motor runs rough after running for a while

[FORD150]

i have a 1988 88hp Evinrude motor that i nned some help on, i have had it for a short period of time in witch i have replaced the plugs,plug wires,fuel line from tank, primer bulb and starter solenoid. It is a little cold natured when first started after sitting for a few days but once it is warmed up runs very smooth and quarter cranks every time after warmed up. now my question is after i run the boat down the lake a bit and the motor gets up to temp and i pull the throttle back down to idel
the motor dont idel so well it almost acts as if you where intermitently puting your hand over the end of the carb and snuffing the air off form it or just instantly stoping fuel flow into the motor . sometimes it dies and some times it dont, it always starts back up if it dies but then i have to use the throttle lever to keep the RPM up so that it dont die. i have ordered 2 carb kits and a fuel pump kit for it should be in any day now does any one have any suggestions as to what it could be??? thansk

 

[fireman57]

Re: motor runs rough after running for a while

Sounds like you are on the right track. From what you say the low speed jets have some crud in them. Soak the carb for a few hours and run a small wire through them to make sure that anything is dislodged then blow every hole you can find out with compressed air.

 

[FORD150]

Re: motor runs rough after running for a while

thanks for your help firman57 do you think rebuilding the fuel pump and carbs could help with the cold nature starting some. i know when you first start it after sitting for a few days it acts like i described in my first post but only this time i have to choak the crap out of it for a bit on and off to keep it running. that was part of the reason i ordered the carb kits i thought that maybe i had a nedel valve and seat starting to go bad letting fuel drain out after a few day making it harder to start. but i will let everyone know what the out come is when all parts have arrived and been installed
thansk again for your help

 

[falkor]

Re: motor runs rough after running for a while

Have you checked to see if you have a crack in one of the coils? This has been a problem that has reared its head before. It will run fine for a bit but once it gets up to temp or warmer the coil expands a bit at the crack and shorts out and shuts down a cylinder. once it cools back down it will work again. I dont discount a carb problem but it is worth checking also.

 

[fireman57]

Re: motor runs rough after running for a while

Your fuel pump sounds like it is doing it's job. just make sure you get all the orafices clean and you will notice a big difference in running. Make sure that the float is parallel to the carb body when turned upside down.

 

[FORD150]

Re: motor runs rough after running for a while

thanks you all very much it looks like i was headed somewhat in the right direction....

and i will check the coils out there are a couple of them that look new and i know one of them is fairly old looking and the heating up part make perfect sence. is there any perticular part of the coil that is prone to craks or it could just be in random places?

 

[fireman57]

Re: motor runs rough after running for a while

could be anywhere. You can try running it in a barrel at night and watch for one of them arcing too.

 

[FORD150]

Re: motor runs rough after running for a while

hey guys also i have been researching trying to find out what exactly the this solenoid primer is?? it is mounted on the air box has 2 wires coming to it and a little red lever that turns 180 deg i have looked and looked trying to understand what its function is if any at all cause i am wondering about mine with the motor running turning the red lever one way or the other dont make a bit of difference in how it runs.
i see that it is conected to the carbs so i am wondering is it some kind of self priming solenoid that worked at once a pon a time and now dont.... let me know thansk

 

[jakedaawg]

Re: motor runs rough after running for a while

This is the enrichener solenoid. Normal position is with the red lever running parrellel to the round body. When the lever is run perpendicular to the body you are manually enriching. It allows fuel to go to the manifold behind the throttle plates. It operates when you push the key in. To test, if I remember correctly, : 1. warme engine up. 2. set engine speed at ~2000 rpm. 3. push key in. If functioning properly you should notice engine richens significantly and you should also notice a drop of 1000 rpms or so. You should get approx 5.5 ohms between the purple / white and black leads. The little hoses and tees can also clog. I also seem to think that there was a ground lead that goes under one of the mounting screws to engage a clean ground.

 

[FORD150]

Re: motor runs rough after running for a while

is this normally only used with motors with self mixing oilers? because i mix the gas myself and that would pretty much just make this solenoid more like a extra choke so to speak????

 

[FORD150]

Re: motor runs rough after running for a while

well after rebuilding the carbs and the fuel pump i found a small crack where the screws go to drain the carbs. also behind this screw was jets for each cylinder, so sucking air was a very big part of my problem..... she starts and runs like a champ now thanks to every one that help me

 

[fireman57]

Re: motor runs rough after running for a while

Glad to hear it. Now make sure that you check back and do what you can to help others. Don't just disappear like some other have. We need good people on this team. It was good of you to come back and let everyone know that it is fixed, a lot of folks don't even do that. Be safe this summer and enjoy!

 

[FORD150]

Re: motor runs rough after running for a while

fireman
i sure will i am no expert at this at all but i have been around them all my life but i sure will help every chance i get.
thanks again for all your help !!!!