Engine troubleshoot help needed please.

[wjallenjr]

I am new to boating and invested in a 1995 Maxum 1800SR for a first boat. However there is an issue I need help diagnosing please. We've taken it on two lakes and getting the boat initially started is fine, but after a while of driving around the lake my son and wife decide they want to stop and swim for a bit. After they're done we get back in the boat and on several occasions it won't start. It sounds like the engine wants to start but won't. It's a inline 4cyc Mercruiser 3.0lx engine. So far I have changed the gear lube and engine oil, changed the spark plugs, distributor cap and rotor. Not sure where else to go from here. Any suggestions would be greatly appreciated. I apologize if this isn't the correct location to post. This is my first time posting in any kind of forum.

[mmwjr]

Welcome aboard!

Perfect place to post for your issue. Does the engine eventually start and what did you have to do to get it to do so? When this happens have you removed the flame arrestor to see if the choke plate is open? Another thing to check is when you first turn the engine off look into the carb to see if there if fuel dripping.

[wjallenjr]

Originally Posted by mmwjr

Welcome aboard!

Perfect place to post for your issue. Does the engine eventually start and what did you have to do to get it to do so? When this happens have you removed the flame arrestor to see if the choke plate is open? Another thing to check is when you first turn the engine off look into the carb to see if there if fuel dripping.

On one occasion I turned the blower on for about 20 minutes, thinking that would help. Unfortunately it didn't. I took the spark arrestor off and I notice the choke plate slightly cracked open. I tried spraying starting fluid in the engine and after about another 30 minutes it finally started.
On a second occasion I tried the same steps I took on the first and unfortunately I had zero success and eventually had to be towed in. It was very embarrassing. I'm hoping to avoid experiencing it again.

[mmwjr]

Does the choke plate move freely? Try removing the flame arrestor and start the boat to verify it opens all the way.

[wjallenjr]

I will definitely try it.

[Overboard]

[QUOTE=wjallenjr;61845]On one occasion I turned the blower


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[Overboard]

Sorry, see my last post I didn’t quote properly...make sure you are turning the blower on a couple minutes before every time you start the engine. My apologies if I misread your meaning but I felt it was worth touching on in case you don’t. Your bilge blower removes any built up vapours that could ignite when you go to start your engine. This can be catastrophic and is why you must “exchange” the air in your engine compartment every time before attempting to start your engine.


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[BrianC72]

Change out the plug wires just because you've done the rest of the tune up stuff. Also the fuel filter.

The electric choke should engage when the engine is cold, but not when the engine is warm. You might want to look at how the choke behaves on your very first start. Then see how it behaves after a quick restart on a hot engine.

How does it run otherwise? Smooth? Stumbling at certain engine speeds? Generally, if a carb has been sitting up and was not drained or run to stalling, it may get a little gummed up as the residual gas evaporates and leaves behind some gunk. Sometimes it will only run on choke because the idle jets and passages are clogged up. If you don't have compressed air (and even if you do) a $5 set of torch tip cleaning rods will clear the tiniest holes. They are basically just a set of tiny spring steel wires in precise thicknesses, you pass the largest one you can through each opening.

Here is a very weird idea. IF you have a timing light with an inductive clip that goes around the plug wire, see if it strobes when you attempt a restart. If the strobe still triggers when you attempt to restart, but the engine doesn't start, then you have a pretty good idea that an intermittent coil or ignition controller is not the problem. If it doesn't strobe during a no start condition, then the ignition system is your problem.

Hey, when you sprayed in some starting fluid, did it at least give you some little kick, and then nothing? It absolutely should. If it didn't even give a little kick and then nothing, that would also point toward an ignition problem. Electronics like it cold cold. If they are going to fail intermittently, they will do so when hot.

I keep a spare spark plug in the glove box, so I can check for spark without pulling the plugs. But the timing gun trick will tell you the same thing without the risk of a little 30,000 volt shock. Not a big deal, like the man in the Taking of Pelham 1,2,3 said, it ain't the volts, it's the amps that kills you.

Good luck,

Brian C.

[Phillbo]

Sounds like it is vapor locking...

[dave4boats]

My son had the same problem with a merc 3.0. Would start great cold and run fine but had a hard time starting when warm. Ended up being the choke. It would not fully open when engine warm. Just needed adjustment and it's been fine for two years now.

[JTT]

Just got my 2005 and when warm the boat struggles to start. Any suggestions?

[Gastill12]

I have had the same problem with my 1995 Maxum 1800 sr. It was running great and cranks but won’t start.
I was measuring the wires from the pickup ignition and noticed I have a resistance to the case. When I loosen the outside screws of the coil the resistance shoot an open. I know the screws make the connection to ground but does it make sense that there is a resistance to the case?
Another thing is I don’t get a spark when I try to use a screw driver from the coil to ground. Brand new coil is installed to the distributor and the wire is good

[mmwjr]

Originally Posted by Gastill12

I have had the same problem with my 1995 Maxum 1800 sr. It was running great and cranks but won’t start.
I was measuring the wires from the pickup ignition and noticed I have a resistance to the case. When I loosen the outside screws of the coil the resistance shoot an open. I know the screws make the connection to ground but does it make sense that there is a resistance to the case?
Another thing is I don’t get a spark when I try to use a screw driver from the coil to ground. Brand new coil is installed to the distributor and the wire is good

This thread is rather confusing as multiple people have posted issues and gotten several responses but no one posted any resolution. It would be better if you started a new post with you problem and included the engine size, what type of ignition it is. I believe you are referring to the ignition pickup in the distributor; correct? What case are you measuring to? Have you performed the coil test be the Mercruiser manual?

[Gastill12]

I just sold it it to a boat mechanic, he thinks the distributor assembly needs to be replaced.
Thanks for the reply it is greatly appreciated