1977 1150 wont go over 3500 rpm's

[Time2fish]

I have been fighting this problem for a couple of months now, at first I thought it was a fuel problem, I rebuilt the carbs to spec, 2 days ago I rebuilt the fuel pump with a complete kit including the check valves, replaced all the hoses and primer bulb, and filter, also ran some Seafoam thru it last week. I also linked and synced per the "Clams procedure". The motor runs great but it just will not go over 3500 rpm's barely can get on plane and yesterday I hard time putting the boat on the trailer on a steep ramp, just dont have any top end power, this all seemed to happen at one time a couple months ago, any ideas?
I did time it like the procedure says but I swear it almost sounds like it is not advancing the timing, could it somehow be off a tooth, I looked at the timing belt and it is pretty loose, was going to tighten it up when I saw it but there is no adjustment, maybe it is off?
Thanks for the help fellas, Rob

 

[Chris1956]

Re: 1977 1150 wont go over 3500 rpm's

What kind of prop do you have on it? What kind of boat is it?

You did check and set the max Timing advance to 21*BTDC, right? Do the carbs open nearly all the way, at full throttle (engine off)?


Did you check compression? Did you check the plug wires for arcing to ground?

 

[Time2fish]

Re: 1977 1150 wont go over 3500 rpm's

The boat is a 1978 17 ft Chrysler tri hull, the boat and motor is an original set up, the prop that is on it is an Apollo 13x19 stainless, I have had this prop on the boat for 4 years.
I did check the timing, like I noted, I used Clams procedure and I have done it this way for 5 or 6 years and nothing ever changes, and yea the max timing is at 21 degrees with the engine off, compession checks out about around 110 on all cylinders except #5 is at 120. Carbs do open fully, everything is set to procedure.
This started all at one time, it was not a gradual thing, ran it one week all was fine, next week was like I only had the throttle half open?

 

[Chris1956]

Re: 1977 1150 wont go over 3500 rpm's

OK, It sounds like it is not running on all six. Look at the spark plug wires when running it at idle. See if any are arcing to ground. Ohm them out. Resistance should be near zero ohms, since they are stranded stainless steel.

Now pull the plugs and compare them. If any are fouled or real clean, you likely have lost a cylinder to carb or water intrusion issues.

 

[Time2fish]

Re: 1977 1150 wont go over 3500 rpm's

Ok, so you are thinking I lost a cylinder, would that happen all of a sudden like that and why would it run perfectly fine below 3500 rpms, just curious.
Have you ever heard of these motors jumping time? I may be off on this but I swear thats what it sounds like its doing, maybe not.
I will check the plugs tomorow as I have been fighting truck issues all day....

 

[Chris1956]

Re: 1977 1150 wont go over 3500 rpm's

They only sound and feel like they are running on all six. Water intrusion can happen very suddenly, when a piece of the water jacket cover corrodes thru....

 

[hemijosh426]

Re: 1977 1150 wont go over 3500 rpm's

Got same problem. Im subscribed

 

[Time2fish]

Re: 1977 1150 wont go over 3500 rpm's

So what do you think Chris, is my motor toast? I am not sure if it is that I want to do a rebuild if its even possibel,Thanks

 

[Chris1956]

Re: 1977 1150 wont go over 3500 rpm's

Take a look at the sparkplugs. If any are real clean, it indicates water intrusion. If any are real dirty, it indicates ign or carb issues. Compare them to each other, or post picture for us.

 

[Time2fish]

Re: 1977 1150 wont go over 3500 rpm's

I will have to look at it tomorow and see what the plugs look like, do you think I would have lower compression on that cylinder? the numbers I gave you before were a few months old I think, maybe before I started having this problem,
Thanks

 

[Chris1956]

Re: 1977 1150 wont go over 3500 rpm's

Water intrusion doesn't affect compression in many cases(depending on how bad it is). It does put out the fire on that (or those) cylinders.

 

[asm_]

Re: 1977 1150 wont go over 3500 rpm's

Have you ever heard of these motors jumping time?

It never cease to amaze me the terminology people use to describe motor problem on this board. I guess that just goes to show we all come from different background.

To answer that, the only motor that can jump time is the wrap drive, but only in the event of severe ionic interference which cause disruption in time/space...

Alright, all joke aside. Besides checking compression, you may want to get a DVA adapter to check your high speed coil stator output. If I'm not mistaken, your motor does have two set of coils to power ignition. One for high speed and the other one for low speed. High speed should take over around 3000RPM. Now. If the one of the high speed coils is shorted, you may experience the problem you are seeing.

B

 

[Time2fish]

Re: 1977 1150 wont go over 3500 rpm's

I guess I should clarified myself a little better, is it possible for the timing belt (the one that goes from the crank and then around the distributer gear) to lets just say skip a tooth on the gear, the belt is in fact loose and I have never seen a way to tighten it any at all.
This motor only has one coil and it directly feeds the center of the distributer cap, just like the older cars.
I have not had time to remove the plugs today but will do it tomorow for sure and I do understand what your saying now Chris, I was assuming when you said I lost a cylinder it was broken rings or hole purnt in piston, etc.
Thanks

 

[asm_]

Re: 1977 1150 wont go over 3500 rpm's

There is no way to adjust tension on those belt. Since only two pulleys are involved, (vs the often multiple pulley on car motor) it's not likely that belt would skip. That's of course, assuming the belt isn't so old that it's stretched. In any case, a timing light can easily confirm your timing.

B

 

[Chris1956]

Re: 1977 1150 wont go over 3500 rpm's

A lot of those distributor ign motors, have the condition where the best you can do is to have the dist. pulley 1/2 tooth off of time. Mercury recommends you set it 1/2 tooth retarded, if I remember correctly.

 

[Time2fish]

Re: 1977 1150 wont go over 3500 rpm's

Sorry I have been away from my post for some time, I had to have a surgery right after I started this and just now getting back to the point of working on it again.
I do in fact have water intrusion in cylinders 3 and 4, question is this, do I have to pull the powerhead off to fix it, I am pretty sure I do but I have never been inside of a two stroke outboard before, I have rebuilt some 4 stroke stuff but that is really irrelevent here.
I have not found a rebuild book (Clymer) yet so I am still at that point.
I guess another question would be this, is it even worth rebuilding it, the motor has about 1080 hrs on it, and also how difficult would it be to fix my water problem, I was thinking it would be more of a gasket issue not really rebuilding the whole motor.
Thanks a bunch fellas,
Rob

 

[jerryjerry05]

Re: 1977 1150 wont go over 3500 rpm's

You won't hurt anything by taking it apart.Get a manual(sometimes at the library)and get busy.Take pics and post them after you get into it.J

 

[Chris1956]

Re: 1977 1150 wont go over 3500 rpm's

Water intrusion in those cylinders is most likely bad gaskets on the exhaust covers or baffle. It could be that the baffle or inner cover has corroded thru, however. Whereas it is possile to rmove the exhaust cover w/o pulling the powerhead, it is not the best way to work. If you break a bolt, which is likely, you will very likely need to pull the powerhead at that time to fix it.

Drop the gearcase first. Pull the powerhead.... Do the repair. Reinstall the powerhead and then the gearcase .... Trust me on this one...