paulofpanama
Recruit
- Joined
- Jan 2, 2008
- Messages
- 5
Saw the good feed back to the gas guzzling 45hp Mariner so I thought I would throw this out there..? I have a 1987 Mariner 45, (without thermostat) equipped with WALBRO carbs with integral fuel pumps & one piece choke plate. The motor came with a boat I bought. I know it ran good in the past then sat for a long time. Anyway one thing my motor does is fouls out plugs in about and hour and I was hoping maybe it was running to cool and I could change the thermostat. That was how I found out it has no thermostat! The thing about this motor is with clean plugs it would run fair to ok but not to full rpm. I will run it full open without reaching full rpm but then sometimes out of the blue it will jump up to full rpm for a few minutes or more running like it should then drop off again, it is more off than on. It is like an intermittent ignition/electrical problem somewhere?? And the fuel economy is not bad. I have dried everything out checked the leads, wiring, grounds etc but I have not run the problem down yet. Some better testing tools arrive soon.
I am in Central America with it and I had a so called Mercury shop here check it but they are real shade tree here with virtually zero diagnostic tools or brains it seems, did not even have a timing light or know what one was I think. They just stuck it in a water tank ran it and said everything was fine which I realized was not true as soon as I started running the motor on my boat again. Have one spare coil & new leads to try also, one cylinder at a time I guess... Any tips appreciated. I am mechanically inclined just not much experience with outboards. Motorcycles & turbine airplanes are my specialty not outboards.
Was leaning in the direction of, plug wires and coil swapping. (waiting on a timing light) I tried getting the flywheel off to inspect there (stators & trigger) but without the correct puller (on order now) I couldn?t. Interesting discovery while I had it apart I decided to pull the carbs and rebuild them. Big surprise..! The bottom carburetor bowl was bone dry the bowl had dust in it and also a small hole where corrosion had pitted all the way through! Anyway this Carb was not leaking any fuel when I was running the motor so it had fuel blockage somewhere..? Nothing ever reached the bowl? Line, internal, etc (have not had time yet to discover where yet?) Anyway was surprised to find that being as the motor ran good sometimes. Is it possible to run ok on one carb and still foul spark plugs..? Seemed like a strange combination to me. Wish I would have checked it under power to see if it was drawing any air through that bottom carb..? I have to have been running it on one carb all this time.
I was short on tools when I first dove into tuning this motor up but when I hit it again I?ll have a timing light, spark gap tester, automotive clamp on rpm gauge, compression gauge, & flywheel puller. And two rebuilt carbs, though I don?t think they are related to the rpm jumping up & down..? That feels like electrical to me, but just where I don?t know...? I will take any troubleshoot tips on where to focus my attention. One other thing when I bought it the exhaust port was coked up with some good sized nodules of carbon like possible from a history of running too rich..?
Thanks in advance.
I am in Central America with it and I had a so called Mercury shop here check it but they are real shade tree here with virtually zero diagnostic tools or brains it seems, did not even have a timing light or know what one was I think. They just stuck it in a water tank ran it and said everything was fine which I realized was not true as soon as I started running the motor on my boat again. Have one spare coil & new leads to try also, one cylinder at a time I guess... Any tips appreciated. I am mechanically inclined just not much experience with outboards. Motorcycles & turbine airplanes are my specialty not outboards.
Was leaning in the direction of, plug wires and coil swapping. (waiting on a timing light) I tried getting the flywheel off to inspect there (stators & trigger) but without the correct puller (on order now) I couldn?t. Interesting discovery while I had it apart I decided to pull the carbs and rebuild them. Big surprise..! The bottom carburetor bowl was bone dry the bowl had dust in it and also a small hole where corrosion had pitted all the way through! Anyway this Carb was not leaking any fuel when I was running the motor so it had fuel blockage somewhere..? Nothing ever reached the bowl? Line, internal, etc (have not had time yet to discover where yet?) Anyway was surprised to find that being as the motor ran good sometimes. Is it possible to run ok on one carb and still foul spark plugs..? Seemed like a strange combination to me. Wish I would have checked it under power to see if it was drawing any air through that bottom carb..? I have to have been running it on one carb all this time.
I was short on tools when I first dove into tuning this motor up but when I hit it again I?ll have a timing light, spark gap tester, automotive clamp on rpm gauge, compression gauge, & flywheel puller. And two rebuilt carbs, though I don?t think they are related to the rpm jumping up & down..? That feels like electrical to me, but just where I don?t know...? I will take any troubleshoot tips on where to focus my attention. One other thing when I bought it the exhaust port was coked up with some good sized nodules of carbon like possible from a history of running too rich..?
Thanks in advance.
