2000 Johnson 115 carb question

[filmtech]

Hey all!!! I recently rebuilt the carbs on my 2000 Johnson 115 V4. I was having issues where it would be hard to start, run fine all day once started, then stall out when putting it on the trailer. I noticed that some of the cups were warped and one had a little leakage, so I pulled the carb bodies (not the throttle body), replaced all the gaskets and cups, new floats and needles, cleaned everything I could think of then put back together. I also pulled the needle valves, cleaned and returned to the original settings (5.75 turns, 6 turns, 7.5 turns, 6.5 turns). Got everything back together and it started right up after I got gas back into it. Runs a lot better than before and idles great at about 1000rpm. I was spraying some carb cleaner in the intakes and noticed that spraying into 3&4 on the port side did not have as much of a stalling effect as on 1&2. I covered carb 3 and the engine bogged down, but didnt die. I covered 4 and the engine barely reacted at all. If I cover 1 or 2, it dies right away. I can feel suction on both 3&4, 4 is quite a bit less, and after I cover the carb I take I can see gas misting inside. Before I did the carb rebuild, I had the marina do a spark test, compression test, and put it on the dyno to see if there was any issue there. Everything came back perfect. What could cause 3&4 to act like this? Thanks! Matt

2000 Johnson Ocean Pro - j115vxsss
14.8x17R aluminum BRP prop
34mph at 5400rpm WOT trimmed up
1999 HydraSport Bay Sport 20

 

[Faztbullet]

You need to check compression on that bank(port). Also port side is 2&4 and starboard is 1&3.

 

[filmtech]

The compression test we did 2 weeks ago came back at 120-125 on all ports after being on the dyno, so hot. That's what's throwing me off.

 

[racerone]

Could be a problem with crankcase compression on # 4

 

[filmtech]

I'll redo a compression test today, both hot and cold and post the results.

 

[filmtech]

Redid the compression test just now. Loaner compression tool from Autozone. I know, I know, but it was free. Cold and warm, WOT.

1:cold-100 hot-90
2:cold-85 hot-90
3:cold-105 hot-90
4:cold-90 hot-90

I thought the marina had much higher numbers, but I cant find the paperwork. I'll see if they have a copy.

 

[Chris1956]

in addition, if your carbs have warped bowls, they should be replaced, as they will leak.

 

[filmtech]

I replaced all the bowls when I changed the gaskets. I just put it in the water and it idles great at about 850rpm, but when I throttle up it won't go above 3000rpm. I can get it to rev higher in neutral. After taking the cowl and air silencer off out on the lake, it looks like one of the small vacuum tubes right under the top, starboard carb got pinched between the bowl and the block. Had the whole family with me, so I didnt have much time to troubleshoot. Toddlers have no patience!! Put the CC back on the trailer and took the kids out on the other boat. Tomorrow, I'll take to top carb off, fix/replace the crushed line, and see if it works better. Could that be why I wasnt seeing as much suction on that side? Picture attached shows the tube that was pinched

 

[Chris1956]

Gee, I see a fuel line nipple in the picture. Shouldn't that have the fuel line connected to it? It looks to provide fuel for the port side of the motor.

 

[filmtech]

Lol! Yes, I took that off to pull the carbs. It was definitely back on when I ran it. I was pointing to the intake manifold primer line behind it. Took the top carb off and got the line unstuck this morning. Put it on the muffs and it seemed to run great. Got it out to the lake and I can rev it in neutral all the way up, but once I put it in gear, I can't seem to get it above 2750ish rpm.

 

[filmtech]

I was able to limp around the corner to a marina that has worked on my other boat in the past. The mechanic says it looks like I have 2 issues. First, it seems like the ignition power pack is hot and looks like it may not be consistently firing on cylinder 4. We can pull the plug for that cylinder and the motor doesnt skip a beat, while it dies if we pull any other plugs. We swapped plugs and the problem didnt move, so the plugs are good (less than 2 months old).He also said that something is wrong with the suction on cylinder 4. He can cover the mouth of the carb and it doesnt stall or slow down. After he moves hi hand, there is a little puddle of fuel oil in the throat. He said that covering the carb should make it draw harder and suck that fuel in. He suggested I start checking that before I did anything with the ignition. Any idea why the compression would be great, but I'm not seeing suction like I should?

 

[racerone]

Issue with crankcase compression as already suggested.------Bottom crank seal or crankshaft sealing rings !

 

[filmtech]

Ok. Is there a way to check that as DIY'er is is that something I need to take in? I've haven't done much besides pull/clean the carbs and throttle bodies before. Is this a much bigger job?

 

[Faztbullet]

A loose reed block can cause this along with leaking manifold gasket. If it has the black manifold gasket there was a TSB to change them to tan one...

 

[filmtech]

I pulled the throttle body off last night and it had a tan gasket on the manifold, but had a few rough spots. I'm going to replace that today and see if it helps. If not, I'll start planning to replace the lower crankshaft seal. My neighbor has a hoist I can use to lift the powerhead. I'll update as I do more. Thank you everyone!!!