Hard To Start
 

OK guys I've got a pair of 1996 EFI 502's, when they are cold they crank right up. If they are hot, like you shut them off to get gas, they are a pain to start. They turn over 30 or 45 seconds and you need to crack the throttle to geet them to catch.

Does anyone have any ideas?

Mike

Both of them?

Dont know if this will help, but my 502 mpi would start great last year when cold, but once warm it would not start unless I helped it out with throttle. Even then would not idle. My mechanic hooked it to the computer and everything checked out okay. He took the IAC valve out and the plunger was broke off.. Put on new IAC valve and has been working like a champ ever since.

Hard to Start
 

Yes, US1 Fountain both of them. I've used the boat very little, ~10 hours since November. Prior to that all was well.

baja bailey, thanks, that gives me something to look into.

Mike

I know there is a service bulletin from Mercruiser on a possible cause for this problem. Your motors may be getting vapor locked. Mercs' bulletin describes this exact problem, but they didn't have any real fix. They recommend running the bilge blowers when the engines are shut down for a while to suck out some hot air. I know there is a website for this, but I can't find it. Anyone else have it to post?

Lickitysplit, Does it idle ok once you do get it started? Also If yours has a VST tank, it has a diaphram in it that vents the tank.
Whats a VST? The gas pumps from the mechanical fuel pump to the VST that has the electric fuel pump in it and sits next to the ECU. Some have a fuel cooler and no VST.
Here is a link to the service bulletins.

Service bulletins: http://www.sterndrives.com/bulletins/bulletins.html
Gasoline Engine Vapor Locking Bulletin
http://www.sterndrives.com/bulletins/mc/99/EN_007.PDF

Hard to Start
 

Thanks for all the info and the explanation on the VST 28Eliminator. I'll look carefully and see if I have this setup. Yes, the engines idle perfectly once they catch.

I'll check out the links and try a couple of their suggestions.

Mike

accually it was the location of the fuel water seperator filters in mercs bulliten,usually it would be the port motor that should have the hardest start while hot,something about the fuel preheating because of its location between the center manifolds,no real fix other than moving the filters......most guys just raise ther hatch a little and let the cool air do its thing!!!!If you have both of them doing it you may consider adding more vents to your engine compartment!

I had same problem last summer. When engine got hot was hard to start without a little throttle. I was told vapor lock was most likely problem. I crack engine hatch and run blowers and it helped.