The GMC CCKW

Hello Everyone,
been trying to move my second CCKW, a shop van, but it has a very sorry habit of starting up fine but then, after running for 3-10 seconds, it dies, with a couple of explosions in the tailpipe. I've repaired the fuel pump, blown the fuel lines and replaced the filter, so it shouldn't be fuel-related. The truck's been sitting most of its life, so anything is possible. I'm suspecting carb and coil, but I'm kind of running out of motivation. Any suggestions? It's a low-milage Norwegian truck, surplused 1995.

Arthur with oily hands

Well, it is either fuel or ignition:

So:

Put a dwell meter on it and watch it from under the hood and
have a can of carb cleaner (flammable kind) and with the air cleaner off
be prepared to give it a shot as it starts to die. If giving it a shot revives it, fuel starvation is the problem (carb, fuel pump, filter, pickup etc), if not, watch the dwell meter, probably ignition.

Doc is right on with this. I suspect fuel starvation to be your first culprit. Have you taken off the carburator and cleaned the bowl or made sure the float is working properly? The float needle valve may be sticking, Something like this needs patience and a one step process with each item in the system. Good luck.

Gentlemen, You were quite right. It was the float needle valve. Parts of black rubber-like gasket material had found their way into the valve and made it stick. I took the healthy carb from my 352 to get the shop van moving, it's blocking a way in our yard, and now it runs quite well, there's actually a exhaust manifold gasket blowing, but now I can drive it. Now I have to fabricate a new gasget between the carb and governor for the 352, it was destroyed in the process of removing the carb.
Thank You again, Gentlemen, Your help keeps my wheels running!

Arthur

Thanks Arthur. That is what makes this site so good. We have all experienced the same difficulties.
Good Luck

arthur.m wrote:Gentlemen, You were quite right. It was the float needle valve. Parts of black rubber-like gasket material had found their way into the valve and made it stick. I took the healthy carb from my 352 to get the shop van moving, it's blocking a way in our yard, and now it runs quite well, there's actually a exhaust manifold gasket blowing, but now I can drive it. Now I have to fabricate a new gasget between the carb and governor for the 352, it was destroyed in the process of removing the carb.
Thank You again, Gentlemen, Your help keeps my wheels running!

Arthur

Make sure you check your fuel rubber hose's if you have any as the can perish internally and block the lines,Also clean out the fuel tank completely as I've had problems with fuel starvation loads of times due to contaminated fuel lines and tanks.

Glad to hear you got it sorted

regards

Steve