Misfiring engine

[Zook4184]

Hello all I have a 1985 50 hp Johnson This engine when I first started it would run at idle them would stall so I cleaned the carbs found some varnish in the one carb put it back together now it’s running worse it’s poppin spitin and spat in then stalls isle going up and down the fuel ball seems to be going soft after running for a bit tighten all connections any ideas would be appreciated thanks

 

[racerone]

Normal for the bulb to go soft once the carburetors are full and the motor has been started.--------What other trouble shooting have you done ?----Did this problem show up suddenly for you?----How did it run last year ?

 

[oldboat1]

Think I would take off the carbs and clean them again. Because there was some evidence of varnish, disassemble and soak tops and bottoms in solvent (I use lacquer thinner), metal parts leaving linkages in place. Open up all orifices/jets, and take off the domed fitting at the top(s). Finish with carb spray in every opening.

 

[Zook4184]

I have good spark I have good fuel I got this motor after starting up my old motor and found out that motor was no good so my buddy gave me this motor that has been sitting for a couple years I replaced thermostat impeller and when I was able to run it for a little bit it would Run and stall but runs worse now also have good compression top cyl is 105 and bottom 110 So thinking clean carbs I did and now it’s running even worse I did take carbs back off to make sure float was working properly and it was I was able to squirt carb cleaner throughout all hole all fuel lines are clamped properly I’m maybe thinking by not not replacing carb gasket could it be a air leak not sure where to go

 

[oldboat1]

Disassemble and soak, as described. Measure spark with an open air gap tester (auto parts stores).

 

[racerone]

Those compression numbers are very bad !-----Test with another gauge first !

 

[oldboat1]

Auto parts store might loan a compression tester. (That spark tester is about $10 US.)

 

[Zook4184]

Ok will do and get back

 

[racerone]

If those compression numbers are taken with a good gauge I would be taking the head off.----Need to inspect cylinders.

 

[Zook4184]

Ok the searching I was doing trying to find what the compression numbers should be I came up with 120 # are my numbers that bad that this would be my issue Before I messed with carbs it would start rite up idle fine for lessthenaminute and then just slowly idle really low and quit so I was thinking carbs idle jet was clogged I’m going to take off and soak carbs and give another shot thanks for your reply’s all we will get this

 

[racerone]

On my gauge( know to read accurately ) a good motor like that would read 140 PSI.-----Taking the head off a freshwater motor is easy.----New head gasket is cheap.-----Will be good experience for you.

 

[Zook4184]

Ok now I have motor idleing but still is back fireing but when I pull the top spark plug wire engine dies and then when I pull bottom plug wire motor keeps running so I checked continuity on wires are good plugs brand new and gapped correctly and I check the coil packs getting the correct reading I was getting 255 on them the plug that keeps running is black and top plug is pretty clean not sure were to check next

 

[jimmbo]

Can the Spark jump a 7/16" gap?

 

[Zook4184]

Don’t know what you mean by that

 

[juno pierrat]

google - spark tester @ advanced auto, not inline tester