen suggested it may be due to use of EtOH fuel? Fascinating since I've never had this condition and I'm perplexed why it doesn't happen on nearly all carburetor equipped engines. Interesting.
Hot engine causes fuel percolation, which results in flooding.
Basically the carb or fuel line gets very hot, the fuel expands or boils and overwhelms the needle and seat and floods the carb.
After a few minutes when it would be hard to start, open the hood and take off the top of the air cleaner, if you smell lots of gas, then this is probably your problem.
To see, on another occurrence, try opening the hood and remove the air cleaner right after you park it. Wait the normal few minutes that would cause the hard start and see if it is any better with cool air circulating near the fuel line and the carb. Solutions could be fuel line routing, insulation and perhaps a fiber spacer under the carb.
I've had this problem, thick fiber gasket under the carb helped about 80% of the time in 100+ degrees weather, never a problem when it's cold in the winter....Tedd
I thought the OP was referring to fuel draining back down the fuel line but what you're saying is a vapor lock (percolation) condition I guess. Hmmmm....interesting. I read some on this and evidently as Glen suggested it may be due to use of EtOH fuel? Fascinating since I've never had this condition and I'm perplexed why it doesn't happen on nearly all carburetor equipped engines. Interesting.
I was just suggesting to try the "clear a flooded carburetor" operation as a diagnostic method to help determine if it's lack of fuel (drainback) or too much fuel (percolation).
Basically the carb or fuel line gets very hot, the fuel expands or boils and overwhelms the needle and seat and floods the carb.
After a few minutes when it would be hard to start, open the hood and take off the top of the air cleaner, if you smell lots of gas, then this is probably your problem.
To see, on another occurrence, try opening the hood and remove the air cleaner right after you park it. Wait the normal few minutes that would cause the hard start and see if it is any better with cool air circulating near the fuel line and the carb. Solutions could be fuel line routing, insulation and perhaps a fiber spacer under the carb.
You might even see the fuel dripping out of the squirters
Ok so here’s the update after trying some of the above suggestions . I took the car for a 1hr plus drive . Got home and parked it . Engine off.
-Strong raw fuel smell from the top of the carb when I took the air cleaner off when hot .
-I did see fuel squirting into the two bowls closest to the nose of the car on the carb when I worked the linkage( see pic with arrows )
-Car starts right up after sitting hot for 5+ minutes with the air filter off. Very interesting.
I did buy some insulation for the fuel line since it’s sitting on top of the manifold and I did buy the edlebrock 9266 heat insulator gasket I was gunna try (see picture). The car also has an edlebrock performer intake .
i Also included a picture of two spark plugs from the drives side .
Btw. just to clear up something about the fuel pump. A fuel pump could drain back, but that won't remove any fuel from the float bowl. Remember there is an air gap between the needle and seat and the fuel level. So if the output line for the pump/input line for the carb completely drained, no fuel would be siphoned out of the float bowl. It would remain at the same level. The car would still start after sitting 5 minutes because the float bowl would not drain.
Does this car have a fuel pump with a return line? If so, is the return line capped off? If not, are the lines in good condition? No kinks, or otherwise restricted?
One of the purposes of the return line is to vent excessive fuel pressure from percolation back to the tank. It also has a built in designed leak to constantly circulate fuel thru the pump.
If you can’t find a cause for the hot restart issue, installing a fuel pump with a fuel return fitting might be a worthwhile fix.
It’s not an issue with the car, it’s the cat urine liquid that is labeled as gasoline.
Hello gentlemen. As the title states, I have some questions about my fuel system. I still have a mechanical fuel pump and I have installed a fuel pressure regulator and pressure gauge, all in line to the carb. My fuel filter doesn’t fill completely with gas. However, my gauge is reading 4psi. Should the filter be filling up with gas?
