TOPIC: Motor starts great but dies at takeoff

My 1979 Evinrude 55 hp started up nicely this weekend at the lake. But when I got ready to take off for the boat ride, it would smother down and die when I pushed forward on the throttle. After a few times of restarting, it finally took hold and went. It then acted fine and I made several rounds out in the lake and come back to pick up my buddy from the boat ramp and it done the same thing again, died when trying to take off. This time it didn't really seem to recover from it so I loaded the boat back onto the trailer so I wouldn't get stranded out in the lake. The boat is a little 14 foot 61' Crestliner Mustang runabout. Motor has good compression and spark, carbs were cleaned a couple months ago and I let the gas pump out of carb when loading onto trailer last trip out and that was a month ago. Everything seemed fine that trip and it didn't die when accelerating. My trim pin is set on the second hole up from the lowest position (I don't have power trim). Was it flooding?

First thing to check is spark from each coil (put timing light on plug wire with motor idleing to see if it is firing smoothly. My 65 Evinrude had no spark from the bottom cylinder's plug (#3). Turned out to be a plug with no gap - once re-gapped all is fine and no-longer stalls going into gear.

If that is not the problem, check to see that the choke is working correctly.

Lastly - check the timing if others did not resolve the issue.

Ok will do, thanks a lot

Couple more easy things
Make sure hose connections are good.
If portable tanks is the vent open?

D

another easy check are the wires. I had an old 69 40 hp that ran fine at idle, but did what you described. turned out that as revs went up, wires failed - they were old and had some tiny cracks that were grounding I guess. Replaced wires (as i had already replaced weverything else)and all went fine...

herters59 wrote:

Couple more easy things
Make sure hose connections are good.
If portable tanks is the vent open?

D

Pretty sure OMC tanks of this vintage are vented through the cap, like a car. Tank itself does not have a vent. Might not be a bad idea to spray out the gas cap with cleaner or try a different one.

Hose connections are a good idea as seals can get iffy at this age and the connectors can be easily found at a marine dealer or even many sporting goods stores.

The vent is on the gas cap, like ggreggc mentioned...it was opened because I actually remembered to check that (I have forgotten it in the past). But the cap is a little gummy so I will clean it, it needs it either way. Will check wires too.

If you are using the OMC (Evinrude or Johnson) 6 gallon tanks from the period, the venting is via a diaphram that is opened when the fuel line is attached to the tank (it is the second pin on the mechanism that the fuel line connects to). These can plug and gum up, but that is unusual.