My 76 Rude 70hp is driving me nuts

[jim_in_day]

Long story, please read throughly. 76 powerhead with 75 midhousing and lower unit. Parts replaced were head gasket, thermostat and bypass and temp sensor, trigger, stator, coils, fuel pump all new hoses, intake and leaf plate gaskets. work done was rebuilt carbs with new kits (4 times now complete with air and wire probing) reset timing pointer per manual, set carbs to open at tdc per manual, set max advance timing, made certain that all 3 carbs are synced using butterfly amplifier (paper clips with alligator clips on end). Compression #1= 102psi #2 = 112psi #3= 105psi Good spark 1/2 jump <br />Now for the problem It will run fine on muffs starts easily sounds good. Take it out on the water, finally get it to start and run, go fishing and then try to restart it and it will not start, I have been fighting this problem for a year, When it runs, it goes like spit 6000 rpm 30mph (GPS) then it won't start again. What do i need to do besides use it for an anchor?

 

[MCM]

Re: My 76 Rude 70hp is driving me nuts

Well it looks like you've replaced about everything but the power pack. those symptoms are similar to a p/pack before it goes belly up. If you have a digital volt/ohm meter you can test the cranking voltage output of the p/pack. You should get a minimum of 125 volts AC to the coils while cranking.

 

[michligj]

Re: My 76 Rude 70hp is driving me nuts

I agree that it sounds like a bad power pack. I don't think that it would hurt to check the stator assembly as well. Check to see if it is dripping any varnish at any point. There are also some simple resistance tests that you can run as per the manual.<br /><br />If the stator is bad and you replace the power pack only, you might be asking for trouble in the form of another blown power pack

 

[jim_in_day]

Re: My 76 Rude 70hp is driving me nuts

oops, i left out the fact that i replaced the power pack and rectifier also. I didn't just shotgun parts at it, they have all failed at one time or another in the last year. JM_00 look carefully, i replaced the stator (thats the most recent part). I will however check the powerpack output and make sure it is ok

 

[MCM]

Re: My 76 Rude 70hp is driving me nuts

I'd be about ready to look for a boat & motor that needed an anchor

 

[Walker]

Re: My 76 Rude 70hp is driving me nuts

Why doesn't it start? Have you tested for spark when it won't start? No spark = no run or if you have spark = fuel problem

 

[jim_in_day]

Re: My 76 Rude 70hp is driving me nuts

Unfortunately when it happens on the water i don't have diagnostic tools with me. However, the next time i take it out i will have everything needed to figure it out (I hope). The biggest problem is that the lake we use to test boats is cloased for the winter (it used to be open year round). That and winter weather makes it difficult to get out. I agree that it has to be spark or fuel, but because the problem comes and goes everytime i think i fixed it and take the boat out it comes back ???? I will be looking at it again this weekend and will repond with anything that comes up. My wife just hates this motor, everytime I take her fishing we get towed. I just want something to work without all these headaches I doesn't overheat at all, and when warmed up runs at about 150 on the temp gauge so I don't think thats the problem. (electronics getting hot ??)<br />

 

[ezeke]

Re: My 76 Rude 70hp is driving me nuts

When you try to restart, are you using the warm-up lever?

 

[rodbolt]

Re: My 76 Rude 70hp is driving me nuts

does not matter what you replaced yesterday if its bad today, an AC multimeter is a teat on a boar hog, you will need a peak reading meter or a digital meter with a DVA adapter. when it wont start test the spark, if it does not spark test the stator and trigger inputs to the pack. if you have good spark start looking for an over rich or lean condition.<br /> when its running how is the in gear idle speed and quality ?

 

[MCM]

Re: My 76 Rude 70hp is driving me nuts

Jim, just a thought but have you considered it being an intermittent problem in either the ign. switch or electrical harness/connections, I notice you didn't mention testing or replacing either.

 

[jim_in_day]

Re: My 76 Rude 70hp is driving me nuts

rodbolt i use a peak reading meter, and will test it again this weekend for output from everything. I live 120 miles from the shop where i work on the boat this time of year so it only sees me on weekends When it is working correctly it idles fine. I do believe that it is an electical problem, but don't rule out fuel. MCM good point, when i built this motor we put in a wiring harness and control box, but they were used parts we had laying around. I do however pull the giant red plug and use the shop test harness when checking stuff on the boat so that I can see the spark while i crank on it and can test other parts. I will take the shop harness out when we test it next to eliminate that possibility.

 

[rodbolt]

Re: My 76 Rude 70hp is driving me nuts

intermittants can drive one batty, I get them occasionally.<br /> I have been known to hook up all 4 of my peak reading meters and go riding to find a problem with a V6 pack, only had to ride 3 hours.

 

[jim_in_day]

Re: My 76 Rude 70hp is driving me nuts

Well, its snowing here now, so may not get to work on motor in the water until spring. I will do some work at the shop before then, but boat is going to be stripped (gutted) and re-gelcoated this winter (to fix leaking hull) so it will probably be spring before i get any serious debugging on this motor. I will continue to read all the posts (i read all the new ones every day) and when i get it back in the water i will repost.