AdamHolroyd

Update, lots of fixes, still an issue. 1990 Omc 3.0 engine

13 posts in this topic

Hey guys, posted a while back and received some help from everyone.

Here is the update and work done so far...

1. Replaced coil pack

2. Replaced distributor cap, new plugs, new wires, cleaned and set points and timing

3. Replaced alternator 

4. Replaced circulation pump and belts

5. Cleaned top half of carb.

6. Cleaned all electrical points we can get to using a Dremel to clean them up. 

Next trouble shooting issue.

We had the boat out the other day and it was running well. Gauges look good, temp, tach, voltage...after about an hour of running it, upon accelerating (pulling up a skier) it starts to cut out, then fires back up, over and over.  Set it back to idle, does fine. Go to accelerate again and it does the same thing. I can keep it running to get back to the dock, just cant push it.

What have I missed so far.  What would be the next steps to check with this issue.

Thanks,

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Sounds like a fuel delivery issue. Has the fuel filter been replaced? It may be clogged up. This can prevent full flow of fuel. I replace mine every 3 seasons.

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5 minutes ago, SterndriveEd said:

Sounds like a fuel delivery issue. Has the fuel filter been replaced? It may be clogged up. This can prevent full flow of fuel. I replace mine every 3 seasons.

I haven't. It looks good, but cheap enough to replace it. Any other thoughts? 

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A slug of slime in a tank will roll back to the tank pickup tube. Smothering the pick up. No fuel is pumped to the carb. Boat falls off plane Slime ball rolls forward. Fuel is pumped to carb again. give it throttle . the slime covers the pick up again. over & over.

Connect a CLEAN outboard tank to the fuel filter INLET SIDE somehow. If it runs great ? tank is in trouble.

Do you run Ethanol gas in the tank?

Did the problem start AFTER the spray cleaning of the carburetor top ? 

 

 

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Did you change the points CAPACIATOR ? 

Did you spray the inside parts of the points & distributor ?

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Problem started after everything listed above had been done. Did not change the points capacitor but did thoroughly clean everything and sanded contact areas. The gas theory is interesting. I'll give that a shot as well. 

Only gas in the area (very small town) that is ethenol free is 91 octane. Not sure if that would help? 

Boat hasn't been run in a couple of years before I got it. Found some water in the fuel already. I've dumped a whole can of sea foam in the tank. Could there still be bad gas, or water that would cause the issue? Would something like heet be worth a shot? 

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The old gas in the tank could have evaporated enough to leave a " Ring of varnish " in place. Gas sloshing around with Seafoam could have created a " bloob of old varnish.

The separate Out Board fuel tank hooked up to the filter inlet will prove if the tank & fuel line needs to be fully pumped & cleaned out. To remove any sludge coming loose. Make sure there is a fuel filter in place. Not sure if there is a tiny filter at the inlet fitting of your carburetor.     Hopefully the crud is trapped between the tank & fuel filter.

I would not add any more solvent types to the tank right now. 

Keep track of the oil LEVEL. SMELL the oil dip stick. See if it getting higher & smells of gasoline. If it has a fuel pump mounted on the engine. Any gasoline smell in the oil is BAD !

Should be cause for a new fuel pump.

Unfortunately a old boat can have several problems at the same time. But the new boats are not much better either in some ways.  A rebuild of the carburetor is definitely in order by a auto or marine mechanic with a adjustment of a possible new float if it is a plastic foam type. Float adjustment is mandatory.

Wingnut & Shepherd can advise on yours being a " SPONGE " with all the years.

It will take lots of testing .

Retorquing of  ALL cylinder head bolts is in order. THen retorque the rocker arm stand bolts.

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Forgot about the inside of any RUBBER types of fuel lines. If in place. Your call.

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I think we've narrowed it down to an electrical problem. 

We went back out with the intent of checking fuel as discussed above. However when we got there the boat wouldn't fire up. So,we started troubleshooting again.  Timing light on the distributor wire showed no spark. Ughhh. Long story short ended up replacing the coil for a second time. Cleaned up everything again. Checked and reset points and plug gaps. Away she went.  

When we were troubleshooting we also checked timing as well.  One thing we noticed I have a question about I'm hoping some one can answer.  We put the timing light on the positive wires coming into the coil and the light showed consistent flicker, light a plug wire. When we put the timing light on the negative wires coming into the coil it showed inconsistent flicker. Is this normal from that side of the coil? Or should it also read consistent? Tachometer no longer works and I believe one of the 3 wires on this side goes to the tech. One of the wires goes to the ground on the distributor...

Any thoughts?

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Cracked insulator allowing arcing...........Bad points capacitor. Change it.

Can be The BIG multi pin connector connecting all the wire of the engine to the dash. The split pins loose enough tension to cause all sorts of erratic problems that come & go.  Only great mechanics find that problem. Geezer old timers. Like mine.    :wub:

I accurate described the symptoms.  He guessed it perfectly the first time. Took 3 minutes to correct it. He wisely went down to my 2nd 2002 186 Merc & spread all the pins.  Preventive Maint.

 

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Back of the engine. on my Merccruiser engines.  Might be different on the OMC 1990 engine

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I checked the plug shown on Marine Parts site.  It IS A Evinrude outboard connector plug.  I have 2 engines with tose plugs. They are using those pins that have a slit on the end of the male pins. If you want to JUST SLIGHTLY spread them ???  REMOVE a BATTERY CABLe to prevent any arcing. Only a .010 to .020." spread would restore rubbing action. Slide it back & forth a few times. That is all it needs.

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