View Full Version : MercCruiser 50L EFI 2000 Electric Problem

04-24-2004, 08:23 PM
" I have twin Merc Inboards. I've have a very difficult electrical problem and am looking for some ideas. My mech is a master tech and this is driving him crazy (and me too).

The first time this happened, I was running at 2000 RPMs and it just shut off. A few minutes later, it start. Then shut off and then I couldn't get it started.

We checked, and there is no spark. He replaced the ignition sensor fired right up. He did the regular service to it (replaced the distributor cap, plugs etc.).

About a week later, I couldn't get it started.
He changed the coil, ran fine for a day.

Week later, same thing. Change the wiring harness and switched out the ECM.

Week later same thing. This time, though, you could muck around with the wiring going into sensor and it would prime with the circuit open, start and run great.

So he though, maybe this isn't grounded right (although he checked all the grounds). Put an extra ground of the cap and changed out the sensor one more time. Ran great. Two days later, started fine, ran it hot.

Week later ... well here I am. Can't get it started at all, this time the behavoir is prime prime looks like it wants to start, doesn't start.

Other things he did is check the wiring up in the front on the circuits. Checked all the grounds, no error codes nothing.

The only thing he didn't do is change the other half of the wiring harness, but he says that just can't be it. A friend of mine says the rotor or the whole distributor might be bad.

It's just mind boggling. Any ideas would be great. "

04-24-2004, 08:45 PM
" Try replacing the ignition switch or look for a loose or poor connection where the harness is plugged together. Sound as if a connection is making and breaking at will and I'd bet most of the goodies that were replaced may not have been needed. Also check all ground connections including large cable from battery to engine. Good luck, Kim "

04-24-2004, 09:27 PM
" Thanks. He thinks the same thing (that it wasn't any of the stuff he replaced). I've had this guy for years and he's honest. I haven't paid for anything, plus it's under warranty. He's in the hole for sure on this thing.

I thought about the ignition switch, because they replaced the Alarm Kit in the front that's not OEM a while back and it humms a little. He checked that, didn't think that was it.

He checked all the grounds. He thinks there is some low voltage connection breaking somewhere. Replaced the whole harness except for the part that connects the things like cooling sensor.

I also get the feeling that it runs hot and then wait for a week, something is expanding than contracting.

The motor turns over great, there is just no spark. Would you get that if the ignition switch is bad? "

04-28-2004, 09:28 PM
" If your running an old condenser and points distributor, I'd replace that. Also, check to see if you have an automatic shut of mechanism for when the engine begins to get hot. I can't think of anything else. My uncle had the exact same problem. These where the only things he hadn't done. I'll find out if they figured it out and let you know maybe tomorrow. "

04-29-2004, 09:19 PM
Does the ecm have a diagnostic plug?

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