I’m thinking the fuel pump is loosing its prime. Reason being, you say you have to crank it till the battery is nearly dead. Also check EVERY rubber section of fuel line, it may be fine cold, but after being exposed to exhaust heat after shutdown the insides can get squishy and close up. I doubt it’s vapor lock, a lot of people like to say that, but I think it’s unlikely
why would it loose its prime after sitting for ten minutes up to an hour but if it sits for two or three hours it gets its prime back? Not being a dick im just trying to understand. thanks mark.
I still think the fuel is boiling. It's vapor lock. You can try filling the bowl with gasoline from a squirt bottle and see if it starts.
You all might try replacing your fuel pump with one that has the fuel return line and see if that cools the gas down.
He will have to run a line back to the fuel tank and change the sender if it didn't come equipped that way from the factory.
Yeah, it would be a pain in the butt if it doesn't already have the line. If I'm not mistaken, 72 should have come with the return line.
Non AC cars have no return. Im still thinking there's too much alcohol in the fuel. My GS is the same way unless I use Cam 2. Forget about the winter blend crap that I get stuck with come spring. Car wont start if I let it sit for 15 minutes and it heat soaks
Jason, last winter, I followed Eric's suggestion and used 10 gallons of VP Vintage leaded. Was still able to get the car out a bunch of times in the winter, and had no problem in the Spring.
LOL, I know your not being a dick, I like questions, being inquizitive If you can crank it so long as to almost kill your battery, and you said you have spark, the only thing missing is the fuel and air. Theres plenty of air, so that leaves fuel. Are you getting a good stream from the accelerator pump nozzles when it refuses to start? If so it means theres enough fuel in the carb bowel and it should fire. When it starts after sitting for a couple hours, does it start with a turn of the key, or do you still have to crank it for a bit for it to fire?
Theres plenty of air, so that leaves fuel. but, as noted above, once prime is lost it doesn't magically reappear. "lost prime" would remain a problem after the car had cooled down, and he's claiming that it starts quite easily if he lets it sit 3-4 hours. therefore, the problem is heat soak. the question is whether it's heat soak of the carb or the ignition coil. the problem is usually the carb.
Same for my 350, if its a cool evening ( 70-80 deg) I have no issues, 85 deg. and up very hard to restart and takes a few seconds for idle to smooth out when it does. Found a guy just down the road from me that sells ethanol free 91 octane gas, filled up with that and have not had an issue. My guess is it s the ethanol. If you can find ethanol free gas give it a try. www.pure-gas.org , has listings for each state.
if you verify that it is the fuel, go through your whole system, paying special attention to line routing in the engine compartment and making sure that a fuel filter / line isn't resting on the intake or laying against the valve covers or anything. you want insulation, shielding or standoffs for all of that.
Thanks guys. Im going to try the racing fuel first I think, seems the easiest thing to try although probably not the least expensive in the long run.... Glad to see that Im not the only one with this issue.
That's what Im curious about, does it start with a flick of the key after a few hours, or does he have to crank and crank until the fuel system re-primes.
That is vapor lock. The evaporating fuel creates a very rich mixture in the intake that won’t easily light. Wait a few hours and it gets lean enough to fire right off.
fires up as normal after a few hours. So Larry do you think the racing fuel would help with vapor lock, of should I just go for the heat shield?
It might help some, but that is not a good solution to your problem. The carburetor is getting too hot. You need to insulate the carburetor from the intake. Insulating the fuel lines may help as well. If you had a fuel pump with a vapor return, that would help as well.
