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Discussion Starter #1
I have a 2001 90hp Johnson Ocean Pro outboard ( only 130 hours on the motor )and it died on my Sunday. I was cruising along about 3500 rpm and the boat had been in the water for about 30 mins. This is the 8th time I have run this boat this season. As I was cruising along I felt that sickening feeling of loss of power. In a 10-15 second period the motor slowly lost power and died. It would crank but would not kick over. After being towed in I went straight to a local marina - 1 mile away. We immediately began to trouble shoot the motor. We chcked the fuel filter, no problem. Checked for spark - no problem. Checked the compression and found one cylcinder appeared to not be getting any compression. The mechanic said probably a blown head gasket. I didn't think so but left the boat with them. About 5 hours later I swung by the marina to get my glasses out of the boat. I couldn't resist turning the key - and guess what - she fired right up. I immediately shut it off and did it again - fired right up!

Any idea what could be going on? A vapor lock? How about the choke possible engaging by accident?

Any help before I spend a fortune chasing down this ghost?

Hellllp Pleeeeze!
-----
Sea Hunt 172 CC
[sad]
 

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Something doesn't add up. Zero compression is terminal - it doesn't magically come back. I don't know about Johnson's and their head gasket but it takes a big hole to result in zero compression if your cranking speed was normal. If it was vapor lock you should have known it before 30 minutes. It's simple to check either way. Based on your post some facts seem askew. Check compression cold, otherwise I would toss out your compression theory and look towards temperature related ignition module failure. I'm assuming your overtemp alarm is working and the engine didn't shut down as a result of internal engine temperatures.
 

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Discussion Starter #4
Bob,
You are correct. My temp warning system appears to be working (via startup system check) and I did not get a temp alarm or any alarm at all. The Johnson does have gaskets at the cylinder head - otherwise you could not open the cylinder up. The mechanice did check the cylinder without compression twice but it is very possible that he didn't get the gauge on there very well. The other three checked out fine. SInce the boat didn't die instantly it makes me think it is fuel related. I have been on boats that run out of fuel and that is the same kind of feeling it had. I was actually able to throttle back and turn the boat around 180 degrees before it totally lost power.

I think the compression reading was an error. One cylinder loosing compression would not neccessairly kill the engine on a four cylinder (i don't think). After the fuel filter was checked (there was a hiss when opened) and the compression was checked the engine was not turned over with the plugs in it until I tried it four hours later. If we had tried it before I left the mechanic, I bet it would have started in hind sight.

At this point I'm thinking of hooking up my kicker motor as a backup and running it again to see if it happens again. Could it be trash in fuel tank filter or the engine filter? If it is in the fuel tank, how do I get to it?

I also think I should put a good fuel filter on the boat with a fuel water separator.

If it was electrical, wouldn't it be an instant kill or simply a miss?
What are your thoughts?
 

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Your tank probably doesn't have a filter per'se. It's probably more of a screen. When was the last time you changed the engine filter? I prefer a spin-on filter that's a filter and water seperater. 30 mintues is long time to run with with a blocked vent or clogged filter. However, the hissing noise indicates a blocked vent. Common this time of year when critters are looking to come forth and multiply. Another consideration is that if it ran that long with blockage it may have been running lean, but since your temperature alarm didn't sound it's probably ok. Electronics don't always fail in the mode you suggested. Ignition modules and coils can be finicky. When they're failing they typically act up after 15-30 minutes. Thermal cycling is hard on electronics unless the design is robust. It takes this long for heat soak to take effect. Check the tank vent and put on a new filter and give it a try. BTW - not all engines have heads, mine doesn't. Cylinders are cast into the block. The outside cover is nothing more than a water jacket. If you have a manual you may be able test the ignition module, but I don't know what Johnson uses so it may require a special meter or adapter. Look over the coils real good for signs of a crack also.
 

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You mentioned a hiss when the spin on filter came off? With enough air space in a tank with a lower fuel level you can get some extended run times with a clogged vent.

I'm Bob H. you need to check the engine screen on the motor and exchange the filter element on the spin on.

Without risk of getting stranded jsut try blowing some air through the vent house gently at first if it obstructed you don;t want to blow a spider nest or mud-dauber into the tank.

If you have more than 10-12 inches of dip or sump in you fuel line and it has accumlated moisture water or fuel I wonder if that can create and back pressure.....at that point the timiing for the problem to occur would probably be more immeadiate.

Some may see this is an aweful recc. but if it's vent related can you run with the filler cap loose? Or maybe if it occurs again crack the filler cap and lissen for the hiss there?

My father had problems once with an obstruction in the pickup tube in a tank and it took a removal and slighter mitre-ing (sp?) to fix it.
 

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Discussion Starter #7
I'm going down to give the baot a try this weekend. I'm mounting the kicker motor just in case. There are many things I will look for as you have indicated. first I will check the fuel tank vent cap to be sure soemthing hasn't clogged it. I will also recheck or replace the fuel filter screen on the engine. You mentioned a spin on filter - I have noticed a blck spin on filter on the motor that looks just like an oil filter - is this a fuel filter? Since I bought the boat from the original owner - I guess it is possible that it has never been changed. I would also like to put a fuel water separator in line where I can see it from the boat. Any suggestions?

If the problem is electronic in nature, would it be likely that is would die slowly rather than an instant kill?

Any other on the water tests I should try?

Thanks for all your great suggestions so far.
Jeff
 

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Most likely what you described as a oil filter looking device is a fuel filter or a fuel filter/water fuel separator. That is defeinately worth checking of you have not yet. If it's easily accsible, i.e. you can get a drain pan under it and you go looking for a replacement Racor makes a drainable spin on. There very handy.

Is you engine oil injected ?? (if so I suppose you could have a oil filter for the oil injection system ??)

For s's and giggles if you take it off empty it into a glass pickle jar or a similar clear glass container. Some times that's good indicator of what's getting caught by the filter, water, bugs, dirt. The fuel and the water will have a strong separation line that you'll be able to see through the clear glass. (same goes for the on the engine screen too)

Re: any other tests ??? I'm not too sure. If I can come up with any I'll repost...

If it dies check the cap for the hiss. You can take off the cap and blow into the vent (not the most sanitary thing) but it will indicate whether or not the vent is constricted or kinked.

Watch the fumes messing with the filter and draining it too. I use to keep a jar in my old boat when I was having fuel issues so when I got into a pinch I could drain the Racor into the jar. If the jar fileld up then I dumped it back into the tank. That's a piss poor setup and eventuallyI hauled the boat jacked it hard to a corner and using a small diameter vynyl tube siphoned the water out of the lowest corner of the tank. After that I last jar and never had to touch it again.( I latter found out that a local shop when tank running the engine dunked the the boat so far the vent was picking up water, then found that the spray off the side was so frequent on the vent that is was picking up water)

Re: the electronics, I'm not very familiar with them as I've not had too many problems with outbaords elevctrolnics except for plugs. (so far cross my fingers) If you're enough splash around the cowl and the cowl is loose I suppose you could get too much moisture in the cowl and ground out the plug wires or pick up too much moisture in the carbs??? (just a wild guess)

The kicker is a safe idea but will you take an auxillary tank? I carried a clean 6 gall to plug in as a just in case.)
 

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Discussion Starter #9
Great ideas Steve, I'll check them all if I can this weekend. I really think this is a fuel problem but won't be certain unless it happens again. Hopefully it is a simple as a mud dauber in the vent (not holding my breath)!

If I figure it out I will post again just as an FYI.

Thanks again.
Jeff
 

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Good Luck
 

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I had the same problem with a power pack. If I ran it at the dock, it would run forever without a problem. Once I put it under load it would run for a while and then shut down until it cooled off. Those are the symptons of a hot diode breaking down to ground in the power pack. It got progressively worse. It's a tough one to diagnose. Even a good tech didn't get it until the second attempt. It was a 150 Johnson. Hope this helps.
 
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