Intermittant loss of power 30HP Evinrude

bigb56

Seaman Apprentice
Joined
Jan 26, 2013
Messages
30
Hello eveyone,
My son has a 30HP 2 stroke Evinrude (1989) that we use for fishing in Mexico. It has developed a problem to where sometimes it will not want to acellerate from idle, and will easily die. However if I baby the throttle and get it going it will suddenly take off and as long as I hold it at full throttle it will keep going. We tried 2 new fuel lines and a new tank. It kind of feels like a fuel delivery problem to me, like it can't get enough fuel till it builds some RPM. My thoughts at this point are maybe a suction leak at the fuel inlet on the motor or fuel pump/carb issue. I got the motor on a stand and I am going to try and replicate the problem in the garage, meanwhile any ideas? Remember this problem is intermittant, sometimes it runs great, then later it will act up. Temperature makes no diff as it will happen hot or cold. At last years trip it ran great for 3 days then on the last day it acted up and we lost a whole day of fishing. That can't happen again.

Thanks, BigB
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Re: Intermittant loss of power 30HP Evinrude

Have a look at the sparkplugs, see if they are saying something. Could be a lean mixture happening here. I use to own one of these, i think you could adjust the fuel mixture on these so you could try backing it out a third turn or so.
Id also check that you are getting a reallly good spark at both sparkplug tips.
Going at full throttle ok eliminates a few things. If the powerpack goes on these they do all sorts of punch drunk behaviour like that so keep that option in the back of your mind too, although what you describe seems quite charachteristic of one going faulty and with it being an intermittant problem.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Intermittant loss of power 30HP Evinrude

When it acts up, hit the primer once and see what happens. If it picks up and goes it may have some carb probs.
 

bigb56

Seaman Apprentice
Joined
Jan 26, 2013
Messages
30
Re: Intermittant loss of power 30HP Evinrude

The plugs were slightly carboned and wet. I cleaned them and checked the gap=.030. Next I startred the motor, it would not idle, every time it began to die I would pull the choke and it would recover (even after warmup). I opened the mixture screw about 1/2 turn and this made it idle and accellerate, but it has a miss. Not a steady miss but intermittant. I am going to go get two new plugs and fresh fuel in case my son mixed in too much oil.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Re: Intermittant loss of power 30HP Evinrude

If you can get hold of a timing light hook it up and see if when it gets the miss if it corresponds with a loss of strobe light on a cylinder at ignition time.
You can buy these timing lights for about $15 second hand.
I still suspect a deceasing powerpack. You can check the values for it with a dva or with a $5 you can test the trigger and stator for faukts, especially shorting to ground on the wires which ive seen happen a bit.
Heres the link to the specifications for the trigger/stator check out page 38 cdi electronics troubleshooter
CDI Electronics Practical Outboard Ignition Troubleshooting
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Re: Intermittant loss of power 30HP Evinrude

If you can get hold of a timing light hook it up and see if when it gets the miss if it corresponds with a loss of strobe light on a cylinder at ignition time.
You can buy these timing lights for about $15 second hand.
I still suspect a deceasing powerpack. You can check the values for it with a dva or with a $5 digitalmeter you can test the trigger and stator for faukts, especially shorting to ground on the wires which ive seen happen a bit.
Heres the link to the specifications for the trigger/stator check out page 38 cdi electronics troubleshooter
CDI Electronics Practical Outboard Ignition Troubleshooting
 

bigb56

Seaman Apprentice
Joined
Jan 26, 2013
Messages
30
Re: Intermittant loss of power 30HP Evinrude

Thanks, I am planning to check everything with a DMM next. I have a Fluke 27 for my job as an electrician. Might have to wait for the weekend, not much time during the week for me. I did put a cheap parts store spark checker on each plug, there does not seem to be a shortage of spark, although it does change in size and duration on the "skips" but it's hard to tell if that is the cause or the effect. I still have my old neon timing light from my muscle car days, do you think that would work better?

Thanks for the link, I also found a, Evinrude/Johnson manual at boatinfo.com, I'll compare the numbers to see if they're the same.

By the way the problem is getting much worse, it is not intermittant any more.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Re: Intermittant loss of power 30HP Evinrude

If its both plugs then check the stator and trigger against spec values. If they are ok its the powerpack in my opinion. This is what i see happen on them when they go. But you want to check that the stator and trigger are in spec as if they arent they would quickly ruin a new one too. Ive bought second hand powerpacks for $35 before. yes you could use your muscle car light to read the timing of it on the flywheel
 
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