Please Help

[fireboy]

I recently bought a used 4tec 155 engine off ebay. The owner knows nothing about the engine. Any how I put it in the ski, I have not installed the drive shaft yet, still waiting for the parts. So I ran the motor to see how it is and it runs irregular. Idles up and down, some times when I push the throttle it idles up to about 2500 rpm and stays their until I shut it off. Its kinda hard to start, takes a few turns to finally get it to run. I changed the spark plugs already and did an oil change. Any ideas on whats up. Thanks

 

[Dennis]

What year is the ski? Is the gauge trying to tell you anything?

DAWG

 

[Bills86e]

Whats the compression>

 

[fireboy]

compression 180 on all three, 2002

 

[voodoo]

Without a untested motor sitting in my shop, I would advise you to search all areas related to fuel/fuel supply, compression, spark/spark control, and read the manual forwards then backwards, you will either find it using knowledge or by accident.

 

[fireboy]

Ive been reading and cant seem to find a place to start, I just ordered the new fuel filter, I pulled the fuel rail to check the spray pattern and it looks to be about right, so I am assuming I am getting good fuel presure, I read some where in the manual that when the throttle body is replaced it can change the way the motor runs if the mpem is not re programed. If I changed out the motor could this be a cause??

 

[fireboy]

is it worth bringing it to the dealer and having them hook it up to the computer, they want 55 bucks to run diagnostics, does the computer most of the time tell whats up with it??