Ignition Tune Up

[abuesing]

Hello,

I did an ignition tune-up on my Merc 350 last week. I put the manufacturer recommended Cap, and rotor on, kept the same Ign. wires because they are fine, and put new spark plugs in. I started it in my driveway hooked up to a hose, started right up, didn't notice anything unusual, ran it up to 4000 RPM no problem.

I then took it out on a lake test, slowly eased the power up, and when it got up to 3500 RPM, the engine started sputtering. I am new to boating, and am wondering what the heck did I do wrong? I checked the wires, they aren't crossed. I checked all the wire connections, and plugs are in tight.

Any ideas? I am trying to avoid taking it into the shop and getting ripped off.

Thanks!

 

[Bt Doctur]

Re: Ignition Tune Up

ran it up to 4000 RPM no problem.
You forgot to include destroying the impeller from lack of water
Did it run good before you did the work?
If it did, recheck all your work inclluding the firing order
On the RPM ,No Load is a BIG NO, NO

 

[abuesing]

Re: Ignition Tune Up

I took it on the lake before running it on the hose, and I didn't have it at 4000 RPM for long. It ran fine before the tune-up. So now that you got me worried about the impeller, how do I know if I damaged the impeller? After running it in the driveway, I took it out again, did the same thing. It runs fine at all RPM's on the lake below 3500. I triple checked the wires, none of them are crossed. Any chance that I have 1 bad spark plug, or broke one putting it in?

 

[terankinjr]

Re: Ignition Tune Up

Heh, this kinda sounds like my issue except for that I haven't done a tune up yet, but all the people that i've spoken to and the folks that responded to my post here think that its fuel related.... i gonna do a full tune up and go from there... might be a carb issue... but I know nothing about carbs....

 

[Bt Doctur]

Re: Ignition Tune Up

"I started it in my driveway hooked up to a hose, started right up, didn't notice anything unusual, ran it up to 4000 RPM no problem. "
Sorry, cant find the word "lake"
Again ,double check the plug wires tracing each one from the plug to the cap.

 

[abuesing]

Re: Ignition Tune Up

I was thinking it may be a fuel issue too, but it started sputtering after I did the ignition tune-up.

 

[Wet Wonder]

Re: Ignition Tune Up

Did you mark where the old rotor was, and put the replacement rotor in the same position so it hits piston 1? Otherwise, check timing advance.

 

[abuesing]

Re: Ignition Tune Up

Did you mark where the old rotor was, and put the replacement rotor in the same position so it hits piston 1? Otherwise, check timing advance.

I believe so, the shaft that the rotor goes on has a groove on it, so the rotor goes on in the same position as it came off.

 

[Wet Wonder]

Re: Ignition Tune Up

If it's not fuel flow, it sounds like timing was knocked off during ignition tuneup, or is not advancing.

 

[abuesing]

Re: Ignition Tune Up

If it's not fuel flow, it sounds like timing was knocked off during ignition tuneup, or is not advancing.

What might I have done to knock off the timing? How can I fix it if that is the problem?

 

[MikDee]

Re: Ignition Tune Up

Do you have points, or electronic ignition? By the way, you can't knock your timing off by just replacing a rotor. Are the wires on your distributor cap in the right order, clockwise? here take a look:
http://www.classiccarauto.com/impala/how_to/images/distributor.png

 

[abuesing]

Re: Ignition Tune Up

Do you have points, or electronic ignition? By the way, you can't knock your timing off by just replacing a rotor. Are the wires on your distributor cap in the right order, clockwise? here take a look:
http://www.classiccarauto.com/impala/how_to/images/distributor.png

Thanks MikDee, I have points I didn't think I could knock the timing off by anything I did. I simply replaced the cap, rotor, and plugs. I do believe they are in the right order, I changed the wires on the cap one for one, and then triple verified they are in the right order, I will print your diagram up and take another look. I also checked the wires, which i don't think are a problem, because the boat ran fine before, no corrosion, or cracks on the wires.

Do you think it could have anything to do with the spark plugs? The only thing I can think may be a problem with the plugs is that I got some anti-sieze on the electrode of one of the spark plugs? Do you think that would cause any problems?

 

[MikDee]

Re: Ignition Tune Up

The antisieze would burn off in no time, unless you completely covered the electrode, which I doubt But, your points maybe worn, & out of adjustment? I would replace the points, & condenser, if you haven't, and set them to the recommended point gap, I think it's .016" of an inch. Every time you set the points you must set the timing though, because it is affected While you're in there, with the engine off, check to see if you can move the rotor a bit clockwise by hand, it should move, then spring back by itself, if not check your mechanical, centrifugal advance weights, & springs, located under the breaker plate, to make sure they're advancing fully, and not rusted, or corroded.

 

[bruceb58]

Re: Ignition Tune Up

You always need to double check your timing after changing points.

 

[MikDee]

Re: Ignition Tune Up

What # spark plugs are you using? and if it's electronic ignition, you must set up your "base" timing first, there is a procedure for that in the manual, or you won't have any spark advance at all.

 

[bruceb58]

Re: Ignition Tune Up

He already said he has points so he does not have electronic ignition. Points should be set with a dwell meter. Setting the gap can be the first step but it is best to get a dwell meter and really set them right...then adjust timing.

 

[abuesing]

Re: Ignition Tune Up

He already said he has points so he does not have electronic ignition. Points should be set with a dwell meter. Setting the gap can be the first step but it is best to get a dwell meter and really set them right...then adjust timing.

Hey Bruce, Sorry I never clarified, I am new to boats so I am an idiot...but the ignition is Electronic.

 

[abuesing]

Re: Ignition Tune Up

What # spark plugs are you using? and if it's electronic ignition, you must set up your "base" timing first, there is a procedure for that in the manual, or you won't have any spark advance at all.

I will have to check on the #...don't remember.