Mercruiser 170 cranks but no start, fuel in the carb and getting spark

[UHHOHH1212]

It cranks and sometimes sounds like its about to turn over but just doesnt get there. I cleaned out the carb, tanks and lines and get a good squirt if i push the throttle. Ive grounded all plugs and have spark. I dont see a safety or kill switch any where but i may be missing it. Not sure where the choke is but ive manually turned the butterflys with no result. Even starting fluid wont turn it over. When i open the butterfly i can see fuel sitting under the carb. This is on a 86 glasstream 192 regatta cuddy.

 

[Scott Danforth]

welcome aboard

was the spark a bright blue color?

did you file the points, adjust the gap and check the dwell? (check out the DIY sticky at the top of the forum, links 18-20)

is your distributor installed correctly?

is the motor spinning over fast enough? many times a bad battery or a bad connection will severely slow the motor down to under its cranking speed.

 

[Oshkosh1]

Yeah, it does sound like a base timing issue.

If temperature has any bearing then look more toward the fuel side of the house...if not the stick with ignition.

 

[hogbare35]

If you have good spark(blue) ,fuel ,air and turning at start speed you should at least get a backfire even if timing is off.

 

[UHHOHH1212]

Thanks for the responses. I have the exhaust manifold off for cleaning today and will check the quality of the spark when it's back together. It has a new battery with 1000ca so no problem there, but I'm going to double check the points before testing the spark. I will update when I know more

 

[UHHOHH1212]

Small update. Finally was able to quickly check the spark and it was yellow. That was from the end of the cables before the plugs, so now I need to chase it back and find good spark. Only question is with a stator what powers the ignition coil on start up, the battery or stator

 

[nola mike]

Battery. Did you replace/file/gap/dwell the points yet? First step if not.

 

[salty3rd]

i would run a jumper, jumper cables work fine, from the + on the battery to the + on the coil and see if it starts. This will give you a better idea where to look to find the problem.

 

[UHHOHH1212]

I cleaned and GAP the spark plugs checked the distributor cap and there is zero corrosion and I'm not sure what you mean by Dwell. Salty3rd I will try that and I'm assuming if it starts then I'm losing power at one of the connections pre coil.

 

[UHHOHH1212]

If you mean the points for the stotor/magneto I have not opened it up yet

 

[UHHOHH1212]

Ok feel like im getting closer but need help understanding. I went through the sticky on the coil and ive determined that i have 12v on the wire going into + of coil, and about 6v on the + post with the wires connected which is in spec per the sticky. It has a weak spark directly from the secondary of the coil. If i run a jumper from the + battery to the + coil it has a healthy spark. The coil is in spec and has continuity between + and - but it still seems like im losing power between the + of coil and secondary of coil. I also noticed that the center shaft of the distributor is not moving the contact point in the distributor. It does not have a lobe just 2 flat sides on the shaft and the rounded sides are supposed to lift the point. It does not look like an adjustment would correct this though. Im going to switch the points to electronic, should i also throw a new coil at it? Thanks in advance, i can fix almost anything but diagnosing the problem is not a strong point and dont have any experience with distributors or stators

 

[kenny nunez]

Your “bypass” circuit from the solenoid below the manifold, purple/yellow is not delivering 12 volts when cranking. Replace the solenoid. Also from all the cranking and weak spark there is a good chance the plugs are fouled. Adding the electronic kit will help. Change the plugs after you get the ignition to put out a good spark.

 

[UHHOHH1212]

I also have a slow crank so was planning on starting with the solenoid and cleaning up all connections, with what you said its just another sign pointing to the solenoid. Once i have good spark i plan on replacing plugs and wires.

 

[UHHOHH1212]

So i just got to it and the purple yellow is going into the slave solenoid. Is that what was referenced as the "bypass circuit. Would that have anything to do with the crank speed or would that be the starter/main solenoid also needing replaced. Thanks again for all the help, this boat sat for a while so theres been alot it needs

 

[UHHOHH1212]

I replaced the boost solenoid and had the starter tested which passed. I have 12v at the starter (red) and 12v at the boost solenoid (red). Im still getting a slow crank and still not getting the right voltage from the purple/yellow to the coil. I tested while cranking and im getting 6v from the ignition switch wire at the boost solenoid and 6v going from the boost back to the starter solenoid. The purple yellow wire from boost to coil has 12v before cranking and 6v during and after cranking, and if i leave the meter on i see the voltage slowly going back up. I hooked my remote starter switch from the battery to the starter solenoid it still cranks slow and it has 12v at both terminals doing it that way. Do you think the starter test was not sufficient and the starter works fine on bench but slow under a load, or could there be something else thats binding up and slowing the crank speed, and the coil not receiving the proper voltage from purple/yellow im completely lost on i just know i still have a weak spark from the coil. I added a bad wiring diagram in case my explanation was not clear