johnson 150 wont stay running

[1976CV16]

I have a 1987 v6 150 with the vro bypassed. I start it up and it will run, and putt putt until it dies. I want to say its a fuel problem since i spray fuel into the carbs and it will kick over however its not consistant. One time i spray it starts another time it does nothing. Ive got fresh mixed gas, new hoses, new primer bulb and im pretty sure all the lines and clamps are tight. Could i have hooked up the fuel/vro pump incorrectly? What else could i try? Please help me out, i promised the kids we would be ready by the 4th!

 

[emdsapmgr]

The engine may not be firing on all 4 cylinders. Check each plugwire for spark when cranking. An easy test.

 

[1976CV16]

Thanks for the tip. I have a decent spark on all cylinders. Im going to try and clean the carbs and replace the plugs. Will update soon...

 

[emdsapmgr]

Is this a choke issue, or will it run long enough for the engine to warm up fully before it quits? The engine is a bear to start if the choke solenoid is not working properly.

 

[Will Bark]

On my same engine I pump the bulb up hard and then depress the key switch in for a count of 5 and then hit the starter still holding the switch in; let off the key when it starts and the push in as need until it warms up. May or may not be the same with your engine. Good luck

 

[archcycle]

if it's running correctly it's not likely that you hooked the fuel pump up 'wrong' unless one of the connections you made isn't good. When was the last time it ran right?

 

[1976CV16]

Ok heres what i got. New plugs, new wires, i cleaned the carbs with carb clean the best i could without taking them off. The motor now starts rough and dies at full warm up throttle. However in low idle it starts and runs still rough but a bit more tame and dies after a few seconds. Because of the rough running i think one or more of the cylinders are dead. Im going to recheck to make sure i get a spark, could a weak spark cause trouble? I have spare power packs from a v4 crossflow i can swap, i know those work.

 

[emdsapmgr]

The only way to clean carbs is to remove them and pull them all apart. Clean all the passages with a carb cleaner. Pull all the jets out to visually inspect them. Reassemble with new carb kits, including new floats and needle and seats. Carb problems generally stem from residual dried fuel (gelatin) clogging the passages or jets. In the places you can't see.

 

[1976CV16]

Ok thank you for the info. So a carb problem would allow it to start although not let it run? Ill take them into the shop in the morning. Carbs are a bit out of my abilities. Thanks again. I will update when i get the carbs cleaned.

 

[1976CV16]

Im not sure if its relevant but i read a how to for decarbing a 2stroke. I did so with spray seafoam and although the motors not running, i have a nice big black gooey puddle under the motor. Im assuming its all the carbon build up dripping out of the exhaust.

 

[Bosunsmate]

Use a spark tester to verify your sparks are strong, then you can do other tests.
Cleaning carbs is easy. Just take them off one by one, take photos if you want so you are sure how to connect them back up.
Then just undo each screw you can see on the carb and blow carb cleaner down every hole and check it comes out of another hole in proper amounts. It the little ones that cause a lot of the problem.
Once thats done then reinstall it and do the next carb.
You should really order the gaskets between carb and manifold, they are cheap.
Does your primer bulb hold firm with engine off?
Yes that black puddle is all the carbon, itl decarb the pistons but it wont unclog any carb passage which is gummed up

 

[emdsapmgr]

Decarbing cleans the cylinder combustion surfaces. Carb cleaning is a different process.

 

[1976CV16]

emdsapmgr, the choke solenoid works ok, it clicks and spits fuel into the carbs. However when the red lever is in manual mode it leaks by the lever. Yes the primer bulb stays firm. I know i could figure this out trial and error however i want it done fast which is why i will take it in. I will test for spark again. If there is no spark would that indicate a bad power pack? If its that simple i can do that in a jiff. Thanks for all the help folks. I will update when i do the spark test. I hear i can have my wife hold the sp wires while i crank it...

 

[1976CV16]

I was hoping a little carb clean, seafoam and fresh plugs and wires would get it going.

 

[Bosunsmate]

emdsapmgr, the choke solenoid works ok, it clicks and spits fuel into the carbs. However when the red lever is in manual mode it leaks by the lever. Yes the primer bulb stays firm. I know i could figure this out trial and error however i want it done fast which is why i will take it in. I will test for spark again. If there is no spark would that indicate a bad power pack? If its that simple i can do that in a jiff. Thanks for all the help folks. I will update when i do the spark test. I hear i can have my wife hold the sp wires while i crank it...

Yes, depends what you think of your wife to whether id recommend that.
Hard to know if itd be powerpack. Depends what spark does, such as are they weak, is it only sparking on certain cylinders etc
You want to check they can jump a 7/16 gap consistently

 

[emdsapmgr]

The primer bulb should stay firm when you first pump it up the first time you start it each day. Once the engine runs and draws fuel through the bulb, it will get softer. But it should not collapse on itself. If it stays hard, likely there is a fuel restriction-perhaps bad ball valves in the hose bulb. That can result in a fuel restriction.

 

[1976CV16]

Ok, i spark tested again and have one dead cylinder. I replaced the power pack, each cylinder has its own and now i have a blueish white spark on all 6 cylinders. I did another compression test and have between 89-92 pounds all the way across. So now it must be a fuel issue. Off to clean the carbs.

 

[1976CV16]

I think i meant coil pack, not power pack. Anywho, the shop wanted 600ish to rebuild the 3 carbs and they are backed up 3 weeks. So i bought 3 carb kits and will attempt this myself. Thank you for all the help. I really appreciate it. Ill update when i get the carbs done.

 

[1976CV16]

Emd, the bulb is new as are the lines. It stays firm although it doesnt run more than a few seconds. Thank you.

 

[1976CV16]

Thank you for all the great tips and ideas. Fresh clean rebuilt carbs, new plugs and wires and i still cant get the damn thing to run. Sadly i gave up and took the motor off and hung a spare 85hp evinrude i have in the garage. It runs great, lacks power but gets me around. Thanks again folks