Hydrostatic lock cause

[ABSunbeams]

While checking electrical items on my Mk2 inadvertly left the key on overnight. Battery dead, recharged the battery tried starting, a couple of rev's and lock. Pulled the plugs to release the pressure #1 full of gas. What would cause a drain down in the carb (stock 2bbl)? No visible gas leak thru the vent.

 

[Warren]

Float valve

Sticky float valve in the carburetor.. possible
If it has the stock fuel pump it could have happened gradually. It'd be a good idea to drain oil pull plugs and top oil the cylinders. When that happens on small motorcycles you can get a big bang on restart as intake valve and exhaust will get run over fuel. They put drain holes in the muffler's for that and for condensation. Since you don't have little weep holes in the mufflers I'd be concerned that you might have some gasoline in the exhaust system so probably want to be pretty careful on restart.

 

[ABSunbeams]

Thanks Warren, there is a new SU pump installed, is there possibly too much fuel pressure?

 

[Warren]

Same one

I don't have the SU number on pressure . I'm pretty sure that it's much lower than the many aftermarket ones. If you see one on a car it's because they're running a different fuel pump than the SU. Unfortunately you have found the disadvantage of using one because they're so quiet. I'd never leave on the ignition with any other fuel pump I've had because I have leave the radio on to forget that the ignition is on.
If you're running points you might want to check and see if you've burnt them while you're at it. I suppose either the ballast resistor works or it doesn't as well as any other type of ignition system that you may have. Is the red dash light in need of replacement too?

 

[ABSunbeams]

The SU does run quite which is a plus & minus. The ignition light hasn't worked so it's hard to tell. Pulled the top off the carb to check the float valve held under pressure. The points were not burnt, got the cylinders cleaned out on oiled. Started and ran with no issue. Still wonder why it filled the cylinder without any sign of gas out the vent?

 

[Warren]

Can't say

I Don't have an auto light carburetor laying around anymore. I know the most marine carburetors will dump their fuel straight down the carburetor Venturi rather than off into the engine compartment. I'd like to see more replies . I've done a lot a lot a lot of little carburetors.. The bigger ones tend to try my attention span too much. Good luck with it keep a good eye on it and get an extra fire extinguisher. It could be something as simple as a little piece of crud in there in the seat that has since been pushed out. These things need exercise and a good warm-up at least once a week if not once every two weeks.. always interesting topic I sure wish there were some more replies..

 

[ABSunbeams]

Bad needle valve

Last year at our local Lions Club car show followed an early Tiger in and parked next to him. Opened the hood and the manifold was filled with gas due to a defective needle valve, gas was coming out the vent hole. Pulled the top off and replaced it. I had a kit at home with a new needle. The rubber tends to harden up over time. This was the first time it had been out in a while, according to the owner. Always carry an extinguisher in any old classic!

 

[KenF]

On mine (new AZX1308 SU Fuel pump, rebuilt AutoLite 2100 with brass float) for cold start, turn ignition on, let fuel pump run 5 seconds or so, pump 3 times, starts right up. When warm, if car sits for 20-40 minutes after running, it seems flooded and I need to hold gas down to start after 5 seconds or so of cranking. I heard somewhere it was typical of that Autolite, don't know. But I think if the fuel pump was left on for hours I can see the potential to dump a lot of fuel out of somewhere. I've played with the fuel level a bit, tried lowering level a 1/16" or so thinking maybe some sort of syphon was going on. Maybe a slow leak through the acceleration pump circuit. Even observed wet level while running (video here) to see what was going on in there, still a mystery. I do carry an Element E50 fire extinguisher, just in case.

 

[Theorangetiger]

I'm temporarily running a stock Autolite 2100 while I'm sorting things out. I had a Carter electric pump which worked fine with the Holley that was on there previously. When I installed the Autolite, the pump would occasionally blow through the needle and seat valve and leak onto the intake manifold, possibly down the throat as well but the stuff on the manifold was easy to see.
I suspect it was an issue of too much pressure from the Carter and a valve on the Autolite that didn't like excessive pressure. It needed a regulator for sure.
I am in the process of installing a new pointless SU pump which do run at quite low pressure.
This is the stock setup which was not an issue so I suspect you may have had a foreign object holding the needle and seat open.

 

[ABSunbeams]

Autolite 2100

Thanks for the replies. Could have had a pc of debris stuck in the needle. The SU is new from SS which may have a slightly higher pressure. Will have to check it, put the old one in a Mk1 in the boot location so can compare pressures. I have had an issue with gas boiling in the carb on a Galaxie I have and starts hard when hot. Took off the heater hose through the carb base off. Made a big difference after that. Don't need that option running in the summer! Got temps around 220f after sitting 5 minutes, could hear the gas boil.