Merc 470 NO SPARK

[udm328is]

Thought I had a starter issue, got that squared away with a new solenoid, then did the plug test against a ground, no spark, replaced coil and still no spark. I am out of ideas and clueless as to what to do now and am trying my best not to lose my my and destroy my boat with a sledge hammer, so and help would be greatly appreciated.

 

[blueagletalon]

Re: Merc 470 NO SPARK

did u check the points and condencer? what about the condition of the cap and rotor?

 

[Don S]

Re: Merc 470 NO SPARK

no spark, replaced coil and still no spark.

Amazing............... why do people always change the coil when they have no spark. It's seldom the coil. Needing new points is the #1 cause of no spark on any engine with a points type distributor.

 

[udm328is]

Re: Merc 470 NO SPARK

Thanks for the replies, that will be my next step. As far as why I replaced the coil is because I am clueless and am teaching myself as I go along So I greatly appreciate this forum and your help. I can see by my spelling yesterday that I was outrageously frustrated, so the cooler calmer me is gonna get to get'n and get this boat running

 

[mdlee]

Re: Merc 470 NO SPARK

Make sure you set the gap on the points to the specified clearance. That motor is very sensitive to ignition settings.

 

[udm328is]

Re: Merc 470 NO SPARK

OK, here is the follow up. Solenoid replaced, new coil, new battery, plugs, points, condenser, cap, and rotor. Now when I turn the key (battery brand new and fully charged) it turns over very slowly. Any ideas greatly appreciated.

 

[boat_chick]

Re: Merc 470 NO SPARK

Mine did the same thing when my points went out of adjustment. It changes the timing so much it wont turn over. Double check your points adjustments. I switched to Pertronix electronic conversion. I love it!

 

[udm328is]

Re: Merc 470 NO SPARK

cool thanks, I will make sure I have them adjusted properly and give it another try, crossing fingers and hoping for the best, I am going crazy wanting to get on the water...

 

[wire2]

Re: Merc 470 NO SPARK

Does it still turn over very slowly if you pull the HV lead out of the coil for a test? If it's faster, you probably have the ignition timing too far advanced.

If it's the same, it may be a poor 12 v electrical connection. After cranking, feel around the wiring/batt/starter for heat.

 

[mdlee]

Re: Merc 470 NO SPARK

My friend you have a problem in the wiring between the ignition switch to the bat, or from the bat to the starter. The large diameter wiring coming from the bat is famous for corroding under the outer sheath. If you don'tt have avoltagege meter, an ez way to check for this problem is to use a set of jumpers and jump power from the bat straight to the starter.The starter should turn the motor over at the same speed regardless of the timing.

 

[udm328is]

Re: Merc 470 NO SPARK

I have become a google/forum mechanic so I am just figuring things out as I go along. I did check all the connections and cleaned all the terminals so I think that is pretty good. I however am not sure what you are referring to in regard to the HV lead on the coil, which wire is that and what do I do, just remove it and crank the engine?

Once again thanks everyone for your tips and info...

Eric

 

[udm328is]

Re: Merc 470 NO SPARK

OK, so if I jump power from the bettery direct to the starter and I know the battery is good and it still turns over slow does this indicate that the starter is bad?

 

[wire2]

Re: Merc 470 NO SPARK

..... I however am not sure what you are referring to in regard to the HV lead on the coil, which wire is that and what do I do, just remove it and crank the engine?

....

Eric

It's the high voltage lead from the coil to the middle post of the distributer.
I wanted to rule out the ignition firing so far advanced that the engine almost stalls when coming up on TDC. That can/will slow the cranking speed down.

Combustion is fast, but not instantaneous.

 

[udm328is]

Re: Merc 470 NO SPARK

OK, I ran a jumper cable direct from battery to the starter and same thing, turned over very slow and the cable got hot. I assume this means I do have a starter issue so I am going to take it off and take it to Auto Zone and have them test it and hopefully that is the issue and the final fix all to me getting this boat in the water...

 

[solar7647]

Re: Merc 470 NO SPARK

OK, I ran a jumper cable direct from battery to the starter and same thing, turned over very slow and the cable got hot. I assume this means I do have a starter issue so I am going to take it off and take it to Auto Zone and have them test it and hopefully that is the issue and the final fix all to me getting this boat in the water...

I would say that the cable was not the proper gauge to care the required current to the start thus making it get hot.

The slow crank could be caused by the fact that the cables to the battery may be ca-roded under the insulation.

I would recommend you replace the cables with new ones and see if you regain the crank speed. Make sure you have the battery fully charged.

If the starter issue is fixed and still dont have spark, then remove the gray wire from the coil and try again. The gray wire goes to your techometer and if it is grounded out or the tech is shorted it will kill your spark. If you get it to start you will need to trace the gray wire to find the issue.


FYI the 3.7L links in my signature may help for future problem the 3.7L is the same as the 470

 

[udm328is]

Re: Merc 470 NO SPARK

THANK YOU, THANK YOU, THANK YOU!!!

Thanks for all the help and advice to everyone. I just got her started. One thing about doing things on your own is learning through trial and error. Turns out the starter is just fine, did a few things before before ripping it out this morning and it worked. Put the wire minus the loose terminal directly to the starter, it then turned over much faster, yaaaay, but still not running. I then tested for spark again, nothing, what the hell. Turns out not knowing exactly what I'm doing played a big part. I finally took the cap off and thought that maybe I didn't understand exactly what I was doing to gap the points, and that was it, I played around with it till what I was doing seemed to make sense and BAM, barely turned the key and she started right up like a bull in a China shop. Not only did it start up, but she purrs like a kitten, I couldn't be happier, so one again thanks to all for the advice!!!

 

[solar7647]

Re: Merc 470 NO SPARK

Thats great....have fun on the water.

 

[udm328is]

Re: Merc 470 NO SPARK

OK, one more question. Got the boat out on the water and it ran like a champ, but the RPM's were running high, at least what I thought was high, they were all the way up. The water temp was good, and everything else looked good. Any ideas? Then when I got back to the ramp just before the ramp the engine died and I could not restart it, could the two be connected? I didnt get a new battery cable so it could be a little loose as far as it dieing, but confused about the RPM's

 

[solar7647]

Re: Merc 470 NO SPARK

OK, one more question. Got the boat out on the water and it ran like a champ, but the RPM's were running high, at least what I thought was high, they were all the way up. The water temp was good, and everything else looked good. Any ideas? Then when I got back to the ramp just before the ramp the engine died and I could not restart it, could the two be connected? I didnt get a new battery cable so it could be a little loose as far as it dieing, but confused about the RPM's

Your WOT RPM is 4200-4600 RPM. If you are running to high you need to make a change in your prop size. So if you increase the pitch of your prop by 1 inch you will loose about 200 RPM. see what your WOT RPM is under normal condition with how every many people you normally have and gear. then subract see how many RPM you are differant and increase your prop pitch till it drops the RPM in place. I would recomend you run about 4500rpm that way you have some play to stay in your range when weight changes.


As far as dieing, there could be a ton of reasons. If you came in to the ramps fast and slowed down real quick you could have starved the motor of fuel. The list goes on.

Also you could be sufering from vapor lock. When the engine is hot and dies the fuel left in the fuel line will vaporize and can cause a pressure differance that can be hard for the pump to over come.

EDIT: Normally that set up would run about a 14x19 inch prop