Gas leak, occasional power loss

[81f100custom]

This is a great story and one that benefits all of us as we work to fix and restore these old trucks. Glad you got it fixed and thanks for following up on the fix, Josh.

Good to hear you got it fixed. I was there once myself and even had the truck towed before figuring out it was the line from the sending unit to the frame that had just deteriorated on the top side open to atmosphere and was sucking air.

[JG2020]

This is a great story and one that benefits all of us as we work to fix and restore these old trucks. Glad you got it fixed and thanks for following up on the fix, Josh.

Of course! It was Gary's solution. It's crazy how the line did not leak gas but I could blow air right through it with my finger pressed on the other end. If anyone can chime in on my spark plug pics and condition that would be great. I ordered a new set and will put them in tomorrow. If they just look rich I will have to look into the carb more in depth , but if it looks like oil blow by I may have to get hotter plugs and just live with it.

Thanks!! Great group.

[Gary Lewis]

Of course! It was Gary's solution. It's crazy how the line did not leak gas but I could blow air right through it with my finger pressed on the other end. If anyone can chime in on my spark plug pics and condition that would be great. I ordered a new set and will put them in tomorrow. If they just look rich I will have to look into the carb more in depth , but if it looks like oil blow by I may have to get hotter plugs and just live with it.

Thanks!! Great group.

I don't think the rubber hose on Bullnose trucks was every expected to carry ethanol, and I suspect that is what is causing the problems with them. But I'm glad you got it fixed.

On the plugs, your pic looked very dark so I've made it lighter as well as bigger. And the plugs show either a very rich condition or oil being burned. Are you using any oil at all? If not, I think your air/fuel mix is too rich.

[ArdWrknTrk]

I don't think the rubber hose on Bullnose trucks was every expected to carry ethanol, and I suspect that is what is causing the problems with them. But I'm glad you got it fixed.

On the plugs, your pic looked very dark so I've made it lighter as well as bigger. And the plugs show either a very rich condition or oil being burned. Are you using any oil at all? If not, I think your air/fuel mix is too rich.

Josh, I think your truck is running rich on idle.

Grey or black is fuel.

Blue haze is more typical of oil.(also more common on startup and trailing throttle)

The plug threads dont look lubricated like they would if there was oil in the cylinders.

 

[JG2020]

Josh, I think your truck is running rich on idle.

Grey or black is fuel.

Blue haze is more typical of oil.(also more common on startup and trailing throttle)

The plug threads dont look lubricated like they would if there was oil in the cylinders.

Thanks all ! I will check the oil but only a few hundred miles since the last change. When I turn the idle screw all the way in it doesn’t stumble or die. It runs better.

I don’t see blue smoke really and not when at speed or if I pound on the accelerator . I have been watching for that when I drive.

[Gary Lewis]

Thanks all ! I will check the oil but only a few hundred miles since the last change. When I turn the idle screw all the way in it doesn’t stumble or die. It runs better.

I don’t see blue smoke really and not when at speed or if I pound on the accelerator . I have been watching for that when I drive.

If it runs better with the idle mix screw turned all the way in then you have a problem. And I'll guess it is the accelerator pump that's leaking.

If everything is working correctly you should be able to get max idle speed with the idle screw open a turn or two. That means you don't have either fuel leaks or air/vacuum leaks. But in your case something is leaking fuel, and about all that can leak fuel on a Carter like that is the accelerator pump.

And that is why your plugs are so dark. And probably why you see smoke at idle.

[JG2020]

If it runs better with the idle mix screw turned all the way in then you have a problem. And I'll guess it is the accelerator pump that's leaking.

If everything is working correctly you should be able to get max idle speed with the idle screw open a turn or two. That means you don't have either fuel leaks or air/vacuum leaks. But in your case something is leaking fuel, and about all that can leak fuel on a Carter like that is the accelerator pump.

And that is why your plugs are so dark. And probably why you see smoke at idle.

Thanks Gary , from my vw days that is a diaphragm made of rubber or the like ? The carb was rebuilt but for all I know it was sitting on a shelf for 10 years and that could have rotted .

I guess I am taking the carb out !

 

[Gary Lewis]

Thanks Gary , from my vw days that is a diaphragm made of rubber or the like ? The carb was rebuilt but for all I know it was sitting on a shelf for 10 years and that could have rotted .

I guess I am taking the carb out !

 

I'm not au fait with that carb. But we have lots of documentation on it: Documentation/Fuel Systems/ CARBURETORS, CHOKES, & EFI/Carter YFA 1BBL. There's the factory shop manual section as well as a document from Walker on the Instructions tab. (Unfortunately the Exploded Views & Part #'s tab isn't working, so I need to figure that out and fix it.)

Also, Bill Vose/85lebaront2, our resident fuel system and ignition expert has written a "Tips" section. And the very first statement in the tips is "The Carter YFA is a fairly simple carburetor, which has one major weak point - the combination accelerator pump and metering rod control. This is a diaphragm with manifold vacuum on bottom and fuel on the top side. When this diaphragm fails the fuel is drawn directly into the intake."

And I'm pretty sure that's what the problem is with yours. So I do think you'll have to pull it off and go through it.

[JG2020]

I'm not au fait with that carb. But we have lots of documentation on it: Documentation/Fuel Systems/ CARBURETORS, CHOKES, & EFI/Carter YFA 1BBL. There's the factory shop manual section as well as a document from Walker on the Instructions tab. (Unfortunately the Exploded Views & Part #'s tab isn't working, so I need to figure that out and fix it.)

Also, Bill Vose/85lebaront2, our resident fuel system and ignition expert has written a "Tips" section. And the very first statement in the tips is "The Carter YFA is a fairly simple carburetor, which has one major weak point - the combination accelerator pump and metering rod control. This is a diaphragm with manifold vacuum on bottom and fuel on the top side. When this diaphragm fails the fuel is drawn directly into the intake."

And I'm pretty sure that's what the problem is with yours. So I do think you'll have to pull it off and go through it.

Thank for all that info Gary! I took the carb off today so I can rebuild it in the basement tomorrow while we get hit with the rain from Ida. A not that tiny amount of anti freeze leaked out from the bottom of the carb mount stand which I know I should replace . Here are some photos. Not sure what the heck is with the goop on the water hoses . There was also antifreeze in the exhaust manifold. Not sure if that was there before I took the carb off.

Thanks ,

Josh

[ArdWrknTrk]

Thank for all that info Gary! I took the carb off today so I can rebuild it in the basement tomorrow while we get hit with the rain from Ida. A not that tiny amount of anti freeze leaked out from the bottom of the carb mount stand which I know I should replace . Here are some photos. Not sure what the heck is with the goop on the water hoses . There was also antifreeze in the exhaust manifold. Not sure if that was there before I took the carb off.

Thanks ,

Josh

Aren't we looking down into the intake manifold?

Odd collection of galvanized plumbing elbows slathered in what looks like RTV.

I'm guessing that is a heated base plate to help atomize fuel in cold weather.