351 Inboard turns over but will not start??

[wakesupreme]

Hey guys,

I have a 1979 ski supreme with a 351 windsor inboard engine. Before the season started I replaced the points and condensor, sparkplugs and distributor cap. The spark plug wires didn't need replaced. The boat was running great until the other day. I was traveling down the river at about 30 mph and it started to sound like the boat was running out of gas. The gauge showed half a tank. A minute or two later the boat died and hasn't started up since. I checked everything in the fuel system. The tank does have half a tank. I checked the pick up hose in the tank to ensure it didn't fall off, which it didn't. I just replaced the fuel pump at the end of last season. I do not think it is a fuel problem because when I dump gas directly into the carbs it still does not start up. It sucks up the gas but doesn't start. I replaced the solenoid at the end of last season as well. Could it be a fuse? The battery has a full charge and is cranking over fine. I'm not sure what else it could be. Any help at all would be greatly appreciated.

Thanks guys!

 

[zinc]

Re: 351 Inboard turns over but will not start??

You did not say in your post.....
Did you check to make sure you got spark to the plugs?

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

Thanks for the quick response.

I didn't do much checking into the electrical side of it yet. I figured it has to be something within the electrical part since when I dump gas directly into the carbs it does not start. I did not check for spark yet, so it may be the ignition coil. For the electrical system the solenoid, spark plugs, points and condensor are all new. As well as the battery. I will check for a spark tomorrow and follow up on this post.

Thanks

 

[mkast]

Re: 351 Inboard turns over but will not start??

Check resistance on the coil wire (plug wire).
Disconnect the tachometer from the coil.

 

[Haut Medoc]

Re: 351 Inboard turns over but will not start??

Check resistance on the coil wire (plug wire).
Disconnect the tachometer from the coil.

^^^^I agree on most likely electircal...
Check for spark...
If none, check for voltage at + side of coil......
If you have voltage at coil, disconnect the tach & check for spark....

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

Thanks for all the great advice guys.

I started testing the electrical circuit from the beginning. I tested to ensure I was getting 12v from the battery, which I was. I then moved to the solenoid and everything checked out there. I eventually checked the voltage on the incoming primary side of the ignition coil. I got -5.23 volts. I disconnected the wires from the coil and checked the wires without having them connected and I got 12v. It seems as if the coil is shooting out the wrong resistance or something of that nature. I'm going to swap out the bad coil tomorrow and hope that solves the problem. Does it sound like this is a coil problem?

Thanks again.

 

[mkast]

Re: 351 Inboard turns over but will not start??

Tachometer wire?

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

I'm not sure which one is the tachometer wire. I haven't worked much with coils.

One point I forgot to add to my last post was if I pull the wire that goes from the coil to the top of the distributor cap, on the cap's end, and lay it on the engine and attempt to start the boat. I do not get any spark what so ever. I'm thinking that it would have to be the coil?

 

[proshadetree]

Re: 351 Inboard turns over but will not start??

If your points didnt slip And they break when engine is cranked over.And the wire going to them didnt short.Id say it was the coil

 

[Don S]

Re: 351 Inboard turns over but will not start??

I pull the wire that goes from the coil to the top of the distributor cap, on the cap's end, and lay it on the engine and attempt to start the boat.

Don't just lay the wire on the engine, that will ground it out. Hold it about 3/8 to 1/2" away from a clean ground and crank the engine over. You should get a bright blue spark.

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

My fault. I did not lay it on the engine. I held it with a pair of channel locks on the rubber boot about a half inch away. I looked for a spark to jump to the ground, but I got nothing.

 

[MikDee]

Re: 351 Inboard turns over but will not start??

Thanks for all the great advice guys.

I started testing the electrical circuit from the beginning. I tested to ensure I was getting 12v from the battery, which I was. I then moved to the solenoid and everything checked out there. I eventually checked the voltage on the incoming primary side of the ignition coil. I got -5.23 volts. I disconnected the wires from the coil and checked the wires without having them connected and I got 12v. It seems as if the coil is shooting out the wrong resistance or something of that nature. I'm going to swap out the bad coil tomorrow and hope that solves the problem. Does it sound like this is a coil problem?

Thanks again.

First things first, if your points are stuck closed, there will be no spark, they must open, & close, to run. Next, the incoming wires on the coil, normally on a points system, one is 12v. during START only then it's dead when you release the key, the other is a resistor wire for the points, & condenser, it has less then 12v in it. when the ignition is on. Normally an external resistor coil is used for this reason. Check the other side of the coil (to the distributor) to see if you have any power going to the points. The tach is on this terminal, it's usually a gray wire, you might want to temp remove it, to see if it's causing the problem.

 

[bruceb58]

Re: 351 Inboard turns over but will not start??

How are you measuring the voltage at the coil? You need to have the ground of the meter to the block and the positive of the meter to the + side of the coil. Measure the voltage with the points closed and with the points open and report back.

Do you have a dwell meter? Measure the dwell while the boat is cranking to see if the dwell is set right. This can also help your troubleshoot if you are getting weird readings.

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

MikDee - I replaced the coil and it turned over like it normally did and it started about 5 times but then died after a second or two each time. I am charging my battery now because I think it may not be cranking fast enough. I was wondering since I checked spark from the wire that connects to the top of the distributor cap and I did not get a spark, doesn't that show that there was a problem with the coil and not something in the cap, since I eliminated the the cap from the picture?

Thanks for the help. I do not have a dwell meter. I will check the ohms though. Also, I will find the tach wire and disconnect it and try to start again without it connect and I will repost.

Thanks

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

UPDATE

I cranked the engine with the cap off and watched the points. They are not stuck to together and seems that everything within the cap is working properly. I replaced the points, cap and condensor at the beginning of the season and it was working great.

Next I connected everything normally with the new coil installed, except I disconnected what I think to be the tach wire. On the coil I have three wires, two from the pos and one from the neg. The neg goes to ground. The one pos (black wire) goes to the distributor and the other pos wire (grey wire) goes into a connector that looks to travel to the front of the boat. I assume this is the tach wire. I disconnected the tach wire and the boat only turned over but did not start.

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

bubba1235- I checked with ohm meter. 1.6 on primary side and 9,000 on secondary side.

 

[wakesupreme]

Re: 351 Inboard turns over but will not start??

After fully charging my battery as stated and with the new coil. The boat started right up. Thanks for all the help guys. It's greatly appreciated.