1989 mercruiser magnum 350 wont start

[blue89turbo]

Hi guys.
I am hoping for some help on getting my boat running again.

I had it running in the driveway about 2 weeks ago with no problems. And pulled it down to the cottage this past weekend and it just wouldn't start. So far I pulled the flame arrestor and can see fuel squirting in. So I don't think there is a fuel issue. What is the best way to check for spark? I figure that's the next thing to look into?

Any other ideas are appreciated

thanks

 

[CharlieB]

Re: 1989 mercruiser magnum 350 wont start

If you're brave enough, pull the coil wire out of the distributor and hang on to that end while a helper bumps the starter.

Myself, I would lay it on the intake manifold leaving almost a 1/4 inch gap and just watch it while a helper bumps the starter. Hopefully I would see a nice fat arc.

A remote starter switch is helpful, you can use it to trigger from the hot side of the starter relay on top of the intake to the relay trigger, the small yellow wire with the thin red line. Remember the key must be turn on and the lanyard plugged in.

Maybe have the water connected and on so if you have spark you won't have to climb out and back in before attempting to run the motor. You can toast an impeller in far less than a minute running.

 

[crazy charlie]

Re: 1989 mercruiser magnum 350 wont start

Pull the plugs,clean them and regap them,pull coil wire inspect and replace or reinstall,pull the cap off and check for moisture and replace rotor.Simple and may do the trick.Charlie

 

[achris]

Re: 1989 mercruiser magnum 350 wont start

If you're brave enough, pull the coil wire out of the distributor and hang on to that end while a helper bumps the starter.

Now now Charlie... You and I both know THAT'S GOING TO HURT!!

Easiest is get an old spark plug, pull one of the leads and put the old plug in it and lay THAT on the engine, then crank and watch....

Chris......

 

[blue89turbo]

Re: 1989 mercruiser magnum 350 wont start

Thanks for the help.

No I guess I'm not that brave (or dumb) to pull the wire and hold it...

I think I will start with pulling a plug and looking for a spark. Then pull all the other plugs and checking them and then check the cap and rotor.

I'll let you guys know what I find.

Thanks again.

 

[Silvertip]

Re: 1989 mercruiser magnum 350 wont start

Is the choke working? Did someone pull the kill switch lanyard?

 

[blue89turbo]

Re: 1989 mercruiser magnum 350 wont start

The previous owner disabled the lanyard switch...I plan on hooking it up again. How do I check the choke operation?

Thanks

 

[blue89turbo]

Re: 1989 mercruiser magnum 350 wont start

So I just checked a bunch of connections and then tried to start it... it almost started but I noticed that only at just the second when i release the key (ie starter motor) is when it kind of ran and backfires too...could it be a timing issue?

 

[CharlieB]

Re: 1989 mercruiser magnum 350 wont start

Aha! There should be TWO wires connected to the + side of the coil. One is a resister wire which supplies

Wait a minute. Which ignition is one an 89? Points or Merc early Mercontrol?

If there is two wires on the + side of the coil it may be a points ignition, one wire is resisted and supplies 6 volts during running, the second wire come off another terminal of the starter solenoid and delivers full 12 volts for starting. A poor or burnt contact in the starter solenoid will leave this wire dead and make for a very weak spark during cranking.

Grab a volt meter and check voltage to the ignition coil while cranking, it should read 12 cranking and drop to 6 running.

 

[blue89turbo]

Re: 1989 mercruiser magnum 350 wont start

Ok so I gave it 10 minutes to sit and it is running now (starting to think it may just be flooding issue)
It was actually running like a top.
On the trailer it was idling fine reving up fine and started up immediately each time since it was warmed up.

I can think of a few things that may a factor.

The previous owner gave me a linkage that goes on the carb that controls a vacuum actuator an is supposed to be hooked up to a coil spring on the engine. What is the purpose of that?
Also the previous owner told me to pump the throttle 5 or 6 times before starting but maybe that is too much?
What is the proper starting procedure on a carbed 350?
Lastly I looked at a picture that I took at the gas pump for fun showing how much it costs to fill her up and noticed a sticker on the pump that says up to 10% ethanol may be present. I never noticed this till now and maybe it is an ethanol issue?

Thanks for your ideas.

Jason

 

[achris]

Re: 1989 mercruiser magnum 350 wont start

There'll also be 2 wires with a Thunderbolt system, and they should both be purple.. One is power from the key, the other is that same power to the ignition amplifier...

Chris......

 

[blue89turbo]

Re: 1989 mercruiser magnum 350 wont start

Thanks charlieb.

I noticed when cleaning and checking some contacts that there is a small flat black connector on the port side manifold that says thunderbolt iv.

 

[achris]

Re: 1989 mercruiser magnum 350 wont start

Thanks charlieb.

I noticed when cleaning and checking some contacts that there is a small flat black connector on the port side manifold that says thunderbolt iv.

That is your ignition amplifier....

 

[CharlieB]

Re: 1989 mercruiser magnum 350 wont start

................
The previous owner gave me a linkage that goes on the carb that controls a vacuum actuator an is supposed to be hooked up to a coil spring on the engine. What is the purpose of that?
Also the previous owner told me to pump the throttle 5 or 6 times before starting but maybe that is too much?
What is the proper starting procedure on a carbed 350?
.................................

Which carb, what spring, pictures would be a big help.

Once tuned and running correctly push the Neutral release or pull the control arm so you remain in Neutral, open the throttle all the way ONCE, pull it back to straight up then forward until you 'just' feel it begin to open the throttle a hair. It should start and fast idle.

 

[blue89turbo]

Re: 1989 mercruiser magnum 350 wont start

Thanks,
Not sure if I follow you.
My boat has 2 controls. One for gear selection and one for throttle.
So 1 full pump and then start with lever in the middle is proper procedure?

Can I post a link to my site that has pix to show the linkage?

 

[achris]

Re: 1989 mercruiser magnum 350 wont start

As long as it's not advertising, you can post any link you like...