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I recently posted an engine problem I was having. My 48 Loadmasters 216 engine wouldn't run without the choke being almost all the way out.I have traced all avenues of a vacuum leak and have found none.Changed carburetors, added a new vacuum advance and got the same results. I pulled the manifold off yesterday and so far can't find any evidence of open holes cracks bad gaskets or rings.It simply refuses to run properly. I am on the verge of throwing in the towel on the whole project. The engine idles and runs smoothly but the choke must be almost completely out. Once again does anyone have any more ideas as to why?

Resp.

JMH

Gotta be a vacuum leak, but sounds like you've checked that.How about ignition? My brother loves to say "90 percent of carburetion problems aren't....."

Highly doubtful that it is ignition, if it runs fine with a choke ON application.....what you have is a LEAN air fuel mixture......vacuum leak or inadequate fuel flow. If you are ABSOLUTELY sure that you have NO vacuum leaks, you should have a steady 20-21" inches of vacuum at idle (choke off), I would perform a fuel pump pressure and volume test to ensure that adequate fuel is being delivered to the carb.

Hi All,

I have an electric fuel pump on it now because I don't think I am getting adequate fuel volume. The carb is rebuilt, the air fuel mixture screw is at factory specs and the timing is at factory specs.I am going to replace the manifold and gaskets with another one from another 216 I have and try that. Don't have anymore options.

Thanks,
JMH

A smooth reliable idle eliminates a vacuum leak in my book so we are back to fuel delivery into the carb bowl if the carb(s) are ok and have acted the same.
Does it do better on first startup when the electric pump has filled the bowl then lean out as the bowl fuel level drops?That can point to restricted supply.With the bowl full you should have several seconds (20-30 or so) of normal operation even if the vehicle didn't have a tank or pump or fuel line on it.Warm the engine first or it will need choke because of being in the warmup mode.
Put a length of rubber line into a bucket from the fuel line at the carb then operate the pump and observe the AMOUNT of fuel being pumped.This test can be revealing of problems on the suction side of the pump.And remember the electric pump should be near the tank pushing the fuel to the engine not trying to suck it from the back to front.It is more efficient at pushing liquid than sucking vapor.
My guess if your carb is truly clean in the high speed circuits we have a holy or plugged fuel line to the rear or in the tank.A perforated line on the suction side of the pump will many times let air in but not leak fuel out.

Hi:

I know this bolters problems, I have many of the same.
I wish I knew the solution my friend, but I an just as stymied as you. Rebuilt engine with everything renewed or rebuilt. When running it needs partial choke and runs rich though I have attempted to lean it. The carb is a brand new rebuilt, and a new in line glass fuel filter. We have adjusted the valves, timed it and checked for vacuum leaks. One thing I note is air bubbles percolating in the glass fuel filter when running, should they be there? and if not where are they coming from. The fuel lines are new from the tank to the carb. Thanks for the help.


Regards,

Dave

Mr Taylor,

Thanks for the tips. I will give them a try and post the results.

JMH

JMH, One thing I have done numerous times to provide a temp gas supply for testing or sometimes to get a old machine home until better things can be done is to:
1) using an available fuel container that can be supported higher than the carb.
2) put enough fuel in the container to have 3-4 inches above the bottom
3)I like to use a clear hose so I can prove that fuel is flowing-start a syphon then close off the lower end never letting it lose its filling of fuel.Also the clear hose lets you see when you have drawn enough fuel up the hose to fill it but not give you a drink.You really have very good control of the filling of the hose when you can see the level in the hose and modulate your oral vacuum.
Good luck and be careful.
4)connect the lower end to the carb inlet and the syphon will keep the carb fed very well for stationary running
5)Fuel in the container needs to be above carb inlet

Caution: Avoid spillage-do not use a container with a large opening-preferrably just large enough to admit the hose-let any spilled fuel evaporate well before trying to start or make sparks-do this outside and prepare for worst case problems.