The Stovebolt Site Forums The Shop Area Engine Shop 235 warm start problem

My 54 235 with Model B hand choke, Rochester starts fine when cold, but when hot it needs starting fluid, or full choke. Dwell set at 32 degrees, timing on the mark, idle mixture set at best vaccum, idle speed at 600. No headers, only mod is 12 volt alternator. Has been setting for seven years, had gas tank flushed and sealed, rebuilt carb. Could not replace pump plunger because pump in kit was different. Used a Walker 15157 kit. Any ideas?

Did you do a compression check?

having to add fuel indicates a delivery problem .
does the pump deliver enough ?
is the fuel evaporating ? whats causing it to get that hot?
is the float level correct?
are the valve clearences correct? :confused:

that kinda points to the valves being set too tight.

Yup ; $5.00 says your valves are too tight - get a new gasket (first!) and adjust them when the motor is really good and hot , that should cure the problem .

realmccoy: Sounds like fuel delivery problem. Maybe junk, trash, etc. in line from tank restricting flow to pump. What about pump volume/pressure? Pump could be bad after 7 years. Pump should output 3/4 to 1 pint per min. (volume), and a minimum of 2 psi to max 5 psi (pressure) to carb. Could also be a carb problem. The needle and/or seat in the float system can be dirty or maladjusted. With low fuel delivery pressure the fuel system can be subject to vaporlock! Check fuel pump with pressure gauge on discharge side. Take line loose from carb base and pump into coffee can to test volume. Can also be a dirty pump strainer or worn pump check valve. Just a few ideas, but this is stuff you should check anyway. :rolleyes:

Its a carb problem. Since it starts with the choke on when it is hot, that tells me the metering system in the carb is probably partly plugged. 7 years is a long time to sit. If all the gunk isn't out of the fuel passages, especialy the air bleeds, you are going to have problems. Todays carb cleaners are not as agressive as they used to be thanks to the EPA. It may need another soaking.

Skip the valve adjustment crap as suggested by Volkswagen Nate.
Its a carb problem.

What is the correct carb rebuild kit? I'm checking out the fuel pump tomorrow. If the pump passes, I will dig into the carb again.

As long as you have fuel in the carb bowl (and you do, if it starts choked), then the engine should start and run for at least 15 seconds without the pump pumping any fuel. It's not like fuel injection. The pump only tops of the carb bowl when the float drops enough to let more in. Trust me, it's not your fuel pump. If it was it would cut out under hard acceleration. It's also not your main jet, because when you are starting hot you don't need to even hit the accelerator normally and you are using the idle circuit to start it. You may have a plugged air bleed though. There are several air bleeds in a model B.
If it is really that hard to start warm, and your idle mixture is correct when the engine is warm, if you shut it off and immediately crank it back up, it should start instantly with no throttle applied unless you have bad compression or a really slow cranking speed. Bad compression is caused by a lot of things, but if it occurs when it is hot only it is usually too tight valves or a bad head gasket. Check the compression, it's really easy. A partial check will tell you what you need to know.

If it is only hard to start after you shut it off and let it sit for a few minutes then it could well be a carb problem. Did you use the thick spacer gasket between the carb and manifold? Did you put the check balls in the power valve circuit in correctly? Did you route the fuel line away from the manifold far enough? Is the manifold heat valve stuck?

hmmm

We have to give our 235 a couple pumps to start it when warm. Same thing as when it's cold. Two pumps of gas. Sometimes three when it's really cold (below 50! ).

Is that a problem? It seems to crank fine. I haven't checked the compression yet.