No spark - 1976 mercruiser

[butkiss]

okay guys here we go - i have a 1976 mercruiser 165 - no spark - new plugs, cap, rotor, condenser, coil, wires you name it- good power to coil at run setting but not during crancking - bad seleniod? New starter costs about 300. don't want to be wrong any ideas or ways to test?<br /><br />thanks

 

[oldboat1]

Re: No spark - 1976 mercruiser

not a starter problem if the starter is turning the engine OK. Check the points -- regapping may solve the problem. (Actually, it may not be the regapping itself that solves the problem -- points may not be opening and closing.) This assumes, of course, that you do not have electronic ignition installed.....

 

[Trent]

Re: No spark - 1976 mercruiser

Dont have the schematic here but...When you go into the start mode their is another wire that provides 12volts for starting (not running) Its usually on the starter solinoid. Somtimes they are fused (or fuseable link). Re-check your wiring.

 

[petryshyn]

Re: No spark - 1976 mercruiser

It sounds like the feed to the coil is being taken from the accessory terminal on the ign. switch instead of the ign. terminal. <br /><br />There should be power to coil when in the on position and while cranking as well. There also should be power coming from the solenoid to bypass the ballast resistor. This is usually not crutial....

 

[Valv]

Re: No spark - 1976 mercruiser

Schematic is absolutely right. I bought a motor once that nobody could start. Well, when the key switch was on On, there was power to coil, when turned to Start it didn't have any juice. Ended up they mistakenly use Accessory wire which was momentary off during cranking. Use a voltmeter or simple light bulb and see if you have + at coil during cranking.<br /><br />Val

 

[rloper]

Re: No spark - 1976 mercruiser

On a 165 mercrusier there is a switch mounted on the cable assembly behind engine ( it momentarily kills the engine when putting it in forward or reverse to help shift into gear). This switch will stick and keep the engine from running. It is connected to the negative side of the coil after the points. Have ran in to this problem before, hope this is it for you. Loper

 

[Trent]

Re: No spark - 1976 mercruiser

Check the purple resistance wire... Runs from the choke to the coil. <br /><br />If you have 12v at the coil before cranking the shift interupter switch listed above is OK.

 

[DJ]

Re: No spark - 1976 mercruiser

I believe the purple wire Trent mentioned acts as a "ballast resistor". This is so the points do not get a full 12 volts which would cook them in a hurry.

 

[wheels4]

Re: No spark - 1976 mercruiser

Do you have an emergency kill switch?My old engine did and that was the same problem you are having.Diconnected one wire (dont rember which one Im color blind) and it ran like a champ.Had to choke it to shut it down though.Good Luck.Wheelage

 

[seahorse5]

Re: No spark - 1976 mercruiser

On the (-) coil terminal, there should be three wires. Remove the gray one for the tach, and the black one that goes to the shift "kill" switch, but the last one, to the distributor, leave connected. That way you are checking only the ignition circuit on the motor. Don't overlook the possibility of a rusty distributor having a bad "ground" to the engine.

 

[butkiss]

Re: No spark - 1976 mercruiser

going to try these all today guys - thanks a million for the advice - I'll let you know how nailed it (I hope!) thanks again