5.7l EFI Mercruiser cranks but won’t start

Hello all, I am having trouble getting my 2000 5.7l EFI Mercruiser to start up. When I turn the key, it’ll crank, but nothing else. No signs of it even trying to catch and fire up.

Quick background, I bought this boat earlier this year and the previous owner had done some different wiring to bypass the starter as I believe it didn’t work and he didn’t want to replace it. So first thing I did was have a mechanic replace the starter and redo the wiring. Once he was done with that, had no issues firing the engine right up.

Fast forward three weeks (wasn’t able to take it out in between then and now due to other commitments), and I go out to start it up before heading to the lake and all it’ll do is crank but not fire up.

With the help of a buddy, I was able to see that fuel was getting to the carburetor, there was spark getting to the distributor, and spark from the distributor to the spark plug. Also pulled out two spark plugs and while not brand new, they weren’t completely foul looking.

At this point I’m not sure what to try next and was hoping some of you all would be able to give me some advice.

Thanks!

Try some starting fluid. Getting a motor started that has resisted it is sometimes cured that way. If it still won't go, however, have a mechanic look for timing issues.

Jeff

Is the lanyard switch off?

Ooooh!

Good one to check. The switch itself could also be defective--had that happen to me last year.

Jeff

Jeff, in regards to starting fluid, you're simply referring to ether, correct? I did buy some and used a tiny bit to try to get it to start, but was trying to be cautious with it. For the timing issue, I've been trying to read up on that to understand it but can't find anything that states specifically what I need to do. Your suggestion would be to have a mechanic check that?

For the safety switch, I have this question. When i have the switch to "run" there is fuel spitting into the carb, but when it's in the "off" position, there is no fuel spitting in. So my thought is that the safety switch is working correctly, but could I be completely missing something there?

Thanks for the replys.

For the safety switch, I have this question. When i have the switch to "run" there is fuel spitting into the carb, but when it's in the "off" position, there is no fuel spitting in. So my thought is that the safety switch is working correctly, but could I be completely missing something there?

If you have fuel injection ,what you calling a carb is a throttle body. With the engine not running , there should be no fuel squirting down the throat. Injectors will only fire on the command from the ecm, has nothing to do with any "safety swtch"

Sorry yes I mean throttle body. My friend just kept referring to it being a carburetor so I've had that stuck in my head. Either way, just not sure if my safety switch is causing the issue or not.

The safety switch cuts off the ignition, not the fuel.

Try a bit more ether. Your engine might just be all fouled up from all this trying to start it.

Jeff

Is there any easy way to know if my safety switch was bad? I'm hoping to get outside tomorrow night and give the engine another whirl with some more ether, but trying to continue to brainstorm other ideas so I'm not endlessly cranking the engine to no avail.

I was able to get outside yesterday and check out the compression of each cylinder. I had consistent readings between 180 - 200 psi. However, I also rechecked the spark that I had coming from the distributor, and noticed that it is a more orange/yellow spark than a nice blue spark like I've read you would want. Does anyone have a suggestion on the next thing to check and/or replace?

I've looked at the distributor cap and rotor and they both appear to be okay, but would it be suggested to go ahead and replace these just in case they are the issue? Looks like I can get those two parts and the gasket for $50 so definitely wouldn't break the bank, but also trying to avoid throwing money away at parts that might be good.

Another item I do want to do though, is test the ignition coil to see if it's good. In reading the manual, it discusses using an ohmmeter. Does anyone know if simply using a $10 ohmmeter from the local parts store would be sufficient? Or is there a marine specific ohmmeter you have to use?

Any ohmmeter will work , no such thing as a marine ohmmeter ... I've had my $29 one for about $20 years.

Wher are you testing the spark at the plugs or going from coil to distributor? Should be able to jump a 3/8 gap on a spark tester. Definitely check the coil but 90% of the time the coil is ok, would be more suspicious of cap rotor wires plugs.

Dieter said:

Any ohmmeter will work , no such thing as a marine ohmmeter ... I've had my $29 one for about $20 years.

Wher are you testing the spark at the plugs or going from coil to distributor? Should be able to jump a 3/8 gap on a spark tester. Definitely check the coil but 90% of the time the coil is ok, would be more suspicious of cap rotor wires plugs.

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I tested the wire going from the coil to the distributor. Originally used a spark tester (one with the light) and got nothing on the light, but then used a screwdriver and got a spark. Then pulled the boot off a spark plug and did the same thing there and received a similar spark.

You need a strong BLUE spark. Orangey sparks are not sufficient.

I suspect you have a bad coil.

Jeff

Ignition coil was the problem. Also gave it a bit of a tuneup with new distributor cap, rotor, plugs and wires.

thanks for all of the help!!