evinrude 100 hp power loss

[schimmi021]

Had the boat out a few days ago, engine was dogging, at full throttle it seemed like the boat was running like it was at half throttle. Checked some things out, found a fuel filter in the line that was in backwards. I removed this since it was pretty gummed up and there is another anyway. Took the boat out again and the motor ran perfectly. Went out again today and we were tubing with the boat. The first time up river the boat ran perfectly, then throttled back, turned around, and throttled back up, this time the motor never got back up to speed. Slowed down, and went back up, got the power back for a little, then lost it again. Checked the throttle, and its moving all the way, just not getting all of the power we can. Any ideas?

 

[oldcatamount]

Re: evinrude 100 hp power loss

You just described perfectly the need for a carb cleaning/re-build. Maybe some new spark plugs while you're at it. The carb kits aren't very expensive and you can do the work yourself. There are guys on this site that will be happy to guide you along with the re-build job if you need it.

 

[kenmyfam]

Re: evinrude 100 hp power loss

Try squeezing the primer bulb when it does this. See if it picks up again.
Let us know.

 

[schimmi021]

Re: evinrude 100 hp power loss

squeezing the primer bulb doesn't seem to do anything as it stays hard even when it looses power

 

[kenmyfam]

Re: evinrude 100 hp power loss

Try a spark check before running and then when it starts running rough.

 

[emdsapmgr]

Re: evinrude 100 hp power loss

The primer bulb should be hard only when you prime it prior to starting and engine when it is cold. Once the engine is running, the bulb should get softer but the bulb should not collapse. If the bulb stays hard while running, you may have a problem with the ball valves in the hose bulb.

 

[schimmi021]

Re: evinrude 100 hp power loss

the ball is new so I don't think there is a problem with it. Ill try using a spark tester and let you know what happens

 

[schimmi021]

Re: evinrude 100 hp power loss

I used an inline spark tester and all of the wires have consistent strong spark. I also replaced the spark plugs because they seemed a bit old. The motor still isnt running even close to how it should. The other day I was out and i was running at full throttle (which is lke 50% power of what the motor really has) and it eventually kicked in and started moving how it should... after a while it died out again and just lugged along as its been doing. Im starting to believe the carbs need a good rebuild.

Any input?

 

[Daviet]

Re: evinrude 100 hp power loss

Good spark and compression, it sounds like it might be time to overhaul the carbs.

 

[emdsapmgr]

Re: evinrude 100 hp power loss

What year is this engine?

 

[schimmi021]

Re: evinrude 100 hp power loss

1971 Evinrude 100 hp

 

[emdsapmgr]

Re: evinrude 100 hp power loss

Did you check for spark when the engine was cold, or when it was running at 50% power level?

 

[schimmi021]

Re: evinrude 100 hp power loss

cold..... Im not sure how I would go about checking it while its running.....

 

[ezeke]

Re: evinrude 100 hp power loss

Use an inductive timing light; you can "read" the spark through the whole RPM range of the running engine.

Your high speed jets may be dirty. They are in the bottoms of the float bowls where they are easily fouled.

 

[Craig-]

Re: evinrude 100 hp power loss

If a dirty filter was re-installed backwards, it got back-flushed clean the wrong way. Pushing in all the crap that it previously filtered out.

 

[schimmi021]

Re: evinrude 100 hp power loss

Well would it be a bad idea to just assume for now that the plugs are firing properly... and just rebuild the carbs? I feel like that is the most likely culprit as the problem is only intermittent and the plugs seem to be firing as they should. Also I dont have an inductive timing light and Ive already ordered the carb kits so Ill try to spend as little money as possible. Not to mention I can still fish with my boat even though it runs like crap : ]

 

[kenmyfam]

Re: evinrude 100 hp power loss

Sure, give the carb's a service. More than likely due for it anyway.

 

[emdsapmgr]

Re: evinrude 100 hp power loss

It is possible for debris to lodge inside a fuel jet in a carb. That can give you a significant reduction in power. When that power goes away, it is due to reduced fuel flow and also reduced oil flow-a possibly bad combination long term for that cylinder. On the other hand, it is also typical that weak ingnition components will fail once the engine heats up to normal operating temps. An inductive timing light will show the quality of spark on each plugwire once the engine has heated up.

 

[Craig-]

Re: evinrude 100 hp power loss

Well would it be a bad idea to just assume for now that the plugs are firing properly... and just rebuild the carbs? I feel like that is the most likely culprit as the problem is only intermittent and the plugs seem to be firing as they should. Also I dont have an inductive timing light and Ive already ordered the carb kits so Ill try to spend as little money as possible. Not to mention I can still fish with my boat even though it runs like crap : ]

Not a good idea to use it when running like crap, you can do some bad damage to it running lean.

 

[schimmi021]

Re: evinrude 100 hp power loss

I dont think it is the ignition because it runs poorly when its still cold also. It only rarely runs at full power and it isnt only right when i start it up. Sometimes it runs well after using it for half an hour or so when its warmed up. So assuming the ignition components fail when its warmed up doesn't seem to fit. If it is the ignition components though, what parts can it be? I have a number of spare ignition components.