Fuel gushing out of carb

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by **vms1942** » November 28th, 2017, 3:34 pm

How much fuel normally blows back out of the carb without the air filter hooked up?
Mine is gushing out of the carb when I stop cranking. Still gushes while engine is running.

Thanks in advance for the help... I am totally lost right now.

by **rickf** » November 28th, 2017, 5:24 pm

Normal for a fair amount to squirt out when cranking and when you stop with the hose off. If you put the hose on it might just start and run good. If it is really pouring out then the float is stuck, have you tried tapping on the top of the carb with a screwdriver handle? I was just testing a few carbs I rebuilt and it would not start but was dumping gas out of the carb. Put the intake hose on and fired right up and purred.

by **vms1942** » November 28th, 2017, 5:48 pm

Thanks for the quick reply Rick.
I will give it a shot tomorrow.

by **vms1942** » November 29th, 2017, 7:37 pm

I didn't have much time to work on the Mutt today, but I hooked up the hose from the air cleaner, cranked and fired up the engine, tapped the bottom of the carb and apparently I still have the gas gushing out. The engine started right up and would run for a short time, then it would flood out and die. Tomorrow I will pull the carb and check the float. I know it was free when I had the carb apart before installing it, but perhaps something is amiss.
Unfortunately I have little knowledge when it comes to carbs, so any suggestions are certainly appreciated. Now for a dumb question... The only thing I changed when I installed the carb is I eliminated the small fuel filter that threads into the carb since it was pretty beat up. Could that be allowing too much fuel to be fed into the carb?

by **vms1942** » November 29th, 2017, 7:45 pm

I have no idea why my reply posted multiple posts.
Sorry, but I don't know how to delete them.

by **rickf** » November 29th, 2017, 8:16 pm

Second post deleted. The filter would not be an issue BUT, You say it was threaded directly into the carb? If it was then that was wrong and it may have knocked a thread off in the carb and that is what is holding the needle off the seat. Long shot but you are right to go back to the last thing you did. How is your fuel line hooked up now? There is supposed to be a special fitting that threads into the carb and it is a straight thread, not a pipe thread. It has a lock nut on it with a plastic sealing washer and then the other side of the fitting is 1/8" pipe thread for the filter.

by **vms1942** » November 30th, 2017, 1:08 pm

Here are photos

Note the hole in the brass plug ! I have never seen an M151 carb with a hole in it. Could this be causing my problem? This is a housing I purchased to replace a cracked housing.

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This is the type filter I removed. It was between the black rubber hose and the carb.
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by **rickf** » November 30th, 2017, 2:54 pm

Well, I see a couple things that get my attention. First and foremost is the teflon tape in the fitting that should not be in that hole! You are very lucky not to have broken that housing. That is a straight thread, NOT a tapered pipe thread and then to put teflon tape on it and lubricate it.................... They usually break. Second is the tape, If a piece got in the carb it can be stuck in the needle and causing your flooding. Third, I see the carb is nice and shiny, did you do this and if so did you do anything inside the carb? The hole should not be there but that is a air vent passage so it will not affect the way it runs. It will let a very small amount of dirt in and if you go into deep water you will have a problem. Are you running now with no filter at all? If so that could be another problem since these tanks usually have some crap in them.

by **vms1942** » November 30th, 2017, 4:14 pm

Thanks again for your help, I will remove the tape. I cleaned the exterior of the carb with Scotch Brite pads. I did nothing in the interior of the carb except install a new gasket to the joint of the top and bottom section. I did no adjustments since this carb was taken off a running engine. (or so the seller advertised).

I can't imagine why anyone would drill a hole in that vent housing, but when I had the air intake hose disconnected that vent area on the inside of the carb is where the majority of the gas was gushing from. Regarding the fuel filter, I have an inline filter mounted on the fuel line from the gas tank at the firewall.

by **vms1942** » November 30th, 2017, 4:14 pm

Thanks again for your help, I will remove the tape. I cleaned the exterior of the carb with Scotch Brite pads. I did nothing in the interior of the carb except install a new gasket to the joint of the top and bottom section. I did no adjustments since this carb was taken off a running engine. (or so the seller advertised).

I can't imagine why anyone would drill a hole in that vent housing, but when I had the air intake hose disconnected that vent area on the inside of the carb is where the majority of the gas was gushing from. Regarding the fuel filter, I have an inline filter mounted on the fuel line from the gas tank at the firewall.

by **vms1942** » November 30th, 2017, 4:50 pm

I just got an email from the seller and he is replacing this carb with another at no cost to me. Hopefully the replacement will not have this same problem.

by **rickf** » November 30th, 2017, 5:05 pm

Good to hear and while waiting don't do anything with the tape. I would not touch that fitting unless I had to. If the tape came off it did so on installation and no more will be coming off. What is already in there will need to be addressed. If you keep that carb just pull it apart and set the float level and clean out any junk from the needle and seat when you take the float out to set it. As far as the hole I would get a little bit of RTV and force it into the hole from the outside, just a very little bit and that will plug the hole.

by **vms1942** » November 30th, 2017, 7:09 pm

Thanks a lot for all of your help Rick.

by **nc715** » June 24th, 2018, 10:48 pm

I am having a similar or same problem. Over the winter something must have gotten plugged and when I start it quickly floods the engine and stops. I have tried 2 different carbs and have disassembled both many times and cleaned all passages; very close attention to float valve and seat. (I think this is irrelevant but I have replaced fuel pump 2 times.)

After the engine floods out, gas runs out of the carb when I remove the inlet hose. Vent line back to tank is clear (when I blow on it).

by **rickf** » June 25th, 2018, 7:22 am

If you start it with the intake hose off does the gas run out WHILE it is running or only when it shuts off? It is normal for the gas to run out when it shuts off because as the vacuum drops off the accelerator pump shoots a shot of gas into the throat of the carb. This is to help with the next startup. If the gas is running out while it is running then you have a float or seat issue. If you have the old brass float it may have a hole in it and be sunk.