Hard Start when hot

[Jay Gadsby]

Hello Ladies and Gents. I have an issue I am hoping someone might be able to help with.

Ok, back story. At first I thought it was an electrical thing, like a draw down on the system and causing it to have a hard time starting. Today I took her out for a few top speed runs, then decided to take a dip in the water. I shut the boat down after idling for a few minutes, hopped in the water, was swept away with the current, decided to get back in the boat since I didnt feel like swimming that hard lol. Well, when I went to start it, it was extremely hard to start. Like the battery is dead sorta cranking. I gave it more throttle and it started up. (5.7L 260 btw) I asked my mom (she is an awesome woman who used to race her Camaro and Firebird back in the day) and she said she had a similar situation with her Camaro (5.7L carbed) when it was hot. It would crank like a dead battery but start eventually with the throttle. She said her issue was actually the starter getting heat soaked I guess and when she installed a heat shield on the starter, no more issues. I may be barking up the wrong tree, but I wish to figure this out either way. Any help would be awesome please!!

 

[cdodds]

first off, its a boat, and things corrode, so check ALL your electrical connections between the battery and starter. it is possible the starter is getting weak as an engine that is warmed up to temp is harder to turn over than a cold one. the other problem especially with racecar type duties that you mentioned could be too much timing. extremely advanced timing will make a motor hard to crank especially when they're hot. check your timing and make sure you're not more than a few degrees more advanced than what is recommended for your motor. i would say though that the heat shield idea will get you nowhere. hope you find the problem

 

[Jay Gadsby]

first off, its a boat, and things corrode, so check ALL your electrical connections between the battery and starter. it is possible the starter is getting weak as an engine that is warmed up to temp is harder to turn over than a cold one. the other problem especially with racecar type duties that you mentioned could be too much timing. extremely advanced timing will make a motor hard to crank especially when they're hot. check your timing and make sure you're not more than a few degrees more advanced than what is recommended for your motor. i would say though that the heat shield idea will get you nowhere. hope you find the problem

I appreciate the help, I didnt think the heat shield was applicable in this situation, but I will check all of the other stuff.

 

[EricW]

I'm not sure about the starter being heat-soaked --- there's really no hot exhaust parts near the starter, like on a car.

I think vapor-lock is a possibility. When you shut off the hot engine, the fuel from the tank to the carb vaporizes due to heat from the engine and intake manifold. Maybe you can re-route the fuel line and/or wrap it with heat tape.

Does running the blower make a difference? Maybe you could keep the engine hatch open for a test and see if it makes a difference.

If its electrical, it could be the starter failing, loose connections, or worn/damaged wiring. Sounds like vapor-lock to me, though.

 

[cdodds]

good point ericw. that's certainly a possibility but vapor lock is not going to make the motor sluggish to crank like described. it will just simply not start. make sure your fuel lines aren't laying on the motor anywhere and you can nearly rule out vapor lock. Vapor lock happens when the vapor pressure of the fuel is higher than the atmospheric pressure. In marine engines pumps close to the engine, the pressure in the fuel line to the tank is reduced by the sucking action of the fuel pump drawing fuel form a fuel tank sometimes ten feet away, and when heated, the gasoline may actually boil creating a vapor of gasoline which the fuel pump cannot handle, thus the name "vapor lock"; i.e. it occurs when the fuel pump, which is designed to pump liquid, loses suction as it tries to pump fuel vapor. so in effect vapor lock leaves you with a condition of running out of fuel.