2003 Mercruiser 5.0 260 HP Alpha 1 Won't Start When Hot

rbondranko

Recruit
Joined
Aug 2, 2015
Messages
2
I have a 2003 SeaRay Sundeck 220 with a Mercruiser 5.0 MPI 260 HP Alpha 1 drive. I can put the boat in the water and it starts and runs with no problems. I can run around for an hour or more starting and stopping, shutting the engine off and restarting, no problems. If I stop and sit for 30 minutes or more, the engine will turn over and not start of if it does start it idles rough and then dies when I try to put it in gear (just like the symptoms for a bad shift interrupter). If I pull off the positive end to the battery cable and then reattach it the boat starts and goes in to gear with no problem and runs fine. Is there some component or relay that gets tripped or reset when the battery cable is removed? I tried just turning off the power switch but it didn't work. You have to remove the battery cable. Ideas?
 
Last edited:

Fun Times

Moderator
Staff member
Joined
May 16, 2009
Messages
8,776
Mercruiser 5.0 MPI 260 HP Alpha 1 drive. If I stop and sit for 30 minutes or more, the engine will turn over and not start of if it does start it idles rough and then dies when I try to put it in gear (just like the symptoms for a bad shift interrupter).
So it seems electrical to you...usually these type of issues are fuel related such as heat soak to the fuel causing fuel vapor locking but some electrical items do become heat sensitive as well.

If I pull off the positive end to the battery cable and then reattach it the boat starts and goes in to gear with no problem and runs fine. Is there some component or relay that gets tripped or reset when the battery cable is removed? I tried just turning off the power switch but it didn't work. You have to remove the battery cable. Ideas?
How many times have you tried this method? There is no "known" reset within the Mercruiser system by disconnecting the battery cable or turning off the battery switch. That mentioned I've seen some members do similar testing with about 5% success but in theory tuning the switch off is normally the same thing as disconnecting the cable to the engine. In rarer cases of some Sea Ray boat's, they may install a different type of power system to the helm area that doesn't seem to work like an ordinary electrical system found on most boats so maybe you have something different going on there as far as resetting when disconnecting the cable heading to the helm/dash area.

What's your engine serial number? Service Bulletin - Marine Mechanic
 
Last edited:

poconojoe

Lieutenant Commander
Joined
Sep 10, 2010
Messages
1,966
Just throwing this out there....Idk... If it's a carb engine, could it be your choke is stuck closed? Could be an electric choke?
 

rbondranko

Recruit
Joined
Aug 2, 2015
Messages
2
Thanks for the replies. I have tried the "disconnect the battery method" on 3 different occasions on 3 different outings. First time I swapped the battery out thinking it may just have a bad cell. The starter did still turn over fine and all of the accessories still worked. 2nd time I swapped the battery again with the spare that I carry. Same deal, after swapping it the boat fired right up. The 3rd time I just removed the positive lead and then reconnected it. Turned the key and it fired right up, put it in drive and off we went.

I was thinking possible vapor lock too and I've tried all the recommended tips in the Mercruiser "vapor lock" technical bulletin. I guess that could still be a possibility but I can't say that the days I haven't had the problem have been any cooler than on the days when the problem has occurred. Engine temp based on my gauges remains at or below the Mercruiser recommended operating range.

I'll match my serial number against the bulletin you referenced. I am still wondering if there is something going on with the shift interrupter switch just based on the behavior. I've never had any issues getting the boat in to or out of gear when it is running right. My understanding though is if the shift interrupter isn't working correctly, the boat will stall when the boat is put in to gear. If the boat is in neutral and the switch is faulty I assume the boat wouldn't start?

It is multi-port fuel injected. No carb.
 
Last edited:
Top