Need Help With My 1996 Mercury 225 EFI Bogging down

[B.gibson2345]

I have a 1996 Mercury 225 efi. wen i try and get the boat on plane it just boggs down and will not tach up. The motor seems to be in a sort of safety mode or something. I had the boat at a reputable shop where i live and they tried all sorts of troubleshooting ,The fuel vapor separator was pulled apart and cleaned,The injectors were cleaned 3 times, replaced all fuel lines,changed a check valve,pulled the lower unit looked in the exhaust,put 2 new computers on it,New spark plugs,tested all sensors,The motor has good compression in all cylinders.The mechanic called me and told me for the first time in 42 years he has no ideal how to fix this motor and to come get it i don't owe him anything. I refuse to believe the motor is shot it starts and idles like its brand new just wen its put under a load it will not produce the horsepower any help suggestions/advice will be greatly Appreciated guys!

 

[Maxz695]

Re: Need Help With My 1996 Mercury 225 EFI Bogging down

not to firmiliar at all with marine fuel injection. I,m not sure of the fuel delivery process be it electric fuel pump or machanical. I am really good with auto and was having an issue with my 1987 van I swapped the computer and the prom chips I rebuilt the throttle body I replaced the intake manifold got new wires new plugs changed the thermostat swich I tryed everything. I had replaced the fuel pump not 4 years prior. Well for shts and giggles I puled the tank and took a look only to find the 25 cent rubber hose and the plastic aligator type clamp had been eaten to hell by ethenol. I replaced it and it ran beautifly after wards. Unless the rev limiter or something of that nature is causing the problem I would try hooking a temporary fuel tank to the engine and try it out. This may reveal the problem lies in the tank or the pump and not the engine. Just a thought. Hope you have good luck with it.

 

[Maxz695]

Re: Need Help With My 1996 Mercury 225 EFI Bogging down

My symptoms where the engine was what they call "Hunting" Uneven idol. You say you have a good steady idol. Although it may be a fuel delivery problem there is one more thing that might be of some kind of help. I recall about two weeks ago there was a post about this type of problem on an EFI engine. The problem was explained by another poster as a choke switch or something of that nature. Maybe someone will read this and have the information about it and give you details.

 

[Faztbullet]

Re: Need Help With My 1996 Mercury 225 EFI Bogging down

What is your fuel pressure?? What is your voltage when running? Was injectors professionally cleaned/flowed and balanced ? What RPM does it bog?

 

[B.gibson2345]

Re: Need Help With My 1996 Mercury 225 EFI Bogging down

voltage is 14 when running and yes they were professionally cleaned with a injector machine

 

[Maxz695]

Re: Need Help With My 1996 Mercury 225 EFI Bogging down

I don,t think they where talking about the choke solenoid but some kind of choke sensor switch that may be affecting the fuel pressure regulator

 

[Mohawkmtrs]

Re: Need Help With My 1996 Mercury 225 EFI Bogging down

Check fuel pressure (as per Faztbullet).

Check TPS and its circuit.

 

[CharlieB]

Re: Need Help With My 1996 Mercury 225 EFI Bogging down

All this talk of what the 'reputable shop' has done to the fuel system but nowhere do I see the first simple troubleshooting done.

SPARK TEST

COMPRESSION

Per Fazt FUEL PRESSURE

A dead cyl and it will not perform, do youself a big favor, check these basics and repost

 

[Richard DePonte]

I have the same problem with my 1996 225 Mercury EFI bogging down at times but idles and starts up great. Any help with this would be must appreciated. Rich

 

[enginepower]

Definitely check the spark and make sure it can jump a gap of at minimum 3/8" as guys seem to use that distance that post here. You could have weak or NO spark on just one cylinder and it will perform like it has less than 50% of it's power but idle may seem normal.