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View Full Version : 78 Mastercraft will fire but not run


cheft557
04-06-2014, 06:49 PM
Hello everyone,

My boat has had the same issue for a while. The engine will fire but when I let go of the key and it returns to the run position it stops. I have seen another thread on this site and went through just about everything. New ignition switch, new solenoid, new distributor, new wires, new coil. Just can't figure it out.

Any help would be greatly appreciated.

KnoxX2
04-06-2014, 07:57 PM
Sounds like a relay is closing. I'm sure someone has seen this before on here and will have more input. Sorry!


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thatsmrmastercraft
04-06-2014, 08:57 PM
Do you have points or electronic ignition? Did you do anything to your engine prior to the happening?

There aren't any relays to fail on this. Pretty basic ignition system if stock.

Sounds like you aren't getting power ti the ignition system with the key in the run position. I would check the wiring harness connectors for corrosion. I had some electrical issues in the past and solved them when I found some corrosion in one of the main connectors.

CruisinGA
04-06-2014, 09:33 PM
If you have points ignition, I would suspect a bad ballast resistor.

Table Rocker
04-06-2014, 09:35 PM
If you have a test light, put the clamp on the block and the point on the (+) side of the coil. Crank the engine and the light should come on. Release the key to the "run" position and the light should stay on. If it doesn't stay on, you know you aren't getting power to the coil. Do the same thing at the ballast resistor (if equipped with a ballast resistor), and so on continuing upstream on the (+) coil wire. Test at the ignition switch to make sure you have the purple "run" wire on the run tab of the ignition switch.

If you don't have a test light, get one.

While having similar problems with a hotrod, I just ran a wire with a simple switch from the positive post of the battery to the ballast resistor. You could flip the switch and then turn the key to start the car. You would kill the car with the switch. It helped get the cars messed up wiring out of the way while I got it running right. After I knew everything under the hood was good, I dove into the rat's nest behind the dash.

Table Rocker
04-06-2014, 09:37 PM
If you have points ignition, I would suspect a bad ballast resistor.I agree, either a bad ballast resistor that has a bypass for starting or the ignition switch is wired improperly.

JimN
04-06-2014, 09:45 PM
Wow! 6 posts and nobody mentioned the safety lanyard. If the lanyard is on the switch, press on the center and try again- if it keep running when you press on the center, get a new lanyard. Over time, the clip can become deformed and it won't press the switch fully.

CruisinGA
04-06-2014, 10:32 PM
Wow! 6 posts and nobody mentioned the safety lanyard. If the lanyard is on the switch, press on the center and try again- if it keep running when you press on the center, get a new lanyard. Over time, the clip can become deformed and it won't press the switch fully.

If there was a problem with the lanyard, I don't think it would fire at all?

Worth checking anyway!

Table Rocker
04-06-2014, 11:08 PM
If there was a problem with the lanyard, I don't think it would fire at all?

Worth checking anyway!
Mine won't fire at all without the lanyard. Did '78s have lanyards?

thatsmrmastercraft
04-06-2014, 11:38 PM
No lanyard in a '78.

cheft557
04-06-2014, 11:59 PM
Thank you all for the info. I have tested the coil and run a jumper from the battery directly to the positive on the coil from the battery, and the engine will stay running after starting. As soon as I remove the jumper the engine dies.

I have a new Pertronix billet distributor, I have a new accel coil, and per the distributor
instructions have removed the Ballast resistor.

It is a basic electrical system and everything I have tried is not working.

thatsmrmastercraft
04-07-2014, 12:01 AM
Wow! 6 posts and nobody mentioned the safety lanyard. If the lanyard is on the switch, press on the center and try again- if it keep running when you press on the center, get a new lanyard. Over time, the clip can become deformed and it won't press the switch fully.

Jim.........you feeling OK? Lanyard in a '78???

cheft557
04-07-2014, 12:02 AM
And to verify, there is no lanyard. There appear to be a safety switch in the Velvet Drive, but that has been bypassed.

thatsmrmastercraft
04-07-2014, 12:02 AM
Thank you all for the info. I have tested the coil and run a jumper from the battery directly to the positive on the coil from the battery, and the engine will stay running after starting. As soon as I remove the jumper the engine dies.

I have a new Pertronix billet distributor, I have a new accel coil, and per the distributor
instructions have removed the Ballast resistor.

It is a basic electrical system and everything I have tried is not working.

Did this problem occur when you installed the Pertronix system?

cheft557
04-07-2014, 12:05 AM
Actually it was on and off throughout the last 3 years or so that I have owned it. I thought that the ignition was the culprit so just like most I went for the most expensive problem, the distributor, only to find the issue has not been fixed, but I have a shinny new distributor.

cheft557
04-07-2014, 12:08 AM
Is it possible it could be a bad ground in the system somewhere?

thatsmrmastercraft
04-07-2014, 12:14 AM
If it fires in the crank position but not in the run position, I wouldn't think it is a ground issue. I would focus on the wiring from the ignition switch to the coil that connects to the run circuit of the ignition switch.

cheft557
04-07-2014, 12:37 AM
The wire from the ignition switch runs right to the S terminal on the solenoid and the coil wire runs from the I terminal to the positive of the coil. This is the way it has always been since I bought it. In the on position there is no voltage to the positive on the coil. I replaced the ground wire from the battery to the bock, cleaned all contacts on the solenoid, cleaned all contacts on the alternator. I dont know where else to check for ground wires.

Table Rocker
04-07-2014, 12:39 AM
I would disconnect everything (take pictures so you can put it back right) from the run tab on the switch and make sure it is hot after cranking and coming back to run. I would then unhook everything else that is on the purple (if they used purple in '78) run wire. I would unhook all the gauges and the wire at the choke. As ThatsMrMasterCraft said, somewhere between the run tab and the coil is your problem.

Table Rocker
04-07-2014, 01:09 AM
The wire from the ignition switch runs right to the S terminal on the solenoid and the coil wire runs from the I terminal to the positive of the coil. This is the way it has always been since I bought it. In the on position there is no voltage to the positive on the coil. I replaced the ground wire from the battery to the bock, cleaned all contacts on the solenoid, cleaned all contacts on the alternator. I dont know where else to check for ground wires.I think your problem is there. I believe the "I" terminal is only hot when the key is turned to start and is used for a ballast resistor bypass. Check to be sure.

If the only wires to the solenoid are the battery/starter cables, the red/yellow start trigger and the wire from "I" to the coil, how can the coil be hot other than while cranking? If there is no input there from the "run" tab on the ignition switch, there can't be an output from it.

thatsmrmastercraft
04-07-2014, 01:14 AM
Thank you all for the info. I have tested the coil and run a jumper from the battery directly to the positive on the coil from the battery, and the engine will stay running after starting. As soon as I remove the jumper the engine dies.

I have a new Pertronix billet distributor, I have a new accel coil, and per the distributor
instructions have removed the Ballast resistor.

It is a basic electrical system and everything I have tried is not working.

I think your problem is there. I believe the "I" terminal is only hot when the key is turned to start and is used for a ballast resistor bypass. Check to be sure.

If the only wires to the solenoid are the battery/starter cables, the red/yellow start trigger and the wire from "I" to the coil, how can the coil be hot other than while cranking? If there is no input there from the "run" tab on the ignition switch, there can't be an output from it.

Sounds like this is getting close to being solved.

Table Rocker
04-07-2014, 01:18 AM
See if the purple wire is hot at the choke when the ignition is at "run." If it is, follow back and see if you can find where the wire for the coil is or has been cut off.

JimN
04-07-2014, 02:09 AM
If there was a problem with the lanyard, I don't think it would fire at all?

Worth checking anyway!

During crank, the ignition switch bypasses the normal ignition wiring, including the ballast resistor.

cheft557
04-07-2014, 07:20 AM
That makes sense with the I post on the solenoid, it had the ballast resistor and have disabled it, or taken it out of the loop. Maybe I wired the coil incorrectly. Where should the power to the positive side of the coil come from?

cheft557
04-07-2014, 07:22 AM
Also because the boat is so old many of the colors don't match.

cheft557
04-07-2014, 07:25 AM
Should the coil be wired from any point on the solenoid? Should I move the coil wire from the I post to the S post or will that cause damage?

occva
04-07-2014, 07:49 AM
Post a picture of your coil wiring and what you did with the ballast wiring.

TRBenj
04-07-2014, 08:48 AM
I think your problem is there. I believe the "I" terminal is only hot when the key is turned to start and is used for a ballast resistor bypass. Check to be sure.

If the only wires to the solenoid are the battery/starter cables, the red/yellow start trigger and the wire from "I" to the coil, how can the coil be hot other than while cranking? If there is no input there from the "run" tab on the ignition switch, there can't be an output from it.
Ding ding ding!

On the solenoid:
S = "start". This is the 12v signal from the ignition switch telling the relay to close (and crank the starter).
I = "ignition". This post receives 12v that is used to power the ignition only during cranking. It is optional- not all marinizers utilized it- and was used to bypass the ballast resistor during starting.

Your coil + should be connected to a 12v ignition source (hot when the key is "on"). If the only wire connected to it is from the I terminal of the solenoid, then your ignition will only be hot during cranking. Which will cause the problem youre describing.

I would remove the wire from the I terminal of the solenoid and connect it to a known 12v ignition source that only comes on with the key in the "on" position.

cheft557
04-08-2014, 12:11 AM
So here is the result. When I pulled the ballast resistor out of the system I did not re-wire everything correctly. I had the positive switched 12v going to the wrong place. When I traced the wire from the switch to the engine I was able to identify which one it was and then reconnect everything the right way. All of the 12v switched lines to the engine; coil choke etc have 12v on and 0 off. The boat starts great and runs great too.

THANK YOU TO TRBenj, occva, JimN, Table Rocker, Mr. Mastercraft, Knoxx2, and CrusinGA, you we all very helpful and I truly appreciate the dialogue and suggestions. This site is great and it is because of people like yourselves who have a passion for this and helping others.

Thanks again!!!

Table Rocker
04-08-2014, 09:26 AM
Great, thanks for checking back in and letting us know you got it fixed. How about a pic of this '78? We would all love to see it.

thatsmrmastercraft
04-08-2014, 10:18 AM
We have all mis-wired something at some point. It is even more inevitable than launching the boat without the plug. glad to hear you figured it out. I too would like to see some pictures of your boat.

cheft557
04-08-2014, 11:31 PM
Here is a picture. Nothing too spectacular, but she does the trick.




108837

Table Rocker
04-08-2014, 11:42 PM
Here is a picture. Nothing too spectacular, but she does the trick.

She's a beaut! Looks really clean and now she runs too! Thanks for posting the pic.

thatsmrmastercraft
04-08-2014, 11:54 PM
Great looking boat. If you ever want to put the stars and proper year graphics on it, send a message to mikeg205. He has done the decals for my '77.