Outboard vapour lock

[Mad_On_Fishing]

So I bought this boat last week and unfortunately it's impossible to troll with the 100hp so i usually just go out to my spot shut it off and jig. Cold starts aren't bad and it idles very well however if i turn it off once its warm and dont start it for 5+ minutes it takes a lot to start. I try pressurizing the line and it still takes well over 4 minutes to get started and even then it does not want to idle. In fact yesterday I was out past the provincial park and nearly got stuck in a thunder storm.

I'm thinking this may be due to vapour lock. It's a 1989 johnson gt100.

Has anyone else had a similar issue? And has anyone found a way to solve this? Am I missing something?

[Dean2]

First off, dump in a couple of Cans of Sea Foam, I use that SH on everything.

Have you pulled a couple of plugs and checked how much spark you have when it is hot? If spark is weak, first replace the plug wires. As they get old and hot they can breakdown. Next check the coil or capacitor depending on ignition type. They often work fine cold but lose a little zap when old and hot.

I get from what you are posting the using the hand pump is not helping to start the engine hot. Make sure the choke butterfly is open all the way when the choke is off. If spark is good have you tried squirting gas into the carb throats to see if priming it starts the motor right away. If it does you have fuel starvation. Is the vent on your tank open or if built in is it actually venting properly. Next check your fuel line to see if it is old and collapsing thereby cutting off fuel. Next step is to check your fuel pump, followed by carburetor seals, floats varnish etc.

If you have spark and fuel they pretty much will run.

[Unregistered user]

Take it in for a tune up, money well spent. If the primer bulb pumps up hard, there is no vapour lock. Your motor also uses a fuel enrichment device (Like a simple injector) rather than choke butterfly valves. Get the job done right rather than risking your ass in a T-storm.

[Kim473]

Could be as simple as moving the fuel lines to the carbs if they are too close to the heads or engine block. If they heat up this could be the cause of vapor lock. Moving 1/2 inch could cure the problem. Have heard of gasket between a carb and engine is too thin and a carb heats up and causes a vapor lock. Also Check fuel lines for kinks. Also check that the fuel line and primer ball don't have a very small crack as this will cause too much air and no fuel. Check the simple things first.