Rude 75 HP will not run under load

[npd4432]

Took the boat out yesterday for the first time of the year. Ran great all day, today after about 3 hrs of running great, it will not run under load. It will rev fine and go into gear no problem but will max out under load at 3000 rpm. It happened out of nowhere all was fine and kaboom no power under load. This year I replaced all plugs, plug wires and put on a new prop. But like I said all day yesterday and most of the day today it ran great, just came out of nowhere. I am perplexed, have no idea where to go from here, seeking advice. 1983 evinrude 75 HP E75TRLCTE

 

[Solittle]

Re: Rude 75 HP will not run under load

Your description fits crud in the carbs. Also need to check for spark. You could be dropping a cylinder.

 

[npd4432]

Re: Rude 75 HP will not run under load

I pulled the plug wires while it was running, all were sparking fine, but I will try to check for spark while it is under load.

 

[5150abf]

Re: Rude 75 HP will not run under load

Dirty carb, start here
http://forums.iboats.com/showthread.php?t=244013

 

[tashasdaddy]

Re: Rude 75 HP will not run under load

all were sparking ok, but was there any change it the motor when you pulled the wires, while it was running. if all are sparking, leads to fuel system. carbs, fuel pump. bulb collasping, clogged tank vent. suck air from a fitting. if when you pull the plug while running, and there is no change in the way the motor runs, that is a indication, there is not sufficent fuel or compression to that cylinder.

 

[npd4432]

Re: Rude 75 HP will not run under load

When I pulled the wires the engine was at idle and did dip the rpm's when pulled. I just rebuilt the fuel pump. The carbs were rebuilt two years ago. I will try to pull the plug wires when under load to see if the engine has any response, like I said earlier in the post, the motor ran great for a day and a half and just quit after some time in the water.

 

[tashasdaddy]

Re: Rude 75 HP will not run under load

but it stated later, or right away? was it hot? it could be a lot of things. coils failing, power pack failing. but most common, is crud getting into high speed jets.

 

[npd4432]

Re: Rude 75 HP will not run under load

The problem came out of nowhere, running the boat all day took a couple of high speed laps around the lake pulled into dock, dropped off a passanger and then when going back out the motor would not go over 3000 rpm. At first I thought the linkage between the three carbs had popped off a plastic grommet as that has happend in the past and created a similar problem. That was not the case, afterward I checked the primer ball, fuel tank, and then pulled the spark plug wires. I could not diaganose the problem. I will get out to the lake and try to pull the spark plug wires under load to see if I can narrow it down to a single cylinder.

 

[npd4432]

Re: Rude 75 HP will not run under load

Ok, here is the deal, went to lake yesterday and tested the motor at idle and under load. Pulled the spark plug wires at idle and all were firing, and all had a dip in idle when pulled. Pulled and replaced all spark plugs, all looked good. Took the boat onto the water and tested under load. Pulled all the wires again and when I pulled the top cylinder, no change in performance, but there was still spark. I am figuring the high speed jet in the top cylinder is crudded up, so I am going to pull the boat from the lake and rebuild the carbs and go from there. Does that sound right??

 

[tashasdaddy]

Re: Rude 75 HP will not run under load

sure does. see what a little troubleshooting will do. if you do it in the right order. be sure to read this. http://forums.iboats.com/showthread.php?t=244013

Good Luck.

 

[npd4432]

Re: Rude 75 HP will not run under load

Finally got to get the carbs off of the boat, and low and behold the high speed jet on the top cylinder was varnished up, could not blow any air through it. Soaked and rebuilt the carb. It appears as if the carb has been building up some varnish or scum throughout time, not a piece of dirt like I expected. Is there any way to prevent this in the future?? I will get to the lake this weekend to test her out, should I expect a performance gain? Just wondering, and thanks for the help guys.

 

[npd4432]

Re: Rude 75 HP will not run under load

???

 

[Outsider]

Re: Rude 75 HP will not run under load

Stabil ...