2000 90HP Johnson random misfire/cough

[Jcstratt]

I've been watching the forums here and am pretty impressed with the quality of people and information. Kudos to you all!<br /><br />I recently acquired a 2000 Fishmaster Travis Edition with a 2000 90HP Johnson J90PLSSE Outboard. This rig was a gift from my brother.<br /><br />It ran great for the first 2 months that I had it. First problem I had was that the shift linkage came apart under the carb pack/intake silencer and it stuck in forward. Of course, it didn't actually stick in drive until I was at the boat ramp/courtesy dock. I fixewd it without much hassle. Both the retaining pin and end clamp came loose.<br /><br />It ran great again until last weekend. I got it in the water and cranked up. After the warmup period it began to miss randomly until I got it over about 3000rpm. 3000-5000 it ran pretty good.<br /><br />This week I figured out which cylinder was causing the problem by disconnecting one plug lead at a time. It was the port side bottom cylinder (I don't have a book so I don't know what cylinder number that is). It coughs/sneezes pretty hard out the exhaust. I swapped plugs and got no change. I compression tested all four cylinders. The 3 good cylinders were about 130psi and within a few psi of each other. The coughing cylinder was about 75psi. I pulled the head off and found the combustion chamber dish was pretty beat up. The cylinder walls looked great, except by one of the ports (the one towards the middle and bottom of the motor with the little orifice right above it)was missing a chunk from the top of the port (the top means towards the head) almost up to the orifice. The piston was beat on the crown and the part of the piston that aligns with the messed up port is missing a same sized chunk from the crown down to the top ring.<br /><br />I guess it needs a new block, pistons, rings, bearings, and seals. Any other way to repair it? Any idea on the cost?<br /><br />Thanks in advance for your opinions.<br /><br />Jody

 

[Solittle]

Re: 2000 90HP Johnson random misfire/cough

Welcome Jody - You may be able to fix yours. I think you can get that cylinder re-sleeved. If the head is beat up it will have to be replaced. The other cylinders are OK and should not need anything done to them or need new parts. I have no idea on cost but it should be like new when done.<br /><br />If it was caused by a broken ring you need to make sure that they rebuild the carbs and that you are able to pull 55-5800 rpm at WOT when you are finished.

 

[Jcstratt]

Re: 2000 90HP Johnson random misfire/cough

I don't believe there has been any oil related problem recently. It seems to smoke just about right and all the plugs look like they've been burning a good mix.<br /><br />I knew the motor had a cylinder go bad 2 years ago and my brother had it fixed. I talked to him today and got more details. It is the same cylinder. He took it to a mechanic who told him it needed a new powerhead. He took it to a second mechanic who said it could be fixed. It was then bored 1 over and has been good for 2 years. <br /><br />The condition of the cylinder walls tells me the the area broken from the port happened last time it broke, 2 years ago. There's not a scratch in that cylinder now. That tells me the only pieces floating around in there, beating up the piston crown and cylinder head, had to be aluminum from the piston. The piston has a chunk missing all the way down to the top ring, but the ring is intact. I could just put another piston and rings in it, but it will do it again. Maybe in 2 years or maybe in 2 days.<br /><br />Resleeving sounds like a great option compared to a reman powerhead. I will check that out.<br /><br />As for RPM, prior to this incident it was pulling 5200-5300 at WOT with a 13.25x17 SS prop.<br /><br />One last thing. I see motors called loopers, crossflow, ficht, 90 degree, and 60 degree carb.<br />Again, it is a 2000 J90PLSSE and it says "loop charged" on the intake. Specs also say it is V4 60 degree. It has carbs and is not FI. I am assuming that it would fall in the 60 degree carb category as that's the only category I ever find (when looking at powerheads and parts) that matches both the year model and HP of my motor.<br /><br />Again, thanks for your time! I greatly appreciate it.<br /><br />Jody

 

[Jcstratt]

Re: 2000 90HP Johnson random misfire/cough

Ok, so after a little cleaning and careful inspection...It broke a ring, tore off the piston crown from that section of ring, scored the cylinder wall to about .005" or so. I still believe the piece of cylinder wall that is missing was missing from the last time.<br /><br />Oh well....looking for a shop now in the DFW area to get it fixed.

 

[Jcstratt]

Re: 2000 90HP Johnson random misfire/cough

For anyone interested...I had the block resleeved and did the rest myself. Here's how it turned out. The cause of failure turned out to be a rotten job of assembly the last time it was rebuilt.<br /><br />1. When they put it together, they put the pistons in 180* out. This allowed the ring ends and the ring alignment pin to ride in the center of the exhaust port. This let the pin back out and catch the exhaust port. I found the pin stuck in the reed cage. I couldn't determine the brand of the pistons. The only marking, inside or out, was 020 on the crowns. I replaced all 4 because I didn't have a warm fuzzy about the pins backing out. The new ones actually say "Port Exh" and "Stbd Exh" or something like that which matches exactly to the book. <br />2. The rods were also in upside down. <br />3. The main bearing guide pins had been pushed all the way in, but the split case markings on the bearings showed them to have been in the correct position. The bottom main bearing pins was bigger in diameter than the hole in the bearing race. I replaced both pins. <br />4. The fuel manifolds on both intake manifolds are double oringed at each carb inlet. The orings had been installed dry and in doing so 6 of the 8 total orings were mangled beyond belief. I had wondered why the motor was always oily. <br /><br />The carbs were absolutely spotless inside, but I cleaned them out and put all new seals in anyway.<br /><br />The block is now fully assembled and sealed. The carbs, VRO, stator, timing base and etc. will go on tomorrow and the powerhead will be complete. Hopefully I can get it back on the boat this weekend.<br /><br />My brother owned this setup before I did. The problem he had a few years ago was similar to this time. One cylinder had low compression. Same cylinder even. He told me only one cylinder had any scoring. Yet when they rebuilt it, the went .020 over on all 4 cylinders. The only thing that makes sense to me about all this is that the last mechanic had no clue.<br /><br />Wish me luck and here's to hoping I didn't screw it up as royally as the last guy!