2003 90 johnson hard start

[harleyman1975]

Hey there, I am usually on the Mercruiser page but today I have a new motor to contend with. Mother in laws 2003 90 hp Johnson is hard starting...seems to either be not getting gas or flooding...not sure. serial number of the motor is j90plstc model is 05035006. Motor is new to us so can't really supply any history other than when it DOES run it runs great. It is just getting lucky enough to get it to fire. Previous owner must of been having problems as he said he put a new power pak in it recently sooooo.....Any thoughts? I plan on having a friend that fixes small engines look at the carbs, check compression, check timing, make sure primers are working. Is there something that is a consistent problem with this particular engine.

 

[racerone]

Key must be pushed in while cranking for near instant starts.

 

[harleyman1975]

Yes were doing that. Just wondering if there is a common problem. Thanks for the reply.

 

[sutor623]

Take the small primer hose off the back of one of the carbs [that comes off the primer solenoid(small black do-job that has a red handle on it)] and have someone push the key in. You should see a small shot of gas shoot out. Check that for each carb. If the gas doesn't shoot out, you either have the red handle on the solenoid turned the wrong way or the solenoid is not activating. If the solenoid isn't activating, check for 12V at the solenoid when the key is being pushed in. If you are getting 12V, bad solenoid (could be electrical, or crack in the housing). If you aren't getting 12v, it is either bad wiring or a bad priming switch.

 

[harleyman1975]

Thanks, will check that!

 

[harleyman1975]

Well We have discovered some issues with this motor...and of course it is firing right up while it is at the mechanics place...first off one of the thermostats is bad (one bank is 90 degrees other is 150, swapped stats and now one bank is 150 and other is 120 so 2 new stats on order) 2. Compression test: 3 cylinders are 150 psi and one is 125 psi. Low compression cyl builds up to 125 after cranking it over a few revolutions. 3. Water coming out all over the place (he's looking into that a little closer today) 4. He's also going to look into primer solenoid. 5. He says it is only running on 2 cylinders when it first starts and then the other two kick in after 5-10 seconds.

 

[harleyman1975]

Update: Mechanic cleaned the carbs (said that they were full of debris and some water) dumped out separator and said same about that, hooked up to clean fuel source and says it runs much better and seems to be starting better...also it is running on all 4 right from the git go now. motor still has major water leak between engine and lower unit (gasket blown out in two places) primer solenoid working as it should. Plan is to replace both T-stats and replace blown out gasket, drain and clean fuel tank, replace primer bulb, replace water separator and install a coastguard approved inline fuel filter.

 

[racerone]

The low compression is a concern.---Remove cylinder head to inspect cylinder wall.