3.0 L OMC King Cobra-won't start

[schmitty66]

I just pulled my 3.0 L OMC out of storage this weekend after a long cold winter. I followed the winterization thread i started last October without any problems. I started the engine and it fired on the first crank. My son and I took it around the lake at about 20mph and oil pressure, volts and temp guages were good. 15 minutes in, i stalled it while working my way through a shallow canal. It started again but seemed to 'surge' a little. We took off again and got about 100 feet then the engine died...like someone turned the key off. No loud bang....just stopped. When i turned the key....the engine will turn over but it sounds like it's having alot of trouble(new battery)...like there's resistence of some sort. The shifting mechanisn also shutterd a little...like it's was still 'in gear'. I'm not looking to repair it myself but rather have the knowledge so when i take it to a shop....i'm well informed and know what questions to ask.

Any ideas/comments would be very helpful

thanks
schmitty

 

[danond]

Re: 3.0 L OMC King Cobra-won't start

Dirty/corroded connections at the starter or starter assist solenoid, maybe. I just had the same issue. Mine were loose and dirty.

 

[schmitty66]

Re: 3.0 L OMC King Cobra-won't start

The engine will crank...but won't start. FYI-there's no evidence of water in the engine oil and the prop will turn freely.

 

[danond]

Re: 3.0 L OMC King Cobra-won't start

I know - the crank and run circuits have different connections. I am still suggesting you clean the connections on both circuits back at the starter and solenoid.

- Pour fuel down the carb throat - does it start?

- Connect a timing light to a plug wire - crank the engine - are you getting spark?

- Set #1 to TDC. Is the distributor rotor pointing at #1?

- Did you pull and inspect the drive this year? How about last year? If not, it needs to come off anyway. Pull it and see if the engine has the same cranking/starting/running issues.

- Did you drain the drive fluid? Anything on the drain magnet?

- When was the last time you adjusted the shift linkage? Cobras blow drives when the cables are out of adjustment.

- Have you checked the shift assist module? Is it kicking in when you don't want it to?

 

[schmitty66]

Re: 3.0 L OMC King Cobra-won't start

-gimbal bearing and tune-up done last season
-no filings or anything on the lower end plug.
-linkage adjusted 2years ago.
-it never had any problem going into gear

I poured some gas into the carb and away it went....with muffs on. I still have to water test it....thanks for the tip

question-if the battery cables aren't tight and lose contact.....would the boat just die while on plane?

#2-my wife took it out last season while i was backing up the trailer and commented on how she liked to go fast. She said she had the throttle buried and with prop i have on.....it would have been rev'ing at over 5500rpm's for at least 5minutes....could that do harm. i was told to keep the RPM to about 4500.

Thanks again.

 

[danond]

Re: 3.0 L OMC King Cobra-won't start

Probably no immediately noticeable damage but I'd suggest not doing that again. You never know when a 20+ year old motor is just going to say f-it and spin a bearing, blow a piston, throw a pushrod, etc.

Keep an eye on compression and oil pressure numbers.

And yes, with bad connections or faulty wiring, especially in the run circuit, the symptom can certainly be a boat that shuts off dead then restarts fine.

 

[Diggerpine]

Re: 3.0 L OMC King Cobra-won't start

Do you have an electric fuel pump? If you put fuel into the carb and it started up, it's possible that your fuel pump isn't working correctly.

 

[schmitty66]

Re: 3.0 L OMC King Cobra-won't start

Thanks guys....i'll trace both the run circuit and fuel lines.

Which manual do you recommend buying?

 

[Susquehanna Squid]

Re: 3.0 L OMC King Cobra-won't start

Maybe I missed it but when you put it away last year did you treat the fuel with Stay-bil etc. It could be bad gas, this would explain the fact it runs at low RPM's but not when you drop the hammer.

 

[Susquehanna Squid]

Re: 3.0 L OMC King Cobra-won't start

Oh and by the way, I have a 3.0 liter Cobra and I use the Clymer's manual.

 

[danond]

Re: 3.0 L OMC King Cobra-won't start

There is only one manual that covers everything and covers it correctly. The OMC factory service manual.

You can "get by" with the others, by why bother? Get the right one. They're available on eBay.