Trouble Starting when Hot OMC 3.0L

[Crusader]

I've read many posts on this topic here at iboats, but none have helped me to figure out what's going on. I have a 1989 Sunbird 198 Cuddy with an OMC 3.0L GM Engine. Battery and spark plugs are new.

Here's whats happening:

Launch the boat - starts right up. Runs great. No rough idle, no backfire, seems to be perfect. Stop the boat for 10 minutes, 30 minutes, or 2 hours. Boat is difficult to start. It may take up to 15 minutes to get it to turn over.

This afternoon I was in the river with the family. Stopped for 1 hour. Took 3 long attempts to start engine, but it kicked over. Drove for 10 minutes and anchored. Immediately pulled anchor and drove into shallower waters then anchored again. After an hour attempted to start boat. It took me about 40 minutes this time to get it running.

When the engine doesn't start, it cranks strong, but it sounds like no combustion is taking place. When it does finally start, it does so as I let go of the key. I can crank away and all I hear is a strong cranking engine.

I pulled #1 plug after much cranking and it was dry as a bone. I looked down the carb while my wife moved the throttle and watched fuel shoot down the carb. The only thing I didn't do was check for spark. (Kids were afraid I was going to blow us up.) :redface:

I also noticed that the choke seemed to hang and was difficult to move by hand. I tried manually manipulating it while my wife cranked, but that produced no results. When the engine finally kicked over tonight, it sounded like one cylinder fired and then a pause and then another. After a little bit of rough running it started running strong again.

I don't believe the problem is with delivering fuel to the carb, because whenever the boat sits for a day and I go out to start it, the engine immediately kicks over strong. It's only after running the boat for a period of time and stopping that the problem occurs.

 

[jsmith3102]

Re: Trouble Starting when Hot OMC 3.0L

This sounds like a carb issue...
I had this problem...

Run the engine until the choke is fully open and engine is warm. Shut it down and check if fuel is leaking into the carb out one of the jets. I think your engine is flooding when you shut it down.

When this happens you need put the throddle in fully open (no pumping), turn it over until it pushes the excess fuel out. (Don't play with the throddle if it doesn't start right away or you will pump more fuel in.)

If this is it. I just took the whole carb off and got a new one from carbsonly.com. You can rebuild it but what I like about this sight is they test the carbs prior to sending them out.

 

[Crusader]

Re: Trouble Starting when Hot OMC 3.0L

Hello jsmith3102, thank you for your response.

If the engine is flooding, shouldn't the spark plug have been wet when I pulled it after cranking excessively?

Once I start cranking the engine, the choke automatically opens all the way up. No need to warm it up for that to happen.

The other strange thing about this boat is that there is no way for me to throttle the engine without putting it in gear. I can only do that if the engine is running. If I put it in gear first, the engine won't crank.

Thanks for recommending carbsonly.com. I just emailed them for a quote.

 

[searay3]

Re: Trouble Starting when Hot OMC 3.0L

Do you have spark when it quits? Ignition problems can mask themselves as fuel problems. Try a full tuneup.

 

[fastinated]

Re: Trouble Starting when Hot OMC 3.0L

Had the exact same identical problem when I bought my omc 3.0 years ago.. It ended up being bad manifold/riser believe it or not.. For some reason a little water getting into the exhaust side of the manifold would not let it start.. Never had ether onboard to try that, but that's what it was. Put new one's on there and never had a problem. Seems strange I know, but hey it is what it is.

 

[Don S]

Re: Trouble Starting when Hot OMC 3.0L

The other strange thing about this boat is that there is no way for me to throttle the engine without putting it in gear. I can only do that if the engine is running. If I put it in gear first, the engine won't crank.

Yes, there is a way. It depends on which control you have how you get to it, but some have a button in the center of the shifter you push in for neutral only, some you pull the lever out for neutral only, while others have a seperate button off to the side of the lever.
A picture of your contol will help us show you where it's at.
Once you can work the throttle, it will probably start fine, and be a lot easier on the starter.

 

[Crusader]

Re: Trouble Starting when Hot OMC 3.0L

Thanks to everyone for your replies. I am new to boating and appreciate all of the help.

Don, attached is a picture of my lever. It has a red toggle switch on the side to raise and lower the Stern Drive. Then it has a large red button under the top handle to unlock and shift forward or reverse. I don't see any other options to this lever.

 

[Crusader]

Re: Trouble Starting when Hot OMC 3.0L

Some other views

 

[chiefalen]

Re: Trouble Starting when Hot OMC 3.0L

You got the same throttle as me. Grab the whole handle and pull out about a 1/4 inch and push the lever forward for neutral reving the engine.

Not supposed to start when in gear a safety feature.

To start pump the throttle 2-3 times in neutral and leave in neutral about a quarter of the way down.

When ever you run it hard, let it idle 2-3 minutes then shut off.

When you start her let her idle 2-3 minutes before running.

Good luck!

 

[chiefalen]

Re: Trouble Starting when Hot OMC 3.0L

Bye the way after i posted i noticed your missing the front plastick cover of the throttle.

Maybe it's in the boat somewhere?

 

[Crusader]

Re: Trouble Starting when Hot OMC 3.0L

Hello Chiefalen,

That's a tricky one. As for the cover, I bought the boat that way. I'll probably have to make something to replace it. I'll give your tip a try after work tonight. Thanks much!!!

 

[chiefalen]

Re: Trouble Starting when Hot OMC 3.0L

You don't need nothing fancy to cover the throttle. Don't duck tape it won't last.

Maybe a old bleech bottle cut out to fit in the grooves.

 

[Crusader]

Re: Trouble Starting when Hot OMC 3.0L

Tiz True! I don't know if the face plate would have offered instructions, but that is a tricky one. Prior to your post, and at the prompting of Don S, I saw the arrow on the top of the handle and so grabbing the handle and attempted to move it out and down, but it didn't give at all. Thanks to your instructions, grabbing the arm itself, I am able to pull the lever straight out and operate.

Due to the throttle sticking, I suspect carburetor maintenance/replacement is in order. However, it would be sooooo nice if this resolves the "Hard starting when Hot" issue. I plan to be in the river all day Saturday and will post the results. Thanks!!!

 

[chiefalen]

Re: Trouble Starting when Hot OMC 3.0L

The hard starting may be a bad connection. Did you try to clean all the grounds?

How about cleaning all the connections at the starter?

Disconnect the battery. Clean the connections on the starter. Shoot some corrosion pro on the connections.

Battery cables good and clean. Make sure they are tight when you put them back on.

You could at night real dark have someone turn the key and crank her and see where all the sparks are. Make sure you have water going to the drive.

Could be a simple bad connection.

 

[Crusader]

Re: Trouble Starting when Hot OMC 3.0L

Well, I had the boat out yesterday. Once it took me 4 good trys to get the engine running (about 3 minutes). Other than that, no problems. I think I've got to learn from experience the proper method of starting - when to give it gas, etc. These modern car engines do everything for you and now I'm going back to starting an engine with carburetor, points, condenser and no onboard computer. Knowing how to throttle the engine sure helps!

Toward evening, we got caught in a downpour! My family moved into the cabin to stay dry and warm. Meanwhile, I learned that it would be good to have at least one poncho onboard for the captain!

Thanks for the insights!!!