The Stovebolt Site Forums The Shop Area Engine Shop Vapor Lock? Flooding?

For reference:
1948 3100 w/ 216 (Carter W-1)

Just did a bunch of major service to get the old girl roadworthy again (all fluids, coil, points, condenser, plug wires, push rods). I adjusted the valves and the engine sounds great. I drove the truck about 10 miles round trip to get a full tank of fuel, and to get some heat in the engine to test everything out. Once I got home it wouldn't restart, but quickly flooded fuel out of the carb. I did end up get it going and it ran fine. Later that evening, I tried to restart it and only got flooding.

Cold starts are a little different. I really have to hold the starter pedal down and it will hit intermittently until it does finally fire up. At which point it runs fine...until I have to do a hot start. Then I get flooding as mentioned above.

Before all of the work I did it used to fire right up, first time no issues.

Some symptoms would say vapor lock, but the flooding aspect is weird. Anybody experienced this? Thanks!

Not vapor lock.

Your carburetor likely needs to be rebuilt. Float stuck/float set too high/needle valve not seating /accelerator pump leaking, etc. are possible problems.

After the engine is hot and idling, look down the throat and see if fuel is dribbling into the venturi

When it's shut off, look down the throat and see if there is fuel pooled on the intake runner. Check this hot and cold.

What type of fuel pump are you using? Test the fuel pump pressure at the carburetor. It should be 2psi-4psi. If it's greater than that, the pump could be forcing the needle valve open and flooding the carburetor.

I am using the stock location fuel pump on the side of the block. It's a newish pump (last 10 years?).

I just ran out and fired it up. I do not see any fuel pooled inside, and there is no dribbling while the engine is running. Looking down the throat of the carb it is pretty dry.

1948FarmTruck,

Since you are talking "engine" related issues, I have moved your thread over to the Engine Shop as it is the best place to continue the conversation.

Am sure many more will provide info and replies soon.

Good luck resolving your problem.

Dan

Thanks, Dan!

Look down the throat after the the engine has been operated at normal temperature. Check while idling when hot and then check after shutoff for 30 minutes or so.

How long after shut down do you experience the hot start problem? Fuel should never leak from the carburetor as you described.

I will try to get it up to temp later today. When I went on a fuel run yesterday it was turned off long enough to get 10 gallons (5-10 minutes), and it started right up. After I got home, and it sat for a few hours, nothing but flooding. When that happens the outside of the carb is wet with fuel.

With my limited knowledge, the leaking carb is the frosting on the cake. Time for a carb rebuild IMO.😃

Yes.

I ordered the W1 rebuild kit. I was idling it today trying to time the engine and while it was idling it died and fuel started weeping out of the carb. I'm guessing that's float related?

Check the fuel pressure first- - - -depending on where you got the rebuild kit, it's also possible you got a generic needle valve and seat assembly that's actually intended for a Ford carburetor- - - -the orfice behind the needle seat is too big and normal fuel pressure will force the needle off its seat and cause flooding, even with the correct float setting. Jon H. (carb king) can supply the right needle and seat assembly, or a complete, correct, rebuild kit.
Jerry

Could be float or sticking needle valve??? Some debris keeping it from fully closing.

You may also want to check your fuel pump output pressure to make sure within normal psi tolerances. Too much will definitely cause over-pressure and flooding.

I know you didn't mention any work on the pump as part of your recent major service stuff, but something to look at as well just to eliminate the possibility.

Dan

EDIT - Jerry beat me to the punch on the fuel pressure info.

I should add that I have NOT done the rebuild yet. I'm still waiting on the kit, but figured I would knock out the timing while its "running". I will definitely check fuel pressure though.

I'd be more inclined to blame the needle valve not seating properly allowing fuel to overtop the fuel bowl.

Check the fuel pressure, though. should be between 2-4 psi. My rebuilt mechanical pump operates at 2.5 psi.

I had a similar problem. How old are the fuel lines? Especially from the pump to the carburetor. You could be picking up rust that is keeping the needle valve from seating properly.

Fuel lines are original, but I did flush the tank, blow out the lines, and install a new fuel filter right before the carb. That isn't to say it wasn't already crudded up though. Lord knows the stuff that came out that tank looked like crunchy motor oil.

It seems to me that if I can remember correctly, you can remove the needle & seat without disassembling the carb. on that model. Disconnect the inlet line at the carb. & then remove the fitting. The needle is in the fitting. You can clean it out & try again.
Its been a long time since I worked on one. I might be wrong. I was wrong once before in the last 75 years.

George