What could be wrong?

[camoto]

I have a 1987 Checkmate Sportfire (small boat) with a 2.0L Merc V150 and an OMC Powerlift. This thing REFUSES to pull a skier out of the water. Saturday I had a 4-blade Trophy 26p Prop on it and it just would not pull out a skiier. I tried every combination of trim and lift and the engine just bogs and will not get "over the hump". So then Sunday I go out and buy a 21p 3-blade aluminum prop. There was a noticeable difference in top speed, but bottom end seemed EXACTLY the same. So now I am starting to wonder if it is an engine problem.

If I put the motor all the way down on the powerlift and trim it all the way in, the engine dies. Someone told me that there may be something with the needle valve if that happens but I don't see how that makes sense. I do however agree that that seems wrong, because if the powerlift was not on the boat, I would be having the same issue, because the powerlift does not go lower than the original transom mount would be.

The strange thing is that if I am not pulling a skiier, it seems to plane out fairly quickly. Sometimes the engine will bog a little, but not too bad. Once you get the boat on plane, it runs fantastic.

Am I wrong? I would think a 150 on a 17' boat would rip a skiers arms off. This thing is pathetic. I have been able to do slalom starts for 20 years now and this thing cannot get me out of the water on two skis!

What's wrong???

I am thinking potentially a fuel starvation problem or timing advance? The compression was checked last year and was OK, but I will check it again.

 

[tashasdaddy]

Re: What could be wrong?

is it turning up rpms, but no push, or is the engine just bogging, and not taking the load. changing props elimanates spun prop. troubles shoot, compression, spark and fuel delivery.

 

[camoto]

Re: What could be wrong?

is it turning up rpms, but no push, or is the engine just bogging, and not taking the load. changing props elimanates spun prop. troubles shoot, compression, spark and fuel delivery.

it plain old bogs.

Compression was tested last year, I will check again. Seems to be getting plenty of fuel and runs top speed ok. All new plugs and wires too....

 

[j_martin]

Re: What could be wrong?

I don't know what's wrong, but with that combination and a 21" prop, you shouldn't notice that there is a skiier behind you unless he weighs 300 lbs or more.

I pop em out of the lake with a boatload of family and a 24" high five, which bites like it has claws. 150 hp XR4 engine, 18' bass boat. 'bout 150 lbs over label. Mine's a 2.4 vs your 2.0, but what a truckload I haul..... I plan to use a little less prop for skiing, though, because the motor isn't real happy with half throttle and damn near displacement running load.

Back to the problem, I guess a real thorough check up and tune up would be in order, starting with compression, then link 'n sync, then carbs and fuel pump if it still needs attention.

I wouldn't be too concerned about the dying. When you put them all the way down, and tuck them under, you have a combination of carburetors not level and exhaust buried in the lake. It's a wonder it runs at all. I tuck mine to launch, but at the last minute. It'll load up if I try to idle it there very much.

john

 

[camoto]

Re: What could be wrong?

I don't know what's wrong, but with that combination and a 21" prop, you shouldn't notice that there is a skiier behind you unless he weighs 300 lbs or more.

I pop em out of the lake with a boatload of family and a 24" high five, which bites like it has claws. 150 hp XR4 engine, 18' bass boat. 'bout 150 lbs over label. Mine's a 2.4 vs your 2.0, but what a truckload I haul..... I plan to use a little less prop for skiing, though, because the motor isn't real happy with half throttle and damn near displacement running load.

Back to the problem, I guess a real thorough check up and tune up would be in order, starting with compression, then link 'n sync, then carbs and fuel pump if it still needs attention.

I wouldn't be too concerned about the dying. When you put them all the way down, and tuck them under, you have a combination of carburetors not level and exhaust buried in the lake. It's a wonder it runs at all. I tuck mine to launch, but at the last minute. It'll load up if I try to idle it there very much.

john

Awesome reply, thank you. I will take a look at those items and report back!

 

[camoto]

Re: What could be wrong?

I think I may have found the problem, but I am still stuck.

While I was checking the first cylinder, I noticed, no spark. So I checked the others:

#6 - No Spark
#5 - Spark
#4 - No Spark
#3 - No Spark
#2 - Spark
#1 - No Spark

I then noticed that the leads that go to the coils seemed dirty, so I took them off of 5 & 6 and cleaned them. Then, I got spark on #6. So then I go and clean 4 & 3 and no spark still on 4, so I recheck 6... no spark again. So then I move to 4, and I have spark....wtf. Then I check 1 and I have spark. At this point I have the blow torch ready. After cleaning contacts and fiddling with it, this is what I come up with:

#6 - Intermittent Spark but mostly dead
#5 - Consistent Spark
#4 - Intermittent Spark but mostly dead
#3 - Never any Spark
#2 - Consistent Spark
#1 - Intermittent Spark but mostly dead

Does this make any sense? What baffles me even more now is how it runs healthy when revved. Maybe something to do with low voltage somewhere? At the end of this before I almost lost my mind I even charged the battery back up and went back to find the original (at the top) findings. I was using a Ignition Spark Tool and had it gapped very small just to see if any of these were just weak. I don't think I could have got it closer without it being touching.

How does this motor even start?? What should I assume now?

 

[j_martin]

Re: What could be wrong?

I would clean all the connections on the switchboxes and coils. Also look for general condition of the coils, ie cracks in the high tension parts.

If after that, you still have this sort of results, it's time to use a peak voltage meter on the stator wires to the switchboxes. I would suspect a bad low speed coil. I think that's what you'll find.


hope it helps
John

 

[redjmp]

Re: What could be wrong?

Check your coils for cracking under the rubber shroud. I have one that reads under one ohm on the primary and 1000 ohms on the secondary just like it should but the motor never ran right until I changed it out. Upon further inspection I found some cracks in the plastic housing.
Install some clean plugs and check them after 10 minutes or so of cruising.
Are they all hot and showing signs of deposits forming indicating they are firing or are some colder and cleaner than others indicating little or no spark?

 

[Bob_VT]

Re: What could be wrong?

Outboards can "free rev" even while missing half the plugs and spark. It is a common problem that the human ear does not pick up.

You have some electrical issues.

Get a good manual for troubleshooting.

 

[camoto]

Re: What could be wrong?

New info:

Moved the primaries around on the coils and the spark did not move. Looks like I have MULTIPLE bad coils. I rang out the leads but that shouldn't matter seeing as when I move the wire the one that works continues to work and the one that doesn't keeps not working.

A.) how the F does that happen?
2.) why?
III.) could it really be that simple?

I am going to ohm test the coils next. more to follow.

 

[camoto]

Re: What could be wrong?

nevermind.... it's definitely the switchboxes. The symptoms change sides when the boxes are completely switched out.

 

[studlymandingo]

Re: What could be wrong?

While you are working on the switchboxes, check all of the wires going from the switchboxes to the coils, and from the coils to ground. I've had several leads that were bad.​

 

[camoto]

Re: What could be wrong?

will do, I am going to clean all the contacts as some of them looked pretty bad when doing the test switch of the boxes.