90's era 48hp twin, dies at high rpm

pcrussell50

Petty Officer 1st Class
Joined
Sep 21, 2008
Messages
296
trying to help a friend with engine troubles...

it's a 90's era evinrude twin cylinder, 48hp

when you run it up to near max rpm, it just dies. it does this on the muffs, too. if you're quick and can bring the fast lever back down to idle, you can keep it from dying, as it idles fine

static symptoms:
-pushing in key produces no audible choking clicks. edit: not true, cleaned the contacts and you can hear it clicking when you push in the key
-there is no visible choke and linkage
-there is a solenoid cylinder with a fuel feed line and two small fuel lines that go to the tops of each carb, [more on this, later]

running symptoms:
-the main problem: when you run it up to near max rpm, it just dies. if you can bring the fast lever back down to idle, you can keep it from dying

-very hesitant to spin up to high rpm
-when it does spin, there is a big billow of smoke, [symptom of richness]?
-i have not been out on the water with it, but i'm told it died on them when they tried to run it on plane, [16 foot glastron tri-hull].
-it floods and then becomes hard to start
-the telltale water flows strongly on the muffs, but was always cold, never warmed up
-took off the thermostat cover, thermostat must be held in with some sealant. i did not pry it out. when i pulled on the plunger, to "open" the thermostat, warmish water did come out

back to the solenoid cylinder
-what is it?
-what does it do?
-can it cause richness?
-it has a red plastic rotary knob with a schrader valve?
-when i took the top off of it, to study the diaphragm there was a plastic knob at the end of the pintle/solenoid shaft. it was loose in the red knob's cutout shaft.
-it looks like the purpose of the solenoid is to prevent full rotation of the red knob when de-energized, and to allow it when energized

that's all i got. i never was there to ride in it and see how it dies. all my observations are from the muffs.

so far, i suspect the thermostat is stuck cold, and that solenoid thing is... ah, well i don't know what to think about it, except that it does "plunge" when i remove it from the motor and jump 12v across it.

-peter
 
Last edited:

pcrussell50

Petty Officer 1st Class
Joined
Sep 21, 2008
Messages
296
Re: 90's era 48hp twin, dies at high rpm

After some research and tips from another site, I find that the primer solenoid's manual valve was in entirely the wrong postiion, allowing all kinds of fuel to be introduced at who knows what inopportune times?

I will get the boater with the stricken motor over to my house later today, and try it with the primer solenoid's manual valve in the proper position. It also has a small leak, that I think is not causing the problem, but the parts are available to fix just the plastic parts, inexpensively, without having to buy the expensive parts, [the solenoid/electromagnet part].

-Peter
 
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