mercruiser wont start 305 5.0L thunderbolt ignition

[wnaplay]

Hey guys the boat is an 89maxum with the 5.0l v8. The boat sat all winter until yesterday when my son decided to open it up and powerwash the engine(I know). Went and bought a new battery and attempted to start. It cranked strong but failed to start. I took the distributer cap off and there was some water but not alot. I blew it dry, sprayed wd40 in it, blew it dry again, wiped it dry, and lightly sanded the prongs inside. Still no start. I checked for spark using the traditional methods but didnt see any. I put in a brand new coil and still nothing. I got 12 volts at the positive side of the coil. I even jumped the battery straight to the coil. I attempted to strike the positive wire from the battery to the negative of the coil to look for an arc but there wasnt one. I bypassed the safety switch, checked all fuses, checked all wiring and still nothing. any suggestions?

 

[wnaplay]

Re: mercruiser wont start

Re: mercruiser wont start

Why do I always have the problems nobody wants to even touch>

 

[Capt Jimbo]

Re: mercruiser wont start

Re: mercruiser wont start

My 89 Maxum did the same thing. A buddy asked if I checked the gap on the points. I thought it was a stupid suggestion but what the hell why not. It started right up.

Now I'm not convinced that little bit it was off was the problem. I wonder if it was the points not making a good ground.

 

[Haut Medoc]

Re: mercruiser wont start

Re: mercruiser wont start

The make of the boat is irrelevant....
The make of the engine/drive package is.....
Post that & you will get help....
p.s> If it's a points type system, try disconnecting the tach.....

 

[wnaplay]

Re: mercruiser wont start

Re: mercruiser wont start

I am sorry, I am not sure what your asking when you say the motor package. It is the 5.0l merruiser as stated I belive with the alpha i outdrive. It has no points.

 

[wnaplay]

Re: mercruiser wont start

Re: mercruiser wont start

Motor is 305 5.0l v8 with thunderbolt ignition. I have 12v at coil, and going into amplifier. I have a good 12 volt at all the fuses. I dont seem to be getting any spark on any of my wires. I bypassed my safety switch at the lanyard to see if that was it and it wasnt. Is there something else that would cause the coil not to throw a psark? Maybe another switch(safety)

 

[wnaplay]

Re: mercruiser wont start

Re: mercruiser wont start

Here is the latest test I did. I removed pulled the dist spark wire and inserted a spark plug. I disconnect the green/white wire from dist terminal and turn the key on. As I am removing the green/white wire from the terminal the spark plug begins to spark. I didnt even get to the striking of the wire as suggested nor can I get it to strike.


Tests for TB ignition: W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.
If 12 volts is present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.
If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.
In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced

 

[wnaplay]

Re: mercruiser wont start 305 5.0L thunderbolt ignition

78 views not one suggestion of something to try?

 

[wnaplay]

Re: mercruiser wont start 305 5.0L thunderbolt ignition

Update: I put the old ignition sensor back in and put everything back together. I put a jumper on the neutral safety switch and still nothing. I take off the jumper and decide to try to fire it up. It almost starts but nothing. I give it a break and go back out and try again it almost wants to start so I keep giving it fuel over and over and it finally starts. I shut it off and hook up the muffs. I again get it to start but it doesnt want to. It finally dies and wont restart even though I can see fuel getting to it. I am hoping that taking out the ignition sensor and roughing up the metal parts that may have given me some indication where my problem actually was. I am hoping that a new one will take care of the problem. The neutral safety switch doesnt appear to ever be triggered. I ran it through all the gears and nothing ever came in contact with it so I dont know exactly what its purpose is.

Will automotive stores have tune-up parts which will work on marine engines? I am really hoping they have that sensor.

 

[John_S]

Re: mercruiser wont start 305 5.0L thunderbolt ignition

I think post #5 of this thread: http://forums.iboats.com/showthread.php?t=415032 was meant for your's.

 

[wnaplay]

Re: mercruiser wont start 305 5.0L thunderbolt ignition

I think so too.

The fact that the engine was pressure washed is very likely the cause of the problem. The reason there are few suggestions is that a pressure washer can screw up lots of delicate things including electrical connections, of which there are many. While you may have 12 volts present on the ignition, is it present while cranking? Have you checked for spark at the coil wire? No spark at the plug wires does not mean the ignition electrics has failed. It may be the fact that you doused the cap with WD-40 and it is arcing inside the cap. Replace the cap and try it. If it runs, flog your brother-in-law with the old one and don't let him do you any favors in the future.

How do you test it while cranking? Can I put the positive of my meter in where the spark wire goes(dead center on top of coil) and turn it over? If this is the way, I should see 12v coming out?