Craftsman 6.25 HP Mulcher Carberator: Help Needed

[primerbulb120]

The primer bulb is supposed to pressurize the float bowl, causing gas to come out the main jet into the carb throat. However, the air filter base can become warped and allow the pressure to leak out at the gasket between the air filter base and the carb. This problem can sometimes be fixed by putting two gaskets instead of one between the air filter base and carb, but in more severe cases I have to apply gasket maker around the gasket to seal it. Works good if you do it right and it's cheaper than buying whole new air filter base.

Also, your primer bulb is supposed to have a small hole right in the center, like this: http://www.ebay.com/itm/SMALL-ENGIN...733978?hash=item35c913069a:g:ceUAAOSwf-VWVRN7

If your primer bulb has no hole, you probably have the wrong primer bulb for your engine. (I say probably because I've never seen one of these 190cc engines that required a no hole primer bulb.) The no hole primer bulbs are for the smaller (3-4.5 HP) Briggs engines.

I hope this post makes sense, if it doesn't I will try to clarify. :laughing:

 

[Berniebac]

The primer bulb is supposed to pressurize the float bowl, causing gas to come out the main jet into the carb throat. However, the air filter base can become warped and allow the pressure to leak out at the gasket between the air filter base and the carb. This problem can sometimes be fixed by putting two gaskets instead of one between the air filter base and carb, but in more severe cases I have to apply gasket maker around the gasket to seal it. Works good if you do it right and it's cheaper than buying whole new air filter base.

Also, your primer bulb is supposed to have a small hole right in the center, like this: http://www.ebay.com/itm/SMALL-ENGIN...733978?hash=item35c913069a:g:ceUAAOSwf-VWVRN7

If your primer bulb has no hole, you probably have the wrong primer bulb for your engine. (I say probably because I've never seen one of these 190cc engines that required a no hole primer bulb.) The no hole primer bulbs are for the smaller (3-4.5 HP) Briggs engines.

I hope this post makes sense, if it doesn't I will try to clarify. :laughing:

Thanks for posting this info. It helps a lot. I do have a hole in the middle of the primer bulb. I suspect you may have found the solution that I need. There is no pressure at all when you press on the primer bulb and it just seems like it is leaking somewhere. I think I will try the gasket maker solution to see if that helps.

Any advice on where to apply it. It looks like it would be easy to block the small port where the primer bulb is supposed to pull the fuel up from the bowl.

 

[primerbulb120]

Thanks for posting this info. It helps a lot. I do have a hole in the middle of the primer bulb. I suspect you may have found the solution that I need.

There is no pressure at all when you press on the primer bulb and it just seems like it is leaking somewhere.

You won't feel any pressure even when the primer bulb is working correctly. There are only two ways I know of to test it:

1. Take off the air filter and look into the carb throat. Press the primer bulb and look for gas coming out of the main jet. If no gas comes out, you have an air leak.

2. Start the engine and press the primer bulb while the engine is running. The engine should miss and sputter each time you press the primer bulb. If it doesn't, you have an air leak.

I think I will try the gasket maker solution to see if that helps.

Any advice on where to apply it. It looks like it would be easy to block the small port where the primer bulb is supposed to pull the fuel up from the bowl.

The primer bulb doesn't pull fuel up from the float bowl. It forces air into the float bowl, which in turn pressurizes the float bowl and forces gas out the main jet into the carb throat.

Apply a bead of gasket maker all around the gasket between the air filter base and carb. The air leak is most likely toward the bottom of the gasket. If you take off the air filter base and look at the back of it, you will see where the air comes out of the primer bulb and goes down a small passage, then through a hole in the gasket and into a hole in the carb. The passage is supposed to be sealed by the gasket, but a warped base can let air leak out of the passage.

 

[Berniebac]

You won't feel any pressure even when the primer bulb is working correctly. There are only two ways I know of to test it:

1. Take off the air filter and look into the carb throat. Press the primer bulb and look for gas coming out of the main jet. If no gas comes out, you have an air leak.

2. Start the engine and press the primer bulb while the engine is running. The engine should miss and sputter each time you press the primer bulb. If it doesn't, you have an air leak.





The primer bulb doesn't pull fuel up from the float bowl. It forces air into the float bowl, which in turn pressurizes the float bowl and forces gas out the main jet into the carb throat.

Apply a bead of gasket maker all around the gasket between the air filter base and carb. The air leak is most likely toward the bottom of the gasket. If you take off the air filter base and look at the back of it, you will see where the air comes out of the primer bulb and goes down a small passage, then through a hole in the gasket and into a hole in the carb. The passage is supposed to be sealed by the gasket, but a warped base can let air leak out of the passage.

Thanks once again for your help with this. I have applied a bead of gasket maker all around the air filter base. Will wait the recommended 24 hours before starting the mower so hopefully tomorrow night I should know if it worked.

 

[primerbulb120]

If it doesn't work, post a picture of the air filter base and I'll show you where to apply it.

 

[Berniebac]

Well, the gasket maker did not work. I primed it with the primer bulb and it would not start. Took the air filter off and looked into the carb while pressing the bulb and no gas is being forced up into the carb. I had put the gasket maker all the way around the gasket so I think I had it sealed up pretty good. I think I will try a new primer bulb if I can get to a parts store in the next couple days and pick one up. It is a pretty cheap part so I might as well put one on.

 

[Vervepipes]

Hey, for the record I use Aliexpress for most of my carb needs, usually free shipping to Canada. Where in NS are you, if you cant find any I have both the filter housing gasket and the primer bulbs in Cole Harbour. I find usually the priming problem to be the gasket, like said before, sometimes it can take two to make it seal.

 

[Berniebac]

If it doesn't work, post a picture of the air filter base and I'll show you where to apply it.

Sorry primerbulb120 I skipped over this post without seeing it. I have the base glued on with the gasket maker and I don't think I will tear it off now to take a pic cause I would have to clean off the all that gasket maker. I am afraid that may screw up my new gasket and result in a poor seal when I put it back on. So I think I will try the new bulb first and take it from there. Thanks for all your help so far, I will post my results to keep you posted.

 

[Berniebac]

Hey, for the record I use Aliexpress for most of my carb needs, usually free shipping to Canada. Where in NS are you, if you cant find any I have both the filter housing gasket and the primer bulbs in Cole Harbour. I find usually the priming problem to be the gasket, like said before, sometimes it can take two to make it seal.

Hi Vervepipes I am in Cole Harbour as well. I would like to get a primer bulb from you if we could arrange a time to meet.

 

[primerbulb120]

Sorry primerbulb120 I skipped over this post without seeing it. I have the base glued on with the gasket maker and I don't think I will tear it off now to take a pic cause I would have to clean off the all that gasket maker. I am afraid that may screw up my new gasket and result in a poor seal when I put it back on. So I think I will try the new bulb first and take it from there. Thanks for all your help so far, I will post my results to keep you posted.

I don't think you'll mess up the gasket by tearing it off. Don't know what gasket maker you used, but I used Permatex Grey and it's easy to clean off.

You could get a picture of the junction between the air filter base and carb without taking anything apart.