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1976 70HP Evinrude Boat Test

J

jim18611865

Regular Contributor
Thanks for all your help getting this far.
Boat tested yesterday.
Started easily. Going into gear was OK but at about 1500 RPMs it wanted to die.
I was able to finally feather it up and get to WOT. I was over 5500 but able to dial that down easily.
I was able to get to WOT 3-4 times, for 2-3 minutes each time.
It started getting worse the longer we were out there.
Finally I really couldn't keep it running.
Went back to the ramp with the 8HP kicker, so I am pretty sure the fuel is OK.
I popped the plugs out of the bottom of the carbs while out there, and they all had fuel in them.


History. This is a 10 yr.+ sleeper motor in great cosmetic shape.
I redid the entire fuel system (fuel pump, lines), with all OMC parts including new carb kits.
New water pump and new thermostat. New gear oil.
The throttle control rod had been messed with because earlier I couldn't get it running in the driveway,
until I set it back to that very precise distance of 4 31/32".


If it was just the mid range issue, I would say I need to do the factory bulletin 1144? But could any one have lived with
this issue for several years? The mods have not been done.
I did the Joe Reeves timing check this morning in the driveway. Appears to be at 12 degrees. Close enough?
I also tested compression and spark again this morning.
All three had very healthy spark.
Compression was T=110, M=110, B=105.


I am open to any suggestions.


Thanks
Jim
 
I would have to say no. You are referring to chapter 4 page 12 of the factory manual?
I didn't hook a timing light and set it at 750 rpms, with the mark at TDC.
Is that what you are referring to?
Is 4 31/32" (throttle control rod) just a starting point or does it have to stay there?

Jim
 
I can't reference the manual until I get home a little later, but it is the procedure to make sure throttle linkage, cam, carb butterflies, timer base, etc, all move when they are supposed to. There's a bunch of good write ups on here or through a google search.
 
Compression should read about 140 PSI.----So test with another gauge first.----Or pull cylinder head.----If nothing wrong a head gasket is cheap.------These motors have also had issues with exhaust covers leaking water.
 
UPDATE! 8/31/2021 Success! It was the link and sync. I think I finally understand this procedure. Did it a few Saturdays ago, but I would swear we live in Seattle now with all the rain.
Ran it for about 3 gallons of fuel today. 5500 RPMs for quite a while.

It does have the Service Bulletin 1144 issue, but I can live with that. It wants to bog down in the 1500 to 2500 RPM range especially when cold.
But it doesn't stall. I blipped the choke like the bulletin said to and sure enough it took right off.

There is one last minor issue but I will start a new thread about that so it doesn't get lost in this thread.

Thanks again everyone!!

Jim
 
jim18611865 said:
I would have to say no. You are referring to chapter 4 page 12 of the factory manual?
I didn't hook a timing light and set it at 750 rpms, with the mark at TDC.
Is that what you are referring to?
Is 4 31/32" (throttle control rod) just a starting point or does it have to stay there?

Jim
Click to expand...

Can I ask you where you got this measurement and from what points to measure this rod? I feel like this is the flaw in my link and sync.
 
Chapter 4. Page 4-12, figure 4-22 of the factory manual.
Stern end of the rod to the stern side of the yoke. Picture 4-22 shows it clearly.
It was just a starting point, I did end up adjusting it a little.

Jim
 
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