1993 Merc issues getting up on plane

[Threewolves]

I have a 1993 Merc 175 HP on a 1993 20ft trophy and I am having a problem with it getting up on plane. When I put it in gear and push the throttle forward it will only get up to 3,000 rpm and not get up on plane. When I take it out of gear and push the throttle it will go up to 4,500/ 5000 rpm without any issue. 

Wondering if anyone has had a similar problem and and answer to this issue.

I tried adjusting the trim, it didn't help.

[addicted1]

It won’t climb in RPM due to the load it is under when you are plowing you way through the water. What does you prop look like? Is the boat new to you or did it just start happening this year?

Have you done a tuneup this year, messed with the timing? I’ve had boats run fine under no load and put under load (in the water and in gear) they struggle. Had a carb that needed a rebuild as the jets weren’t working well. Have experienced a similar issue when the timing was off, but your timing should not be off unless something was messed with. Is it possible the boat was overloaded with gear and people?

[teanawayslayer]

I’m not a boat guy but I wouldn’t think adjusting the trim isn’t going to help if your motor only goes to low rpm.

[MADMAX]

I suspect its a fuel issue, probably 20 years of gas at the pump with ethanol

[Caseknife]

Check the plugs, fuel filter, prop, fuel quality, any and all could be causing the issue.

[timberhunter]

Is this boat new to you? Or have you added weight to the boat? If yes, I would also look at the pitch on the prop

[Threewolves]

It won’t climb in RPM due to the load it is under when you are plowing you way through the water. What does you prop look like? Is the boat new to you or did it just start happening this year?

Have you done a tuneup this year, messed with the timing? I’ve had boats run fine under no load and put under load (in the water and in gear) they struggle. Had a carb that needed a rebuild as the jets weren’t working well. Have experienced a similar issue when the timing was off, but your timing should not be off unless something was messed with. Is it possible the boat was overloaded with gear and people?

Thanks for replying. I will tell the saga after I answer your questions.
The prop looks new. Not even any paint missing. Pretty sure it is not "spun" because the RPM's didn't go up underload.
The boat is new to me, but I have been on it a couple of times and it ran fine.
It id just start happing this year. see below
Not overloaded, no one on board but me. I totally cleaned out everything.
The tune up question, timing and such. It just came out of the shop. More clarity in the saga:

So, I was gifted this boat by one of my best friends who recently became paralyzed as he puts it "from the nipples down"  Oct 24 he can shoot and cast.

The last time he ran it was in the spring of 24. Launched it, left it idling why he put the truck away, came back to alarms, motor smoking, wires melted.

I checked it, it turned over, it was not seized. The compression cold was over 100 psi. I decided to risk it and took it into a shop to see if it was a viable motor. (I was thinking of a brand new motor until I saw the cost of one.) So, they replace some wires, components, spark plugs and checked the compression, said it was good. I'd list the replaced  components, but can't find the receipt.

I took it out yesterday for "sea trials" to check everything out when I had the not coming up on plane issue. I called the shop from the lake to see if I could get this issue checked out and they suggested disconnecting the rev limiter.  After reading your post, I was thinking if it was running with the rev limiter hooked up before it over heated, it should be able to run after unless that was affected too. Anyway I was talking to them while on the lake and they were offering up suggestions.  So, I have not disconnected the rev limiter yet. I have to watch a couple of YouTube videos.

I was really trying to get it back in for them to check it out. The one guy said I could drop it off. Also, said they didn't have a tank big enough for a motor this size. They hook it up to a hose. I said I would take it out to a lake and check it out. I realize in a situation like this there are going to be issues until things get figured out. I think this is coming close to being fully operational.


So, my buddy just want to give me this boat, down riggers and all. If you are thinking he wants me to fix it up to take him fishing that is wrong. He has bigger ideas. He wants a whole new bigger boat that he can just roll his wheel chair in. I was thinking I would be crewing on the new boat and didn't need one. He is talking about having a place in WY and spending winters in FL.

With new information, what do you think? and what do you think about the rev limiter, it lets me rev it up when it is not in gear? And thanks again for replying.

[92xj]

My vote would be a bad coil, especially with the amount of heat it saw during the "fire".
Also, I would check the pitch the prop.  Since there is no wear or scratches or anything, sounds like a new prop was installed.  The pitch will throw off rpms.

[EnglishSetter]

Stale gas and/or restricted flow.

Try running off a portable tank of fresh gas.

[Henrydog]

Thats an old black Max oil injected.  Owned Merc's since the 70's. Grew up in an outboard shop and have worked boat insurance claims for 27 years

My idea in order
1) Stator, that is likely what the "fire" was Merc ran a much hotter ignition back then that OMC
2) bad Coil.  Get welding gloves and removed on plug wire at a time until you find the bad coil
2)  Bad primer bulb or hose  Run it on a separate remote tank and get some fresh non Korn gas

[Threewolves]

Thanks for the replies.

Henrydog, I took it back to the shop to be re-checked. First words I heard was Stator. I will up date when it is fixed. Thanks All.

[TommyH]

Stater... could be.. they have a high and a low.. not sure why yours would be working on the hose but not in the water tho if it is the stater.? I Just did one, went with the jet unit brand off eBay. Only a couple hours on it so far but seems to be working fine and fixed my intermittent spark issues. Really easy to swap a new one in.

[JKEEN33]

Thats an old black Max oil injected.  Owned Merc's since the 70's. Grew up in an outboard shop and have worked boat insurance claims for 27 years

My idea in order
1) Stator, that is likely what the "fire" was Merc ran a much hotter ignition back then that OMC
2) bad Coil.  Get welding gloves and removed on plug wire at a time until you find the bad coil
2)  Bad primer bulb or hose  Run it on a separate remote tank and get some fresh non Korn gas

I was reading the string wondering if anyone was going to say bad bulb. They will feel like they are full, but a small pinhole or crack will kill your power.

[Happy Gilmore]

Rotten fuel lines. Contaminated carbs. Melted gaskets. Fuel tank full of junk. Fuel filters clogged. Bad fuel. Carbs need rebuild. Fuel pump. May be overheating too.

[addicted1]

Haha, this is starting to to every “free” boat story I have ever heard. But, sounds like you have some good starting points.

[Threewolves]

Haha, this is starting to to every “free” boat story I have ever heard. But, sounds like you have some good starting points.

Yeah, you are right. A lot of good info. The shop called just before 5 PM yesterday. 3 July, pleasant surprise, they weren't supposed to be able to get to it until next week. I told them I would pick it up on Monday.

I haven't been in that big of a hurry. As stated in other posts, I figured there were going to be more than a few issues because of the engine over heating to the point wires to where melting. And sometimes it takes more than one try to get something fixed.

I had to think really hard before accepting this gift for a couple of reasons.  I didn't want anything I would have to be constantly working on. I know the best boat is your buddies boat. And a boat is a hole you throw money into. I looked at the prices of new boats, and from what I would like is about 78,000 stripped. I also looked at putting a new motor on this one, under 20, 000. So, I am OK with letting the professionals work on this one.

It all ready has down riggers, fish finders, and such. It is a nice step up from my 15 ft. 20 hp. Also, I thought about my shelf life, how much time before the big dirt nap. And a grand son who is coming back to fishing.

Also, I do have some time slots in my schedule that need to be filled with fishing. I sped a lot of time hunting.

This is the year to change out coolent on our vehicles. Replaced the carb on the riding mower, the MAPP sensor on the 01 turbo. I have rear break rotors and discs to be replaced to the 2011 2500. It's nice to have a shop get this boat right before I have to think about putting a wrech to it.

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[Threewolves]

Rotten fuel lines. Contaminated carbs. Melted gaskets. Fuel tank full of junk. Fuel filters clogged. Bad fuel. Carbs need rebuild. Fuel pump. May be overheating too.

Aw, to your points, I checked the compression cold, but I should have done a pressure bleed down to determine if it developed ahead gasket leak before taking it to the shop. They checked the compression warm and said it was good. No matter, it is a project in motion now.

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[Happy Gilmore]

My buddy just had this problem coming home from San Juans. Low pressure fuel pump. Replaced for $150 problem solved for his yamaha 225.