2005 Merc 115 EFI 4 Stroke - No Power

davidgmiller

Cadet
Joined
Jul 2, 2010
Messages
11
Folks, I've been troubleshooting my power loss issue, and keep in mind the boat has been sitting for several years, started ever so often but no lake time.

Took boat out this past weekend and she fired right up, idled fine and on the trailer rev'ed up with no issues. Put the boat in the water (24 foot Starcraft Pontoon) and at low throttle in gear she ran pretty good however when throttled up bogged and kept dying.

Today I checked to see if the fuel rail had pressure and it did not, so I turned on the key, thinking that the HP fuel pump would build up pressure and it did not. Started the boat and it cranked right up, turned it off and depressed the valve and there was pressure and fuel. I plan on putting my gauge on it tomorrow to get a real reading.

My question is (and I'm thinking yes) that there should be pressure at the rail when the key is switched on? I also cannot hear the pump running but I do hear a few clicks but by the time I get back to the back of the boat it stops, but still no pressure.

I'm thinking that either the VST is gummed up or the HP fuel pump is dead and the mechanical pump is providing just enough to keep the boat running.

Kind of long winded for a question, but thank you in advance for the help.
 

papspontoon

Cadet
Joined
Aug 18, 2021
Messages
22
I don't think it would start without the electronic pump running. But I think you are in the right area to check. Pressure is supposed to be 41 psi.. I have 2001 115 hp 4 stroke EFI. had loss of power. Put new fuel injector in, problem gone. Injectors were less than $40.
 

davidgmiller

Cadet
Joined
Jul 2, 2010
Messages
11
Update, Took the injectors out, cleaned them and it helped but still not 100%, so I just bought 4 new injectors and she is running like new.

Thanks for the help.
 

Dave1027

Lieutenant Junior Grade
Joined
May 25, 2010
Messages
1,080
I know that automotive fuel injectors can be removed and sent to companies that specialize in rebuilding them. It's usually a fraction of the cost of new injectors. Not sure if they accept outboard motor injectors.
 
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