1974 mercury 115 has issues need help please

[Chris1956]

Re: 1974 mercury 115 has issues need help please

My post (4 posts ago) tells a real easy way to test the stator and rectifier. Alternatively, disconnect the rectifier from the stator wires and put a voltmeter on the stator with the engine running. You should read some AC voltage.

BTW- get a flusher device for your motor. They are less than $10 and will make sure your engine has a water supply. Your bucket will likely lead to an overheated motor.

 

[bassboy416]

Re: 1974 mercury 115 has issues need help please

Chris1956, thank you for your help. I am quite a novice at all of this and probably made an error, but I tried the method you suggested testing and felt like the results I got were really strange. My battery tested at 12.63 volts before starting... My tach doesn't work for pinpointing a specific rpm but i didn't rev it at all (forgot about that part). I ran it for a while and my battery actually seemed to test lower like 12.48-12.58 while running, but when I shut it off and tested again it was 12.63 again... I did this several times and the numbers when motor was running changed slightly but the 12.63 stayed constant. Also, I started using this method of running water through my motor because the rabbit ears I had used on my chrysler 120 seemed to barely spit any water out of the peehole and when i threw it in a wine barrel it seemed to get more water... I am very concerned with frying my impellor so I am totally open to suggestions about the safest way to run a boat out of water.. as far as the rectifier goes... I didn't know how to test it (I tried to remember from posts here but really should have printed this forum out). I put the black lead on one side and red lead on the other side of the wire and tested volts. it would flash from nothing to like 18.9 constantly. It was pretty obvious I wasn't doing something right... Thanks for continuing to help me despite my ignorance and inexperience. I really want to get this thing done right and there is no substitute for experience. I value your advice

 

[bassboy416]

Re: 1974 mercury 115 has issues need help please

chris, i just looked back and realized all of your advice has been 100% accurate so far.... im gonna do what you say

 

[Chris1956]

Re: 1974 mercury 115 has issues need help please

Bass, That motor uses some battery voltage to run the ignition. That is why you will see a voltage drop when the motor is running. If the voltage doesn't rise when the motor is running at 1500 RPM (or so), there is a problem with the rectifier or wiring (common) or the stator (rare).

 

[bassboy416]

Re: 1974 mercury 115 has issues need help please

So I took it out on the lake today to test everything... brought my multimeter... Battery voltage 12.63 before outing... came in after 3 hours of wakeboarding and fishing and tested 12.63... Ran the rest of the day until 8:30 so about 4 more hours and 7 total hours.... pulled out of water, trimmed up... tested 12.57.... Not sure why the drop but it seems to be charging... Also, the tach started working!!!! bout halfway through the day I opened it up all the way and the tach popped up to 4,000 and worked the rest of the day.... Boat ran great, easy starts, a little hesitation when going from idle to WOT (wakeboarding), but if you ease in and then hammer it it does fine... thinking carb clean would probably knock that out.... Thank you for all your help! You really made a difference and any future advice is much appreciated... I might start a new thread on the hesitation when going to WOT... So to recap: PROBLEM: boat left me stranded on the lake. was delayed between turning key and starter engaging... would be hard to start and crank for days.... finally starter would not have enough power to turn flywheel and wires were hot... SOLUTIONS: pump ball, use choke, advance throttle in nuetral, splice damaged battery cables with new cables, new starter, repair stator wires that looked damaged.... Thanks again!

 

[canoemang]

Re: 1974 mercury 115 has issues need help please

Its wot rpm is 4k ?

 

[mr 88]

Re: 1974 mercury 115 has issues need help please

To get the hesitation in your acceleration to go away adjust your idle screws out. Try turning them a blade width out,then test. You may end up a quarter turn out more on each carb. The carbs have a poor transistion circuit and the only way to get from slow/idle to WOT is to almost flood them in the idle circuit.