Having same issue myself. I have a 1995 3cyl 25hp that acts like no fuel. Will run well, warm up and die. Pull all you want but it won't start. Leave it for a while, starts first pull, runs a but and dies again. Changed thermostat, fuel lines, filter, both pumps, water pump and still no go. Feel your pain ! Carlbrower

Carl, and jr, you both should go to harbor freight and buy a laser temp gun (think $15 ish). Both of your motors sound like you may have blockages in the water jacket around cylinder(s) preventing cooling water, going through motor, to keep motor cool. Aim the temp gun at sides of cylinders to see where your motor are getting the hottest, that should indicate where the water pa.ssages are blocked up.

You can try a chemical/ corrosion flush in large container (trash can) for a couple hours (flush till motor heats up, then let cool, repeat the process until you total a couple hours run time- same flush). You can use vinegar, or salt-away, or another corrosion flush. After running about a half, to one hour, check cylinder temp with gun to see if any changes. If blockages are too bad, they may have to be cleaned by opening and scrapping?

Have you both checked your thermostats? If they are stuck closed, you will have to remover and clean, or replace before the flush. No need for flush if just a thermostat problem in first place.

Once you have cooling system working again, motors will probably run fine again. Flushing after each use doesn't always stop corrosion, but it does slow it down.

Good luck, let us know what you find out.

I have already replaced thermostat and run heat gun around block but am unable to find any hot spots. Where is the block temperature sensor located. Seems like that maybe my only option.

Jr, The temp sensor should be at the top area of your cylinder block, a manual would tell you how to test it, and show you where it is mounted. Can look at parts diagram to find it.

Good luck, let us know what you find out.