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I have small fuel-related issue with my new truck. If the truck sits for a couple days it will not start unless you use the handle on the fuel pump to prime it. Once you've done that, it fires right up and runs great, accelerates just fine.

Is this typical behavior for these trucks? I noticed in the manual that some trucks have a hand primer pump which led me to believe that this was a common occurrence. My truck doesn't have this but does have the handle on the fuel pump. I thought maybe it could be a problem with the accelerator pump, as well.

I had planned on rebuilding the carb and fuel pump both, at some point, but I wanted to see if there was an easy fix in the mean time. Thanks!

Is the carb bowl empty? Open the drain plug in the carb bowl to find out.

WCarlsrud wrote:Is the carb bowl empty? Open the drain plug in the carb bowl to find out.

I'll check it out. If that's the case, that would mean a leak, right? There's no reason it would drain back out the fuel lines, is there? Once it's in the bowl, I would think it would stay there.

I haven't noticed any leaks around the carb, but I'll give it a look.

There should be fuel in the bowl after it has been sitting for a couple days.

It could be dripping into the carb throat/manifold. You might also look at the gasket between the governor and the intake manifold. You might see some fuel weeping out there. Especially if the carb isn't tightened down very well.

A leak like that could make it hard to start, if you tried to restart it an hour or two after shutting it off.

The only other thing that comes to mind is that you may have a very small leak in the fuel line somewhere between the tank and the carb. I found one in one of my trucks by noticing a patch of dead grass under the leak...

chicklin wrote:I have small fuel-related issue with my new truck. If the truck sits for a couple days it will not start unless you use the handle on the fuel pump to prime it. Once you've done that, it fires right up and runs great, accelerates just fine.

Is this typical behavior for these trucks? I noticed in the manual that some trucks have a hand primer pump which led me to believe that this was a common occurrence. My truck doesn't have this but does have the handle on the fuel pump. I thought maybe it could be a problem with the accelerator pump, as well.

I had planned on rebuilding the carb and fuel pump both, at some point, but I wanted to see if there was an easy fix in the mean time. Thanks!

Unless you see something obvious, it's a good possibility the fuel pump is on its way down. Could be it's losing prime due to pin holes in the diaphram. If this break down is just starting to occur, it may not be pumping sufficient fuel for start up except by use of the hand primer, that is the lever on the pump. Once the engine has started, the pump may furnish enough to keep it going. I would strongly recommend you go ahead with that pump rebuild right away, if the diaphram fails, it will dump gas into the crankcase which will thrash the engine quickly if you were unaware & kept driving. Not worth the risk of chancing engine catastrophy.The other primer pump you speak of is only for extreme cold climate use such as the arctic, was not typically used on trucks other than the ones used in extreme cold.

MSeriesRebuild wrote:

chicklin wrote:I have small fuel-related issue with my new truck. If the truck sits for a couple days it will not start unless you use the handle on the fuel pump to prime it. Once you've done that, it fires right up and runs great, accelerates just fine.

Is this typical behavior for these trucks? I noticed in the manual that some trucks have a hand primer pump which led me to believe that this was a common occurrence. My truck doesn't have this but does have the handle on the fuel pump. I thought maybe it could be a problem with the accelerator pump, as well.

I had planned on rebuilding the carb and fuel pump both, at some point, but I wanted to see if there was an easy fix in the mean time. Thanks!

Unless you see something obvious, it's a good possibility the fuel pump is on its way down. Could be it's losing prime due to pin holes in the diaphram. If this break down is just starting to occur, it may not be pumping sufficient fuel for start up except by use of the hand primer, that is the lever on the pump. Once the engine has started, the pump may furnish enough to keep it going. I would strongly recommend you go ahead with that pump rebuild right away, if the diaphram fails, it will dump gas into the crankcase which will thrash the engine quickly if you were unaware & kept driving. Not worth the risk of chancing engine catastrophy.The other primer pump you speak of is only for extreme cold climate use such as the arctic, was not typically used on trucks other than the ones used in extreme cold.

Where is the best place to get a rebuild kit? It looks like VPW only had civvy or military WC kits, no m37 dual-action kits.

I've used these guys in the past to rebuild my M38 fuel pump, they didn't have a kit for it so I had to send in to them took about a week and it looked new when I received it back!

http://www.maritimedragracing.com/then_ ... motive.htm

chicklin wrote:

MSeriesRebuild wrote:

chicklin wrote:I have small fuel-related issue with my new truck. If the truck sits for a couple days it will not start unless you use the handle on the fuel pump to prime it. Once you've done that, it fires right up and runs great, accelerates just fine.

Is this typical behavior for these trucks? I noticed in the manual that some trucks have a hand primer pump which led me to believe that this was a common occurrence. My truck doesn't have this but does have the handle on the fuel pump. I thought maybe it could be a problem with the accelerator pump, as well.

I had planned on rebuilding the carb and fuel pump both, at some point, but I wanted to see if there was an easy fix in the mean time. Thanks!

Unless you see something obvious, it's a good possibility the fuel pump is on its way down. Could be it's losing prime due to pin holes in the diaphram. If this break down is just starting to occur, it may not be pumping sufficient fuel for start up except by use of the hand primer, that is the lever on the pump. Once the engine has started, the pump may furnish enough to keep it going. I would strongly recommend you go ahead with that pump rebuild right away, if the diaphram fails, it will dump gas into the crankcase which will thrash the engine quickly if you were unaware & kept driving. Not worth the risk of chancing engine catastrophy.The other primer pump you speak of is only for extreme cold climate use such as the arctic, was not typically used on trucks other than the ones used in extreme cold.

Where is the best place to get a rebuild kit? It looks like VPW only had civvy or military WC kits, no m37 dual-action kits.

www.then-now.com talk to Tom, he will sell you the needed kit or he also offers complete rebuild service at a reasonable cost.