volvo aq131a stalling after 15 minute run

ok i need some external advice here ... i am trying to help a friend out and i have done some work on his boat ... he was having problems 4th of july week and told me after he went out and ran the boat for about 15 minutes it would bog and then die ... ran fine prior to that and when he would let it set for about a half an hour it would start back up and run for a while again before dieing again ... i took it to work and pulled the carb apart ... it had a little sediment in the bowl but not bad i cleaned it checked the float and the accelorator pump and all seemed fine .. pulled the anti siphon valve and it seemed to be working fine ... drew about a gallon of gas through the fuel line with a pump and looked for water settling in the fuel and there was none ... fuel smelled fine ... pulled the tube from tank and it was clean as a pin ... so i went to ignition system ... replaced points and condensor with electronic conversion set .. replaced coil and checked voltage there .. it was fine .. i didnt replace the fuel pump because i figured with a mechanical either they work or they dont ... no fuel in return tube or oil to indicate pump failure ... we took it back out yesterday and still dies after running for a while... the carb seems to be drawing fuel thru the main orfice when throttled up at first then it seems to slack off ... i removed the anti siphon valve and it did the same thing ... any ideas ... thanks in advance

Re: volvo aq131a stalling after 15 minute run

I'd go through the carb again. Those solex carbs are absolutely intolerant to any kind of debris.

Re: volvo aq131a stalling after 15 minute run

well i ordered a new fuel pump today and will see if its the problem ... it runs great when its running ... takes off fine and does full throttle fine .. then just bogs and dies ... after 30 minutes of sitting it starts and runs great again

Re: volvo aq131a stalling after 15 minute run

Have you checked for spark imediately after the engine dies? I have seen in a few cases where an engine starts and runs great cold, , when the coil is cold. Then after 15, 20 or 30 minutes she all of a sudden shuts down. Let it cool down and it starts right up.
Turns out that when the coil would heat up and expand it would get an "open" in it and stop functioning until it cooled down and contracted.
I would test your coil cold, have all your test equipment ready and test the coil again imediatly after the engine stalls and see if there is a drastic difference in the ohms or voltage.

Good luck.

Re: volvo aq131a stalling after 15 minute run

alright i think thats worth looking at and i can test it ... i know what the ohm readings are cold but i did replace the coil when i changed the ignition and the place it is mounted i wouldnt think its heating up ... i also went on and ordered a new fuel pump which i hadnt replaced after seeing the carb seem to squirt less after heating up i am thinking maybe the checkvalves in the pump are failing ???

Welcome aboard Herbcw:

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