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Reving to 6000+ RPM at Cold Start

K

Klink

Regular Contributor
I've tried every which way to cold start my friend's 1990 70hp Evinrude without over reving it, but it seems almost impossible. It has a priming pump which is controlled at key switch. I don't not like to rev my own 1990's Johnson/Evinrude engines at more than 2000 when I start them, but this one is impossible, on it's own it'll shoot up to who know what, 6000++, when the throttle is in a spot where it'll be 1800 rpm. Isn't harmful to start that way? Could it be puddling of fuel because of clogged fuel recirculation valves? Or is it just that some engines are like that?

I have not used the engine but in a tank so far, so I'm only talking about the initial cold starts
 
The electric primer is a VALVE that opens when key is pushed in and that item is not a pump.-----Time to check and adjust the linkages as per a factory manual I would say. ---Are you pushing the key in and holding it in while cranking it over ??
 
This engine uses a solenoid primer assemble, it squirts fuel directly behind the carb and into the intake manifold, I have looked at others like it on my 25hp and 115hp Johnsons and I could see the fuel squirts whenever I push the key in, I think it is an on-off switch, if you hold the key down it'll only squirt once. I have used these pumps to determine if the carb has a problem, for one can keep an engine running if the carb jet is clogged, since the pump can squirt directly past the carb​

Primer Solenoid assy.JPG
 
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It is not a pump.-----It is a valve that opens when you push the key in.------Pressure comes from the fuel pump when the motor is turning !!
 
OK, now I fully understand. Thanks for the explanation. That means I can just hold down the key like you instructed, so that I'll try it that way today on the water test. I was just pumping the key before.
 
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The system works when there is fuel pressure supplied to the solenoid valve.-----That pressure comes from the fuel pump when engine is cranking.-----Or from the primer bulb when operated.-----Some simple testing can be done.-----When you understand how things work boating can be so much easier.
 
In short.-----If there is no fuel pressure to the solenoid valve you can push the key in all day long and nothing will happen.-----Note that the supply hose to the electric primer tees into the carburetor supply hose from the pump.
 
Took the boat out for a sea trial, and holding down the key switch while starting the engine, I was able to start the engine without it reving past 3000. Later, after the engine was run at high speed for 1/2 hour, 4200-4500 rpm, when we turned off the engine to fish for like 1/2 hour, the engine was hard to re-start and run at idle in gear, it was idling too slow and kept turning off. You had to rev it up for a while to get it to stay on. This engine is difficult, not like the 25's and 115's I have had before, which just turned on again with a flip of the switch. Will have to go back and increase the idle speed again. Manual says to do the throttle cam adjustment over again if you re-adjusting the idle speed.
 
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Increased the idle speed screw to 1220 rpm on my hand held tach and now the engine turns on easier, without reving up. When it is run for a while at 4200 rpm when you turn it off and let it sit a while and the engine is cold, it now turns on easier and runs better.

That the end of that.
 
Correction:
Increased the idle speed screw to 1220 rpm in neutral on my hand held tach and now the engine turns on easier, without reving up. I do not know what the revs are once it is in gear, but there is no bump in the shift. It sounds like it is about 800 rpms (I forgot to check the rpm's in gear at idle speed when I sea trialed it). When it is run for a while at 4200 rpm, when you turn it off and let it sit a while and the engine is cold, it now turns on again much easier and runs better. ​
 
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