Late 70's 350 Chevy OMC ....no spark from coil

[Alws55]

New gas, water sep, points conds cap rotor coil wires 2 yrs old.
With key on, power to + - side of coil power to points also, cranks like hell won't fire tried grounding coil wire from cap connection no spark.
Could it be timing chain or resistor or volt reg? Goin there tonite to advance or retard timing to see if it will fire.
Am I on the rite track?

 

[RogersJetboat454]

Re: Late 70's 350 Chevy OMC ....no spark from coil

As long as the distributor shaft is turning (might want to check to be sure the drive gear isn't stripped) it doesn't make 1 lick of difference if the timing chain is off time, or the ignition timing is incorrect. It should still make spark.

What is your the voltage at the B+ terminal of the coil with the key on? What is the voltage at the B+ terminal of the coil when the engine is cranking?


Did you set the points with a feeler gauge with the distributor lobe in the proper position?
Have you cleaned the points up with a file?
Did you clean the points with acetone or contact cleaner when you were done cleaning/setting them?
Are the connections at the coil for both + and - clean and tight?

 

[MRMonteith]

Re: Late 70's 350 Chevy OMC ....no spark from coil

Aside from what Rogers said the typical issue with those type systems is usually the condenser. But of course the easiest to check is for spark off the coil, voltage going to the coil, and the points. My first check was always to take the coil wire off the distributor cap and put it near the engine block to see if I get a spark when the engine is turning over. If not, remove the distributor cap and check that the points look clean and open and close ok and look clean. Usually at that point the gap shouldn't have changed but easy enough to check at that point. You can disconnect the input to the coil and check the resistance with an ohm meter. Typically when a coil goes out the input is an open circuit so infinite resistance. After those checks it's usually just as quick to replace the points and condenser at the same time and more than likely fix the problem. My first guess is condenser, 2nd only to coil. I do miss these simpler engine systems you can work on without computers.

Keep us posted on what you find.

Michael

 

[Alws55]

Re: Late 70's 350 Chevy OMC ....no spark from coil

Thanks fellas...everything you both mentioned was done from new pts n condens,new coil, clean tite contacts, checking for spark against motor. I am going there over weekend I will meter volt while cranking n key on. Only other thing is I haven't cleaned n tighten all contacts to n from starter even tho it cranks strong.
Thnx again ill post again

Frank

 

[Alws55]

Re: Late 70's 350 Chevy OMC ....no spark from coil

The voltage on + side of coil is 12v then drops to 9v while cranking.
The gray wire on - side of coil is the tac right? That's discon for now.
Still no spark at all while grounding the coil wire while cranking.
Gonna switch coil again & try.

 

[Alws55]

Re: Late 70's 350 Chevy OMC ....no spark from coil

"If not, remove the distributor cap and check that the points look clean and open and close ok and look clean. Usually at that point the gap shouldn't have changed but easy enough to check at that point'


So I dug in my parts box and used a set of used points that looked good not burnt. Threw them in there set gap and she fired right up with gas I dribbled in carb. The fuel in pumping strong and the filter is new it's not getting fuel. Since I have 2 rocherester quadrant-jet carbs ill get one rebuilt they've been sitting for 2 yrs b

Odly they both show the same prob when switched on motor.
If I attempt to blow air into the fuel line to carb it acts like its blocked no air in at all. Is this normal?

 

[NYBo]

Re: Late 70's 350 Chevy OMC ....no spark from coil

If I attempt to blow air into the fuel line to carb it acts like its blocked no air in at all. Is this normal?

Yes, if you are holding the carb with the base horizontal but upside down. It would be hard for you to blow with enough pressure to overcome to weight of the float holding the needle in the seat. However, holding it in any other orientation, you should be able to get some airflow. Don't Rochester cards have a filter in the fuel line mounting?

EDIT: This is the filter I was thinking of. It mounts inside the carb. http://www.iboats.com/Fuel-Filter-f...7061373--session_id.526506047--view_id.173337

 

[Alws55]

Re: Late 70's 350 Chevy OMC ....no spark from coil

I paid close attn to the filter I am currently using
Fuel Filter for Volvo Penta, Mercruiser 35-53336Q 3302-9033, OMC Sterndrive/Cobra 908034, GLM 24840 - Sierra 18-7859 - iboats
Well the floats must be gummed up although I did run it 5 miles 2 weeks ago then I tuned it up and stumbled with the elec problem.
What it I try to get carb cleaner to the float bowl, like I mentioned earlier if I dribble fuel down carb she runs n starts fine. Probably should just rebuild it for max operation.

THANKS!! For all replies the wisdom and experience is 2nd to none.
Frank aka alwsfishin

 

[stratcat88]

Re: Late 70's 350 Chevy OMC ....no spark from coil

New gas, water sep, points conds cap rotor coil wires 2 yrs old.
With key on, power to + - side of coil power to points also, cranks like hell won't fire tried grounding coil wire from cap connection no spark.
Could it be timing chain or resistor or volt reg? Goin there tonite to advance or retard timing to see if it will fire.
Am I on the rite track?

i had a coil problem on my 260 mercruiser. it turns out it was the tach takin it out. good luck.