Mercruiser - Hard to Start After Idling/Warm?

[Brandma]

I have 22' Imperial with a 260 HP V-8 Mercruiser. Starts and runs fine off the trailer initially. After it has warmed up though and especially after idling such as trying to manuever boat F-R on to trailer, it will not stay running. If I drop to nuetral,or try to reverse directions, it dies. It won't restart then unless it gets a couple shots of gas. I have to accelerate aggressively to keep it going.<br /><br />Idles at 800-1000 RPM in nuetral, points and plugs are perfect. Timing was not checked but the motor runs strong. Had new shift cable installed recently. Temperature runs aprx. 180 degrees. It has a bi-metallic coil for a choke. I started it up with ears on yesterday and choke opens up to 3/4 open right away, but did not confirm yet that it opens all the way after warming up. I also un-screwed the jets on Rochester Q-jet and sprayed carb cleaner thru holes.<br /><br />Any help would be appreciated.<br />Mark

 

[Don S]

Re: Mercruiser - Hard to Start After Idling/Warm?

Idles at 800-1000 RPM in nuetral, points and plugs are perfect. Timing was not checked but the motor runs strong.

That idle rpm is too high, you should be at 650-700 in gear (around 750 in neutral) on the V8.<br />The points may "Look" perfect, but are they? On boats, new points (and full tuneup) are almost manditory to keep the engine running like it should.<br />You really need to check the dwell, and timing, and advance timing, along with adjusting the idle mixture of the carb in order to get it to idle properly.<br />You may find that after all the proper adjustments that the engine you say "Runs Strong" will actually be stronger and more fuel effecient.

 

[Brandma]

Re: Mercruiser - Hard to Start After Idling/Warm?

Don,<br />Thanks for the advice. I'll look to have a tuneup / timing check performed and go from there.

 

[MrBill]

Re: Mercruiser - Hard to Start After Idling/Warm?

Symptoms also tend to indicate electrical problem, in distributor or with distributor cap. Check for cracks and/or wear in cap...replace if in doubt. Also, hard restarting after warm, etc often indicates short in distributor...so when you're checking or replacing points be sure everything's in good shape particularly wire exiting distributor. Make sure it's not frayed or shorting due to the metal clamp often used to prohibit it from pulling through.

 

[Mikevn1500]

Re: Mercruiser - Hard to Start After Idling/Warm?

Did it do this before you had the new shift cable installed? Sounds like a cable adjustment problem.Maybe the shift interupter switch is out of wack. I would look into this first. My boat did this over 4th July,cable needed adjusted..

 

[Brandma]

Re: Mercruiser - Hard to Start After Idling/Warm?

The cable was replaced by a dealer and the problem occurred before the cable was replaced. To me is seems like a vapor lock problem, which I don't know what causes that other than motor temperature being too high. One guy suggested a crossover pipe for cooling being plugged but this is not the probem either.

 

[jamesgreen]

Re: Mercruiser - Hard to Start After Idling/Warm?

I am having this same prob. with my 3.0 merc. I had the gasket below the carb replaced and that helped some. It was sucking air at low idle but running at speed it was fine.