no fire

[mikestirewheel]

i have a 72 viking w/ a 305 mercruiser. i had the timimg fixed got it back ran good for 30 min then stalled got it running again then stalled again now it will not start at all i put a new coil , points, and condenser in it but still no fire i have power to th coil but no fire out of the coil

 

[Don S]

Re: no fire

Did you set the points? (Dwell) Remove the cap and turn the engine till the points are open. Turn on the igniton and see if have power at the points?

 

[mikestirewheel]

Re: no fire

all the points are set

 

[Bondo]

Re: no fire

That's a Pretty Skimpy reply,............<br /><br />We're Trying to Help you Diagnose Your Issues,..........<br /><br />Don asked a Direct Question,......Which you Haven't Answered.........<br /><br />5 word Responses are Not Sufficient..........<br /><br /><br />Btw,.........<br />Welcome to the forums here at iboats............

 

[ron7000]

Re: no fire

have a 1976 boat with 351 mercruiser, been repowered. Have been through the same thing, new points, condensor, cap, rotor, plugs. Engine would run well for brief amount of time, seems like only thing that fixes it is a whole new set of points, don't know why.<br /><br />points suck!<br />if you haven't heard of pertronix, check out pertronix.com For a little over $100 you can fix it once and for all without having to set anything.<br /><br />Thats assuming that the distributor itself isn't shot, if it's the original which would make it 34 years old.

 

[mikestirewheel]

Re: no fire

i bought new points and condecer but still have no fire from the coil. i still have power to the coil but not out of the coil. is it posible that i bought a bad coil or is there some other problem?

 

[ron7000]

Re: no fire

hard to say without seeing it. If you just bought a brand new coil, then I doubt it's bad. What I was referring to in my last post was that when I use to run points on more than one occasion I've gotten a BAD brand new set of points and condensor.<br /><br />someone correct me if I'm wrong, but there are coils that say "internal resistance" and those that say "external resistance" or "use with external resistance". Maybe he bought a replacement coil that's the wrong type- like an internal resistance coil which is also using the resistance wire from it being a points ignition? So it's not getting enough voltage?<br /><br />In any event, to check the coil you should be able to do the following:<br />disconnect the negative wire going to the coil from the points in the distributor and rig up a wire to manually connect the negative side of coil to ground. Turn ignition key to run so coil gets power on + side. Have a glove on when holding the wire from neg side of coil, hold it to ground for a second then remove it- you should see a spark on the lead wire which goes from the coil to the distributor, have this wire removed from the distributor and have the metal end (which plugs into the distributor) no more than a 1/4" from any clean metal on the engine which would be a ground source. you should see spark when you pull the negative wire from coil off ground.

 

[mikestirewheel]

Re: no fire

am i supose to have power to the coil with the key on or while the motor is turning over

 

[Limited-Time]

Re: no fire

Originally posted by mhjd:<br /> am i supose to have power to the coil with the key on or while the motor is turning over

Both. No power to the coil = no fire. If you have no power to the coil with the key in the run position the engine will fire with the key in the start position but quit when the key is released from the start position. If there is no power in the start position the engine the engine will turn over but not fire.

 

[mikestirewheel]

Re: no fire

what do you think i should do to get power to the coil in the run postion

 

[Limited-Time]

Re: no fire

You can run a hot wire (for testing) from the positive battery terminal to the positive side of the coil. Just remember in order to kill the engine you have to disconnect the hot wire. The real issue is why your not powering the coil through the key switch.

 

[mikestirewheel]

Re: no fire

could the key switc be bad or is there a fusable link somewhere

 

[Don S]

Re: no fire

Get a test light or a DVM and test it and find out. It could also be a broken wire, I have found a lot of corrded and broken wires and the round 10 pin connector on the engine, there is also other wiring on the engine that could be the problem. Earlier you said you had power to the coil, now it's missing?? Does the engine fire when you crank it, you aren't really helping at all with your answers<br />Also, HOW did you set the points?

 

[Limited-Time]

Re: no fire

Time for a test light and a little circuit checking. One of the pros here may be able to fill you in on wire color to chase. But a 34 year old wiring harness to me would be suspect at best. Good luck.

 

[mikestirewheel]

Re: no fire

i set the points with a feeler guage. no i have power to the coil while cranking and no fire while key is on the motor will not fire at all i took a spark plug wire off to see and i got nothing

 

[Don S]

Re: no fire

Did you have the points set on the high spot on the lobe when you set the points?

 

[paulrfrancisco]

Re: no fire

Not to sound belittling, but are you familier with setting point? The part of the points that rubs against the distributer cam needs to be on the peak of the cam. Then the feeler gauge should just fit with ever so slight drag without forcing the points open further.<br /><br />Then make sure the hold down screw is tight. I've personally had a situation where the points moved because the screw was not tight enough. If the points close up on you, or open up as it may be then the coil gets no charge time, or no trigger to discharge. Recheck the gap and make sure it accurate. Next, get a wire and run it from the battery + directly to the + of the coil. Use alligator clips if necessary to make it easer. If the points are adjusted fine, and the jumper wire corrects the problem, then the issue is in the wiring harness.<br /><br />The only other comment is that you said it run for 30 minutes or so, then began failing...my guess is the points out of adjustment...

 

[mikestirewheel]

Re: no fire

the pionts where on the high side and they are still at the right gap ( i think they are supposed to be .019) ialso will try the jumper wire if it is in the harness how difficult is that to change

 

[fendersfender]

Re: no fire

if you're not sure how the system works, or how to troubleshoot it, youre best bet is a trip to your local marine service department is in order

 

[paulrfrancisco]

Re: no fire

If I'm not mistaken, there is a resister wire in the wiring harness that provides reduced voltage from the Alternator to the + side of the coil... MercCruiser makes a replaceble resistor wire to run outside the harness..... Now that I mention that, I wonder if your alternator has the bad connections or if there is a problem with the alternator...