Ya don't ever want to brag about how good your jalopy is running, been getting the 40 ready for the round up, been bragging on how great shes running until last night ,Heres the run down , 40ish flathead, rebuild about 3000 miles ago, 12 volt system, electric fuel pump , fuel pressure regulator and gage, 2-3 pound pressure, rebuild 97 , max temp around 185 . When shes cold fires right off , never misses a beat, drive her , gets to temp, shut her off, heat soaks to about 195 , go to start , spins like crazy , no starty. Plug a plug dry as a bone, OK Nettle and seat, pull the top of the carb off all appears to work fine, accelerator pump? Looks fine, shoot a little starter fluid to her barks right to life and runs fine..............shes about to get grounded !
Sounds like the fuel in the line might be vapor locking from the heat maybe a possibility. How far is the fuel line away from the engine? Just a thought......
Maybe put in a carb spacer? Your fuel pressure sounds about right, but without checking it out, seems like you have vapor lock. What are you running for gas?
I don't know if this is your problem, but I believe your fuel pressure is too high - 1 1/2 lbs is all you need for a single 97 for a flattie, especially if running an electric fuel pump. I'm running dual 94s on my 40 Ford Fench block motor @ 1 1/2 lbs pressure - 97s and 94s do not seem to like any more pressure than that in my experience.
I'll back it off, but i would think with the electric fuel pump it would eliminate any possibility of vapor locking
Start easy, Check your filter first blow it backwords on to a piece of paper see what ya get. Them maby change hose if its old might be collapsing or flapping inside. Have you changed anything right before it started doing this?
Where is the electric pump mounted? It should be low, back by the tank so it pushes rather then pull the gas to the carb. Do your fuel lines run close to the exhaust system anywhere between the tank and the carb? Are you sure the pump is pumping when it's hot? Just some things to check out. Good luck Brian
I think it is because the roadster wants to make the trek to Austin and not the 40. Flatheads do talk to each other you know. Rusty
Rusty, you are exactly right, I threaten to chain her to the fence post and make her watch me load the roadster up to take to Austin! Fuel pump is mounted back at the tank, new lines and filter , regulator is mounted on the firewall drivers side as far to the left as possible . Did not have a way of checking to see if the accelerator pump was squiring,going to play with her some more to night and if i can get her to act up I'll check it. Thanks for all the comments!
That sounds a lot like a weak coil to me,,, just thinkin out loud. Luck buflochp (If you don't believe a dog is mans best friend, Take your wife and your dog, and lock each one in the trunk of your car for an hour. Then see which one is happy to see you when you let them out....)
Hey, didn't tthink about the coil.............. just happen to have a good one on the shelf, if i can remember which shelf! Thanks.
Ok this is becoming a common problem, Lets address it this way. First your engine wont fire because it has no fuel. The first step as suggested by Casey is to check the accelerator pump circuit. No rocket science, engine off, take off the air cleaner, Look down the carb throat and pull back on the throttle linkage one or two times. You should see a stream of gas from the discharge nozzle in to the throttle venturi. If you don't you don't have any fuel to start the engine. The next step is to carefully pull the top of the carb off to check the fuel level in the float bowl. If your float level is to low it may not refill the accelerator circuit and create difficulty in priming the carb at initial start. Check the specifications of the float level and reset if necessary. If your float level is correct the next step is to examine the grade of fuel that you are using. Many of the newer fuel mixes contain ethanol, this has a lower vaporization point and due to the engine temp may be evaporating as the hot engine cools down. The heat transfer to the carb when stopped causes the fuel level in the accelerator circuit to evaporate and there is no fuel to prime the engine during restart. This problem also manifests itself if the vehicle sets for a couple days, difficult starting, shot of starting fluid starts right up. Most new vehicles operate on a high pressure fuel pump in the tank and a pressurized fuel delivery system. This allows the car to operate on lower vaporizing fuels because the fuel is pumped at a high pressure to the nozzles. A carb fuel system usually relies on a suction/pump pressure system and low vaporization fuels create start up problems. Since you have a rear mount pump you should also check to insure that a fuel line does not run parallel to a heat source or crossover a heat source like a muffler or exhaust pipe. This will create the same problem as an ethanol based fuel will boil in the fuel line and vapor lock the car. The carb runs until it runs out of fuel and then it appears that the fuel pump is not functioning correctly. Thats not the problem its the gas boiling, once it has cooled and the air pressure bled off, its back to normal. To help over come this evaporation problem I have been using a fuel additive like Marvel Mystery oil to change the evaporation point of the fuel or just taking the time to check the percentage of ethanol in the fuel at the pump. It is supposed to be posted. If there is ethanol listed as a portion of the fuel, just go to a different gas station. Try changing fuels before you tear anything apart.
WOW.........Thanks, it appears when the engine is cold, it is pumping fuel just fine , but will take you advice and check out the rest, excellent response thanks for taking the time ........
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