Engine died down at high RPM.

mushman

mushman

Junior Member
I put the boat in this morning, took her out for a good run.It was going great for a while, but after I opened it up for a minute she died down from 4200 to like 2500, I thought it stalled out.
I threw it in neutral and saw it was still running so I threw it into gear and there she went.
I kept it at low rpm heading back to port, the throttle seemed to be pushed farther down than usual, but the rpms stayed low.
It idles fine, and starts right up,and all the plugs seem to be getting spark.
I didn't open it up again because I didn't want to get stuck and have to call for a tow.
I didn't run it last year, but I did drain all but 15 gallons of gas out of it last week,then added 10 gallons fresh gas ,oil,and sea foam.
I just changed the thermostats also, the old ones were shot.
I did notice that the 3 starboard plugs were really "wet" while the port plugs looked alost new.
I hope it's a fuel issue or something managable, because I can't afford a new powerhead right now.
It's a 1986 150 hp v6 Evinrude.
Thanks.
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Checked the usual?

Bubble flat due to vent blockage or the like?
Fuel hose crimped? (this did happen to me once on another boat, the cooler was mashing the fuel line)
Filter possibly almost stopped up?

Don't like the sound of one side keeping the plugs wet.
 
Thanks Tsubaki,I was just reading another thread at continuouswave, and fuel,water issue seem to give same almost the same syptoms for the bogging, which would make me happy.
I don't like the one side getting fouled up either.Any ideas on what may cause this?.
I dread the thought that it may be the PH, and of course that's all I can think of right now.
I did notice when I was draining the gas that I was seeing lots of air bubbles getting into my syphon tube.I had it connected to the gas inlet under the cowling.Is this normal?, it would bubble up so much it would stop the flow so I had to keep pressing the bubble the whole time.
 
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I had the same thing happen to mine, low RPM's and wet plugs on one side. It was a power pack.

Mine was 86 175 so they are the same motor. Skools told me the deal at the time. I forgot how I tested it?? Or I just bought one and changed it?

Well Therm, Spare, Skools, and the rest will be by soon to help.

Good luck
 
Easy There

lets not go crazy thinking the worst
it sounds like a fuel problem to me
do you have a fuel/water sepperator?
if you do change it also check the vent line on the outside of the hull make sure its clean and open
could also be an electric problem
stator/switchbox
oh wait i just remembered the switch box operates half of the plugs so went it cuts off it will shut them down causing half to get wet
while its running bad be careful and pull 1 wire off hold it to the block and see if your getting spark then the other side if no spark the switch box is the culprit
you didnt say what kind of engine you have
i had the same problem with my merc but it was sounding the oil alarm it depends on what switch box is bad it would run great then throttle would cut to half speed with the oil alarm going off
 
a 150 evenrude i should have read to the bottom sorry but it can still be the same problem let us know there easy to change on a merc
 
Thank guys, It's a 1986 150hp 6 cyl Evinrude.I'd be happy with either the power pack (power pack looks to be just under 100)or switch(havn't looked that one up yet).
When I had the engine running at idle back at port I pulled each wire and I could hear the spark clicking and feel the engine bog.It would right itself once I plugged it back in.
I never held it to the block though.
Steplift, are you saying do them one at a time, disconnect then reconnect and move on, or disconnect one side leave it off then disconnect the other side?.
Thanks again guys.:beer:
 
I did the same now that I remember, while running pull the wire off one plug, then again on the other side, one side makes no difference then thats the bad side. and means the switch.
I did that to find out why my motor was not shutting down after I shut it off, the yellow & Black wire on the left side was not connected, I found the break and all was well again
 
We had a 115 do the same thing.
After a couple of weeks swapping powerpacks, unplugging plug wires, etc,etc, we found in a repair manuel somewhere how to test the powerpacks (gave resistance values).
The powerpack did work but had weak values at high rpms when warmed up.
Come to find out the first powerpack purchased was also bad, apparently someone used it, returned it and they resold it.
Try the cheap and easy stuff first (might as well call it annual maintenance), plus it gives you a piece of mind.
 
I have the clymers manual it has a voltage test I'm going to try first.
I did find some on ebay from 55.00 and up.While I'm at it I'll try the plugs to see if the switch is bad, and remove the fuel water separator and see what's in there, plus check the vent.
Does the air in the fuel line sound like it could be an issue?.Should I try changing the bulb out?.
 
What boat do you have?
Better yet where are the fuel tank(s) located?
Almost sounds like a split at the top of the pickup tube in the tank.
 
Air in the line could be a number of things.
Usually it will straighten out by pumping the bubble till it's hard.
If no fuel leaks or smells are evident and the air persists, you may have to check the pickup tube coming out of the tank for a split.
 
It's a 1986 steplift, the tank is in between pedestal and back to back seats in the front of the boat right before you step into the cuddy.
I was using a clear hose to get the old gas out and I kept getting so many bubbles in there it would kill my syphon flow.
I had it attached to the fuel line before it went into the fuel filter under the cowling.
I didn't clamp it, but it was a real tight fit, and I didn't see bubbles comming in from around the seal.
How would I check the pickup tube for a split?.
 
If you're sure there aren't any loose connections between the tank and the point where you're getting the bubbles, remove the hose at the tank and try the same thing at the fitting at the tank.
Useing the clear hose helps a lot.
I'm sure this is going to involve removing a floor hatch and a lot of other crap.
Try everything else first, replacing filters, checking for loose connections (there should be a gas leak)
If you have to access the tank, might as well inspect the fitting and tube by removing it. Last resort.
 
This is off a saddle tank

The pickup tube rests down below the place where the fittings tighten into the tank and have a filter.
Picture065.jpg

The fittings have a ball valve in them to reduce siphoning.
Picture074.jpg

Try everything else first.
 
i would check each wire see if your getting spark
the prblem is you can be getting spark but one side can be wee=ak
also check the vent
while your driving and the engine cuts down take the fuel cap off and see if it returns to normal if it doesnt its not the vent
 
First things first, get you a helper and go for a ride. Have somebody pump the primer while it is acting up and ses if that clears it up. If it doesn't change anything, swap the powerpacks from side to side. Then see if the wet plugs clean up and the good ones look wet. The simplest ignition diagnostic tool is a spark tester with an adjustable gap in it, you can get them from any auto parts store. Open the gap up to at least 7/16" and check each wire idividually. If you have GOOD bright spark at each cylinder then most likely it isn't an ignition problem. The proper tool is a peak reading volt meter. MAKE CERTAIN THAT IT IS A PRV STYLE METER! Just because your meter says it will measure peak voltage, doesn't mean it will read correctly. My DVOM would read barely good on some systems and great on others, but with the CDI PRV adapter it reads consistent voltage. If you don't have access to one, then try swapping the packs from side to side. This will help you to narrow it down if it's a pack or not. The PRV eliminates alot of the guesswork though.
 
THEFERMANATOR said:
First things first, get you a helper and go for a ride. Have somebody pump the primer while it is acting up and ses if that clears it up. If it doesn't change anything, swap the powerpacks from side to side. Then see if the wet plugs clean up and the good ones look wet. The simplest ignition diagnostic tool is a spark tester with an adjustable gap in it, you can get them from any auto parts store. Open the gap up to at least 7/16" and check each wire idividually. If you have GOOD bright spark at each cylinder then most likely it isn't an ignition problem. The proper tool is a peak reading volt meter. MAKE CERTAIN THAT IT IS A PRV STYLE METER! Just because your meter says it will measure peak voltage, doesn't mean it will read correctly. My DVOM would read barely good on some systems and great on others, but with the CDI PRV adapter it reads consistent voltage. If you don't have access to one, then try swapping the packs from side to side. This will help you to narrow it down if it's a pack or not. The PRV eliminates alot of the guesswork though.
Click to expand...


You gotta love him!!:clap:
 
Thanks guys.I'll look into getting the meter.It would be way easier and quicker with the meter than switching packs around.
According to my manual it says to open the 3 wire connector then go one side to ground then crank engine and check 2 wires.My manual has a diagram, and it looks pretty straight forward.
I'm looking for 180v or more right?.What is the minimum before a pack is considered bad?.
I have different volt meters at work I just need to see what the specs are with them, but I won't go there till Monday, so tomorrow I'll try some of the other suggestions before I'll be heading out with the family.
 
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