Mercruiser 4.3 EFI Gen+ TBI

[stevetrojo]

No spark, changed the distributor pickup, cap, rotor, coil, coil wire and starter. Serial number 0L680884. 12 volts at coil but no spark at plugs. HELP Please Could this be the Ignition module... Not available and conversion is $4,300.00 dollars.

 

[alldodge]

I don't have the V6 wiring but do have the V8 which is the same in your case. You have a MEFI 3 ECM with a TB-V distributer. Power to the coil comes from the main power relay, and power to the distributer comes from the ECM.

If you remove the sensor wires in the distributer the resistance should be less then 100 ohms. If there are any cracks in the sensor it needs replacing.

There is a TB-V troubleshooting guide but I'm not sure if it was done with a ECM controlling if it would not cause an issue. Whish I had better news but there were very few of these made and the manual doesn't go into much about them

You could send it off the get looked at and or repaired
http://www.mefiburn.com/mefiecms.asp

Bit hard to read but here is the wiring

 

[stevetrojo]

Thank you. I will try checking the sensor otherwise I'll be sending it off for repair.

 

[Pete104]

Running on the assumption that you have an Alpha 1.

Take a look at http://boatinfo/ is what I have stored. Mercruiser book #25 page 352 & 3 have the diagram that AD had but in V-6 mefi 3. And the red dot location identifiers. Several things to look at before going for big $.

 

[stevetrojo]

Pete104: I do have the Alpha 1. I will take a look, so far this problem has me stumped. Thank you

 

[stevetrojo]

Still can't figure out why the motor has no spark. This has me stumped. I hear the MEFI rarely goes out, but I can't find another reason why the thing has no spark.

 

[alldodge]

Being an Alpha drive, disconnect the shift interrupter and try

 

[stevetrojo]

I will try that. Thank you

 

[stevetrojo]

The good news... I sent my MEFI out to http://www.mefiburn.com/mefiecms.asp and it checked out as good. Still no spark, but I will try the shift interrupter switch when I get the MEFI back and installed. Bob at OBD Diagnostics was good to work with and he was honest about the diagnosis of my MEFI. I recommend them for MEFI and EFI problems.

 

[stevetrojo]

ok, I got the EMFI back and it is not the problem. I installed it, then I unplugged the shift interrupter switch. Did not install a new one though, just tried to start with the switch unplugged. Still no start and no spark. New coil, new rotor cap and rotor, new coil pickup, new battery, new starter, MEFI inspected and OK. Can anyone give me some direction? I'm out of answers and a bit frustrated with this boat.

 

[stevetrojo]

No spark, changed the distributor pickup, cap, rotor, coil, coil wire and starter. Serial number 0L680884. 12 volts at coil but no spark at plugs. HELP Please Alpha outdrive

 

[alldodge]

Remove the distributor cap and with a flashlight and magnifying glass, look close at the sensor. Check the wires coming out of the distributer for cracks.

As before you have 12V at the coil with key ON.
Remove all wires off the negative side of the coil and install one short jumper wire. Remove coil wire and hold it close to ground or use a spark gap tester. Turn key ON, then strike the jumper wire to ground real quick to see if you get spark.

If you get spark then I would like to test part of the TB-V using part of the troubleshooting guide.

Disconnect the Wht/Red wire coming from the distributer.
Turn key ON, then check power to round, there should be 12V
If 0 volts, need to check wiring back to ECM

If 12V is present
Reconnect Wht/Red wire

The next step would be to disconnect the Wht/Grn and measure the voltage on the wire coming from the distributer sensor with key ON.

I'm hesitant to go any further but if its not wiring I lean toward the sensor.

 

[stevetrojo]

distributor sensor? I placed a new one in there, no change.

 

[stevetrojo]

Distributor sensor? I already replaced it, no change. ??

 

[alldodge]

Wanted to check to make sure the wiring and power is OK, the above is all I have for now. Maybe someone else can provide another thought

 

[stevetrojo]

Help please

 

[Fun Times]

Help please

Posts 12 and 15 are some tests you're going to have to do as it seems like you may have a wiring issue not making contact someplace such as a wire pin connector has backed out somewhere.

You don't have spark coming out of the coil tower correct? or you don't have spark at the spark plugs wires? Own a timing light? If so, connect it to the coil wire between the dizzy cap and coil tower and watch for the light to flash while cranking the engine over to start. Makes things easier on you.

Does your RPM gauge move up to around 300 RPM while cranking the engine over to try and start?

Try disconnecting the gray wire off the back side of the tachometer gauge and see if you have spark coming out of the coil tower / will the engine start.

You need to separate the engine from the boat wiring to see if you have an engine issue or a boat issue. To do that test, try jumping the engine to start at the main canon plug wiring harness such as this past forum member demonstrated on video.... https://www.youtube.com/watch?v=NUoXFIo2Ab8 Also try wiggling the cannon plug connector at the engine for possible better contact.

The mercruiser safety lanyard switch at the shifter controller is in the up/on position correct? http://www.bing.com/images/search?q...y lanyard switch controller &sc=0-0&sp=-1&sk=

 

[stevetrojo]

Yes, the safety lanyard is in the up position. I played with the switch by putting it up and down to insure correct position. Do those switches go bad while a boat sits for a few months? I will try pulling the harness and jumping the motor. Thank you so much for the help. I also tried pulling the gray wire from the tach and no change.

 

[stevetrojo]

Does the cannon plug push in or are they screwed down? It's really hard to get to in my boat. I can see 4 screws looking down on it. Do I have to remove the screws or just pull it apart?

 

[Fun Times]

Sometimes there may be a hose clamp or wire zip tie holding the plug on but the plug will just pull off from the base...But don't unscrew the 4 base screws to the bracket like seen in the photo below or you described above....No need for that.

The base,

The wire plug,

Sometimes spreading the male terminals on the main engine harness helps make better contact. Loosen the hose clamp or wire zip tie, pull the harness from the plug, and with a small flat screwdriver, carefully spread the male terminals for better contact. Put back together, taking care to only snug up the hose clamp when finished.