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Pura Vida · 27-06-2007, 17:33

Sean,
You're welcome. I am glad it helped you move forward with a diagnosis. But I will have to pass the credit on to where the credit is due, my dad. You gotta watch those old guys.

pv

ssullivan · 29-06-2007, 04:55

Well, like most engine problems before you figure them out, it has gotten less and less logical:

Replacing the fuel hose and priming bulb has resulted in a longer period of time before the outboard stops working at full throttle. Now, it works for maybe 4-5 mins before losing the upper RPMs and power.

I have tried:

Squeezing more fuel up to the carb with the bulb while at full throttle and lagging. Nothing.

Triple checking all connections (hose clamps) in fuel line. Nothing

Re-inspecting fuel filter (perfectly clean).

The only thing I haven't done is open up the fuel pump. Guess that's next.

Also, does anyone know if "bad gas" can cause this type of issue? I am not 100% certain, but seem to remember this problem starting not long after buying a stock of gas (several gallons) from a new gas station. I filled the 5 gal outboard tank and another 5 gallon reserve tank from this station, as well as our car. The car burnt the gas up a long time ago without any problems. Just another thought.

I have showing of the boat almost every day and with 3/4 ouboard power and extra people, they are all looking at a 25 min dinghy ride each way. Hope they're not too angry. I might have to buy a new outboard, then fix this one up later and sell it or keep it as a spare after I fix it. Ahhh.... the fun of living aboard at anchor.

Pura Vida · 29-06-2007, 05:20

Sean,
Sorry the engine is still unhappy. SkiprJohn mentioned ethanol in the gas. This was a problem for an old MG I once owned, it made the rubber in the fuel pump gummy and stick causing a reduction in fuel flow. It could be a sticky float. Sorry I can't loan you the compression tester. Please let us know how it is going.

ssullivan · 29-06-2007, 07:45

Thanks, PV.

I guess I'll have a look at the fuel pump next to see if the rubber bladder is degraded from the ethanol. Fixing this is tough, since I need to use it several times a day. Would be much easier if it wasn't my primary mode of transportation.

**Alan Wheeler** · 29-06-2007, 12:52

I would be strongly looking at fuel now as well. I also suggest it is a reaction from the methanol. It could be something as simple as an "O"ring or seal that is swelling and blocking off a jet or gallery in the carb.

jaydh · 29-06-2007, 15:47

ooh...just remembered this....if it was posted, sorry, too lazy to re-reread through the post!

Did you try tapping the carb bowl with a screwdriver handle or like? Ours had a sticky float one time and this fixed it for several years.

Also, can't recall if you mentioned drainging the carb bowl? If you didn't do that yet give it a go...takes a few seconds....

- J

Inthewind · 29-06-2007, 16:12

Did you check the spark when it's running good and then check it again when it's running crappy to see if there is any difference in the spark? If your not getting good spark when it's running crappy, then I would concider the coil packs.

**Ex-Calif** · 29-06-2007, 18:02

Another "cheap" check is to spray carb & choke cleaner around and near the intake system but not in the air intake when the problem appears.

If you are getting an intake leak that appears or opens up with "heat" the carb cleaner will snoop it out. Look for a change in RPM as you spray around the intake pipes and clamps. There are usualy a couple of short rubber tubes between the airbox, the carb and and intake port on the engine held on with hose clamps.

ssullivan · 30-06-2007, 05:08

Thanks for the tips. I'll try all of these out shortly when I fix the engine. It almost didn't start last night picking up my wife and now it's getting maybe 1/4 of the RPMs and horsepower when it craps out.

Very unfortunately for me, I have to buy a new outboard now so that I can take this one out of service to fix it.

**Alan Wheeler** · 30-06-2007, 13:50

So why don't you trade it in on a new one, or....why don't you shoot ashore and get someone to quickly look at it while you are ashore.

ssullivan · 30-06-2007, 14:03

Today I did the following to the outboard:

*Inspected the fuel's path from the tank to the fuel pump, cleaning the filter with some acetone

*Took apart the fuel pump (it looked like new)

*Took apart the carb, took out the needles and float, etc... (it looked like new as well)

*Took the cylinder head off (plug was a little bit gummy for a new one I just put in, and piston and cylinder head dome were sooted - cleaned both up)

*Ran though entire electrical system checking connections and WD-40ing.

*Inspected the reed (all in one piece and flexes properly)

*THEN went to fuel dock and dumped out old fuel and bought new fuel and new outboard mix oil.

The thing worked so-so on the way back. It was getting maybe 7/8 power after working well on the initial start. I think that leaves me with only the electrical to check into. There aren't really any other parts of the engine!!

So, if it doesn't work on Monday when we commute in to work, I'll post that up here and follow up the thread with hopes that someone will be able to learn from this problem when they Google it. If it doesn't work, I'll be getting a new set of everything electronic (brain unit, capacitor, etc... CDI parts).

If that doesn't work... well... I'm stumped!

southernman · 01-07-2007, 00:26

symptoms you describe are most likely to be a sticky float. I had these symptoms on our 5hp as well. My advise is replace the float. They can look perfect and yet be sticking. If you starve the outboard of fuel by turning off the fuel from time to time, you may find it goes better. As the float is not regulating fuel flow correctly it provides too much gas to the engine causing loss of power. Anyhow that was what happened with our Yamaha 4hp.

ssullivan · 03-07-2007, 13:31

Finally was able to get my hands on the repair manual.

For those who played the game... "is that your final answer?"

The answer to the question is.......

It was a slightly corroded connection that caused the current to build up and burnt out the ignition coil (to some degree). Could have never figured that one out without the service manual, since I didn't have the specs on the resistive tests.

Well, at least maybe someone can learn from this thread and I got myself a *squeaky* clean fuel system, piston, cylinder head, etc... from the adventure.