1987 150 hp Evinrude possible power pack problem

[muchco]

I have a 1987 150XP Evinrude. I just purchased it and have given a check over before using. Link and sync checked, timing checked and carbs cleaned and new kits put in. The engine starts excellent. It idles great and will run slow with no trouble. As soon as you try to run it hard when it's warm it seams to be missing a bit and is slugish on the top end. Today when I took it out it was busy at the launch and I did not let it warm up very long, took off and it ran great pulled up to 5600 rpm no trouble. Its ran well for a while, then I stopped for about 15 mins and when I started again it started fine but stumbled on accelaration and would not pull more than 4000 rpm. I loaded the boat and took a look at the plugs. 1, 3 & 5 all looked normal(nice tan color). 2, 4, & 6 looked similar execpt the electrodes were black instead of tan like on 1, 3 &5 the starboard bank. Is it possible that when the power pack on the port side heats up the spark is reduced? It appears that all three port cylinders are firing but not hot enough. Do power packs paritally fail like this? Or are they either working or not working? Or is this not a power pack issue at all. It's confusing because I have not had an outboard that starts as well as this one does. Look forward to someones response. Thank you for your time.

 

[OBJ]

Re: 1987 150 hp Evinrude possible power pack problem

Possible muchco. Or, your dropping a cylinder altogether when warm. Have you checked the head temp for the port bank after the engine is warm? Could be running cold which can cause the black looking plugs. Each head has it's own t-stat right at the top of the head. When the problem developes again, check the spark at each cylinder on the port side. If you lost one or two, easy troubleshoot is to swap power packs over and see if the problem follows. If it does, replace the power pack. <br /><br />So you got two things to look at....check the head temp after the engine warms up and then when the problem developes, check the spark at each cylinder on the port side. Keep us updated to your progress.....Thanks and good luck!

 

[muchco]

Re: 1987 150 hp Evinrude possible power pack problem

Thanks OBJ, I have checked the heads when warm and they both are about the same temp. Do power pack get warm and cut out like this, or do they either work or don't work? I will do the power pack swap and keep ypi informed. Thanks for the response.

 

[OBJ]

Re: 1987 150 hp Evinrude possible power pack problem

Did you check the flat areas on top for temp? They should be about 140 to 143* F at idle. <br /><br />Power packs can kick in and out when hot.

 

[muchco]

Re: 1987 150 hp Evinrude possible power pack problem

OBJ, I will borrow a laser heat sensor and check the next time I have the boat out and let you know I find. Thanks for the input on the power pack.