1989 Johnson 88 running rich at idle

[RoGun_Mako171]

I'm trying to figure out why my engine is running very rich at idle. I'm seeing a lot of oil in the water that is bubbling up from the exhaust when idling on the lake, a considerable amount of smoke, an oil slick around the engine at idle and black sort at the waterline on the stern of my boat at the end of the day. Following the service manual, I have gone through the carbs many times to clean them up and make sure I do not have plugged orifices, put in new floats, float valves and valve seats and adjusted the float setting with the Johnson float setting tool. Have done the tests on the primer solenoid and it checks out ok. Hoses appear to be routed correctly. Still, running very rich at idle.

Looking at the service manual Fuel System Trouble Check Chart for Engine Rich at Idle, I'm thinking it's either the float valve stuck open or the float valve is installed incorrectly. However, when I pump up the primer bulb it gets hard so I'm doubting the float valve being stuck open. What are other tests of the float valve being stuck open? And as for the float valve is installed incorrectly, maybe I'm missing something, but how is that possible when it's just a wire clip that hangs off the float arm? Any other ideas why this is happening? Compression is #1:125psi, #2:115psi, #3:125psi, #4:110psi and spark test looks good on all 4 cylinders. Am I just blowing oil/fuel past the piston ring on #4 and that is ultimately my problem?

 

[boobie]

Sounds like your oil recirt system is not working.

 

[RoGun_Mako171]

Thanks for the feedback Boobie. When I went through the recirculation system servicing earlier this year, I found a bad check valve and replaced it. Also found 2 clogged fittings, which I unclogged. Maybe something is clogged again. I will go through the service procedure again and will replace all of the recirc hoses too.

 

[boobie]

Keep us posted.

 

[RoGun_Mako171]

Will do. I expect to do look at the Recirculation system on Thursday.

Also, there is a lot of black sludge on the gear case in front of the prop and inside the prop too. It's pooling on the ground below the prop, it's unspent 2 stroke oil and not gear oil. It has not been run since I took it out of the lake on Sunday, but a good bit of the sludge has leaking out since parking it. The primer bulb was completely empty too, but does get hard when pumped 3 or 4 times.

 

[havoc_squad]

Have you attempted to see which cylinders are getting too much oil/fuel?

If it is equally bad on all spark plugs, I would guess the VRO is messing up the oil mix ratio with too much oil in the fuel lines.

I can't comment on whether the VRO itself is bad or some part of it that can be fixed/replaced for the oiling part.

You should be able to determine if the carbs are working correctly or not at idle by doing a test lake trial running a premix only test fuel tank with the VRO harness disconnected.

You would want to first purge all the non premix fuel before disabling the VRO temporarily.

Do check that this can be done without issues in the service manual. It may require blocking off the oil line, even for a temporary lake test.

I have a 1990 90hp that I am converting to premix only soon to eliminate the expensive VRO hassle. Mine has a diaphram leak and I researched enough to conclude for me that VRO is not worth the high price it demands for the conveience of not mixing gas and the danger of sudden loss of oil in fuel.

 

[RoGun_Mako171]

I guess I should have mentioned that I do not have a VRO, running pre-mixed fuel.

 

[havoc_squad]

Hmm, I guess that would answer part diagrams referencing 88 model early production and late production fuel pumps.

My thoughts are defective/stuck needle & seat, damaged idle mixture screw, fuel pump diaphram leaking into crankcase, carb unit defective on some non-servicable part.

If you haven't checked to see if fuel is leaking behind the diaphram, I would do so because that can dump gas in the crankcase. For a small leak, at idle would probably be the only time it would act up.

Ethanol in gas eats those diaphrams up like candy, probably why the one in my VRO is leaking.

On a side note, I do know if you haven't replaced the plastic carb bowls with aluminum, that will fail sooner or later by warping. It would leak fuel or suck in air in which would cause a lean condition.

If you do replace the bowls with aluminum, you'll need to order special intermediate jets to fit the new bowl. The old ones in the plastic bowls won 't fit.

 

[oldboat1]

Maybe a bunch of build up from a lot of trolling. Might get a big trash can, and flush with a mix of detergent and water ("rinse and repeat").

 

[RoGun_Mako171]

The fuel recirculation system checked out ok, all 4 check valves pulled air, but I could not push the isopropyl alcohol. And I could push isopropyl alcohol into all 3 fittings. Air travels freely in the hoses too.

In looking at the fuel pump, I did see some a little bit of fuel on the engine side of the diaphragm, but could not find any holes in it. I will be doing a fuel pump rebuild when I get parts next week.

While I had things apart, I decided to put in the old float needle and seats after polishing them up with some flitz. I was surprised to see how much I needed to alter the float adjustments to get them correct and am still scratching my head as to why. The needles and seats appear to be identical and I though I would just be able to replace them without any change to the float, but I was wrong about that. Maybe the new adjustments will help with my problem, will find out more when I take it to the lake on Sunday.

I plan to test it in a tank tomorrow, what kind of detergent would you suggest oldboat1? I'm thinking some power laundry detergent or some liquid dish soap. I really like the idea of cleaning my exhaust out and keeping as much sludge out of the lake as possible, thank you for the suggestion.

 

[RoGun_Mako171]

After doing my test in a barrel, it appears that nothing I have done has helped. There was a lot of smoke while the engine was running. There is lots of sludge in the barrel when done, sludge oozing from the prop and there is gas/oil dripping from the drain hole on the underside of the gear case after running in the barrel for 5-10 minutes. What am I missing?!

 

[RoGun_Mako171]

I am running a 50:1 ratio using 91 octane non-ethanol and Pennzoil Marine XLF 2 cycle oil.

 

[racerone]

Some will argue, but that sludge may be normal for that motor.-----I myself would do further inspection.----Remove the 4 bypass covers.---just 6 screws on each and a cheap gasket.-----Allows you to inspect pistons / rings.

 

[oldboat1]

(Dawn liquid soap. Good for little ducks too, apparently.) I use it around the garage and shop.

Agree with above -- pull off bypass covers and have a look.

Additionally, maybe a PO replaced the top orifice plugs. [Edit. will stand corrected, but think those are air bleeds -- if partially blocked should produce rich running(?) if it would idle at all.]

 

[RoGun_Mako171]

Ok, thanks for the input racerone and oldboat1. I will order some gaskets and remove the bypass covers next week to have a look at the pistons and rings, starting with the piston with the lowest compression.

The top orifices in the carbs appear to be clean, can pass a wire through them and used some carb cleaner earlier this season to remove any varnish.

 

[Fed]

Has someone removed the thermostats and or the relief valves?

 

[RoGun_Mako171]

I changed the thermostats and relief valves earlier this season. The starboard thermostat was stuck open and not allowing the engine to come up to proper temp. The cooling system works great now and the temp gauge registers somewhere in the middle quarter of the gauge once warmed up.

 

[RoGun_Mako171]

I took oalboat1's advice and ran the engine in a barrel with about a 1/4 cup of dish washing liquid (7th generation) for 5-10 minutes. Then did so again, then one more time with no dish washing liquid to rinse. The result amount of sludge in the barrel was considerably improved after the rinse (see photo). This looks like a much more reasonable amount of sludge and perhaps closer to what one would expect? So now I am hopeful that my carb readjustment with the old needle and seat actually did help. I will take it to the lake tomorrow to test it out (and do some fishing) and will post again with the results.

 

[RoGun_Mako171]

My optimism lead to some great fishing, but the amount of fuel in the water problem did not improve. I will be rebuilding the fuel pump and pulling the by pass covers to check the pistons and rings later this week.

 

[matersammich]

I have an '88 88 spl that was doing very much the same thing at idle. It idled very poorly and seemed to be flooding, excessive smoke and oil on the water but ran great at 1/4 throttle on. I rebuilt the primer and seemed to help a little. Rebuilt the carbs and checked the fuel pump with vacuum. Still the same, so I decided to redo the link and sync last Saturday, imagine my surprise when I wouldn't start when I finished. After several hours of careful diagnosing and testing per the manual, I decided it was the power pack. I cleaned the connections, (especially the ground) and tried it one more time. It fired up and ran much better. We went to the lake Sunday and it run MUCH better. I will still order a new power pack just for a spare, but I think my problem was the ground wire connection.