Boat engine won't turn over

[johndavidross]

Merc 3.0 LX 4 cyl

I was out boating yesterday and everything was running great until we stopped at an island for about an hour. The engine wouldn't turn over when we were ready to leave. I have ruled out battery and starter since the engine was turning over and both of those components are new as of last week. I am thinking that it might be fuel pump or carb. I wanted to get your opinions though. I'd like to do the work myself to save a couple bucks but I have never done work on either of those components.

Thanks!

 

[Don S]

Re: Boat engine won't turn over

What do you mean by turning over? The starter spinning the engine is turning the engine over, starting is when the engine runs.

Carb and fuel pump will not prevent the engine from turning over.

 

[johndavidross]

Re: Boat engine won't turn over

Sorry, it is turning over but it is not starting.

 

[abrx7]

Re: Boat engine won't turn over

Check to see if you have spark. The ignition module could have gone bad if you don't have any. I had the same motor and I lost 2 of mine.

http://www.******.com/p/811637001/M...rce=feed&utm_medium=cpc&utm_campaign=shopping

 

[CaptainMak]

Re: Boat engine won't turn over

Did it eventually start after sitting for a bit and cooling down ?

I had a similar problem on my 165, turned out to be the choke out of adjustment.
Is this an on-going problem ? have you had the same problem happen before ?

 

[johndavidross]

Re: Boat engine won't turn over

I haven't tried to start it since yesterday. I'm going to give it a try when I get home from work tonight. That will give it 24 hours of sitting since the last attempt to start. This is the first time I've had the boat out since I purchased it. It started up beautifully without priming it on the way out which makes this even more confusing.

 

[Don S]

Re: Boat engine won't turn over

Did you check for spark?

 

[CaptainMak]

Re: Boat engine won't turn over

It started up beautifully without priming it on the way out which makes this even more confusing.

Actually it makes it LESS confusing. I bet you the boat starts up beautifully tonight. I'm 95% sure it's your choke that's out of adjustment. I had the same thing on my boat. After a hard run and about 30 minutes off, it would be a pain to start. Before you start it tonight, take off the spark arrestor on the top of the carb and see where the choke flap is. Should be almost closed. As the engine warms up, keep an eye on it. It should slowly start to open until the flap is vertical at operating temps.

The other thing it could be is fuel filters or gummed up carb. Do you know when the last time the boat was run before you purchased it? Was it sitting for a while ? If that's the case, I'd start by replacing the fuel filters, dumping the old fuel out and putting in some high-octane stuff in there.

 

[johndavidross]

Re: Boat engine won't turn over

I'm going to check the plugs today when I get home. Just to clarify, I need to pull the wire off a plug and hold it about an inch from the plug and I should see a blue spark?

 

[johndavidross]

Re: Boat engine won't turn over

@CaptainMak
Is it okay to start the engine without the spark arrestor on?

The boat was just worked on last week and they did an entire tune up which included the fuel filter. They didn't flush out any old gas though, although I did fill it up withe 87 octane which the tech said is the only type he would put in the boat.

 

[CaptainMak]

Re: Boat engine won't turn over

@CaptainMak
Is it okay to start the engine without the spark arrestor on?

The boat was just worked on last week and they did an entire tune up which included the fuel filter. They didn't flush out any old gas though, although I did fill it up withe 87 octane which the tech said is the only type he would put in the boat.

I always start it without the arrestor on when working on the carb/choke.
Just use common sense: well ventilated area, open cover a couple mins before starting, and don't have a cigarette in your mouth while working there. Also, when the engine warms up and choke fully opens, shut off the engine and look into the carb throat. If you continue to see fuel dripping into the carb, it's time for a carb rebuild.

I'm not sure why the mechanic told you to use 87 ONLY. I thought these engines need at least 91 octane, I could be wrong.

 

[Don S]

Re: Boat engine won't turn over

I'm going to check the plugs today when I get home. Just to clarify, I need to pull the wire off a plug and hold it about an inch from the plug and I should see a blue spark?

That's not how you do it, remove the coil wire from the center of the distributor cap and hold the wire about 3/8 to 1/2" away from a clean ground and check for spark. It will never jump an inch.
You should see a bright blue/white spark snap across the gap, a weak yellow spark will not start the engine.

 

[johndavidross]

Re: Boat engine won't turn over

@CaptainMak - If the gass continues to drip into the carb after shutting the engine down does that mean it will eventually flood the motor as it sits for an hour or so? Originally I thought that the engine would start because it was flooded.

@Don - Where would be a "clean ground" around the coil wire? I'm sure that it won't reach very far.

 

[CaptainMak]

Re: Boat engine won't turn over

@CaptainMak - If the gass continues to drip into the carb after shutting the engine down does that mean it will eventually flood the motor as it sits for an hour or so? Originally I thought that the engine would start because it was flooded..

No, if the carb is flooded it will not start until you crank the engine enough to burn it all off. THAT, mixed with incorrect choke operation only makes the problem worse. I'd start troubleshooting with checking the choke operation. Let us know how that goes.

 

[johndavidross]

Re: Boat engine won't turn over

Whoops, I meant to say "Originally I thought that the engine would NOT start because it was flooded." Either way you gave me my answer. Thank you and I will post my findings after I do my troubleshooting.

 

[fat fanny]

Re: Boat engine won't turn over

Troubleshooting does not start with checking to make sure your choke is working! 1st should be to ensure you are getting spark! and then fuel and then diagnose from there the choke should be down the list near the end in my opinion. I have ran my rig for over a year with the choke coil disconnected if your engine is tunned correctly and the weather is nice what need is there for a choke!

 

[johndavidross]

Re: Boat engine won't turn over

@CaptainMak - I just got home and pulled off the spark arrestor. The choke was fully open. I pushed it closed and am about to give it a start. Why would it cause the engine not to start if the flap is open?

 

[Bondo]

Re: Boat engine won't turn over

@CaptainMak - I just got home and pulled off the spark arrestor. The choke was fully open. I pushed it closed and am about to give it a start. Why would it cause the engine not to start if the flap is open?

Ayuh,.... To much air, 'n not enough Gas to light a cold motor....

The choke Should have been Open, when ya looked...
On a Carb, ya move the throttle to Wot, atleast Once, to set the choke, on a cold motor....

It also usually takes abit of throttle durin' the start up...

 

[CaptainMak]

Re: Boat engine won't turn over

Troubleshooting does not start with checking to make sure your choke is working! 1st should be to ensure you are getting spark! and then fuel and then diagnose from there the choke should be down the list near the end in my opinion. I have ran my rig for over a year with the choke coil disconnected if your engine is tunned correctly and the weather is nice what need is there for a choke!

Judging from easy starts at cold, I don't think it's ignition related. His finding the choke valve wide open tells me that is the problem. I just fixed my problem which sounds identical to his.

 

[johndavidross]

Re: Boat engine won't turn over

Here was the issue. I checked everything that was suggested and found that I wasn't doing something. My shifter has a button on it to pop it into neutral yet gives it gas and I wasn't engaging that while trying to start. This is a new boat to me and wasn't familiar with this. Thank you all for all the suggestions. I learned a lot!