1990 evinrude 90 ran away!

[whalerfreak22]

hello all just got done putting my motor back together got my battery and gas tank out,hooked it up.started it and it ran for maybe 6 secs then shut off,noticed 2 plug wires were unplugged,connected them.restarted the motor nothing.put up my cold start half way( motor is on a stand out of the water),hit the choke started it fffffffffffffffffffrrrrrrrrrrrrrrrrrrrrroooooooooooooooommmmmmmmmmmmmmmmmmmmmmm rpms picked up and got way out of control i thought i was doing 9000 at least.choke was now worthless and i didnt have my wire harness hooked to it(hot wired by touching positive wire to the starter),then realized i wasnt hooked to any water so the motor ran for roughly 20-30 seconds without water.pulled the fuel hose died in the amount of time above.sorry that my storys long i wanted to be sure i didnt miss any details.my question is what could i have damaged?(impeller is fine i ran the motor a second time with the muffs and a kill switch).ran a compression test and i have 1.)120 2.)120 3.)120 4.)135 model number is e90tlesb

 

[whalerfreak22]

Re: 1990 evinrude 90 ran away!

???????

 

[Mntom]

Re: 1990 evinrude 90 ran away!

20 to 30 seconds would probably not do much. I have seen them run a lot longer than that and there were no issues. I would just go ahead and run it. Go have fun with it!!

 

[bob johnson]

Re: 1990 evinrude 90 ran away!

many times motors are started without water...but just to make sure it starts and then shut off,

yours going to super high rpms, surely could damage the edges of the impeller...

you could do one of two things...change it out right now..

or go buy a water pressure guage( nice to have anyway)... and monitor your water pressure and keep an eye on your temperatures.

you wont damage your motor if you pay attention and shut it off when it appears to be over heating!!!!!!!!!!!

no water isnt what kills your motor...

it is what happens inside because there was no cooling...

people run their motors with no lower unit for minutes at a time...motor starts to get warm..they shut it down...( obviously this scenario is during other diagnosis probably!!) ha ha


good luck

bob

 

[jtexas]

Re: 1990 evinrude 90 ran away!

The choke didn't shut it off? Or you forgot it can be manually engaged?

Myself, I'd replace the impeller. Neoprene rubber at 9000 RPM inside a chromed housing...don't you know that thing generated some heat!! You're betting $3000 to save $40. I'd bet $40 to save $3000.

If you do decide to take a look at it, post some pics...it might be in pristine condition, might not, I'm curious.

What was compression prior to this incident?

 

[whalerfreak22]

Re: 1990 evinrude 90 ran away!

The compression before this happened was 110 on 1-3 and 120 on number 4.my compression went up after it happened it now reads 1.)120 2.)120 3.120 4.)135 very odd if you ask me but maybe I burned up all the carbon bits in the engine.what do you think?and yes I manually was using the choke but it only slowed it down about 1000 Rpms no difference if no water in my opinion.the next time I run it I will have the airbox cover off and put my hands over the carbs making sure it kills instantly like insect repelant.

 

[jtexas]

Re: 1990 evinrude 90 ran away!

I guess that's one way to "decarb" a motor.

I really thought you could kill it by flooding it out with the primer. Sounds like you dodged a bullet.

 

[Craig-]

Re: 1990 evinrude 90 ran away!

I'd be more concerned with the cause of the over rev, the impeller is cheap to replace. Was the throttle wide open at start? Rev limiter in power pack should cut in at 6600 if there is one for that year, not sure.

 

[whalerfreak22]

Re: 1990 evinrude 90 ran away!

No I went half throttle just so it would stay running.I immediately put it back to normal but the rpms just kept getting higher and higher.I've checked my spark advance that's ok and my butterfly valves were closed but I think what caused it was That it was running it without water.all i wanted to do was see it would pop a couple times to know it runs.anyone have any idea what may have triggered it or do you think it was because I had no water running to it?I've done this to previous motors and never had this issue.

 

[DSinOR]

Re: 1990 evinrude 90 ran away!

....my question is what could i have damaged?...

My 2 cents:

From your post, there's no way to know how high it actually revved, or how long it was up there.

A boat engine that held 6500rpm for 15 seconds dry could possibly have no damage.

A boat engine that held 9000rpm for 30 seconds dry likely has a cooked impeller and possible damage to crank, rods, or related bearings.

When the piston comes up to TDC or down to BDC, it is moving fast. In between it must come to a stop and then reverse direction. The tensile strength of crank & rods and the load capacity of the related bearings is engineered to withstand the forces encountered within a certain rpm range. If you get outside that range, you can ruin bearings or bend cranks or break rods.

If your motor has a rev limiter, you might be okay with just changing the impeller. If not, who knows?

As far as why the compression increased, this could be attributable to different environmental factors (different cylinder and piston temperature, different cylinder lube conditions, etc), or fouling on the cylinder walls, etc.

I'd change the impeller and go for a ride, proceed carefully, see what happens. It may run for years, it may not.

Good luck!

 

[whalerfreak22]

Re: 1990 evinrude 90 ran away!

I really had no idea how many rpms I was doing it was just very high and loud(I live in a quiet neiborhood).also take note this motor is on a motor stand on dry land.I must say when I got the motor it felt very tight like it had compression now it's loose and has more compression.Is it because every thing got blasted with oil?I'm afraid to even start this motor I'm afraid it will do it again!the motor was also in neutral when this happened.thanks for your inputs btw.

 

[jtexas]

Re: 1990 evinrude 90 ran away!

Rev limiter works by controlling spark timing.

In this case, spark timing was irrelevent. Even the spark plugs were irrelevant.

You could have pulled all the spark plug leads and it would have kept running, as the source of ignition was hotspots inside the cylinders.

 

[whalerfreak22]

Re: 1990 evinrude 90 ran away!

So now that it's "decarbed" it shouldn't happen again?

 

[JustJason]

Re: 1990 evinrude 90 ran away!

if it ever happens again, and the air silencer is off, put your hands over the carb, that will kill it.

 

[1946Zephyr]

Re: 1990 evinrude 90 ran away!

If you didn't have the wiring harness hooked up, how can you tell what the RPM's were? At the length of time that motor ran at high RPM's, it's a very safe bet that the impeller is fried. It only takes a few seconds to roast one and in less time than you were running.

As far as loosening up the motor and getting more compression, that tells me that it's been a while since the motor has ran and you just soaked down the internal parts with fresh fuel mix. A very normal thing.

The real dangers in a "runaway situation" is when it twists your flywheel off and it chases you down the street. I would also check your flywheel key and make sure that it hasn't been sheared and check the condition of the crank, where it mounts.

 

[Craig-]

Re: 1990 evinrude 90 ran away!

Rev limiter works by controlling spark timing.

In this case, spark timing was irrelevent. Even the spark plugs were irrelevant.

You could have pulled all the spark plug leads and it would have kept running, as the source of ignition was hotspots inside the cylinders.

Huh? He said it ran a total of 30 seconds and had no way to kill ignition. I doubt it over ran the limiter, 9000 sounds more like panic.

 

[jtexas]

Re: 1990 evinrude 90 ran away!

Huh? He said it ran a total of 30 seconds and had no way to kill ignition. I doubt it over ran the limiter, 9000 sounds more like panic.

ah...so...not really a runaway then? I hadn't considered that.

Curious...wonder what might have caused RPMs to continue climbing even as he lowered the hi-idle lever? With spark advance back to idle timing, closed throttle valves....

"I went half throttle just so it would stay running. I immediately put it back to normal but the rpms just kept getting higher and higher."

without water, it would heat up faster than normal.

 

[noelm]

Re: 1990 evinrude 90 ran away!

thats why it is called runaway, it is quite common, and no amount of rev limiters, throttle position or anything else is going to stop it, you need to completely choke the air off, or remove the fuel hose and hope like hell! what RPM the motor achieved is anyones guess, but out of the water, in a panic it would seem like 9,000 easy! pretty exciting when it happens hey.

 

[bob johnson]

Re: 1990 evinrude 90 ran away!

could you pull a certain wire to stop that??

what about pulling the fuse....

bob

 

[Craig-]

Re: 1990 evinrude 90 ran away!

ah...so...not really a runaway then? I hadn't considered that.

Curious...wonder what might have caused RPMs to continue climbing even as he lowered the hi-idle lever? With spark advance back to idle timing, closed throttle valves....

"I went half throttle just so it would stay running. I immediately put it back to normal but the rpms just kept getting higher and higher."

Really doubt 30 seconds would result in hot spots. The impression I got with motor being on a stand, he was working the throttle by hand. Grounding the mag wire(blk/yel) should shut it down. Unless it really was running on it's own fire, in which case choking it should do the trick. Which makes me wonder if the throttle linkage was somehow skewed. Good thing it didn't kick itself into gear, picturing Wiley Coyote trying to catch the Roadrunner, riding it like a buzz-saw off a cliff.