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Water Dawg 6

Twin Mercs Trim Pump Schematic

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Anyone out there have an electrical schematic for twin Mercs?  There are tons on line if you only have one motor.  But I need one for two motors.  Not getting power to either Trim Pumps and from what I understand the power to the Sterndrive Trim Pump runs to the Port Side, so if your fuse is blown on the Starboard Side you get no power to your Port Trim Pump either.  Just wanted to look over the schematic before I go investigating any further.  Thanks

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Was it working nicely for months or a sudden stop after work was done on the boat ?

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After, I reinstalled the pump.  I attempted to raise the opposite motor.  I heard that pump run for moment but then it stopped.  I do know that one of my four batteries hasn't been holding a charge very well.  But I was able to start the boat with no issues, so I assume there should be enough power from the batteries to runt these pumps.  I even tried putting my battery selector switch to "all" which pulls current from all four.  Of course it's poring rain today so I can't get to the Marina to check those fuses.  However, if it's not the fuses I don't have a clue what it could be.  I did check my ground wires as well.

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1 hour ago, Water Dawg 6 said:

After, I reinstalled the pump.  I attempted to raise the opposite motor.  I heard that pump run for moment but then it stopped.  I do know that one of my four batteries hasn't been holding a charge very well.  But I was able to start the boat with no issues, so I assume there should be enough power from the batteries to runt these pumps.  I even tried putting my battery selector switch to "all" which pulls current from all four.  Of course it's poring rain today so I can't get to the Marina to check those fuses.  However, if it's not the fuses I don't have a clue what it could be.  I did check my ground wires as well.

Were you attempting to raise of lower the drive when it suddenly stopped? Could be the trim limit switch taking it out. Will it go up with the trailer button over-ride employed?  W

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in most applications the trim pump wiring for a single is the same for a twin. You dont want to raise or lower both drives with 1 button.

Most are wired directly to the starters main lug thru a 90A fuse link while some are wired to the motors starting battery

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It sounds like the heavy gauge positive lead was shorted to negative. POP

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Haven't tried the trailer switch yet.  I'm going to check the fuses and one is blown, I'll look for the short.  If everything looks good there, I'll turn to the batteries I guess.

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13 hours ago, Water Dawg 6 said:

Haven't tried the trailer switch yet.  I'm going to check the fuses and one is blown, I'll look for the short.  If everything looks good there, I'll turn to the batteries I guess.

Another thing I have seen is a cylinder lock up. The shaft seal has a wiper ring and as corrosion builds up between the SST ring and aluminum cylinder end cap, it can squeeze the shaft so tight that the hydraulics can't overcome the resistance. This causes the drive to go down but not go up as the weight of the drive itself and the drag from the ring just becomes too much for the pump. Even on the work bench, I need to screw out the end cap and then put the shaft/end cap assembly in a bench press to get them apart. Easy rebuild after you get it apart and less than $20 in parts. If your pump runs after the fuse replacement, and blows again then you may have a cylinder issue.  W

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Wingnut is right about a mechanical jammed O ring.  Battery switch off . Extra body to help. Large pan under the cylinder to catch dripping oil. See if you & helper can disconnect the cylinder from the drive housing. Without dropping to fast. Fully lowered.   Disconnect BOTH hydraulic lines into the cylinder. Try to push the piston FULLY UP & DOWN. Should easily be able to do it.  Oil CAN SQUIRT OUT QUITE A DISTANCE. I put a rag around the oil holes to make sure the oil drips into the pan.

 

Get lucky

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It was the fuse going to the Port Side Trim Pump.  It was shattered, haven't put a new one in yet to see if it blows again.  We'll see next weekend.

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Found these drawings. Don't know if they will help

Dual Trim controller.jpg

Dual Trim.jpg

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Thank you.  Just got back from the boat.  I installed the new fuse and still nothing.  No power going to the motors themselves.  So I do think it's the trim switch or the any mechanism jamming up.  Because power has to be going to the pumps first before anything else can happen.  Going to bring my tester down next weekend to test the power going to the pumps.  Then connect a wire directly to the battery, etc.  The problem could be by the switches on my throttle controls.  Who knows at this point

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Trailer switch does not work either.  From the diagram above though there is another 20 amp fuse under the dash close to the ignition switch.   So I'll have located and check that one.

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The blowing out of the fuses in a second or 2 IS burning up the POWER RELAY CONTACTS of 1 motor. I would recommend you replace that relay AFTER the short is removed. It will soon bee causing intermittent operation WITHOUT BLOWING a fuse.

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I don't know my fuse was blown or not.  I took the entire pump out of the boat and worked on it in my shop.  The fuse wasn't blown, the glass was actually crushed.  So I'm thinking it could have gotten crushed by the pump falling over and landing on top of it in the back of my truck.  Sounds crazy but possible, since normally they would blow the filament on the inside - I've never seen the glass totally shatter.  I'll bring my ac/dc tester to the boat next weekend and start the testing.  First thing is to test to see if power is getting to the pump, then I plan to put a wire directly to the battery and to the blue wire on the pump, that pump should immediately kick on and that motor should start to go up.  From there I guess I'll trace the switches on my throttle and try to find that other 20 amp fuse.

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Gentlemen,  ok here we go.  I replaced both fuses.  I took a wire directly from the battery and touched the blue (up) wire on both pumps and the pumps work and the outdrives go up.  I used a multi-meter and tested the power block on both pumps and they are receiving constant power.  I looked under the helm and I was only able to find one 20 amp fuse under there and it is good.  The switches on my controller just aren't turning on the pumps on and also the trailer up switch is not doing anything either.  Any ide where I should look now.  It's obviously between the switches and the pumps.  Don't know if they plug into some sorta relay or what (mercathod)?  Any assistance would be greatly appreciated

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3 hours ago, Water Dawg 6 said:

Gentlemen,  ok here we go.  I replaced both fuses.  I took a wire directly from the battery and touched the blue (up) wire on both pumps and the pumps work and the outdrives go up.  I used a multi-meter and tested the power block on both pumps and they are receiving constant power.  I looked under the helm and I was only able to find one 20 amp fuse under there and it is good.  The switches on my controller just aren't turning on the pumps on and also the trailer up switch is not doing anything either.  Any ide where I should look now.  It's obviously between the switches and the pumps.  Don't know if they plug into some sorta relay or what (mercathod)?  Any assistance would be greatly appreciated

There are trim up and trim down relays on both pumps, a redundant pair of relays atop the engine (on some models) marked trim up and trim down, and trim limit switches outboard affixed to the port side of each drive at the pivot point that will limit trim up operation but not trim down.  W

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The solonoids/relays on the pumps work.  I test both up and down by connecting a wire directly to my battery and touching the respective green for down and blue for up on the  solonoids.  The outdrives went up and down just fine.  They're just responding to the switches at my throttle control or the trailer up/down switch.

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2 hours ago, Water Dawg 6 said:

The solonoids/relays on the pumps work.  I test both up and down by connecting a wire directly to my battery and touching the respective green for down and blue for up on the  solonoids.  The outdrives went up and down just fine.  They're just responding to the switches at my throttle control or the trailer up/down switch.

Take a look atop the engines for a bank of small relays. One will be marked Main, one fuel pump, and the other two trim up and trim down. Not a engines have them but some do.  If they are not there then it's time to trace/test control wires.  W

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FIXED IT!  On a boat with two Trim Pumps the wiring harness going into one of the trim will have a red wire, the other pump will not.  This powerwire goes up to your remote control and trailer switch and provides power back to your pumps via the blue and green wires.  At some time a previous owner cut that red wire and had it twisted back together and black electrical taped it.  That is were my connection was off - the wires came apart. 

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