New to Me Evinrude 8HP won't rev under load

[Camdenites]

4 days ago I purchased a 2008 13' Gheenoe with a mid 80's?? Evinrude 8HP tiller motor. Everything seems to be in excellent shape and very well taken care of, but I cannot seem to get the motor to reach full RPM'ss.... The PO said the motor was running well with no problems and i didn't test drive before puchase......
On the initial test run it would severely bog down and surge anywhere above idle and not reach any more than 5mph. I assumed it just needed a carb cleaning like every other small engine i run across these days. I have now cleaned the carb several times and still do not have the result I'm looking for??? The motor idles absolutely perfectly and now smoothly accelerates up to 3/4 throttle, but bogs down past that. I am confident the the carb is clean, I have researched the link and sync on the timing and believe that is ok, I have adjusted the lean rich mixture to optimum..... When you initially "gun it" it seems to sound good and surge, but almost immediately lose power somewhat and then just plod along. it's now maxxing out at 7 mph.... I assumed it was a fuel flow issue, but now i'm lost??? I have not checked the plugs, and am wondering how to test the timing and ignition system. Please advise Thank you!!

 

[orbanp]

Hi Camdenites,

Do check if enough fuel is getting to the carb from the fuel pump. Do pump the priming bulb when you throttle up, see if that helps. If that makes a difference then your fuel pump needs to be looked after (rebuilt/replaced).
You should check/replace your fuel lines, ethanol in present day fuels is not good for old rubber fuel lines, those could be full with disintegrated rubber pieces and crud.
Do check the compression of the cylinders.
Do check the spark. You should get close to 1/4" - 3/8" spark in free air, that engine has some type of CD ignition.
Ignition timing is only set by the break point gap on that engine according to the manual.
Do check the gap setting and the ignition and throttle synchronization as per the manual.
<boatinfo.no> has an online service manual for your motor, among others.

Good luck, Peter

 

[racerone]

There are no breaker points on the engine asked about in post # 1

 

[Vic.S]

I think you will find that if its a mid 80's model it has CD ignition .... no breakers so no gap to set. With CD you should get at least the spark size Orbanp suggests

Check the other things orbanp has suggested .

Also check the plugs. From 1977 to 2001 it should have Champion QL77JC4 or QL86C gapped at 0.030" . Be sure it does not have resistor plugs fitted.

Check its actually firing on both cylinders.

But what is the model number. ?

 

[Camdenites]

Thank you for the responses! The model is E8RCEC which appears to be an 89.
The link to the service manual will be most helpful. After reading about fuel pump issues, I am leaning toward that issue and will try to clean the screen filter and check it out this afternoon. I pulled the plugs and they were very worn.... I purchased and installed two new plugs of the same part # L77JC4, but now realize that my model should run a L86C. Is this a problem?

I'll update after the fuel pump inspection and hopefully a test drive.

Thank you!

 

[Tim Frank]

Thank you for the responses! The model is E8RCEC which appears to be an 89.
The link to the service manual will be most helpful. After reading about fuel pump issues, I am leaning toward that issue and will try to clean the screen filter and check it out this afternoon. I

The timing of the bogging suggests to me that the problem is within the carb itself. Your OP says

I am confident the carb is clean

I would recheck it....and you do not mention a rebuild kit. If you did not use a kit....all bets are off.
Pay particular attention to the high speed jet....R&R and really clean that.

I pulled the plugs and they were very worn.... I purchased and installed two new plugs of the same part # L77JC4, but now realize that my model should run a L86C.Is this a problem?
I

No.

 

[orbanp]

There are no breaker points on the engine asked about in post # 1

Hi racerone,

Thanks for the correction, looks like I looked at the wrong page in manual.

Camdenites:
Here is the relevant info in the manual: <http://boatinfo.no/lib/evinrude/manuals/1971-1989johnsonevinrude.html#/212>

Peter

 

[Camdenites]

I pulled the fuel pump off and took it totally apart. I found a loose plastic "mushroom" shaped piece lodged in an open cavity of the pump! I couldn't figure out where it was supposed to go, but there was an identical one on the top of a small spring which pushed on one of the diaphragms. I've struggled to find an exploded view of the parts inside the pump assembly but it looks like the fuel pump repair kit comes with two of the small springs and two mushroom shaped tops..... I'm wondering if a previous repair left the pump missing a spring???? I ordered a fuel pump kit and a carb kit as was suggested. I'm really leaning toward the fuel pump issue, and also plan to replace the fuel lines inside the engine as the tank to engine line is new. Thanks for the help and i'll update you after i have received and installed the new items....

 

[Camdenites]

Success!!!!!!! My fuel pump rebuild kit and carb kit came in today and I installed both of them after work. The fuel pump was a bit tricky, but the instructions were excellent, and extra hands from my son proved beneficial. The motor cranked and idled well as normal but now it opens up perfectly and planes the little boat and produces 18.6MPH at WOT. I'm still thinking that the fuel pump was the most likely issue, but I can't be certain since I did replace parts in the carb today also.

Thank you for your guidance!

 

[Camdenites]

I thought I was done....... So I tested it without mounting the plastic breather cover and the cowling and it ran beautifully. 18.6MPH! With the breather cover and cowling mounted it topped out at 12 or so???????? I tried readjusting the mixture adjustment with the breather on with no improvement. I tested it on and off several times without any other adjustment and here are the results.... no cowling,no breather cover = 18.6 cowling but no breather cover =17 cowling and breather cover = 12

I assume this is just due to the restriction of air flow to the carb, but i wouldn't have thought there would be this much effect???? it doesn't seem that there is any filter in the plastic breather housing that could be clogged??? Any ideas?

 

[racerone]

Post some pictures of the cowling along with model # of motor.

 

[Tim Frank]

That almost mirrors a problem I had with my 1990 8HP 'rude.
Check that the heavy/thick washer/gasket between the intake cover and the carb is not doubled over and obstructing the carb throat.

 

[Camdenites]

The motor is still running great without the air silencer @18mph wot, but not planing the boat with the air silencer on???? 9mph wot??? The foam gasket on the silencer is as it should be and not restricting air flow. I would understand and be satisfied if it reduced top end 1-2mph, but cutting it in half and not planing the boat is annoying!! I have tried adjusting the air/mixture to account for the silencer and it doesn't help...
????Do you think it will damage the engine to run without it????

 

[Camdenites]

1989 Evinrude 8HP E8RCEC

 

[Camdenites]

Am I damaging my engine? I've set the mixture a little rich at idle to offset the extra air. any other ideas?? it's like a different motor with the silencer on?????

 

[oldboat1]

I think there is a chance your carb is not venting properly. Removing the silencer cover may be compensation for a venting issue, imo. If it were mine, I would pull the carb off and clear openings -- would take off the cover and the bowl, and soak the metal carb top. Finish by clearing with soft wire or monofilament and carb cleaner (followed by compressed air, if you like). Gaskets are fresh from the kit, and you should be able to reuse them. (Good to have a parts diagram in front of you: http://www.iboats.com/Carburetor-La...415344--session_id.577783894--view_id.1546124 )

 

[flyingscott]

Check the silencer itself for a blockage more than one mouse has found their way in there.. You cannot set the high speed mix on that motor has a fixed jet.

 

[Camdenites]

thank you for the responses! I checked the silencer for blockages and it is clear. I've been through the carb looking for blockages so many times that I didn't want to pull it off again but did anyway thanks to your encouragement! I found a problem! I studied the schematic that you linked to me last night before i pulled it apart, and realized that the gasket that seals the nozzle well to the bottom of the bowl was missing! I totally overlooked it when assembling...... I found it in the package that my carb kit came in and istalled it. I also checked all of the passages very carefully and confirmed that they are all clear.
I'm planning to run it this afternoon and will give you an update. Thanks for the help!

 

[Camdenites]

18.6 MPH with the air silencer on!!! Smooth, quiet, and strong!

Thank you for all of your help.

 

[oldboat1]

glad you got it Camdenites. Well done.

Fast boat!