Loose Spark Plugs cause high idle?

[herefishyfishy]

I was warming up my motor this morning for a compression check and after about 3 mins of running it started to rev up really high so I shut it off. I waited a few mins and started it back up and it did it again. I decided to go ahead and check the compression and found 2 of the spark plugs were really loose. Would this cause the engine to act this way?<br /><br />Also, does anyone know the difference in the 3 model #'s for a 1978 115HP Evinrude? Someone painted over the tag and then it looks like the paint was scraped off, but part of the # was faded and/or scraped off with it. Is there any other way to figure out the model of this motor?

 

[JB]

Re: Loose Spark Plugs cause high idle?

Did you open the fuel tank vent, HFF?<br /><br />It is acting like it is running out of fuel.

 

[DHPMARINE]

Re: Loose Spark Plugs cause high idle?

What happened when you tightened the two plugs and ran it again ?<br /><br />DHP

 

[herefishyfishy]

Re: Loose Spark Plugs cause high idle?

I'm sure the tank was vented because I bought the gas today and by the time I had it home gas was coming out of the fitting because of the pressure. I loosened the cap and heard the pressure release and left it cracked so it could breathe.<br /><br />After I did the compression test I started her back up with the tightened plugs and it idled on the muffs for 10 mins without ever idling up like before.

 

[OBJ]

Re: Loose Spark Plugs cause high idle?

Where the plugs lose enough to suck in air? Be the same as leaning out the mixture.

 

[herefishyfishy]

Re: Loose Spark Plugs cause high idle?

I'm pretty sure they were loose enough to let air in. I noticed them because there was oil/fuel coming out of the plug holes and running down the block. I could turn them 1/4 to 1/2 turn by hand before they tightened up.

 

[reeldutch]

Re: Loose Spark Plugs cause high idle?

so how did your compression test turn out??

 

[herefishyfishy]

Re: Loose Spark Plugs cause high idle?

115, 118, 120, 120

 

[OBJ]

Re: Loose Spark Plugs cause high idle?

That ain't bad.