TheSamba.com :: View topic - 32-PHN Flooding

Sun Mar 02, 2014 8:14 pm

I'm having a problem with both of my T34 engines - as soon as I shut off the engine, the carb and manifold starts filling up with gas. Both engines have rebuilt carbs; one has an NOS fuel pump, the other has a rebuilt pump. I when I shut off the engine, I can see the gas pouring into the 90° rubber elbow. I'm running the engine out of the car, out of a 1-gallon gas can, so I know it's not a too-full tank. The engine in the '63 exhibits the same symptoms, but to a lesser degree.

I went through the 32PHN book and I've tried shimming the float valve, adjusting the float itself, made sure the accelerator pump isn't hung up. I did some searching and found a reference to using a "T" fitting from a later model, but I don't know what that would be. I even went through threads on a light plane site, but still didn't find a definitive fix.

It would seem that I need to reduce the fuel pressure, but I'm not sure what the best way to do that would be. The '62 engine ran better with a torn fuel pump diaphragm!

Sun Mar 02, 2014 10:24 pm

I suspect the float needle valve may be buggy. I've found that it's usually better to reuse old ones than to use the new ones that are included in rebuild kits. But it's weird that it's happening after the engine is shut off. Maybe it has something to do with your out-of-the-car gas can feed? Is the can higher than the engine?

Do you have the electromagnetic cutoff valve installed, and if so are you sure it's working?

Mon Mar 03, 2014 9:27 am

t3kg wrote: I suspect the float needle valve may be buggy. I've found that it's usually better to reuse old ones than to use the new ones that are included in rebuild kits. But it's weird that it's happening after the engine is shut off. Maybe it has something to do with your out-of-the-car gas can feed? Is the can higher than the engine?

I tried playing with that. There's less than 1/2 gallon of gas in the can, so I can't imagine even directly above the engine there would be that much of a pressure head

Quote: Do you have the electromagnetic cutoff valve installed, and if so are you sure it's working?

Yes and yes. If I disconnect it, the engine dies.

I wonder if I made a spacer for the fuel pump if that would reduce the pressure. The only question then is if would it lean out at WOT.

Mon Mar 03, 2014 10:10 am

The VW-approved method is to add additional paper gaskets at the base of the fuel pump. It shouldn't take much shimming to make a difference in fuel pressure.

Mon Mar 03, 2014 7:12 pm

t3kg wrote: The VW-approved method is to add additional paper gaskets at the base of the fuel pump. It shouldn't take much shimming to make a difference in fuel pressure.

I did that tonight - I cut two shim gaskets out of some fairly thick (.75mm) gasket material and that seems to have fixed the problem.

Thanks!

Mon Mar 03, 2014 8:54 pm

thom wrote: t3kg wrote: The VW-approved method is to add additional paper gaskets at the base of the fuel pump. It shouldn't take much shimming to make a difference in fuel pressure.

I did that tonight - I cut two shim gaskets out of some fairly thick (.75mm) gasket material and that seems to have fixed the problem.

Thanks!
Glad you found the solution. I was curious to know what that was going to be.

Sat Jan 26, 2019 5:48 pm

Well, the problem is back. It seems to come and go - I went quite some time with no issues, then it started flooding a little, so I added more carb spacing, and I was good for a while, and now it's back again.

I did a little GoPro video of the carb inlet, and you can see it start to fill up with gas just seconds after shutting off the engine

Sat Jan 26, 2019 9:40 pm

I had the exact same trouble with my 32PHN-1 flooding after shutting the engine off. I used a pressure gauge to test the fuel pressure & it was within spec. I ended up adding another gasket to the needle valve & it solved the problem. My carb had an aftermarket needle valve that required the float to be higher than normal to cut the fuel off. After adding the extra gasket the float level was normal. The kit I used was made by Royze.

Fri Feb 01, 2019 12:10 am

there is some great info in the samba archives..... see link below

https://www.thesamba.com/vw/archives/manuals/carburetors.php