1991 120hp Force not pulling fuel into 3 & 4 cylinders

I am having a bit of a problem with cylinders 3 & 4. compression is good and the carb is working great. I inspected the reeds and those look good as well. If you hold your hand over the top carb you can fell it pulling in the air, but the bottom carb does not. I was having this problem last year and pulled the block apart and changed the lower seal and the spaghetti seal for the crank case. I also put on new gaskets to the head. I never had a chance to run it till the other day and same problem. I am hearing that the 3 & 4 cylinder should have a seal to keep them separate and that could be bad. Just looking for any ideas before I rip into it again.

FYI on a side note when I have the muffs on it and run it after i turn it off I get what looks like sludge coming out of 4 little holes near the lower unit, wondering if it is related or a whole other problem. Smells like gas, but feels and looks similar to grease.

Thank you for any help or ideas that get thrown my way.

Re: 1991 120hp Force not pulling fuel into 3 & 4 cylinders

Have you checked the compression on all four cylinders?

Re: 1991 120hp Force not pulling fuel into 3 & 4 cylinders

Remove the carb, manifold, and reed plate. Inspect the gasket between the two vee blocks and also check the condition of the aluminum web on the block. Remove the vee blocks and replace the gasket--you have the plate off, so you might as well. When replacing the vee blocks to the plate, use locktite on the four mounting screws.

While you have the reeds off, have someone crank the engine while you hold your hand over the openings. See if it is alternately pulling a vacuum then pressure on both cylinders. If it is, you are gold. If it is not, then look for bad seals OR worn piston skirts.

In this case, a compression test is meaningless as it will not tell you the condition of the lower end of the block.

Re: 1991 120hp Force not pulling fuel into 3 & 4 cylinders

130, 130, 130, 110

Re: 1991 120hp Force not pulling fuel into 3 & 4 cylinders

Frank Acampora said:

Remove the carb, manifold, and reed plate. Inspect the gasket between the two vee blocks and also check the condition of the aluminum web on the block. Remove the vee blocks and replace the gasket--you have the plate off, so you might as well. When replacing the vee blocks to the plate, use locktite on the four mounting screws.

While you have the reeds off, have someone crank the engine while you hold your hand over the openings. See if it is alternately pulling a vacuum then pressure on both cylinders. If it is, you are gold. If it is not, then look for bad seals OR worn piston skirts.

In this case, a compression test is meaningless as it will not tell you the condition of the lower end of the block.

Click to expand...

I will see if i can give this a shot today or tomorrow. Thank you

Re: 1991 120hp Force not pulling fuel into 3 & 4 cylinders

Well, I should clarify: Normal compression readings are almost meaningless. If you have 0 compression or a really low number, that means the whole piston is trashed and , of course, it will not pull vacuum through the carb.

Re: 1991 120hp Force not pulling fuel into 3 & 4 cylinders

Frank Acampora said:

Remove the carb, manifold, and reed plate. Inspect the gasket between the two vee blocks and also check the condition of the aluminum web on the block. Remove the vee blocks and replace the gasket--you have the plate off, so you might as well. When replacing the vee blocks to the plate, use locktite on the four mounting screws.

While you have the reeds off, have someone crank the engine while you hold your hand over the openings. See if it is alternately pulling a vacuum then pressure on both cylinders. If it is, you are gold. If it is not, then look for bad seals OR worn piston skirts.

In this case, a compression test is meaningless as it will not tell you the condition of the lower end of the block.

Click to expand...

I pulled it apart and inspected, all looked ok. when I held my hand over it, it seemed to pull then push. Also held reeds in and they seemed to open and close with cranking.

Re: 1991 120hp Force not pulling fuel into 3 & 4 cylinders

Hockmed said:

I pulled it apart and inspected, all looked ok. when I held my hand over it, it seemed to pull then push. Also held reeds in and they seemed to open and close with cranking.

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These last symptoms do not jibe with the first posted symptoms that you do not feel air moving into the lower carb. After the installation of the reeds and there is an indication of vacuum and pressure (as you have mentioned) then there is no reason why there would not be the same with the installation of the carb. You need to be sure with your symptoms so you can diagnose properly.