Merc 5.7 WOT when engine warm issues

jthor3277

Petty Officer 2nd Class
Joined
Jul 25, 2009
Messages
104
After a year of having my Sea Ray in dry dock, I took her out for a Maintenance run. I was pleasantly surprised that it ran pretty well except for a couple of hiccups. After running at wot for a bit, I throttled back to idle and opened the engine compartment for inspection. When I went to bring it back up, around 2K, to get on the plane the engine would stall out. I could keep it going if brought back to idle. I would get an acceleration and then drop off to a sputtering engine and then it quits. I could get the engine up to speed after messing with it. The engine restarts fine. The oil pressure and water temp are in the green. Also the throttle is stiff when shifting but the drive shifts normally. Any ideas would greatly be appreciated.
 
Joined
Jun 17, 2012
Messages
940
Re: Merc 5.7 WOT when engine warm issues

First guess would be fuel. Did you put fresh gas in? Or is it a year old?
Did you check/replace fuel filters?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,524
Re: Merc 5.7 WOT when engine warm issues

First guess would be fuel. Did you put fresh gas in? Or is it a year old?
Did you check/replace fuel filters?

Ayuh,... I agree,... Sounds like a fuel issue,...

Everything from the tank to the carb is suspect,...
Start with the fuel filters to see what yer dealin' with,...
Bad fuel,..?? Water,..?? Crud,..??
 

jthor3277

Petty Officer 2nd Class
Joined
Jul 25, 2009
Messages
104
Re: Merc 5.7 WOT when engine warm issues

I thought about that. There's 20 gallons of gas from last fall in the tank. I fuel stabilized and ran sea foam through it. I also replaced the water separator filter before running it. I had the fuel tank boiled last year and the carb was rebuilt by pros. I'll check the carb filter at the inlet. I replaced the anti siphon valve recently. It's never had this issue before.
 
Last edited:

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,524
Re: Merc 5.7 WOT when engine warm issues

I thought about that. There's 20 gallons of gas from last fall in the tank. I fuel stabilized and ran sea foam through it. I also replaced the water separator filter before running it. I had the fuel tank boiled last year and the carb was rebuilt by pros. I'll check the carb filter at the inlet. I replaced the anti siphon valve recently. It's never had this issue before.

Ayuh,.. To Test it,.... Run it on a remote tank with fresh fuel, hooked to the filter or fuel pump,...
 
Top