J90TSLECM 1998 90hp Johnson outboard Runs for 5 minutes then stops instantly Help!

[J90TSLECM]

I purchased a 1998 90hp Johnson outboard and I can get it started but it will run for only 5 minutes. After the 5 minutes+/- are up the engine stops immediately as seen at the end of this video. Compression is good. Carb is clean. Fueloil 50:1mix new/fuel filter new/Fuel line/primer bulb and fuel tank is new. The fuel pump looks clean but not 100% sure it is pumping fuel. I think it is a wiring problem or based on what i have read online..it could be bad igniton coils when it heats up they fail? This doesn't make 100% sense to me because ok maybe 1 fails..it should still run on the other 3 right? Any ideas on what this problem could be? Also should the manual primer valve be closed while running? Help! any ideas?


See my youtube video of the engine dying. Thanks: http://www.youtube.com/watch?v=cToPj3ZYi54&feature=youtu.be

 

[Solittle]

Re: J90TSLECM 1998 90hp Johnson outboard Runs for 5 minutes then stops instantly Hel

The audio on the video does not sound like you are running on all four. What troubleshooting have you done? The conditions you describe in your post are to vague to have much value - for example "compression is good" or"fuel pump looks clean"

Have you verified the condition of the spark? Is spark getting to all four? What do the plugs look like when it quits? And the manual primer should be open when running. Its role is to get a richer mixture into the cylinders.

The key here is troubleshooting - find out what works and that will lead you to what doesn't.

 

[J90TSLECM]

Re: J90TSLECM 1998 90hp Johnson outboard Runs for 5 minutes then stops instantly Hel

Thanks! Well the only definite test I have done is a compression test with the gauges..i am getting 110 on all cylinders. The spark test..i didn't even bother because I thought if it is running then I am getting spark..but you have a point..test it to be 100% sure. How do I do a spark test without accidently starting the motor or shooting fuel out of the cylinder? ..also how would I go about testing the fuel pump?

Thanks again!

 

[J90TSLECM]

Re: J90TSLECM 1998 90hp Johnson outboard Runs for 5 minutes then stops instantly Hel

Thanks! Well the only definite test I have done is a compression test with the gauges..i am getting 110 on all cylinders. The spark test..i didn't even bother because I thought if it is running then I am getting spark..but you have a point..test it to be 100% sure. How do I do a spark test without accidently starting the motor or shooting fuel out of the cylinder? ..also how would I go about testing the fuel pump?

Thanks again!

Also, The plugs are wet with clean fuel after the engine dies. (does that mean the fuel pump is working?)

I was running the engine with the manual primer closed because otherwise it shoots gas into the carb and starts dripping. Would that affect this?