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70 up evinrude overheating!

T

Two Rivers

Member
seeking some direction?
Over the past winter I replaced the water pump and fuel pump on my1990 70.
Both pumps are OEM.
The original fuel pump was a bipassed bro replaced with non bro pump.
Changed all the fuel lines.

Compression is 120 across all cylinders.
Good spark. Motor is peeing strong. I removed tstat and checked in hot water.
Motor starts instantly and runs well at low rpm’s. Get up to or over 4k and shortly the steady overheat horn goes off and motor dies down.
I’m thinking it’s leaking air somewhere?
I didn’t remove the fuel pulse limiter when I put the new fuel pump in. I just ran a line from it to the pulse port on the pump.
When the overheat horn goes off I check the top of the motor temperature with a surface thermometer and it’s hot. Around 172.
Any ideas how to troubleshoot?
Could it be something other than an air leak?
Thanks in advance for your consideration.
 
Make sure the water intakes on the gearcase are not broken & they should be reasonably flush.

*Was it overheating last year?
*Did you replace the impeller as a precaution?
*Did the old pump have any broken off pieces that were unaccounted for?
*Did you use OEM pump, Sierra pump or some Amazon or EBay Chineesium pump?
 
Droid said:
Make sure the water intakes on the gearcase are not broken & they should be reasonably flush.

*Was it overheating last year?
*Did you replace the impeller as a precaution?
*Did the old pump have any broken off pieces that were unaccounted for?
*Did you use OEM pump, Sierra pump or some Amazon or EBay Chineesium pump?
Click to expand...
Once last year on July4 weekend had bunch of people on the boat in turbulant water the alarm went off.
Thought maybe trim was set wrong and had some cavitation going on?
Used the boat for the rest of the summer into late fall on lake Erie alone or with one other fisherman and zero issues.
Boat is only used in fresh water and always trailered.
This winter while inspecting motor I noticed some white discoloration around the seam of the VRO pump.
I thought maybe if was pulling some air (being 35 years old) so I decided to replace with a regular pump.
Water intakes look good. Get water shooting out all of the ports while on the muffs. Peeing strong.
Impeller / water pump kit replaced as part of regular maintenance. Old impeller looked good and was intack.
All OEM parts, no junk.
I'm no expert but I've replaced maybe a dozen or so water pump kits over the years and never had a problem.
Could I have messed something up?
I'm going to go over my hoses again.
Primer bulb doesn't stay hard but makes no difference in performance while pumping the bulb while running?
Summer is rolling on by and I haven't caught a fish yet.
 
racerone said:
No---Nothing to do with overheating.-----Did you install the latest water pump kit and do the modifications?
Click to expand...
Yes.
Years ago with your help I drilled and tapped the top of the housing and moved the hose to that position.
Instructions in the new kit said to replace the tstat housing cover with new supplied cover and straight (red) spring.
I did.
 
tried and failed uploading a video of motor at idle. Exhaust mist and light smoke coming out of prop shaft area.
Is that normal?
Never paid attention before.
Checked lower unit oil and it's clean with no water.
I used fuel pump number 438559 OMC
Is this the correct pump?
 
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