1987 Evinrude 100hp - Need help regarding way it starts/runs and possibly overheating

[tuggeyt]

Hello, First let me say I apologize for the length.. but I have a 1987 Evinrude 100hp Commercial outboard...
Been working on it/restoring it and stuff for a few months now(slow process I know).
Anyways, I have a couple questions regarding the motor and some of them are just me being a little cautious as I am nervous I might mess something up
and be out of a motor....

Now here's a list of things I have done to this things....
Impeller, Prop shaft seals, Electric Solenoid, Starter, Carbs rebuilt, Thermostats, plug wires, fuel filter/water separator, fuel hose/bulb.
The motor was a VRO but that was all also....
Compression for all four cylinders are between 111-115...
Now here's a couple questions about it....

1 - When I start the motor - I put the Fast Idle Lever on the control box up to the start position, I turn the key a little and push it in twice, to activate the primer solenoid. I then turn the key all the way over and start the motor... Now right when the motor starts because the Fast Idle Lever is up it starts with very high RPMs, now I mean it sounds like its a max throttle and itll backfire some... I then turn the Lever down to the idle position where the RPMs drop down and the motor sounds pretty normal for a few seconds.

After that the motor while run normal for a few seconds but then it starts to choke and sputter and back fire it sounds, and right before it dies I will lift the Lever back up a little to rev it up and it revs up high again like its a max throttle and itll back fire and sputter more. The longer I run the motor the lighter these symptoms get. After about 10 minutes of this routine itll start to idle with the lever at the position for a little longer like a minute or two but then itll start to try to die again....

Now Ive taken the boat out on the water once so far and at first it didnt go to well. Once I got the motor running if I put the throttle down there was absolutely no power to the motor, I would be in idle speed at all times.... So I kept the throttle in gear just to idle the boat around at a low speed for about 10-15 minutes. After that I put the throttle down and the motor work kicked up and seemed to run perfect... Only used it about another 15 minutes like this as it was just a test run and had to go back to shore....

Is this normal for a old motor? What can I check? I know it sounds a lot like carburetors but they were rebuilt.... Now before I tear them down does anyone have any other ideas?

2 - Another thing that happened, I started it up one day on the hose and ran it like I mentioned above... for about 10 minutes... After that I shut it down and got curios and touched the heads on both sides of the motor. The starboard side was warm and I could keep my fingers on it as long as I wanted... Now the port side was pretty dang warm... I put my fingers on it and had to remove them after about 1 second... The motor was pissing great out of the tell tale.

So this it what led me to change the thermostats, which is a horrible job :mad-new: lol... But when I took the thermostats out, the starboard one was stuck open by debris.... the port side was corroded some( pretty sure they were the originals) but if I push hard enough it would open... So this could explain the temp difference between heads... Now the starboard would be cooler since it was stuck open but the port shouldnt have been so hot to the point I could only have my fingers there for about a second...

Whats the normal operating temp for my motor? at idle off a hose and if Im running it in the water what should it be between? Now since I replaced the thermostats I havent started the motor ( lack of time recently) but when I go to start it again what are some things I can test to make sure its cooling the port side?



Thank you for your opinions and help in advance....

 

[Bosunsmate]

first thing, you only push the key in to activate the choke while you are activating the starter (very important).When the motor starts to die again you push the key in again, thats called bumping the choke. This should mean you can drop the start up rpm quite a lot

 

[Bosunsmate]

a motor doesnt take ten minutes to heat up, check its warm after two, check spark can jump a 7/16 gap on all cylinders.
just read your bit about replacing thermostat, that might fix all your problems. You should be able to put your hand on it for ages, if not, shut it down, let t cool then return to base asap.
ps running on muffs isnt good for long, test in a barrel thats got water halfway up the leg or in the sea etc

 

[Bosunsmate]

60-70deg celcius at idle, lower at full throttle as more water goes through it

 

[emdsapmgr]

Best to have changed both stats. They will open when the block reaches 143 degrees. At idle, the engine should run between 143 and 150, maybe 155 in the summer in a warm lake. Use a laser temp gun to check temps on the heads. The head temps will go down significantly if you rev the engine or when the boat planes out. That's when the thermostat pressure relief valves open and floods the powerhead with extra cooling water. Temps could go down maybe 20 degrees at that point-depending on the lake water temps. The valve body in the stat housing has either two pinholes or one larger hole. Those holes are part of the cooling system and must be clear (open) for the stats to work properly.

 

[tuggeyt]

Ok well the temperatures are normal so mainly just focused on its running condition now.
I finally got another chance to take the boat out again and it was a little bit of a pain.. Here's what it does..
When I start the motor and have the idle lever up itll stay running as long as that's up.
When I put it down so I can put it into gear, it dies instantly.
I managed to get it into gear a couple times but only after playing with it for a little.
But then if I keep my motor at a slow idle speed like a no wake zone it dies.
I put the throttle down all the pay for a brief second and it kicked up perfect and ran.
Just at low speeds and when I try to put it into gear it dies a lot.

 

[emdsapmgr]

Check to see what the idle rpm's are. You validate the idle rpm's when the boat is floating normally in the water and the engine is shifted into forward gear. Should idle at 650-700. Maybe 750. You can't set it on the trailer. If the idle rpm's are set correctly, it should idle for hours without a problem.

 

[jakedaawg]

If you have the manual do a lynch and synch. If you don't you may be able to search under my name and find a really long post i wrote out that will fit your engine except for the timing degrees.

 

[tuggeyt]

Ok, started to play with it again and was going to check the RPMs but now have a new problem....
The rpm gauge does not work also noticed that my motor does not charge the battery anymore.
So I'm going to play with the wiring and see if anything is loose or broke. But if nothing is,
then would it be the stator or the rectifier? My model has power T/T, so I believe it's the water cooled rectifier.
How do I test them both?

Thanks

 

[Chinewalker]

The primer solenoid is nothing more than a valve. It is NOT a choke. Bumping it twice before starting the motor does nothing. The key MUST be held in while you're starting the motor for it to work. The fuel pump's action pushes fuel through the primer solenoid valve into the carb body, squarely into the manifold to richen up the fuel charge. If the motor isn't turning over, activating the primer solenoid does nothing. Once the motor starts, you may have to bump the primer a few times until it warms up. As noted above, this should take no longer than a minute or so.

There are test procedures for both the stator and regulator outlined elsewhere on various iboats threads.

 

[emdsapmgr]

That engine shows a combination rectifier/regulator was stock on that engine. That device is responsible to re-charge the battery and to send the signal to the tach. When the tach starts to act up-likely the device is about ready to fail. As it does, it quits re-charging the battery. Probably need a new water cooled combination rectifier/regulator.

 

[tuggeyt]

ok well.... while I was playing with stuff I found out why the tach was not working. The plug that goes into my control box came out without me noticing... I plugged that back in and gained my tach back... however I'm still not sure if the battery is charging, and something is going on with the tach its pretty jumpy.. I took some videos so you can kind of see whats up. Also notice how in the first video the rpms just randomly jump? It did that a couple times today when I was running it... it jumped anywhere from 3000ish down to 0 while.

 

[tuggeyt]

another thing is..... when I took it on the water in the third video.... there were a couple times i put the throttle down all the way and it felt like it was at half power.. had to cruz for a minute before putting it back down al the way and it would kick up again...

 

[emdsapmgr]

A poor-idling engine may be due to dirty carbs. You may find that disassembly and through cleaning may make them function better. When that engine idles, the carb butterflys are closed. The only fuel the engine gets is from the idle passages in the carbs. If these are restricted at all, the engine won't idle well. (A common problem on dirty/restricted carbs.) If you bump the throttle up just a little, the butterflys open slightly, and the carb will provide fuel from the mid-jets. Likely the engine will run fine from midrange up to WOT. If you want to solve the idle problem-a good carb cleaning may be the answer. These idle passages do get restricted from years of accumulate dried fuel gelatin-left over at the end of the boating season. If your engine suddenly loses/regains power, likely you have some ignition component which is acting up. Stator, timer base or power pack.

 

[tuggeyt]

The day before I shot those first two videos I went ahead and tore apart the carbs and cleaned them.
You mentioned loosing and regaining power could me a sign of ignition problems.
There were a couple times at WOT that the motor would only run at about half power.
To stop it I would have to run at idle or half throttle for a minute then kick it back up.
That coupled with the tach being very jumpy and I don't think the battery is chargeing.
What's something I can test/ how do I test?

E/ also do my carbs have idle adjustments? Here's a diagram of my carbs.
If I do can someone point out which number it is on the diagram and how do I adjust it.
bo.ats.net/parts/search/BRP/EVINRUDE/1987/E100WTLCUA/CARBURETOR/parts.html
Take the period out of boats

 

[emdsapmgr]

Your carbs have fixed idle jets. The actual idle rpm's are set by adjusting the spark advance. (higher or lower.)

 

[tuggeyt]

Ok I'm still learning stuff on the motor, so what's spark advance lol?
I'm assuming it has to do with the spark plugs? Lol....
How do I test/ adjust them to make sure they're right.
thanks.

 

[Chinewalker]

When you operate the throttle control, you'll see the linkages moving on the starboard side of the motor. The top arm of that linkage is attached to the timer. The timer controls the spark advance in relation to flywheel rotation. At higher RPMs the spark is advanced to provide more power. At lower RPMs it is decreased to provide better idle. That timing of spark vs. throttle is critical and should be done with a manual in hand. HOWEVER, unless it has been messed with, it generally doesn't go out of whack on its own, so unless you suspect someone has adjusted the timing, leave it be for now.

On a side note, the timer should move freely with the throttle advancing/decreasing. If it sticks, or acts jumpy, that could cause running issues.