1979 85hp evinrude only gets to 3000 rpm

[yjfun]

My outboard ran great at the beginning of last summer wot was 5000 rpm. After trolling with it for an afternoon it wouldn't rev pas 2600 rpm on the way home. I discovered a bad powerpack and replaced it and all 4 coils and rebuilt both carbs and the fuel pump and did a link and sync on the motor. Still can't get more than 3000 rpms out of it. I am pulling my hair out with frustration trying to figure out what else could be wrong. Compression is 115,110,110,112 I checked spark on all 4 plugs with a spark tester. Does anybody have any other ideas?

Thanks for the help

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

Solid compression. You might try to check the spark when you are out boating next time. Take the cowling off and have a friend steer while you run the boat under power. Put a timing light on each plugwire and see what the flashes in the gun look like. It will show the condition of the spark on each wire. You could be running on only 3 cylinders. (Weak ignition component problems tend to show up once the engine reaches normal operating temps.) If everything checks out when the engine is under load, turn your attention to the fuel system. Always possible that you have a speck of dirt in one of the carb main jets-did you pull the jets during your carb overhaul? Did you happen to take a fuel sample to test for water in the fuel?

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

I ran the motor with the boat on the trailer last night and did the timing light test. I got the same flashes from all 4 cylinders and they were all very fast. I also tried changing both the fuel tank and fuel lines with no change in the motor. All this testing was done with the motor warmed up. I let it idle for at least half an hour and before I took it to the launch I pulled all the plugs cleaned them and gapped them correctly. When I pulled them out today they looked just like they are supposed to light tan. I completely dismantled the carbs and pulled all the jets when I rebuilt them.

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

A couple more small things you can check. The upper carb has a small roller which gets pushed by the throttle cam. Sometimes the outer plastic skin deteriorates. When this happens, the carb won't open fully. A cheap fix. Check the timer base to make sure it is moving when the throttle is advanced. You want to make sure the timer base moves through it's full range by the link arm. If the grease dries out, (typical on older engines) sometimes this timer base can move slowly or stick-not permitting full spark advance. Double check to make sure the butterflys on the carbs are fully open when the throttle handle is in the full throttle position. Those butterflys need to be fully level when at max throttle. They will actually overrotate and can close slightly if misadjusted.

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

I finally got to work on the motor again and checked the things you suggested and they all seem fine. The plastic bushing on the throttle is in good shape, I checked and greased the timer base assembly and the butterflies are opening to the correct position. I was able to run the motor in the dark tonight and saw that the coils appeared to be grounding themselves out. I pulled all the coils cleaned the connections and applied dielectric grease to the connections and reattached them. After doing this I ran the motor again and it still sparked between the mounting screws and the plastic housing of the new coils. This didn't make any sense to me since the plastic is non condutive. Would this shorting of the grounds cause the engine to not be able to achieve higher rpms? I also noticed that you can see the flashing of the ignition spark in the white porcelain part of the plugs is this normal or should I change the plugs?

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

Checking spark on an engine at night is a good idea. It really highlighted the problem. Usually this type of ignition breakdown occurs when the engine is under extreme load, such as at higher rpm's when it really starts to make hp. You said you replaced all 4 coils on your first post. Were these coils new ones from Bombardier? Your new coils must be the new style-the leads are plug-in on both ends. It is unusual for all 4 coils to break down at once. Usually these are pretty reliable-they have low failure rates. The plugs could be the issue. If you have hot spark, and the plug won't fire, the spark wants to go somewhere. What type of Champion spark plugs are you using?

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

It has NGK B7HS plugs in it right now which is what the Evinrude dealer told me to run. I think he also has champions on the shelf but he's not open today so I'll check the auto parts store today and if they don't have them I'll get some tommorrow. The coils are a Sierra product not OMC. What would cause the inside of the plugs to glow like that. They are only 8 months old.

I put new champion L77JC4 plugs in the motor tonight and all the random sparking around the coil grounds appears to have disappeared. It looks as though the plugs are still glowing slightly which makes me wonder if the new wires that came with the sierra coils have cheap boots and are allowing leakage around the plugs themselves. I still want to know why this motor is already needing new plugs after only being used for a couple months last summer. Thank you very much for the suggestions you have made in troubleshooting this motor.

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

Bombardier only recommends Champion plugs in their engines. They always seem to work great, so stick with them and you should be fine. It is very unusual for a Bombardier dealer to recommend an NGK plug. If you have any continued problems with the coils, I'd swap them out with 4 OEM coils. They will work great. Also, check the bottom two coil wires. If the wires are weak and if the wires run close to the cowling latches, you can get arcing to ground through the latches. Your engine comes with special rubber-coated wire holders which are designed to keep the wires from arcing to ground. Make sure you use them to hold those high voltage wires.

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

Sorry it took so long for me to get back to this but it had to take a back burner for a couple weeks. I took your advice and swapped the plugs to champion yesterday and ran the motor in the dark again. All random sparking appears to be gone now so this morning I took the boat to the water to test it again. It couldn't get above 3000 rpm and when I move the throttle the motor increases in rpm until the lever is 90% forward which is 3000 rpm and then drops to 2800 rpm at 100% throttle. I tried pulling all the coil wires again and get a consistent 300-500 rpm drop from all 4 cylinders. I also tried pulling the plugs going from the power pack to the coils on each side and get a 1500 rpm drop on both sides. Since these results were consistent I would have to assume that the ignition system is operating correctly and since I know my compression is good the only thing left would be a fuel issue correct? I ran the motor up to full throttle and then moved the ignition advance stop forward and was able to gain 200 rpm. Now that the motor was running at 3000 I started messing with the choke on the carbs and noticed that if I close it about 30% then I get an increase of about 400rpm but it wavers a little bit. This bit of information made me think that there is a fuel delivery problem of some kind so I checked the primer bulb and it was firm and pumping it had no effect on operations. This is making me wonder if I did something wrong when I rebuilt the carbs or if I didn't adjust them correctly or if there is a blockage of some kind between the pump and the carbs. Any other thoughts on this?

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

Pulled the carbs again today and couldn't find any debris plugging jets and both floats are set correctly. Anybody have another idea on what may be wrong?

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

I think your testing and your conclusion of your findings are logical. An rpm increase when slightly choked indicates an engine which is running lean. That could relate to your comment about the max rpm's dropping off to 2800 from 3000 when you go to full throttle. Basically, at 3/4 throttle the spark is already at max advance. The only difference further advancing of the throttle makes is to open the carb more. That normally would mean both more air and fuel at the same time=more hp and rpm's. Since you had the carbs off, normally a quick check of the sync and link relationship is done. Did you do that? Are you running all fresh fuel this year, or is any of it over 6 months old. Have you tried to run the engine without the cowling? (make sure a mouse didn't make a nest under the upper cowling top handhold vent and restrict the air intake.) There is another vent under the bottom carb....

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

All tests were conducted with the cowling removed and the front panel removed from the carbs. I did a link and sync according to the factory manual. Both throttle plates open to 90* at the same time and the nylon roller lines up on the linkage arm mark. I also pulled the flywheel to check for a partially sheared woodruff key just in case but that was fine and the flywheel was re-torqued to spec. I just replaced the fuel line from the fuel pump to the carbs today with alcohol resistant line just in case there was degradation but when I looked through the old ones there was no cracking or missing pieces. The fuel I was using was probably between 4 and 6 months old but had stabil in it. That fuel is gone now so I'll be filling up a tank with fresh stuff in the next couple of days and trying again. I'm also going to try and squirt some mixed fuel into the carb barrels one at a time to see if I get a consistent rpm increase or any other strange side effects.

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

How does the engine sound when at full throttle? Does it seem to be firing properly? Perhaps an occasional miss...any surging? Does the engine change it's sound while at full throttle? Any difference from when you first start it to when it is warmed up? Do you still have your original 4 coils that were on that engine? I might be inclined to put them back on at this point, just to see what happens. You can force extra fuel into the carbs by constantly priming the fuel hose bulb when at full throttle. Try that and see if the engine runs any better. You are probably running 5/16" fuel hose.

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

Motor doesn't surge but doesn't sound quite right either. A little on the rough side but no detectable miss and definitely louder than when running under 2500 rpm. The motor purrs nice and smooth below 2500 rpm. It was quite hard to start when I ran it the other day. I tried pumping the fuel hose last time I tested it but there was no effect on operation and the primer bulb stayed hard. The fuel line is 5/16". I'm hoping that the original problem has been fixed and that the hard starting and low wot rpm are being caused by the older gas that was in the tank. Are 2 strokes a lot more picky about fuel quality than 4 strokes?

 

[DargelJohn]

Re: 1979 85hp evinrude only gets to 3000 rpm

After reading this thread, I think you do have a fuel restriction issue. I know you have replaced the line from the fuel pump to the carbs. I would try a portable tank and fuel line setup.

You said the primer bulb was hard while it was running? Should be soft.

FYI - I use NGK plugs in my 88 SPL with no issues.

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

One of the first things I did during testing was switch to a portable tank but this problem has been going on so long now that I think the gas may have degraded to a point where that is now also an issue. As soon as the rain lets up for more than a minute I'm going to take the boat down to the launch with a brand new tank of mix and pick up a brand new OMC fuel line and primer in hopes that this will all go away and I will be happily boating again. Thanks for letting me know about the plugs I'll keep the ones I pulled for spares since they still looked good.

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

Two stroke outboards are very senstive to poor fuel, unlike all 4 strokes. They don't like stale gas and don't like any moisture in the fuel.
I empty my tanks at the end of the fall season in order to start with fresh fuel each spring. The engine requires 89 octane fuel according to the original owner's manual. That was superceded by OMC factory service bulletin 2159, dated 10/1986 which applies to 1985 and older crossflows. That bulletin states that if you convert/upgrade to 91 octane fuel, that no changes are required. If you opt to run any cheaper (lower level) fuel grade, that the timing on the engine must be retarded by 4 degrees in order to prevent long-term engine damage. The addition of a water separator filter is not a bad idea, considering the ethanol in today's gas.

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

Thanks for the info on the fuel I'll start running the 89 octane in it and see if that helps starting and performance. I do run a water separator and will reconnect it after the problems are fixed and it's running good again. I guess I should have been more specific on my fuel question, I have a 1988 70hp evinrude that doesn't seem to care what kind or how old the gas is that goes in it. That motor burns everything and hasn't given me a lick of trouble in the 10 years that I have owned it so I guess I should have asked "Are the V4 crossflow motors particularly picky or have I just been extremely lucky with my 70?"

 

[emdsapmgr]

Re: 1979 85hp evinrude only gets to 3000 rpm

A little luck always helps! I don't take a chance with my V4 and V6 crossflows anymore. I have experienced a number of issues with bad fuel.. The 3 cylinder is actually a loop charged engine. That's a different type of air/fuel charge and it may perform differently on poor fuels than a crossflow. I ran a 76 short shaft 3 cyls 75 for 6 years. Never had a lick of trouble and it always got 87 octane. Maybe I was lucky also. That was during the same time I had fuel issues with the V6.

 

[yjfun]

Re: 1979 85hp evinrude only gets to 3000 rpm

Well I tried it with brand new mix and still the same old story. Tried pumping the primer bulb and that didn't seem to help any but the bulb stayed soft like normal. Do you think that doing these tests with the boat on the trailer at the launch could be affecting my readings? Should I be doing this on open water instead?