1986 Mec BlackMax XR2 Power issues

[Speedy150]

Hello all,

I have recently inherited my grandfathers 1986 Bass Tracker (fiberglass hull not aluminum) with a Merc 150 BlackMax XR2. It was purchased brand new and has been used very very little until about 5 years ago when I would take it out on our camping trips. The last time it was taken out it would fail to get up on plane, the motor would sound fine but would not kick over to the higher rpm range or seem to get the power to come up on plane even with the throttle buried. Having someone sit all the way out on the bow and nursing it along it would finally come up on plane and go as fast as it ever had. It seems to me like it is losing it's torque to get over the plane speed barrier. This boat was very rarely used and is in pristine condition. Could this be a carb problem from sitting for extended periods of time? I have the manual and was thinking on tearing them down and cleaning them but if anyone has heard of this problem and it is due to some other issue please let me know if there is anything specific I need to look for. I have ran a few carb treatments through a few tanks but to no avail. Summer is coming and I wanna burn up the water, please help me out!!

 

[Texasmark]

Re: 1986 Mec BlackMax XR2 Power issues

Don't know how long nor heavy your boat is, nor the hull design, but probably not 18' long nor over 2000# fully loaded. A 150 should put a well hulled 18 footer out to 50 - 55 mph on a good day. Considering planing speed around 20 mph, you are moving right along.

You have your work cut out for you. Biggest problems over time is fuel contamination hence carbs varnished up and all, plus hoses cracked and leaking.

A fuel pump diaphragm can be added to the list. Then there is carboned up cylinders and sticking rings.

The procedure is all over the archives.

Real quick common demoninator is to remove the air baffle from your carbs air inlet. Firewall it while shooting Deep Creep (Sea Foam in a spray can) into the carbs. If she responds, clean up your fuel system.

Need more, ask,

Mark

 

[Speedy150]

Re: 1986 Mec BlackMax XR2 Power issues

Thanks for the info Mark, much appreciated. The boat is 17' and fairly light. The performance of old is just not there anymore. I could have 4 people in it and pull ski'ers / tubers no prob. Sounds like it is time to tear it down and rebuild. It has just been sitting to long.

 

[studlymandingo]

Re: 1986 Mec BlackMax XR2 Power issues

Did it sit over the winter with fuel in it?​

 

[Windykid]

Re: 1986 Mec BlackMax XR2 Power issues

I dont think you need to rebuild the motor. But you said it was hardly used until the last couple of years. Has there been any routine maintenance??? Impellor changed??? Fuel stabilizer??? I would start with what Mark said. Take it one step at a time.

 

[Speedy150]

Re: 1986 Mec BlackMax XR2 Power issues

It did sit over the winter with fuel in the tank but not in the engine. Prior to storing it I removed the gas line while the engine was running until it cut off so there would not be any gas sitting in then carbs. I am not sure if that is the best for them or not? The impeller has been replaced once relatively recently. Not much in the way of routine maintenance has been done that I know of. I have known this boat since it was purchased in 1986 and it has done nothing much except sit covered in the garage since then. These problems have just recently came about the last time it was taken on the family camping trip. While I am not going to rebuild the engine just yet I will take the advice given and start small and hopefully the problem will reveal itself.

 

[Windykid]

Re: 1986 Mec BlackMax XR2 Power issues

Good luck!

 

[hkeiner]

Re: 1986 Mec BlackMax XR2 Power issues

It did sit over the winter with fuel in the tank but not in the engine. Prior to storing it I removed the gas line while the engine was running until it cut off so there would not be any gas sitting in then carbs. I am not sure if that is the best for them or not?

It has always been my understanding that running a motor until it cuts off does not necessarily remove all of the fuel from the carbs. There will still be a small amount of fuel left in the carbs, which can gum things up if no gas stabilizer was added to the fuel beforehand. I always use fuel stabilizer and don't drain the carbs. It has worked well for me. I have no experience with doing it the other way. Perhaps I am wrong and either way is OK. Can others comment on this?​

Also, the fuel in the tank can go bad and cause problems if fuel stabilizer is not used.​

 

[Speedy150]

Re: 1986 Mec BlackMax XR2 Power issues

Yea leaving fuel in the carbs vice draining them has been inconclusive to me. Stabilizer is def a must though.

 

[studlymandingo]

Re: 1986 Mec BlackMax XR2 Power issues

I would definitely start with a good carburetor cleaning first off; then go from there if there is still any issue.​