95 Merc 225hp Offshore

[leckbass]

I have a 95 Merc 225hp 3L Offshore carbed motor serial # 0G200991. I've been having intermittent problems with this motor since late spring.

The first problem happened after a few hours of trolling. I went to go put the boat on plane and pull back the throttle for cruising range at 3500 RPMs and the motor would not run at 3500, it would either lose RPMs or flat-out die. It ran fine at Full Throttle and at idle but not in the middle.

I replaced all of the fuel lines from the racor fuel filter to the primer bulb to the fuel pump to the motor filter and to each of the three carburetors. I also rebuilt the fuel pump which definitely saw a better days. I also changed the plugs. I also checked the stator and it was to spec.

Today I took the boat out, it jumped on plane no problem, I ran about 4 miles, then I stopped to scan a spot. Went to go put the boat on plane and I could not get the engine past 2200 RPMs. It was definitely running rough like there is a miss. I tried multiple times and could not get it past 2200. I was able to idle back to the boat ramp without a problem.

Maybe I need to check the coils? I'd appreciate any advice.

[EuropeanAM]

Did you use an OEM Mercury/Quicksilver kit for the pulse fuel pump or an Aftermarket (VERY important question)?

[leckbass]

Did you use an OEM Mercury/Quicksilver kit for the pulse fuel pump or an Aftermarket (VERY important question)?

Definitely OEM, p/n 857005A1, I just double-checked the receipt

[leckbass]

I'm thinking about removing all the plastic hose clamps on the connections from the fuel pump through to the carbs and replacing them with metal. Maybe leaking air?

[EuropeanAM]

Did you use the Mercury RADIUS-HEAD Tie-wrap, Part# 816311T (THAT is the correct clamp to use for this purpose, it differs from traditional sta-straps or tie-wraps).

I do not recommend using metal clamps in place of these as they can potentially damage hoses, and may also cause additional vibration at critical joints.

[leckbass]

Did you use the Mercury RADIUS-HEAD Tie-wrap, Part# 816311T (THAT is the correct clamp to use for this purpose, it differs from traditional sta-straps or tie-wraps).

I do not recommend using metal clamps in place of these as they can potentially damage hoses, and may also cause additional vibration at critical joints.

I did not use them on all the connections, but I will pick some up tomorrow. I did not like the way the zip tie looked on the hose that connected to the top carb from the fuel filter, so I used two smaller zip ties there.

[Savage]

Worm gear clamps can cause vacuum leaks, which causes the pump to suck air and not fuel.

[leckbass]

What's the proper size for the hose that connects the on motor fuel filter to the top carburetor. I originally had 5/16, that was the hose I can never get to fit well. I just just replaced it with 1/4 and used OEM zip ties.

[EuropeanAM]

Part# 8M0108355 is 57" of the common fuel line used for the carbs, filter, etc. As you've found, using Fractional line sizes you would have to go 1/4".

[leckbass]

Part# 8M0108355 is 57" of the common fuel line used for the carbs, filter, etc. As you've found, using Fractional line sizes you would have to go 1/4".

No dice... I pumped the primer bulb, motor started right up, idle out from the launch, but the boat would not go on plane and I could not get the motor over 2200 RPMs, constant shutter at 2200.

I noticed some unburned fuel in the water, and a strong exhaust smell, but this engine always seem to have a strong exhaust smell since I bought it.

[Savage]

I would check to see if the VST is overflowing. You could have an issue with the needle and seat/float in the VST.

[leckbass]

I would check to see if the VST is overflowing. You could have an issue with the needle and seat/float in the VST.

I'm not an expert, but I dont think I have one of those.

[Savage]

I'm not an expert, but I dont think I have one of those.

Your right you don't.....my bad. Check the needle/seat/float in each carburetor.

[rvaha]

Any chance it’s the stator? I had this happen on a 2.4. Wouldn’t rev past 3000!rpm under load. Replaced stator and problem cleared. Stator wouldn’t work on high speed. Experts can comment if this is relevant to a 3 liter.

[leckbass]

Any chance it’s the stator? I had this happen on a 2.4. Wouldn’t rev past 3000!rpm under load. Replaced stator and problem cleared. Stator wouldn’t work on high speed. Experts can comment if this is relevant to a 3 liter.

I did test it with the ohmmeter and it was to spec.

[Savage]

"Unburned fuel in the water" needs investigated ASAP, or fire maybe the next problem.

[leckbass]

"Unburned fuel in the water" needs investigated ASAP, or fire maybe the next problem.

I wasn't sure if it was me being hypersensitive to this engine not running correctly right now. This motor has always run pretty rich and always been thirsty.

[leckbass]

Your right you don't.....my bad. Check the needle/seat/float in each carburetor.

I tried and gave up, I brought it to my tech and he said rebuild the carbs. Found that the top carb seat was falling apart. Rebuilt the carbs and back to business!

I have renewed confidence in that every hose, filter, pump, primer, and clamp has been replaced/rebuilt in the last 2 months. Time to catch some fish.

I appreciate everyone's help with my motor. Thank you for all of the advice.