Help me be the hero :-), Mercury 4.3 – no spark

[birdpiper]

2004 Mercury Mercruiser 4.3 Thunderbolt V Ignition (model: MCM 4.3 Litre)



We are at the lake for the week, took the boat out yesterday, 5 or 6th trip this season all previous with no issues. On the trip yesterday it sputtered and died, could not restart, nice neighbor towed us back to dock.



It turns over strong (starter turns), but no ignition

I’ve tried the following:

-Verified full gas

-Verified run switch is on

-Pulled a spark plug, reseated into plug, and had someone turn the key while I held the plug – no spark seen

-Removed the distributor cap cover, cleaned up a little bit of corrosion, reseated, no start



Here at the lake I only have access to limited tools (no multimeter or test light). A mechanic is scheduled to come out in two days, but I wanted to see if there is anything else I can check or try in the meantime (maybe salvage a few days of boating).



Any help or thoughts are appreciated

 

[alldodge]

Find a 12V bulb from one of the gauges, Navigation lights or other. Would be great if you could find a socket with a bulb in it. Otherwise need to figure out how to rig it up as a test light. With no meter use the light to see if light is bright enough to show 12V

No go thru the troubleshooting guide

 

[birdpiper]

Thanks for the feedback, not much luck rigging up a test light.
Are there any other "low hanging fruit" items I can check with limited tools?

 

[alldodge]

Here is a meter for $7
That should be cheap enough right?
https://www.harborfreight.com/7-function-digital-multimeter-63759.html

 

[Scott Danforth]

do you have the old 2-wire trigger assembly or the new 3-wire trigger assembly in the distributor?

 

[poconojoe]

That troubleshooting chart is very thorough.
You will find the answer while going through those steps.

If you can't rig up a test light, go to any auto parts store or Wally world and pick up a cheapo 12v test light or better yet, get a multimeter.

I keep a very small Radio Shack compact multimeter in a weatherproof box along with the rest of my tools, fuses, bulbs and other emergency items.
That little multimeter folds up into it's own box. Its tiny and works great. I don't know if you can get that same meter. Is Radio Shack gone? They closed the one by me a while ago.

 

[prc03sx195]

I just went thru this on my boat, 2003 4.3L TB- V ignition. Went thru the steps and it was the ign sensor inside the distributor. Mine was the original two wire sensor so got a three wire replacement quicksilver sensor and new cap and rotor. The cap contact points were all corroded so I am not sure if that wasn't part or all of the problem but changed the ign sensor anyway. Ordered in ebay and got the stuff in 5 days. Good luck

 

[poconojoe]

I just went thru this on my boat, 2003 4.3L TB- V ignition. Went thru the steps and it was the ign sensor inside the distributor. Mine was the original two wire sensor so got a three wire replacement quicksilver sensor and new cap and rotor. The cap contact points were all corroded so I am not sure if that wasn't part or all of the problem but changed the ign sensor anyway. Ordered in ebay and got the stuff in 5 days. Good luck

I have the same year and engine (2003 4.3L) and went through this a few years ago too.

Mine also had the original two wire sensor. It was just an exposed circuit board. It was all corroded.
The new one is completely sealed and has three wires. The old one got its ground from the mounting screws and the new one's third wire is the ground.

The hardest part of the job for me was removing the old rotor! They glue them suckers on at the factory. I had to cut it in pieces to get it off gently as not to damage the distributor shaft.

 

[MichaelBC]

2004 Mercury Mercruiser 4.3 Thunderbolt V Ignition (model: MCM 4.3 Litre)


-Pulled a spark plug, reseated into plug, and had someone turn the key while I held the plug – no spark seen

Did you press the thread of the plug against a good ground connection during this test ?

So the mechanic was there yesterday ? What was wrong finally ?

 

[birdpiper]

Thank you for the responses folks, much appreciated. We left the lake yesterday, mechanic still had not come out. Will try to post the results if I get some feedback from the repair.
Lesson learned for future years - Bring a few basic testing tools (test light, multi-meter, etc.) with me to the lake (it is very remote).

 

[poconojoe]

Thank you for the responses folks, much appreciated. We left the lake yesterday, mechanic still had not come out. Will try to post the results if I get some feedback from the repair.
Lesson learned for future years - Bring a few basic testing tools (test light, multi-meter, etc.) with me to the lake (it is very remote).

Get yourself a small weatherproof box to keep tools and other small essential items in.

I have a pocket sized multimeter that folds up into it's own hard case. It was a Radio Shack item, but I just saw some similar ones on Amazon for $14-$16.

I keep spare fuses and bulbs, electrical tape, wirenuts for temporary emergency connections, various crimps, linesman pliers, channel lock (pump) pliers, screwdrivers, scraps of wire, adjustable crescent wrench, maps of the lakes, etc....etc...
Anyone care to add anything?

 

[nola mike]

Get yourself a small weatherproof box to keep tools and other small essential items in.

I have a pocket sized multimeter that folds up into it's own hard case. It was a Radio Shack item, but I just saw some similar ones on Amazon for $14-$16.

I keep spare fuses and bulbs, electrical tape, wirenuts for temporary emergency connections, various crimps, linesman pliers, channel lock (pump) pliers, screwdrivers, scraps of wire, adjustable crescent wrench, maps of the lakes, etc....etc...
Anyone care to add anything?

Ratchet/sockets, spark plug socket, a few box wrenches, spare spark plugs, clear bag/jug (to check fuel), gorilla tape