Can't get my 3.0L to run!!

[Condor1970]

I just can't seem to get this old Merc 3.0 to run. It wants to, but I can only keep it going around 2000rpm. It won't idle down, and it gasps when I punch it to rev it up. If I goose it back and forth a bit, I can get it to rev up, but that's it. Once I come back down, it wants to stall out. I checked the flapper on the carb, it's set to a little open and moves freely. Isn't the flapper suppose to be almost fully shut? It is sort of dangling open about 1/3, with nothing touching it. I thought this is normal for carbs when set at idle? it's been so long since I've toyed with a carb, I can't remember. The gas is new. The plugs looked good when we pulled them. and all filters are clean. There are times when I first start it, it seems to want to run, but then starts having problems, backfiring, and stalling. Maybe I need to let it sit overnight with new gas in the carb. Maybe there's a bunch of gunk in there?

Any ideas would be greatly appreciated.

 

[Fishermark]

Sounds like your carb needs rebuilt. What the history of the boat? Has it been sitting for awhile? Is it new to you? Give us a little more detail.

And no - sitting overnight with fresh gas in it will do nothing.

 

[Condor1970]

Yeah, it sat for a year or two. What's weird is the first time we started it up, we managed to get it going, and it seemed like it wanted to run fine. It was idling and everything. Then. it started having issues, so I dumped the gas and put in some fresh stuff, because it was old gas. And now I can't seem to get it running for the life of me.

 

[Condor1970]

oops. double post.

 

[Eric 3.7LX Alpha 1]

The flapper is called a choke.

You checked/cleaned the filter on the carb itself at the fuel inlet?

 

[Condor1970]

Yes. I cleaned the inlet filter. I also shot carb cleaner down inside a few times. I can't help but think that when I first got it running, it seemed like it wanted to run ok. Then, it started bogging down after a few minutes, and won't run well at all now. I wonder if the bad gas varnished the inside of it.

 

[Condor1970]

I checked the carb and these are the only numbers I could find on it. I'm not sure which rebuild kit to buy. I was going ot get this one.

http://www.ebay.com/itm/Marine-Roch..._Accessories_Gear&hash=item20e83d4621&vxp=mtr

The only numbers I could find on the side, was these.... 830070 06 7426

 

[airshot]

Everything needs to be "right" in order to make it run well, that includes ignition, caps wires, rotor, plugs etc. Also fuel flow which includes carb rebuild, fuel pump test, and assurance that "all" filters are clean and flowing. Also do a compression check to be sure engine is sound. If all these are done correctly it "will" run right.

 

[thumpar]

Which "flapper" are you referring to? There is the choke at the top and the throttle body at the bottom. If the choke is not opening it would cause some of the issues you describe.

 

[Condor1970]

No, the choke is opening as I believe it should. Sorry, I didn't mean to call the choke a flapper. I must have been thinking of the exhaust at the time, for some reason. My brain is all over the place with this thing.

Ok, I managed to get it up and running and even idling, if that's what you want to call it. I hooked up the timing light (inductive), and I noticed at the rough idle, I am getting intermittent light flashing, and it seems like it is missing, because at idle the timing light should be constant and smooth flashing light, right?

I also noticed it bouncing around between 0-8 BTDC. Nothing is consistent.

I did manage to use some Berryman's carb cleaner and shot it several times down the throat while at fast idle, and it did seem to help.

There was a short time when the timing light was constant, but now it just won't stay that way. I can manage to goose it back and forth slowly, and get it to rev up, but if I try to just push the throttle forward without intermittently backing off, it will die.

I'm thinking I should just give it a good tune up from the distributor to plugs.

Anyone recommend a link to a tune-up kit for a 1989 Mercruiser 3.0L?

 

[daman4469]

Is the ignition a 'points' ignition or a solid state electronic? If electronic, the coil may be bad. Had similar symptoms on my omc 5.0 and replacing the coil fixed my issue. Heat from the engine had ruined it.

 

[Condor1970]

It's a points ignition system. Nothing electronic on this thing. It's a 1989.

 

[Maclin]

Did you do a tuneup yet with new points, setting gap then checking dwell and adjust points gap to get proper dwell? Then setting the timing?

 

[Condor1970]

No, I have not done that yet. That's my next step, is the do a tune up, and finally a carb rebuild if necessary.

 

[Fishermark]

I'm thinking I should just give it a good tune up from the distributor to plugs.

I'm thinking that is a good idea.

Anyone recommend a link to a tune-up kit for a 1989 Mercruiser 3.0L?

You can shop around... but you basically want spark plugs, distributor cap, rotor, points, and condenser. The spark plug cables are cheap - you might as well replace those as well.

 

[Condor1970]

To heck with it. I despise points. Setting gap. Measuring dwell every year. What a pain.

I went ahead and bought a Pertronix Iginition kit, Sierra cap and rotor, and Sierra wires. I will pull the plugs and get some from the local auto shop.