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Author Topic:   Mercury Optimax Won't Run

redbrad1 posted 06-25-2011 07:32 AM ET (US)
I have been out of the water two weeks and it's another two before I can get a commitment for someone to look at my 2005 Mercury Optimax 225-HP outboard motor. I am desprate for help! While I don't have the serial number it appears to be in the Mercury Parts schematic of "225 DFI/0T801000_UP USA", because the vapor separator components of this model reflects what I have (and it's the only one that does). The correct serial number isn't on the transom plate.
The [Mercury OptiMax 225-HP] has been running fine and was run through the winter for duck hunting and seal watching. Ran [the Mercury OptiMax 225-HP] for 20-minutes last week, anchored out, started it fine to run back, got up to plane, lost RPM, sputtered, then died. [The Mercury OptiMax] would re-start with throttle opened, but died as throttled back. [The boat was] towed home and put on trailer. [The Mercury OptiMax 225-HP] cranks, tries to start, but doesn't stay running.
Attempts to locate problem:
--replaced plugs (two-season's old), each was covered in soot;
--replaced fuel filter in Vapor Separator (red cap);
--used fuel bulb to pump gas, appears to flow feely into Vapor Separator fuel filter chamber;
--drained fuel in Vapor Separator, fuel had some debris but no water and not terrible;
--searched for other filters on motor, but none are apparent;
--confirmed strong spark at plugs. I expected to see gas fouled plugs after attemps to start failed, but each was dry; and,
--tested bleeder valves on the starboard side (on top of rail) had fuel under pressure without having the key turned, the bleeder valve on aft side of vapor separator only had pressure following key being turned - gas bled out easily. The bleeder valve on the port rail never seemed to have fuel in it, following engine being turned over air came out, but after several engine cranks there was still only a very small amount of gas mixed with the air, and that was inconsistent. The bleeder valve on the port side rail was the only valve that I couldn't get a steady flow of gas.
I have a don't know a lot about outboards nor do I have a ton of mechanical experience, but the prospect of missing both Father's Day AND the 4th of July is serious motivation for learning. Any suggestions would be much appreciated

phatwhaler posted 06-25-2011 07:36 AM ET (US)
Is the compressor and alternator belt still intact? The last time I lost a belt the motor would start then immediately die.
redbrad1 posted 06-25-2011 07:44 AM ET (US)
[The drive belt for the air compressor and automobile-style alternator] is still intact and appears to have the right amount of tention. I had a problem last summer with the belt, so know exactly what you are talking about. In my case last summer the pulley wheel sheered off. [The cause] turned out to be bad screws, so a quick fix.
jimh posted 06-25-2011 08:03 AM ET (US)
Move to REPAIRS/MODS.
captbone posted 06-25-2011 09:12 PM ET (US)
You need to check Air/Fuel pressure at the rail. One schrader valve (tire inflator) will have only fuel and one will have air.
You should have 80psi on the air and 90 psi on fuel. It wont run otherwise.
redbrad1 posted 06-26-2011 11:26 AM ET (US)
I got a buddy of a buddy to stop by this morning who works mostly on Optis. Pressure was the first thing he checked and it was too low. He quickly honed in on the compressor, and bad news - the piston and connecting arm are shattered when he took it apart.
Off to ebay or dealer looking for new parts.
Thanks for the help trouble shooting.

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Author	Topic: Mercury Optimax Won't Run
redbrad1	posted 06-25-2011 07:32 AM ET (US) I have been out of the water two weeks and it's another two before I can get a commitment for someone to look at my 2005 Mercury Optimax 225-HP outboard motor. I am desprate for help! While I don't have the serial number it appears to be in the Mercury Parts schematic of "225 DFI/0T801000_UP USA", because the vapor separator components of this model reflects what I have (and it's the only one that does). The correct serial number isn't on the transom plate. The [Mercury OptiMax 225-HP] has been running fine and was run through the winter for duck hunting and seal watching. Ran [the Mercury OptiMax 225-HP] for 20-minutes last week, anchored out, started it fine to run back, got up to plane, lost RPM, sputtered, then died. [The Mercury OptiMax] would re-start with throttle opened, but died as throttled back. [The boat was] towed home and put on trailer. [The Mercury OptiMax 225-HP] cranks, tries to start, but doesn't stay running. Attempts to locate problem: --replaced plugs (two-season's old), each was covered in soot; --replaced fuel filter in Vapor Separator (red cap); --used fuel bulb to pump gas, appears to flow feely into Vapor Separator fuel filter chamber; --drained fuel in Vapor Separator, fuel had some debris but no water and not terrible; --searched for other filters on motor, but none are apparent; --confirmed strong spark at plugs. I expected to see gas fouled plugs after attemps to start failed, but each was dry; and, --tested bleeder valves on the starboard side (on top of rail) had fuel under pressure without having the key turned, the bleeder valve on aft side of vapor separator only had pressure following key being turned - gas bled out easily. The bleeder valve on the port rail never seemed to have fuel in it, following engine being turned over air came out, but after several engine cranks there was still only a very small amount of gas mixed with the air, and that was inconsistent. The bleeder valve on the port side rail was the only valve that I couldn't get a steady flow of gas. I have a don't know a lot about outboards nor do I have a ton of mechanical experience, but the prospect of missing both Father's Day AND the 4th of July is serious motivation for learning. Any suggestions would be much appreciated
phatwhaler	posted 06-25-2011 07:36 AM ET (US) Is the compressor and alternator belt still intact? The last time I lost a belt the motor would start then immediately die.
redbrad1	posted 06-25-2011 07:44 AM ET (US) [The drive belt for the air compressor and automobile-style alternator] is still intact and appears to have the right amount of tention. I had a problem last summer with the belt, so know exactly what you are talking about. In my case last summer the pulley wheel sheered off. [The cause] turned out to be bad screws, so a quick fix.
jimh	posted 06-25-2011 08:03 AM ET (US) Move to REPAIRS/MODS.
captbone	posted 06-25-2011 09:12 PM ET (US) You need to check Air/Fuel pressure at the rail. One schrader valve (tire inflator) will have only fuel and one will have air. You should have 80psi on the air and 90 psi on fuel. It wont run otherwise.
redbrad1	posted 06-26-2011 11:26 AM ET (US) I got a buddy of a buddy to stop by this morning who works mostly on Optis. Pressure was the first thing he checked and it was too low. He quickly honed in on the compressor, and bad news - the piston and connecting arm are shattered when he took it apart. Off to ebay or dealer looking for new parts. Thanks for the help trouble shooting.