lean sneeze 83 175hp johnson

[bleedblue94]

EDIT:
after cleaning the carbs and replacing both fuel pumps and upgrading all lines the motor still has a miss, but it does not seem to sneeze the way it use to. i think it may be more of an ignition miss. one reason im leaning this way is the motor does not level out when the choke/fuel solenoid is used, instead it dies out. if the condition that is causing my issue were a lean condition, i would suspect that using the choke/fuel solenoid would help the condition. bc it drowns the motor out i am leaning towards a timing or ignition issue. any help would be appreciated.







1983 175hp johnson. Runs very well but at idle it misses and occasionally cuts out. at WOT it runs well and pushes the boat at 40mph. at times i do think i hear a very sporadic miss in the mid range, but im not sure if its just my ears playing tricks on me

J175txctd

Thanks

 

[schematic]

Re: lean sneeze 83 175hp johnson

no needle adjustment, only jet sizes. Try cleaning the carbs and verify float levels first. Could also be crankcase leak or intake manifold gaskets, carboned up or even too advanced timing....wouldn't hurt to check your fuel quality either.....

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

Thank you. That explains why I couldn't find it. Fuel is new and fresh. Sneeze goes away after running at wot for awhile. I plan to take the carbs apart anyway to clean so hopefully that will take care of it. Never know what someone did to a motor.

I did notice some oil inside the motor under the cowl. Its very dirty. Not sure if this is spillage from up tilting for storage and fuel spilling out of the carbs.

I would like to test the strength of the spark and I'm wondering if anyone knows where I can get a not so expensive tester that can handle the standard 7/16ths test

 

[emdsapmgr]

Re: lean sneeze 83 175hp johnson

As schematic noted, no idle screws-only fixed jets. A lean sneeze is usually related to a fuel restriction in the very small/ dedicated idle passages in the carbs. At idle, all the fuel to run the engine goes through these passages. If they get restricted at all, you'll get a lean sneeze. Once you crack the throttle just a little the engine will draw fuel from other jets and usually run ok through the rest of the rpm range. You'll need to pull the carbs down to clean them, esp pull all the jets out and visually inspect them. The idle is set by adjusting the idle timing. There is a large screw on the spark advance lever. Turning it clockwise will increase idle timing and hence the idle rpm's. You'll want to set the idle timing when the boat is floating normally in the lake and is in forward gear. Set to 650-750 rpm's. You can't set it on the trailer.

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

thanks guys. ive pulled the carbs off and done a pretty thorough cleaning. im probably going to reassemble everything tomorrow. i also tested my recirculation check valves and 3 of them were not working anymore. i just received 6 replacements. plan to change those all out as well as all the hoses under the cowl to be sure they are updated to handle ethanol. i took one valve apart and it appears the rubber inside the check valves deteriorated from ethanol and that was the cause of the failure. could those check valves not working contribute to any sneezing issues, or a very intermittent bog when coming out of the hole?

also just curious if you guys would recommend pulling the manifold off and inspecting the reeds while i have the carbs off? ive dealt with carburetors several times, but never reeds on an outboard. just looking for a suggestion on that. motor does run very well. im just debating inspecting the reeds now as a precaution versus just putting the carbs back on and seeing if any issues are gone

 

[emdsapmgr]

Re: lean sneeze 83 175hp johnson

Doubt the sneezing is related to the check valves. Usually the reed valves need inspection if you get any fuel spitting back out the throat of the carbs when the engine is running. If you have had the airbox cover off and that is not a problem, I doubt you need inspect the reeds.

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

Thanks. I just want clarification on one thing. In searching around for information on the recirc system I have found ALLOT of conflicting information about the flow direction. Some saying excessfuel stored behind the reeds is sucked into the crankcase, and others saying excess fuel from the crankcase is sucked back into the manifold to be burnt. Maybe different year/designs of motors function differently w regards to this system, but I want to know if anyone knows for sure how they should function on this particular motor. Again: 1983 175 sea horse; J175txctd

Thanks

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

Well I reassembled the motor and ran it for 6 hours yesterday. Its basically acting the same. I completely disassembled and cleaned all three carbs, changed all fuel lines and both fuel pumps. There are no leaks anywhere. My motor still will cut out at idle and I can hear a miss sometimes at midrange. I'm begining to wonder if its an ignition issue.

 

[Sgtfda]

Re: lean sneeze 83 175hp johnson

I had all kinds of issues with my 86 110hp. Stalling, racing full throttle. Hard starting. Had a local boat shop check it out. Everything was out of adjustment. Running like new now and only cost $120. Sometimes you can spend a lot more trying this part and that.

 

[emdsapmgr]

Re: lean sneeze 83 175hp johnson

If the engine has a weak ignition component, it will tend to show up once the engine heats up to normal operating temps. May run ok when it is cold. You can check for spark while the engine is running-use an inductive timing light. The flashes in the gun will show the quality of spark on each spark plug wire. The ignition system works hardest when it is in gear. Best to check for spark when the engine is under load.

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

Thanks. At wot there is really no issue at all. The issue is only at idle or just above idle.

I don't know if I'm over simplifying this: When its missing if I push in the choke/fuel primer solenoid the motor will just drown and die. This is making me believe it is ignition related and not a lean condition bc if it were a lean condition wouldn't the additional fuel from pushing in the choke/fuel soleniod help the motor rather than make it cut out?

Again maybe I'm over simplifying it

 

[emdsapmgr]

Re: lean sneeze 83 175hp johnson

It is normal to flood out the engine when it is warmed up, running and then choked. If it was lean, it would pick up rpm's. A good sign. Always possible you have a spark plug wire periodically going to ground. Try running it at night outside the garage- in the dark. Look for spark jumping to ground.

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

Thanks for the help. I might have to use a tarp during the day bc the neighborhood I live in people would have heartatttacks w an engine running at night. I just bought a spark gap tester that ill have to use tomorrow. I fear I will have the same issue w seeing spark during the day but ill give her a go

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

well yesterday i removed the boots from all the plug wires and found almost all 12 wire ends were covered in rust. i know they need to be replaced and have already ordered new ones, but i did sand all the rust off them to see if it would help the issue. when i put the motor back it seemed to miss more often but did not cut out.

i think this is an ignition miss and i have one or two cylinders playing around with me with an isolated miss

im thinking tomorrow i will run the motor and rotate disconnecting one cylinder at a time and see if the miss disappears. atleast if i can isolate it in this way i will have an idea where the issue is. i think most likely its a damaged plug wire or a shorting coil

 

[bleedblue94]

Re: lean sneeze 83 175hp johnson

well i think the issue is fixed. i tested the ignition system and most all of it checked out. i have already ordered new wires, and i may swap out the coils this winter since some of the resistance numbers were dipping just below the ranges set in the shop manual, but as the issue continued i looked at the synchronization linkage for the carbs and it just did not look right.

when i removed the carbs to clean them i noticed they did look as if they had been cleaned recently, and sure enough the previous owner had probably removed the carbs for cleaning, but when hey reassembled the synchronization linkage he installed it wrong. he mounted it onto the main plate that is directly attached to the throttle butterfly shaft, and not to the adjustable plates. the bar was actually mounted on the outer side of the plates and not the inner side, so all the carbs must have been out of sync. i overlooked this when i rebuilt the carbs myself bc i was so anxious to see if the rebuild fixed the problem. i only realized this was the problem when i took the synchronization bar off and started the motor. it just purrrrrred. it is a pain to synchronize them with the screws to tighten the plates together, but thankfully this looks to be figured out. i should have it at the lake next weekend if not sooner so i will know for sure then.

Sgtfda looks to be correct!!