Evinrude problems???

[Hajile]

Hi. This is my first post, though i have found loads of help reading through the posts here. Now I need a little more help. I have a '98 90 hp Evinrude spl. After the motor runs for a while its hard to get it to crank, and wont idle without throttling it up. its very hard to get it in gear without it dying. I did a compression test and got 90 105 105 105. After doing a carbon treatment they all checked at 120 and the motor ran fine for about 15 hours of use after that. then the same problems again. I did another compression test and got 85 95 100 100. The motor pushes my 17' neptune loaded down and with three big men 37 mph @4600 rpm at WOT. Any suggestions?

 

[Chris1956]

Re: Evinrude problems???

OK, it sounds like a problem I and others have been chasing on the Johnny 60* V6 motors. First of all, 4600 ROM at WOT is a bit low, even with 3 big guys. What is the WOT RPM with a normal load, say you and 3 cheerleaders?

Just a joke, but, with a normal load you will want ~5500 RPM at WOT.

I have had some luck fixing the "bad idle when the motor is warm" issue, by blowing out the off-idle air orafices. Each carb has one. Remove the airbox and look for a small brass tube on the carb. Give it a blast of carb cleaner and see if it sprays out of the side covers. If so, try to tighten the cover screws. Protect your eyes as the spray can blast back. No promises, however, it worked for me.

A mitigation is to advance the throttle when warm starting the motor. Let her run herself clear and the idle should be better.

 

[archcycle]

Re: Evinrude problems???

You probably have some variation in how you're compression testing. IMO you (you=all of us that aren't compression experts and have $15 testers that we got from harbor freight) will always get different readings on different days no matter what you do but if you have to always try to test the same way and you'll probably keep them closer. For example I generally warm it up first, ground all plug wires to the block, pull all of the plugs, set WOT in neutral, then test.

 

[Hajile]

Re: Evinrude problems???

I just did another compression test today just to make sure i did everything right and got the same results. I warmed the engine and set it to wot. Does this mean my engine is just worn out?

 

[Hajile]

Re: Evinrude problems???

I have just recently rebuilt the carbs so i think they should be clear. I will try that tomorrow just to give it a try. Do you think my problems are related to my low compression numbers? Could testing compression soon after running Engine Tuner through my engine have given false results since I got all 120's after? And i hope to test my rpms with the cheerleaders soon, but i have always been loaded so I'm not sure about a light load.

OK, it sounds like a problem I and others have been chasing on the Johnny 60* V6 motors. First of all, 4600 ROM at WOT is a bit low, even with 3 big guys. What is the WOT RPM with a normal load, say you and 3 cheerleaders?

Just a joke, but, with a normal load you will want ~5500 RPM at WOT.

I have had some luck fixing the "bad idle when the motor is warm" issue, by blowing out the off-idle air orafices. Each carb has one. Remove the airbox and look for a small brass tube on the carb. Give it a blast of carb cleaner and see if it sprays out of the side covers. If so, try to tighten the cover screws. Protect your eyes as the spray can blast back. No promises, however, it worked for me.

A mitigation is to advance the throttle when warm starting the motor. Let her run herself clear and the idle should be better.

 

[watergecko]

Re: Evinrude problems???

Now who could pay attention to throttle settings and rpm's with three cheerleaders in their boat?? Thats a die hard mariner there!

 

[Chris1956]

Re: Evinrude problems???

Any compression readings that are even on all cylinders is fine. Even the 85PSI you received. I would doubt that is your issue.

Get the three cheerleaders into the boat and check WOT RPM. If it is still low, request they lighten the load by removing their clothing. Then retest if you still can.

 

[Chris1956]

Re: Evinrude problems???

sorry, couldn't resist!