4.3L Mercruiser Won't Start

[Baur]

Motor was running at idle and stalled, will not restart. Motor turns over, appears no spark to start. No 12V on red/wht wire to ignition sensor. Disconnected red/wht wire and with key on still no 12V to wire from ignition amplifier. Is amplifier bad?

 

[alldodge]

Purple wire?

 

[Rick Stephens]

Alpha drive and the shift interrupt is engaged?

 

[dubs283]

are you following the t bolt trouble shooting guide? you're a couple steps beyond some preliminary checks with the wht/red wire check.

as asked is there voltage on the purple (ignition) wire with key on engine off?

 

[Baur]

Sorry for delay, daughters boat and was waiting for a replacement ignition amplifier to try and see if that was issue (it is not). In answer to the question regarding the purple wire, if you are talking about the purple wire that feeds one of the connectors on the amplifier, there is 12V at the plug. In regard to the red/white wire, with the key on, wire connected and using my test light, the bulb is very, very, very dimly lit. Almost like something further on(ignition sensor? distributor) is shorted, however, if I disconnect the red/white wire I still don't show 12v on the open end. ?????

 

[Baur]

It appears that the shift interrupt is functioning properly by the way, if I move it into FWD the motor will not turn over, when in neutral motor turns over, fuel pump runs however it just does not want to start.

 

[Baur]

Maybe this isn't a Thunderbolt ignition? How would I know that?

 

[alldodge]

I said "Purple wire" only because I have no idea what your working on other then a 4.3. While this is a clue with the red/white being mentioned, it still does not assure me of what you have.

Using a test light on the amplifier is not what should be done. A test light can draw more current then the amp can take. Unsure if it will damage it or not, but your looking for 12V, not if a light turns ON or is dim.

How about telling us what 4.3 your working on and serial numbers are best but I can make due with a year and size of motor

 

[Baur]

I'll have to get more specific info from my daughter, its a 2011 Tahoe Q5i 4.3L V6 Mercruiser

 

[alldodge]

Thanks, and that's a new can of worms
2011 means, PCM09, MPI, Flat top distributor and CAT's

 

[Baur]

Well, by flat top distributor comment, if you mean the top of the distributor doesn't have plug wires coming out of it then this is not a flat top. And also what is CAT's? I told my daughter to bring me her manuals and other information she has with the boat, maybe I can find out engine serial number from her.

 

[alldodge]

Flat cap is what most call carp cap because they are always going bad, but are the HVS distributor and look like this



CAT's mean catalytic converter exhaust system

 

[Baur]

My daughter sent me a label that was in her documentation, it says 4.3 TKS A, Serial number 1A627259, model number 4-211025U U Any help with this info??

 

[Baur]

Distributor does not look like photo you sent, it is what I would call a "normal" looking distributor like on older style motor vehicles, center coil wire surrounded by the cylinder plug wires.

 

[alldodge]

My daughter sent me a label that was in her documentation, it says 4.3 TKS A, Serial number 1A627259, model number 4-211025U U Any help with this info??

Dang, let me go dunk my hat in the creek. A 2011, not a 2001 but 2011 with a TKS, I never would have thought that

OK, I'll go with it but TB ignition is not longer available

So you used the TB% troubleshooter?