1991 90HP Force problem updated motor is shot & rebuild started

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

While waiting for an answer on the above question I have been working on cleaning up the carbs. I just noticed that the carbs have different main jet screws. The upper and bottom carbs have a .076 main jet screw and the middle carb is a .074 main jet screw. Is this normal?

 

[Frank Acampora]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

They started making changes around 1991. It is possible that the center carb could have a different sized jet.

As far as the spaghetti seal: Was it a factory manual calling for it? If there is no groove for the seal to sit in, then the flanges will not seat together tight. Unless you are absolutely certain that it belongs in there, double check now before mounting the block.

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Thanks Frank.

Yes, it is the service manual but the picture shows a groove so, I guess I'll crack it back open and take it out. In addition, It didn't have one when I took it apart.

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

I don't know why I was stressing over cracking it back open... the sealant hadn't set up so, everything came apart easy. I had it taken apart and cleaned up in about 30 minutes.

The carbs are all reassembled and I'll have the crank case sealed back up tomorrow morning.

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Sealed the case and mounted the block this morning. I need to bolt on the carbs and electrical tonight or tomorrow. In addition, I have the lower unit off so, need to throw it back on.

I should be running with a day or two. Anything else I need to do prior to firing her off? I know to break in the motor I need to run double oil ratio and not run at WOT but anything else? Should I even run it on dog ears or just go to the lake?

Also, I have the split drive shaft and am having a hard time remembering how things are oriented putting everything back together. Part of the problem is things kind of came disassembled when I removed it.

The splined shaft coming out of the water pump housing has a rubber seal washer that slides on top of it is there anything that holds that in place.

Than the top of the drive shaft that enters the motor has a metal ring and a rubber boot how is that oriented? Like this? Does the boot just butt up to the motor or does it slide into the bottom of the motor?

Also, on the cooling tube is there anything that goes on the tube as it slides into the water pump housing?

 

[Frank Acampora]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

The white plastic collar that sets into the pump outlet is still on the water tube. It would be easier to remount the lower unit if you remove it from the tube and put it back into the pump, because the top is tapered. BUT, it is not necessary to do so.

The groove in the metal ring faces up, and the flat end of the rubber boot fits into it. The tapered end of the rubber collar sits up as you have it, and it just butts against the crankshaft end, "sealing" out moisture. Coat the splines with a light film of anti-seize before shoving them up into the crank.

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Alright, the electrical and carbs have bolted back on. Lower unit will go back on tonight or early tomorrow. That means I'll be firing this thing off (with fingers crossed) tomorrow. Frank, you have anymore advice prior to turning the key over?

 

[ezez]

Thanks Frank!!! Rebuild complete!

Thanks Frank!!! Rebuild complete!

Well, the boat hit the lake today










I ran it for 2 hours without a hiccup. Thanks for all the help folks (especially Frank). I know I have a few more hours to go until I am out of the woods but I feel pretty confident that she is going to run like a top!

I adjusted the carbs idle mixture 7/8 out prior to going and didn't touch those when I was out running it. I figure I would dial those in after I am done breaking in the powerhead and running a rich gasoline mixture.

Thanks again!!!

BTW Frank check your PMs I have requested some info. from you

 

[ezez]

Re: Thanks Frank!!! Rebuild complete!

Re: Thanks Frank!!! Rebuild complete!

Welp...2 more hours on the lake this evening and she is still purring like a kitty. In addition, that miss at high RPM that started this whole fiasco has vanished. So, it must have either been fuel system causing it (I cleaned/adjusted the carbs, and replaced all the fuel lines, bulb, filter and added another inline filter pre-carb) or the weak top cylinder.

Now that I have 4 hours on this bad boy I may see what the compression readings are. I am also going to add a tach.

Frank you are ignoring me. Please respond to my PM from the other day. You have been of great assistance and I want to be able to show you a little appreciation.

BTW for the actual powerhead rebuild it cost me about $500. That included 3 new pistons, 1 rebored cylinder, 2 honed cylinders, gaskets, and misc other stuff. If I would have need the other 2 cylinders rebored it would have been $50 more per hole.

 

[ezez]

Re: Thanks Frank!!! Rebuild complete!

Re: Thanks Frank!!! Rebuild complete!

I checked compression this morning on the rebuild. Mind you it only has 4 hours of run time and I did the compression check COLD all the reading dialed in at 125-130. Obviously, those numbers will be better with a little more run time and if they were taken when the engine was hot.

 

[Jack Daniels]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Nice work, on the rebuild. Your gunna be a pro before you know it.

 

[ezez]

Frank!!!

Frank!!!

Nice work, on the rebuild. Your gunna be a pro before you know it.

LOL I'm not so sure about that. With that it appears that any fool (<---me) can work on these things.

Hey FRANK

please respond to my PM.

When this whole thing started I bought a complete motor from the mid leg up minus electronics for a couple bucks. It ate a ring in one cylinder and he decided to repower rather than rebuild. That same guy has the matching lower unit. I might pick it up to have a spare laying around. He wants a couple hundred bucks seems like it might be cheap insurance. Whadya think?

 

[Frank Acampora]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Couple of hundred is not too bad if it is in good condition. Then, why not rebuild the whole engine in your leisure? It is almost as easy to change an engine as a lower unit.

AND, since you don't NEED it, you can go whole hog, porting it boring out 030. and playing with other mods.

Don't see a PM. Try again.

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

I think I am going to go snag that lower unit. I really think it is cheap insurance and I may get a wild hair and do a fresh rebuild for another motor like Frank suggested. (too many projects)

Anyhow ran the rebuild for another 2 hours today, so, it now has six hours on it. Runs like a top. With that I have run it for very short spurts at WOT and I do get a rattling noise. If I back off even a smidge it disappears but at WOT it is present and I have read that might be an issue. I did set the timing advance to 28 degrees static when I rebuilt. In addition, the timing and carbs are synced.

Any thoughts?

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

I went and bought that lower unit yesterday afternoon. I ended up giving $150 for it which seems like a pretty good deal (cheap insurance).

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Well, I figured I would give this one last bump before letting it fall off into internet cyberspace.

I am now through the 10 hour "break-in" period and all is going well. The outboard runs great. Again if I can complete a rebuild on one of these blown motors than almost anyone can.

A special thanks to Frank for all his help.

 

[foxtrotboss]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Hey what happened to the noise at WOT? I getting ready to do a rebuild of a four cylinder force 125.

 

[ezez]

Re: 1991 90HP Force problem updated motor is shot & rebuild started

Hey what happened to the noise at WOT? I getting ready to do a rebuild of a four cylinder force 125.

Following the advice here, after the rebuild I initially had the carbs set at 7/8 out. I really was trying to avoid touching them until after the "break-in" period and running double oil/gas mix. However, since the motor was running a little lean at WOT (rattling noise) I adjusted them out to 1-1/8 and it than ran too rich. I than adjusted all of them 1 turn out and hit the sweet spot. At WOT the rattling noise is gone and it jumps out of the hole like it is supposed to. HTH

BTW I did adjust the timing advance during the rebuild to 28 degrees static. I did confirm the timing when I began hearing the "rattling" noise to ensure the timing was correct.