Merc 350/260 HP No Spark?

[81 Checkmate]

1986 Merc Chevy 350/260 HP Thunderbolt Ing. Boat started and ran fine last weekend. One thing i did notice was a spark coming from the center post to the + side of the coil. This past friday went to the dealer and picked up, New cap, Rotor button, Plug wires and plugs.
The boat has sat all week at our cabin in the driveway. I installed new plugs, then went to put new wires on and they gave me the wrong ones ( For a V-6 ) i said dumb a''''''
at the dealer, So i went to local auto parts store and matched up a set of wires.
Installed the wires.
Then went to take cap off, screw heads all buggerd up (Bummer)! Couldn't get them to break loose. So i had to drill all the bolt heads off to remove the cap.
All good, went to remove the studs 3 broke off flush and one came out ( Bummer Again)
Proceded to drill out and re-tap holes.
Success, Installed new rotor and cap with new wires.
Go to start it nothing NO SPARK
Called local marine mech and he said sounds like the coil is bad, Installed new coil and still NO SPARK.

The lake is 1 1/2 hrs from the house, so I gave up and brought the boat back home with me to work on.

Any Ideas what should be next? Thanks

 

[Bondo]

Re: Merc 350/260 HP No Spark?

and still NO SPARK.

Ayuh,.... How, 'n where are you checkin' it,..??

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

First i pulled the spark plug then grounded to block then turned over, No Spark. Next i pulled off the coil wire, put a spark in top of coil then ground wire from block turnd over no spark. Then mech said to put a wire from pos side of battery to pos side of coil and it sould start. No start

 

[Bt Doctur]

Re: Merc 350/260 HP No Spark?

Make sure you hooked up the dist wires correctly after you reinstalled the dist.
Remove tach lead(grey) ,bad/shorted tach will kill spark.
Remove the cap, remove the rotor , now check for spark at the coil. Sometimes the rotor is defective and grounds to the dist shaft.
check the black wire from the base of the dist, it`s a ground lead incase the dist doesent ground from mounting.

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Thanks for info. I looked up Thunderbolt trouble shooting and i did this,


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

#1 - 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.

#2 - 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.

#3 - 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.

#4 - 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."

It pointed me to a bad sensor in the dist, Pulled it out and will pick up new one today. Will post findings after install!

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Ok picked up new Dist sensor, Part # 18-5116-1 Teleflex Marine witch replaces Mercruiser 87-861780Q4 for V-6 & V-8 with Thunderbolt ignition 1981 - 1997 nut conectors.

Installed New Dist sensor,New cap, New rotor, New coil, New wires.

The Good: The Boat firerd up on first turn of the key.

The Bad: Idols fine 800 to 900 RPMS, But when i give it more throtle it revs to 1000 rpms and then it runs rough and will not get above 1000 rpms, it acutuly drops rpm and back fires thru carb.

Went and quaddrupled check firering order, check rotor button placement ( in slot on dist shaft) also removed gray tach wire from neg side of coil and still the same thing.

It just acts like the plug wires are crossed. But they are not. Maybey they gave me the wrong sensor. I do have the Thunderbolt IV Ignition and package says for Thunderbolt Ignition. Dont know if that makes a differents or not.

Any help would be greatly appreciated.

 

[Don S]

Re: Merc 350/260 HP No Spark?

First, you need to get the idle down, it should be 650 to 700 rpm. then check your timing.

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Don i might be off a little on the numbers. the boy was at the key last night and told me around 800 rpms. By the sound of the motor it is not running at high idol. Same as always, What is getting me is that 2 weeks ago it ran fine other than it sparking from the center of coil to the pos side of coil.

Would i need to redo the timing after the sensor install?

 

[Don S]

Re: Merc 350/260 HP No Spark?

Would i need to redo the timing after the sensor install?

Hard to say, but you do need to check it and verified nothing changed.

Also, count the tabs sticking down on the rotor.

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Ok will check timing tonight. There is 8 tabs on the rotor button !

Anything else to check?

 

[Fishermark]

Re: Merc 350/260 HP No Spark?

Anything else to check?

What plugs did you put in? (Brand and number).

Have you replaced / checked fuel filters and water separating filter?

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Plugs are NGK'S from the dealer, i do not have the number with me. I have not changed the filters as of now. We have had a lot of rain lately. When i look in the carb and have someone move the throtle i have a good squirt from both squirters.

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Question for Don. when i installed the new sensor the bolts i got with it are a lot longer, but the heads are much smaller. when i was putting in new bolts ( phillips head ) One was starting to strip so i put in the old one ( bigger head ) then a new one (LONG ONE) for the grond wire under th dist. When you look at the new sensor it is a one peice unit and the old was two peices with the mount bolts closer to the bottom of the inside dist. when you look at the rotor tabs it almost touches the bigger head bolt. Do you think that has anything to do with it?

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Update: Installed new plugs ( AC Delco )
Checked idol RPM 650 to 700 on the spot.
Switched out long (Big Head) screw for new one on sensor inside dist.
Double check rotor button and firing order.
Checked timming 8 Deg BTDC at idol.
Installed new fuel filters, Check gas in old water seperator and no sign of water in the fuel.

Still same performance !!!

Will rev to 1000 rpm then loose power and will not get above 1000 rpm.
Drops rpm when it hits 1000. RPMS go down on the gauge as you add more gas.

I am stumped? The only thing i can come up with is?
The control module box on the riser elbow is not letting it advance the timing?

If anyone has anymore ideas before i drop it off at a marine mech please feel free to advise.
I really hate to take it somewere as Hourly rates are so high.

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Well it's been 7 hrs and counting and no reply. I guess ive stumpd the best with this one.

Off to the dealer i go.!!!!!!

 

[ussoldier_1984]

Re: Merc 350/260 HP No Spark?

thats sounds like somthing similar that my boat started doing. Mine was the ignition module although Im still waiting to buy one

 

[6meter]

Re: Merc 350/260 HP No Spark?

Make sure the plug wires are going around the cap clockwise. From the sounds from your original problem, you just needed a coil wire replaced.

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Update: Mech said he is sure it needs a control module. I want to verify this as everyone has said in all the hundreds of post i have read, (You can not test a Thunderbolt module) YOU JUST HAVE TO REPLACE IT.

I have another points setup dist from the boys boat. 1982 Merc V-8 305

My question is what would i need to swap the dist to check the sytem out?
Could this be done ???

 

[Bondo]

Re: Merc 350/260 HP No Spark?

My question is what would i need to swap the dist to check the sytem out?
Could this be done ???

Ayuh,... Sure, just pop the distributer out, 'n drop the other 1 in....

Did yer Mechanic run through the diagnostic tree in the factory manual,..??
That Test tree will determine whether it's Workin', or Not...

 

[81 Checkmate]

Re: Merc 350/260 HP No Spark?

Update 5-2-11, Merc guy tested system buy the manual and said he is 90% sure is the control module. So i paid him for his time and brought the boat back home. Waited untill it stop raining cats and dogs for the last 4 day's.
Pulled out the thunderbolt system ( Dist, coil and box )
Installed the boys points dist/coil
Boat firerd up, Idols and revs thru the RPM RANGE. No other issues, its all in the Ignition system
Great now i solved the problem!

So i pulled that system all back out and installed the old Thunderbolt system back in.
Thought would try something and installed the new cap,wires and OLD Rotor button.
funny thing is it would rev to 1000 and die off/shutter for a second then rev to 3500? WTF!!!!

So now what? I am tired of working on this.

Going to go with a whole new system.
Anyone have any rcomndations for a new system?