Fuel supply help

[armydriver]

My truck has developed a fuel problem. I can start her and the truck will idle just fantastic, then all of sudden it will start to die, like there is a lack of fuel. I increase the throttle some and it will continue running but real rough and is smoking, like the choke is deployed, but it is not. After I let the truck sit for a while, the same thing all over again. I disconnected the fuel line at the carburator and the fuel pump is pumping a full stream of gasoline, so that is not the problem.
Might there be trash in the carburator bowl that when allowed to settle, does not create a problem, but then new fuel starts flwing in it gets stirred up? Help Dr. Deuce or anyone else that might have an answer. I just put a new T2 AC original equipment filter on her but the trash might have already gone through into the carb. Could there also be water in the carb. bowl too, what do you think?

[John V Cliche]

Hi Jim
You diagnosis might be right .
When I first put my CCKW on the road ( MID SUMMER ) I had the same problem . I cleaned and flushed the filter and drained the fuel bowl problem went away . Since then I always include dry gas in the tank , 4yrs now no water problem. The entire fuel system is as orig. built including the brass filter element. So with a little PM it does function well. Hope this Helps.
John

[armydriver]

Thanks John.

[armydriver]

Well so much for that diagnosis, I removed the carburator, cleaned out the bowl and put it back on.The bowl was not that dirty and no water was present. The truck started up and ran fine for about 2 minutes then started acting like the choke was deployed and started choking down. When the accelator was opened, it would catch up, after a few seconds and run fine, then when the accelator was released, it would idle for a few seconds then start to choke back down again. I have replaced everything but the fuel tank itself. When it starts to choke down and the accelator is opened it acts as if the cylinders are being flooded with fuel.
Help me learned ones. I am at my wits end.

[John V Cliche]

Well Jim ,
Sometimes you gotta take a bunch of little steps.
You know it ain't water !!!
But if there's no dirt in the bowl it don't mean no dirt in the carb.
When the carb chokes up at idle you probably got black smoke too don't ya?
Try winding out the idle mixture when its running if there's no change you got DIRT and its probably in the idle mixture passage giving a RICH idle mixture sort of like to much choke.You could try compressed air in the hole where the screw goes (engine OFF)You just might get lucky.
Jim somtimes it just a process of elim. Could also be a vac. leak,look and listen. Hope this helps.
John

[Karoshi]

Did you rebuild the carb?. I had a similar problem some years back and although I cleaned the sediment out of the bowl the problem remained.

I had to strip the carb, remove ALL the jets, and non return valves and rebuild with new before I solved the problem. Rust sediment from the tank was so fine it carried thro' into the internal passageways of the carb.

The other BIG problem I had was the suction pipe in the tank was clogged. The sediment would settle to the bottom of the tank and clog the feed pipe . When the engine was stopped and the "suction" from the pump released, the sediment would fall away and everything would be ok again ....for a while.

Hope this helps

[Chappers]

It could be your needle valve not seating properly,the carb has to have the float set to give the right amount of fuel in the bowl to give the right mixture.
if its not shutting off the fuel when its full it will be like running very rich.
try giving the carb a tap by the fuel inlet pipe to see if the valve is sticking open. Check to see if its seating correctly by stripping the carb top off and blowing into the fuel inlet whilst holding the float up.
Have you put a carb rebuild kit in your Carb?,It's well worth it for the money.

regards

Steve

[dr deuce]

Try the hand over the carb trick I explained a week or so ago. It creates trememdous suction on the carb and will suck small stuff thru. I have seen it work many times.

[armydriver]

Thanks guys, I really appreciate the input. The carburator was professionally rebuilt about a year ago and I have not driven the truck that much. I believe it is really fine trash in the system. Doc I have tried your rememdy and it helps for a short period of time, then chokes back down. I really need to replace the tank as it is apparantly full of rust particles and I do believe they are clogging up the intake tube from time to time. I will also utilize the compressed air to see if it blows out what is in the carb and see if that helps. I will keep you guys posted on my progress.
Thanks again, you are a great bunch of guys.

[Karoshi]

AD your carb may have had a pro rebuild but it only takes one dose of crap fuel to screw it up again !!

Rebuild kits are pretty cheap here in Europe at about £20.00 and you get all the fiddly little bits ( spindle seals, washers, valves etc) to allow you to take the carb right down and "get in there". There are some real itty bitty passageways and you have to remove some bits to get to them, but the build itself is pretty straight forward.

As for the tank, well I took 4.1/2 lbs of powdered rust outa my 352 tank!!

Pressure washed it, added gravel and shook it about, pressure washed it again, but obviuosly didn't remove it all. Took about 50 road miles to suck the remainder into the draw pipe, before it choked up. The darn stuff was so fine it packed in like cooking flour settling in water.

Whatever you do with the carb, it sounds like you aught to do that tank first, else it will surely happen again. I think the 353 tank will be easier to clean though.

Good luck.

[armydriver]

I took the tank off and the inside is really crap. Looks like that 4 plus pound of rust you talked about Karoshi. I have another tank that is not as rusted inside but has a couple of rusted weep holes in the bottom. However, I think I will purchase a new tank from VOV this week and get this over. I agree with the rebuild on the carb. I will get it taken care of also, but first the tank, then the balance.

[42cckw]

Hi AD
I was just wondering how old betty boob was runing and if you got your problem corrected,haven't heard from you lately when are you going to tell us about your C 47 days looking forward to reading it, I just love that old bird, what a classic. When air planes are no longer and there flying space ships or something I think the last plane to fly will be a C47 on its way to a museum

[armydriver]

Betty Boop is running great with the new tank and blowing out the carburator with air. I also installed a NOS AC T2 filter I got off ebay.
I agree on the DC3/C47 still will be flying.
Not a real fun airplane to fly in but very reliable and safe. I like the aircraft high front cockpit as it an easy airplane to taxie for a tail dragger because you have high visibility from the cockpit. It also has excellent STOL capablities.
Will post some flying stories someday.

[John V Cliche]

Hi AD
Thats good to hear
Clean that fuel filter semi-annually and you should remain problem free.
Enjoy
John

[armydriver]

Thanks for that info John. That is what makes this forum so great, the sharing of information to keep these old trucks rolling and their history out there for all to know.