89 30hp missfire after 10min warm up

[wormz]

Re: 89 30hp missfire after 10min warm up

got some diodes wired into the circuitry. everyting seems ok, no fall-out and its still charging 13.8volts!
all seems well. going to the lake on tuesday and give her a run for the money!

 

[wavrider]

Re: 89 30hp missfire after 10min warm up

Sounds good and congrats, alot of trouble shooting on your part.
Make sure the diodes you installed meet the amperage rating or else you may have another "episode" of stray ac

 

[wormz]

Re: 89 30hp missfire after 10min warm up

they are 20A (i put them on all three wires.) im not sure of the rating they should be...i just went safe. the choices were 1/2/5/10/15/20/50/100 amp
i figure that thing doesnt put out much amperage.
or am i wrong there to? lol

 

[wavrider]

Re: 89 30hp missfire after 10min warm up

3 wires??? should be two wires for the A/C from stator, most likely yellow, input to rectifier, output of rectifier probaly red, make sure you have it connected as a bridge rectifier, anode to cathode of doide, one gives neg dc this goes to ground, forward biased diode gives off positive dc, should take 4 diodes, unless you are only making a half wave rectifier in that case, 2 diodes would work, seems like you would need a full wave to get the "charge" effect, any waty as long as it is working good deal.

Just got back from the maiden voyage, 17' skeeter starfire with a 1973 85hp rude, old engine did great, specks were hungay also

 

[wormz]

Re: 89 30hp missfire after 10min warm up

i did all three. it works, charging the battery at 13.7 volts running down the lake. good enough for me! went out today for 5 hours no problem, wide open running 3 gallons of fuel for several miles down lake!
id call it licked!

now its time to get fishing for some striped bass!

 

[wavrider]

Re: 89 30hp missfire after 10min warm up

Sounds great, good luck on the fishing

 

[Harker]

Re: 89 30hp missfire after 10min warm up

It's great to hear that things worked out and it's running fine. Seems a lot of times people never post back and leaves helpers guessing. % hours on 3 gallons is pretty good fuel economy!

 

[wormz]

Re: 89 30hp missfire after 10min warm up

well, 5 hours of running time, not all wide open. we trolled for a majority. this motor is actually great on fuel consumtion... my 20 hp mercury doesnt go as long as this 30hp evinrude.

 

[wavrider]

Re: 89 30hp missfire after 10min warm up

Sounds good, think you got it right.

 

[carter]

Re: 89 30hp missfire after 10min warm up

I'm the poor soul spoken of earlier, exact same problem, 30 hp '90 evinrude. i have a donor motor that ive been switching parts with. one thing i hadnt tryed yet was the rectifier. switched it out today. just got back from a 2 hour run. no problem till 70 mins out. stoped the motor for about 2 mins. after cranking up, same problem again! shut it down again for about 30 sec. after cranking again it ran fine for another 50 mins. im ready to try the diodes, my question is did you put the diodes between the rectifer and the terminal block, if so did you cut the wires or did you put them at the end of the yellow wires that lead from the rectifier. switching the rectifer was a big improvement, before the problem would start after about 10 mins.if you can please be specific about how to install the diodes. i under stand the anode side should be up current and the cathode side down current , but this part is all Greek to me. thanks for any help

 

[iwombat]

Re: 89 30hp missfire after 10min warm up

Carter, the diodes ARE the rectifier. If you looked inside it'd be something like this.

Although, I'm sure there's some capacitors added in for good measure.

 

[carter]

Re: 89 30hp missfire after 10min warm up

the rectifier on this evindude has 4 wires , yellow, yellow&gray,yellow&blue, and red.I think the three 20a diodes were wired inline on the the yellows(input) between the power pack and the rectifier, leaving the factory rectifer in place and the red(out put)on its original terminal. I've read somewhere that the evinrude rectifier is 5a, not sure about that.

 

[wavrider]

Re: 89 30hp missfire after 10min warm up

Great pic Iwombat, bridge rectifier.

Wormz take a lok at that diagram, you need 4 diodes for your set up.
a bridge rectifier block, encapusalated in epoxy can be purchased at rat shack. YOu mentiond you are only running 3 diodes???? How did you install them what configuration?

 

[ezeke]

Re: 89 30hp missfire after 10min warm up

You will just keep on killing rectifiers and diodes if you don't fix what is causing it.

 

[wavrider]

Re: 89 30hp missfire after 10min warm up

i did all three. it works, charging the battery at 13.7 volts running down the lake. good enough for me! went out today for 5 hours no problem, wide open running 3 gallons of fuel for several miles down lake!
id call it licked!

now its time to get fishing for some striped bass!

Ezeke,
It appears he got the engine running correctly, I am just concerned about the "three" diodes, need four to make a bridge, Wormz may be running on a halfwave bridge only rectifying the positive part of the AC sine wave, makes the rectifier 50% less efficient, but it will keep a battery up just not charged.

 

[tsteve29]

Re: 89 30hp missfire after 10min warm up

I followed that thread of wormz like a good book because I have the same exact problem on my 98 30 hp johnson. Problem is, when I switched out the rectifier last week my problem wasn't solved. It wasn't as bad but it definitely started to skip when it was wide open. I was told at the shop that it didn't matter which yellow went to which terminal as long as the red went to the same as before. Is this correct?

 

[HighTrim]

Re: 89 30hp missfire after 10min warm up

I followed that thread of wormz like a good book because I have the same exact problem on my 98 30 hp johnson. Problem is, when I switched out the rectifier last week my problem wasn't solved. It wasn't as bad but it definitely started to skip when it was wide open. I was told at the shop that it didn't matter which yellow went to which terminal as long as the red went to the same as before. Is this correct?

Steve the best thing that you can do is start yourself a new thread so that ppl do not get confused. Welcome to iboats, Im sure you will get plenty of help

 

[tsteve29]

Re: 89 30hp missfire after 10min warm up

Will do, thanks

 

[wormz]

Re: 89 30hp missfire after 10min warm up

Ezeke,
It appears he got the engine running correctly, I am just concerned about the "three" diodes, need four to make a bridge, Wormz may be running on a halfwave bridge only rectifying the positive part of the AC sine wave, makes the rectifier 50% less efficient, but it will keep a battery up just not charged.

i put one diode on each yellow wire. there were only three wires from the rectifier. so far the battery has held a charge, went night fishing and i use the troller motor quite often. have not had to recharge anything yet. ive probably logged over 25 hours of fishing time i the past few weeks. i even went in the int coastal waterway for half day.