tducksoup1
New member
I have been looking all over the internet for an answer that I have had recently. I watched all kinds of videos and threads on the primer pump system and all the explanations came close to telling me really how sensitive this motor is to air leaks and that I believe causes more problems than the fuel problem.
my son in law brought his boat to me and said he can't seem to get it running right. I asked him what he has done so far and he said I rebuilt the carbs replaced this and that and no help.
The issue I found out was that when I went to start the engine with the primer in the normal position the engine would start use up fuel from primeing and die. When I went into manual feed and allowed fuel to go into the carb from the top side it ran great! I went on line to look for answers and they all had great things to try but none helped me in this case. I decided to go back and look at dual carbs because I knew it was starving for fuel when the primer was in the normal position (red pointer facing fwd of primer) I seen all kinds of carb rebuild videos and they all seem to skip the answer to my problem I had to finally figure out. As an aircraft mechanic/avionics tech I have worked small planes jets airlines jets for 40 years and it never failed, by the time They would call me to fix the problem I found out some other mechanic got in there first and screwed it up worse than it was!! drove me nuts and I have the same issue here. when My son in law who is in construction had said he rebuilt the carbs I had to go over them and make sure it was done correct. I checked every orfice and jets and air inlets and they were all clean everything looked great. I left them open went back to the videos of people rebuilding the carbs I noticed one thing no one ever mentioned but I was able to see and it can cause all these fuel problems.
what I saw was there is a special gasket that is designed to stop air leaks yet let fuel flow up to the carbs. My son in law failed to take pics or whatever and never put the gaskets back on both carbs. it is the one that goes around the jets and when you put the fuel bowl back on it does its very important job metering fuel. I did not have the gaskets but I had some gasket material and made one that would at least stop the air leak (the gasket is round and has like 3 teeth like a gear in the center) when I ran the motor it would not run so great without correct ones) with the primer in the normal position.
without this gasket there is not enough venturie effect, suction to pull up the fuel from the bowl through the orfice to the cylinders. I could not get the answer from anyone if I really needed the primer pump in the first place? got different answers of yes and no. because of this weird problem I could not determine that on my own. Now that I got the carbs to suck the fuel normally with correct gaskets I see you don't need it in warmer areas really but up north I would say you do need it for cold starts.
I have gone through at least 4 new tops for the primer pump and everyone of them leaked behind the Schrader valve past the o ring that is suppose to stop it. Its nuts I see many people writing about that so really if you live like me in Florida I can trash it after bypassing it.
I posted this because if my son in law can screw the pooch on something so small yet creates such a big problem how many others out there who are not mechanically inclined but do there rebuilds on there own. this drove me nuts for days and came down to the same old problem, someone making the problem worse than what it was. he said he knew exactly which gaskets they were but did not know where they went. (they may have come off when he opened bowel and did not see them but both? lol) I hope this will help those who may have given up on getting there motors to run right, make sure that gasket is there and in good condition.
my son in law brought his boat to me and said he can't seem to get it running right. I asked him what he has done so far and he said I rebuilt the carbs replaced this and that and no help.
The issue I found out was that when I went to start the engine with the primer in the normal position the engine would start use up fuel from primeing and die. When I went into manual feed and allowed fuel to go into the carb from the top side it ran great! I went on line to look for answers and they all had great things to try but none helped me in this case. I decided to go back and look at dual carbs because I knew it was starving for fuel when the primer was in the normal position (red pointer facing fwd of primer) I seen all kinds of carb rebuild videos and they all seem to skip the answer to my problem I had to finally figure out. As an aircraft mechanic/avionics tech I have worked small planes jets airlines jets for 40 years and it never failed, by the time They would call me to fix the problem I found out some other mechanic got in there first and screwed it up worse than it was!! drove me nuts and I have the same issue here. when My son in law who is in construction had said he rebuilt the carbs I had to go over them and make sure it was done correct. I checked every orfice and jets and air inlets and they were all clean everything looked great. I left them open went back to the videos of people rebuilding the carbs I noticed one thing no one ever mentioned but I was able to see and it can cause all these fuel problems.
what I saw was there is a special gasket that is designed to stop air leaks yet let fuel flow up to the carbs. My son in law failed to take pics or whatever and never put the gaskets back on both carbs. it is the one that goes around the jets and when you put the fuel bowl back on it does its very important job metering fuel. I did not have the gaskets but I had some gasket material and made one that would at least stop the air leak (the gasket is round and has like 3 teeth like a gear in the center) when I ran the motor it would not run so great without correct ones) with the primer in the normal position.
without this gasket there is not enough venturie effect, suction to pull up the fuel from the bowl through the orfice to the cylinders. I could not get the answer from anyone if I really needed the primer pump in the first place? got different answers of yes and no. because of this weird problem I could not determine that on my own. Now that I got the carbs to suck the fuel normally with correct gaskets I see you don't need it in warmer areas really but up north I would say you do need it for cold starts.
I have gone through at least 4 new tops for the primer pump and everyone of them leaked behind the Schrader valve past the o ring that is suppose to stop it. Its nuts I see many people writing about that so really if you live like me in Florida I can trash it after bypassing it.
I posted this because if my son in law can screw the pooch on something so small yet creates such a big problem how many others out there who are not mechanically inclined but do there rebuilds on there own. this drove me nuts for days and came down to the same old problem, someone making the problem worse than what it was. he said he knew exactly which gaskets they were but did not know where they went. (they may have come off when he opened bowel and did not see them but both? lol) I hope this will help those who may have given up on getting there motors to run right, make sure that gasket is there and in good condition.