Questioncar starts no prob when cold. after running till it's warmed up and turning off, very hard to start. smell gas so it might be flooding. also sputters a little @ high rpm. new plugs,points,condenser,rotor,dist.cap,fuel filter and air filter not fixing problem. whatya think
AnswerHi Steve,
Hard starting and misfires at high RPM may or may not have anything to do with each other so you must concentrate on one item at a time. Instead of tossing money at the problem you need to run tests that isolate the problem into a smaller area. And continue to isolate into smaller and smaller areas. I was forced to use this method working in dealerships. I was always surprised what I found but always found the problem.
Look at the "no start when hot" problem first. All piston gas engines require only 3 items to run. Compression, fire & fuel to run. There are conditions on each of the three.
Compression --- sufficient compression-- for your car that is about 125 to 180 PSI (throttle open and 4 or 5 revolutions) with little variation between cylinders. In your case you must test it while the engine is hot.
Fire ---- a good spark at the correct time --- Without a scope to tell how many kilovolts, you can just remove a spark plug and attach it to the plug wire and lay the plug on a metal part of the engine and spin the starter and watch the plug. You want to see a thick blue spark. (thick as the lead of a pencil) (a hair thin yellow or orange spark is a weak spark) In your case you must check it when it is hot and not in sun light. Also check the timing.
Fuel ----- A combustible fuel available to the combustion chamber and in close to the correct air/fuel ratio. In your case you want to know for sure that you have form 1.5 to 3 PSI fuel pressure to the carburetor (when hot). And to see if it is getting to the combustion chamber you can try to start and after a failed attempt, remove all of the plugs and note if they are wet or dry. If they are wet, you are getting either too much fuel per air or not a good spark. If you have checked the spark already and they are wet, that tells you it is getting too much fuel per air. You can try the standard method of starting a flooded engine by holding the throttle wide open when trying to restart hot. If the plugs were dry and you found the fuel pressure (Hot) to be in range then you need to spray starter fluid into the intake when the engine is spinning over.
Two different problems can give you trouble when shutting off a hot engine. When an engine is hot and shut down the fuel gets hotter than normal and starts to boil which in turn will force excess fuel out of the jet and that fuel will run into the intake and puddle. so when you try to restart hot you get a flooded engine. Another problem is when you shut down an engine hot the heat will boil all of the fuel out of the float chamber and vaporize, with most of the vapors going into the charcoal canister and into the air filter and outside. Then when you try to restart hot the float chamber must get full again before any can get into the engine. (noted by dry plugs)
To boil the problem down it is "Wet" plugs = too much fuel and "Dry" plugs = not enough fuel and need to spray starter fluid into the intake to restart.
Let me know,
Howard
