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115hp EFI Fuel Problem

biesmeyer

New member
Thank you in advance. New to the boat forum. I have a 2008 Mercury 115HP EFI. Launched the boat idled over to the dock. Parked the truck, came back tried to start the boat and it wouldn't start. Brought it home an pulled the plugs ad found some raw fuel in cylinder #3 and then pulled #4 plug to have a ton of raw fuel pour out of the cylinder. Pulled all the injectors and cleaned and checked them all good. Put injectors back in and crank over with plugs out. Tons of raw fuel again in #4. nothing in# 3 . I know it isn't the injector, what else can keep putting raw fuel in #4 cylinder? Pulled wires from injector so not to fire off.
 
The injector is stuck open and may need to be replaced. You cannot clean injectors unless you have an injector cleaner.

Ok here is part two now.
Took your advice on stuck injector. I pulled #4 out and swamped it with #1 One of my 3 dry holes
#1 is still dry and #4 is still dumping raw fuel
Now where is this fuel coming from??
When I checked and cleaned these injectors I put them under pressure with cleaner, Fired them off, spray is good and didn't leak.

Please any ideas will help
Just confused
 
The driver on the computer for the injector is shorted to ground the transistor is damaged and you will need a new one computer that is. Before replacing the computer check to see if the wire coming from the computer to the driver side of the injector is shorted to ground or battery positive as the case may be for triggering the injector.
 
Its not a injector or puter problem, the float in VST tank is stuck or has debris under needle causing it to overfill and fuel is dumped back into #4 intake.
 
Its not a injector or puter problem, the float in VST tank is stuck or has debris under needle causing it to overfill and fuel is dumped back into #4 intake.

Bingo !! You are the man!
I didn't see your reply till I figured it out. But THANK YOU !!!
You are right. Pulled the vapor hose going to intake ran pump and tried cranking it over
and along comes the stream of fuel. Right in the intake-flows right into #4 cylinder

THANK YOU !! THANK YOU!! YOU ROCK!!
Its all good. Didn't want to be on that crazy lake this weekend any way
 
Bingo !! You are the man!
I didn't see your reply till I figured it out. But THANK YOU !!!
You are right. Pulled the vapor hose going to intake ran pump and tried cranking it over
and along comes the stream of fuel. Right in the intake-flows right into #4 cylinder

THANK YOU !! THANK YOU!! YOU ROCK!!
Its all good. Didn't want to be on that crazy lake this weekend any way

Okay after looking this up. Mine doesn't have needle and float.
It has a pressure regulator and a small piece of hose. There was a service bulletin to replace this piece of hose
and also the electronic float.
My piece of hose was cracked due to the ethanol fuel
Thanks again
 
12/2022…
Thank for posting your problem…I have a 2007 Mercury 115 EFI….with the same exact symptoms…the feedback and info posted led me to the problem…..the small 5”+- hose from the fuel regulator was split …which allow raw fuel to be “sucked “ into the air intake path behind the throttle butterfly….in my case the raw gas also seeped into the crankcase…raising the oil level…
note to others…do a hands on inspection of this hose …mine was hairline split running 3+-“ inline ..had to squeeze to find…
 
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