1969 55hp Evinrude - Problems at more than 2/3 throttle

[rdh2059]

I asked about this motor last year, but none of the items identified made any difference. I'll explain it again - maybe I can do a better job explaining this time...<br /><br />Motor was purchased on eBAY for cheap - $300 after shipping. It needed a LOT of work.<br />- Main wire bundle had so many shorts that I swear more wire was bare than insulated - replaced wire bundle<br />- Rectifier was burned out - replaced it. <br />- Removed, cleaned in carb tank, then rebuilt all 3 carbs.<br />Removed lower unit - replaced solenoids (they were both burned out. Also replaced impeller. <br />- Repaired broken cavitation plate aluminum welded plate on, then ground to shape.<br />- Replaced fuel pump.<br />- Replaced T-stat.<br />- Usual tune-up parts - plugs, points, etc.<br />- LOTS of cosmetic work...<br /><br />Motor starts perfectly with choke on for about a second when cold, then restarts every time. When on the water, the motor trolls very smoothly - I usually use a kicker for trolling, but this last weekend trolled with it to see how smoothly it would work - worked great. The motor even runs up to about 4000rpm at 2/3 throttle fine. Its on a heavy 1961 fiberform runabout, so it only does about 20mph. <br /><br />Here is the real problem:<br />When I throttle it above 2/3, the motor starts kicking and sputtering, etc. I have taken it to two different marine mechanics and they both say nothing is wrong, but neither have a tank that they can tank the motor in. Here is what's wierd, I discovered that when throttling above 2/3, if I press the choke switch it smooths out and I gain around 3 mph and several hundred RPM. <br /><br />I have tried the squeeze the bulb trick, but that does nothing. I have checked the timing and it seems to be correct too. Compression check indicates 120, 120, 119, so its good.<br />Is this a case of some air leak causing the fuel mix to lean out until at about 2/3 throttle it cannot run anymore? That explains the choke trick, but I cannot find any air leaks on the carbs. <br /><br />Does anyone have any ideas? The motor I used to use is a 67 evinrude 40hp. This motor gets on a plane MUCH easier than the 40hp did, but I doubt I'm getting more horsepower than the 40... Is there any hope short of plastique and starting over?<br /><br />Rick

 

[Silvertip]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

If hitting the choke causes the engine to smooth out, you have a fuel delivery problem and I suspect its carburetors, not fuel pump since squeezing the primer bulb doesn't help. Even though you said you rebuilt the carbs, did you totally disassemble them, soak them good and clean all internal passages and then blow them out with compressed air before reassembly? And did you use new parts? Is the float level set correctly? Have you done a compression check just to make sure the engine is sound in that regard. Was link & sync performed after reassembly?

 

[rdh2059]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

When I rebuild carbs, I always take the carb apart down to the housings and components, then put all metallic parts into a carb cleaner dip tank and soak for at least 60 minutes before removing, rinsing with water, blowing out with air, then cleaning again with cans of carb cleaner. Sounds like my best bet is to strip the carbs down and do this all again... The motor so close to working perfectly now...<br /><br />One more thing - I know from experience that carb dip cleaning tanks will even strip off corrosion from brass fittings, is there any plastic parts in any of the passages inside the housing that could be dissolving or warping in the cleaner, on this particular carb?

 

[R.Johnson]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

Starting from the beginning, touch the wire's on that era engine, and you have a handful of crumb's. Did you replace the wire's from the ign. stator plate to the pulse pak. That engine has point's, what condition are they in? It has a vacuam diaphram, is the rubber cover cracked, or have any holes? When you rebuilt the carb's, did you replace the nylon bearing seat's under the low speed needle's. The carb's have nylon retainer's for the link arm's on the carb's, they have to be shot by now. Is that engine in proper time, along with the sync, & link. I had a post about cleaning carb's by using letter, or number drill's for clearing all jet's, and passage's, ( I use pin guages in a pin vice) you can't always count on cleaner, and compressed air. Has that engine ever had the cylinder head off?

 

[rdh2059]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

The wire bundle from the ignition back to the motor was not only resistance checked, but also visually verified. 2 wires required replacement, but other than that, the bundle is ok. <br /><br />The points are in good shape - were not corroded at all, just normal point burn (filed and regapped).<br /><br />The vaccuum diaphram is in very good condition. Still flexible with no holes or cracks.<br /><br />The retainer arms on the carb linkage were all replaced. Yeah, they were brittle and in dire need of replacement<br /><br />I did check the jets for their diameters with wire gauges. I did not check every passage via drill bits.<br /><br />The cylinder heads have never been off that I can tell. Just down to the reed valves. The compression is good (120, 120, 119 psi), so removing the heads seems like overkill, if the compression is good and the motor runs fine at 3000 rpm...<br /><br />Seaway Marine LOVED me the week this purchase order came in...;-)

 

[Joe Reeves]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

Hitting the choke and having the engine smooth out momentarily at a high rpm indicates that either fuel isn't being delivered to the carburetors, or the high speed jets in the center bottom portion of the float chambers aren't fully cleared.<br /><br />However, that engine has three (3) lobes operating dual points. Check the point setting on all three lobes, seting the points to .010 . If a one lobe results in a different setting, have the widest setting set to .010 .<br /><br />Example:<br /><br />Lobe-1=.010, Lobe-2=.009, Lobe3=.010 is acceptable.<br /><br />Lobe-1=.010, Lobe-2=.010, Lobe-3=.012 is not acceptable as this will usually result in having the .012 setting float and cause erratic ignition.<br /><br />This type problem (points) would show no improvement simply by spraying fuel in the carburetors (as mentioned above), but it's something you might want to check.

 

[rdh2059]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

So this evening I checked the float levels on all 3 carbs. I don't know exactly why, but the floats on all 3 carbs was 1/32 inch too high. If I am doing my right side/upside down thinking correctly that would make the carb run lean, which tends to support the choke making it run better. I remember working on older carb based cars and the floats in them was so inexact that you could be an eighth of an inch high or low and it would work normally. Are these outboards that precise on their float levels?<br /><br />Also the points were all .010...<br /><br />I guess I'm back at doing another fishing trip, er that's fishing trip this coming weekend...;-)<br /><br />You all are great help!<br />Rick

 

[Silvertip]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

If the float were set too high the engine would have too much fuel in the float bowl and therefore run rich -- not lean. If you meant the float was high with carb inverted then what you said was correct. I doubt that a 1/32" error is causing the problem. Double-check that the tank vent is open, anti-siphon valve (if there is one) is operating properly, the tank pickup is clear, and all other fuel related components leading to the engine are clear. I still feel this is fuel related and not electrical. Where did this engine come from? Could be high altitude jetting which would be way too lean for sea level to 1000 feet or so.

 

[rdh2059]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

I bought the motor on eBAY, from someone in Ohio.<br /><br />I don't remember the exact numbers on them, but when I rebuilt the carbs, the jets checked out as normal diameter holes. The specs are in the book, not in my head though...<br /><br />When I described the float adjusting as being too high, I literally meant the gap as measured with the carb upside down...

 

[R.Johnson]

Re: 1969 55hp Evinrude - Problems at more than 2/3 throttle

Rick: As long as the float is level with the carb body, you will be just fine. I have alway's set float's this way with never a problem. That smoothing out with the choke, but not the primer has me wondering. If you have a timing light, put it on each cylinder, and see what it shows. What does the plug look like on each cylinder? You could try this, make up a plastic squeeze bottle with a plastic straw such as that which comes from a can of WD-40. Spray mixed gass into each carb throat at full throttle, and see if the engine pick's up.If so! you have a fuel restriction. I'm not sure what you have, fuel, or spark problem.