Johnson 87/48hp Fuel question

[Highdog1]

Could anyone please tell me what gas spitting or spurting out the orifice above the carb means? It's the top carb and the more I put the idle lever up the more it spurts gas out the small #36 orifice. I found a small screw with washer and rubber washer laying in the bottom of the motor (not sure this screw has anything to do with this problem or not) but cannot locate it's purpose yet. Please advise, thank you

 

[Highdog1]

No Title

found this screw in motor cover look like it is important? has anyone seen this? or where does it go? the size looks to be 1/8 dia X 1/4 length

 

[Highdog1]

Update on fuel issue. Part of the problem solved! Gas dripping out of the carb was caused by a worn out intake manifold gasket (on the reed valve side). Big fix for $6.49, took out for test drive and the boat will not go full speed it won't get to plain! This started out as a problem with the motor bogging or not going into wot.

 

[Chinewalker]

Start with compression and spark tests. Compression on the far side of 110 psi and spark jumping a 1/2-inch gap.

If it passes those, try a cylinder drop test. Remove one plug wire and run the motor, noting what it does.

 

[Highdog1]

Thx Chinewalker; tried three diff. compression tests hot an cold, flooded, tsp. oil. Past every time. Doing the drop test, Bottom cylinder works fine. Top cyl. seems to be getting too much gas? tried to lean out carb (screwing adj. all the way in) still very wet plug? got a rebuild kit. Doing drop test top cyl. does run by its self? Both cyl. should idle, an run (just one cyl. at a time?) Doing more checking today (possible top cyl. only runs in higher speed )

 

[racerone]

Check the fuel pump diaphragm.

 

[Highdog1]

Thx racerone, I checked the fuel diaphragm and checks out good. I still have this ongoing problem and it's kicking my butt. Compression and spark is really good but took carbs and swapped them out just to see if I had a bad carb and the problem is worse , bottom cylinder now runs like crap as where before it ran really good its been the top cylinder giving me the troubles and not passing the drop test and getting excess of fuel into the cylinder and on the plugs. I took to a mechanic and he tested spark with a timing light and said its good . They don't do leak downs but said it could be an internal exhaust issue going on losing some compression on that end. I don't see exhaust leaking anywhere evident from the motor but possible when it overheated from the water pump going out something got hot or melted internal. Any advise where to check or a good place to begin would be appreciated and does that seem like a likely culprit at this point??

 

[racerone]

Only if spark jumps a gap of 3/8" or better can it be called " good "----So if you have spark and compression it leaves fuel / carburetion and crankcase compression as the items to look into.

 

[Highdog1]

Thx racerone, will do and update when I can get that checked out.

 

[Highdog1]

Hi racerone, the spark is jumping gap with really good blue spark. I got all the way down to the crankshaft and piston rings look really good no problems there, but I have noticed that there is some oily substance down around the bottom seal at crank shaft but the seal looks fairly new. The top o ring looks good too but I also noticed some gas/oil substance coming out under the flywheel and there looks to be like some black carbon build up around the top inside cylinder where the crank shaft and o ring go. Could it be the bearings and is there anyway to tell at this point? And should I just replace them ? There is no other visible damage i can see coming from those bearings . The bottom motor gasket came off when removing and there was one bolt that when I removed had oil spilling out of it the others all were good and dry. I definitely have to replace that gasket but not sure what that is a sign of going on . Any ideas ?? Tnx and need some advice!!

 

[racerone]

It sounds like an issue with the top carburetor.--That gasket should always be replaced when powerhead is off.

 

[Highdog1]

Tnx racerone, I took the bottom carb and put on the top just to see if it made any difference and it ran on top cylinder and passed a drop test while in the drive way on ear muffs but got it in the water and it was same problem, and had the top carb on bottom and it seemed worse on that cylinder. My motor is 87 48 spl so not sure if swapping carbs would work but thought Id give it a try to see. Those carbs have been cleaned and rebuilt so not sure what more to look for on those? Maybe two issues going on cuz it does act flooded on that top cylinder won't staying running but motor just sounds muffled under load in the water. And that top cylinder would stay running but only on high idle as if it wanted more gas so I made an adjustment to the carb and it floods the valve at the primer solenoid, which does click as it should, and if I lean it too much more it won't start at all. That gasket may of had a leak there and causing some problems near the exhaust port is what I was also thinking also.

 

[Highdog1]

I also bypassed that primer solenoid valve and capped those hoses just to see if that could be an issue, and it made no difference. Really stumped and appreciate your help, thanks.

 

[bonz_d]

Check the float, float needle. Sounds like the needle isn't closing.

The top hole is the low speed jet and it has a breather hole in it and this things always drip a little fuel but spitting as I have read is an indication of a faulty carb base gasket.

 

[racerone]

Sounds to me that there is an issue with the top carburetor.----Did you remove the high speed jet that is found --INSIDE THE CARBURETOR BOWL ?-----Many folks over look that jet / orifice plug.----It is screwed in horizontally and found behind the drain plug.

 

[Highdog1]

Tnx bonz_d, I did check the float and needle and seems good after I replaced the reed valve seal it stopped spitting gas at me out of the the barrel and small orifice above it. Still was getting excess of gas into top cylinder.

 

[Highdog1]

Thx again racerone I sure did check the high speed jet in the bowl and when in the water and seems to be working ok. I did find the top crankshaft seal was shot and ordered new seals and that powerhead gasket. Also took that top lead plug out on top carb to check and clean those jets, so going to get it back together and see how it goes. On my old 10hp johnson after putting rebuild kits in them they were good to go . that leak Im sure was causing some major havoc in there but wasn't sure if that would explain the top cylinder wanting more idle throttle to stay running.

 

[Highdog1]

Update thnx , got put back together the seals and gaskets and still same problem. Top cylinder runs and stays running with higher throttle but not in lower or idle throttle. Compression and spark still good but ?? I can start and idle all day long. I can not get it to pass the drop cyl. test, (at less then 900 rpm) Idle speed, The bottom seem to be perfect. the top cyl. drops out. Seems like carb to me. but cant verify?

 

[Highdog1]

Question on heating issue, as i was going through the wiring I seen the previous owner had just cut the wire to the heat sensor in half to disconnect it and doesn't go to the console no hook up there. That top cylinder seemed to be getting hot so I pulled the head again and the top cylinder looked good no excess of fuel, water but the bottom looked like it had water in there. The poppet valve I took out and the spring in there seemed like 10lbs psi and the wrong psi for the motor. Replaced the head gasket tightened put back on and top cylinder doesn't seem too hot but I guess I will need temp gun to know for sure? Is it possible the power pack even with that sensor wire cut know if engine overheats without that sensor hooked to it? I got the carb to keep the top cylinder run in idle throttle and slow pass a drop test but when I get in water (after it seems to heat up ) the top cylinder will not start again very well or pass a drop test, maybe heating issue?? please help! thanks

 

[Highdog1]

Wow this SOB! is kicking my butt! Took the boat to a Super Tec. He did a comp. check, a blow down, looked good? pulled the plug and found water in the head! I pulled the head, got a perfect flat surface, 800 to 1000 emery paper (using a marker to find low spots) sanded for 3 days couldnt get the low spots out! took the head in a had it milled down! installed the head, and another head gasket. Took it for a test drive and found more water in the head can not torque down any tighter ( 265 inches) Arrrrrr guess it got to find a good used head? and see if that does'nt stop water in the head problem???