bwguardian
Seaman Apprentice
- Joined
- Jul 19, 2016
- Messages
- 31
Mercury 90-125 no power under load...not the common dirty carb fuel and/or stator issue...
I am trying to get my ole 182 Mako flats up and going. I purchased this hull some time back and have been restoring it. I removed all the wiring and fuel hoses...but did keep the battery cables given they run to the front of the boat for weight distribution purposes. I also installed all new gauges, switches, controls, etc. as well as cleaning the tank. I had a 2000 Mercury 90 elpto rebuilt and hung on the hydraulic jack plate. The engine ran good on the muffs but when put under load on the trailer and/or in the water it would not get over 1,800 rpms. The compression check showed 120-125 on all three cylinders. The prop on the lower unit is a 15" pitch but may be altered. We cleaned the carbs twice with no change. I checked the fuel system and there is no anti-siphon valve at the fuel supply on the tank. The tank vent is clear and working. We also rebuilt the fuel pump with no change. We bypassed the fuel water separator filter and primer bulb to a portable tank with no change. The battery is a couple months new with 1,000 cca; however, it won't hold a charge now so I had it tested yesterday and it is bad so I will be picking up another new one tomorrow. I think it may have gone south when we had an electrical storm. After it passed, I checked on the boat and the motor was trimmed all the way up and trim motor was still running...the trim motor was hot, so I disconnected the battery and let it cool. Don't know how this happened but it seems to function fine now.
We have since pulled the fully dressed power head and installed another fully dressed 2001 power head. The compression on all four cylinders were about 140 psi. This motor is doing the same thing except the maximum rpms it will make under load is about 2,100 rpms. Thinking the common denominator is the lower unit, and given the 90 utilized the 2.3 gear ratio and the 115-125 utilize the 2.07 gear ratio, we have another correct lower unit installed though the other seemed to turn freely and will be testing tomorrow.
It is odd to me that the 125 did make a little more power in the rpm range which is the reason for looking at the lower unit. At this point I am thinking the only other common denominator would be the engine harness from the motor to the controls and the battery cables. I purchased the engine harness from a friend that had a 2000 Mercury 200 on a Robalo that lost a cylinder. The kill switch looked like an aftermarket and must be bypassed given the motor cranks without the clip though the wires are still hooked up to it. The ignition switch is a new Mercury "push to choke" unit. I wouldn't think the binnacle controls or cables would have anything to do with this given I checked to make sure the throttle blades fully open. I did also install a Perko "on" "off" switch that I had, so not new.
I am trying to get my ole 182 Mako flats up and going. I purchased this hull some time back and have been restoring it. I removed all the wiring and fuel hoses...but did keep the battery cables given they run to the front of the boat for weight distribution purposes. I also installed all new gauges, switches, controls, etc. as well as cleaning the tank. I had a 2000 Mercury 90 elpto rebuilt and hung on the hydraulic jack plate. The engine ran good on the muffs but when put under load on the trailer and/or in the water it would not get over 1,800 rpms. The compression check showed 120-125 on all three cylinders. The prop on the lower unit is a 15" pitch but may be altered. We cleaned the carbs twice with no change. I checked the fuel system and there is no anti-siphon valve at the fuel supply on the tank. The tank vent is clear and working. We also rebuilt the fuel pump with no change. We bypassed the fuel water separator filter and primer bulb to a portable tank with no change. The battery is a couple months new with 1,000 cca; however, it won't hold a charge now so I had it tested yesterday and it is bad so I will be picking up another new one tomorrow. I think it may have gone south when we had an electrical storm. After it passed, I checked on the boat and the motor was trimmed all the way up and trim motor was still running...the trim motor was hot, so I disconnected the battery and let it cool. Don't know how this happened but it seems to function fine now.
We have since pulled the fully dressed power head and installed another fully dressed 2001 power head. The compression on all four cylinders were about 140 psi. This motor is doing the same thing except the maximum rpms it will make under load is about 2,100 rpms. Thinking the common denominator is the lower unit, and given the 90 utilized the 2.3 gear ratio and the 115-125 utilize the 2.07 gear ratio, we have another correct lower unit installed though the other seemed to turn freely and will be testing tomorrow.
It is odd to me that the 125 did make a little more power in the rpm range which is the reason for looking at the lower unit. At this point I am thinking the only other common denominator would be the engine harness from the motor to the controls and the battery cables. I purchased the engine harness from a friend that had a 2000 Mercury 200 on a Robalo that lost a cylinder. The kill switch looked like an aftermarket and must be bypassed given the motor cranks without the clip though the wires are still hooked up to it. The ignition switch is a new Mercury "push to choke" unit. I wouldn't think the binnacle controls or cables would have anything to do with this given I checked to make sure the throttle blades fully open. I did also install a Perko "on" "off" switch that I had, so not new.
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