Mercruiser 5.0 MPI no start/spark

[ofirlevy1]

Hi, I have a 2007 Searay with Mercruiser 5.0EFI engine. The engine now cranks but will not start. A day before out on the water I had a message on the Smartcraft- saying- Ignition coil not working". Changed the ignition coil and now the massage is gone, but the engine still will not start. Checked voltage going into the ignition module and into to the coil- all checked good. Any ideas?

Thanks.

 

[alldodge]

Howdy

I would replace the distributer cap. These distributer caps go bad even if they look good. If it still will not start, its good to keep the old one on hand because they go out without warning. In any case remove the cap and have a look under it.

Also what is your engine serial number?

 

[Chigwalla]

Pull one of the plugs to see if you have spark, then work your way upstream till you find where you have spark again.
The code won't come up again unless the fault is still active.
You could still have an intermittent ignition fault somewhere else.
While the dist cap is off, check that the spring tab on the rotor is sitting up about 3/8" off the top of the rotor.
Try cranking the engine in the dark to see if it's arcing. If do you see that, turn the lights back on and look for carbon tracking on the plastic.

You might check the coil for that as well since you're there anyway: old school coils were bad for that until they changed to the bakelite housing. Being SmartCraft, your coil is likely electronic and they're not usually as bad for that...but still worth checking. Serial number would help with that.

Not to state the obvious, but double check that the wire boots are fully seated, esp on the coil lead.

 

[QBhoy]

Having had the same...I can Defo tell you that AD is right on the money for starters. Change the diz cap and rotor. They are famous for failing on this engine
Also worth noting that you need a strong battery. Despite the engine apparently turning over healthily enough...sometimes the cranking takes that much current away from the ignition system it will not fire and throws a coil fault amongst others at you. Symptoms of this will be the engine back firing or spluttering when you release the key after cranking.
The latter being the case, you can get it to eventually fire is you turn the key back on quickly whilst it?s spluttering after release of key.

 

[QBhoy]

How did you get on ?

 

[ofirlevy1]

Hi guys, thanks for the replies.

Just an update- Pulled the out the plugs- nothing. The plug wires are new BTW. I replaced the coil and the ignition module- nothing. Replaced the crank sensor- still nothing. My next step is the distributor cap and rotor, even though both were replaced about 6 month ago. The batteries are also about a year old and fully charged- have good voltage coming out.

Serial number is 0W682644.

Question- does this engine use a camshaft sensor in the distributor? maybe...

 

[alldodge]

Question- does this engine use a camshaft sensor in the distributor? maybe...

Yes it does, but unless there are wires connected to the sensor it is not used. VP uses the sensor but Merc mostly does not.

Assuming this is a Alpha drive
Check fuel pressure (item 18) and does your tachometer show at least 300 rpm when cranking

http://www.mercruiserparts.com/bam/subassembly/31852/12840/90

 

[ofirlevy1]

Looks like there are three wires going into the camshaft sensor.

It's a Bravo 3 drive.

Rpm tach show 0 when cranking. Smartcraft display also shows 0 rpm when cranking. I thought that was strange.

 

[Fun Times]

Looks like there are three wires going into the camshaft sensor.

It's a Bravo 3 drive.

Rpm tach show 0 when cranking. Smartcraft display also shows 0 rpm when cranking. I thought that was strange.

If all the other 12 volt things seem to be working such as the helm gauges, fuel pump prime, relays clicking, warning beep sounding for about 2 seconds at key up, etc. then the tachometer not moving is generally an starting point indication that the crankshaft sensor or wiring isn't working properly...While it might be the Camshaft sensor not working properly as they've been known to do odd things, the scale is on the low side for them to affect the tachometer to read 0 but again not impossible.
https://axleaddict.com/auto-repair/Bad-Camshaft-Position-Sensor-Symptoms

Triple check all the wiring at/going to the Crankshaft sensor for damage, connection, power issues....It's possible the crankshaft sensor wiring became compromised during say a bravo sea water pump service as their general area is in close enough proximity of each other.

If all that seems okay and you don't have any fault codes pulling up on a scan tool type read-out then I'd be concerned with having an possible internal ECM issue with either the Coil Driver side since you had a coil fault code or a 5 volt or 12 volt power issue or possibly a few other internal issues that could happen.

Just so you're aware should it become needed, The following link offers ECM testing for minimum $100 inspection and if the ECM can be repaired sets you back $600.00. https://whipplesuperchargers.com/index.php?dispatch=products.view&product_id=73

 

[alldodge]

When key is turned to ON do you hear 2 beeps and the sound of the fuel pump?

Check for 12V at the Pink/White wire?

Remove the crankshaft position sensor connector and see it contacts are clean

 

[ofirlevy1]

Thanks guys.

When key turn on everything comes up-beeps, display, relays and fuel pump. Smartcraft indicates everything "ok". The crankshaft sensor was replaced but I didn't check the voltage going in yet. That's my next step.

I hate to think it might be the ECM, but not giving up yet. I'm thinking maybe a bad wire somewhere.

 

[alldodge]

Some wiring diagrams

 

[ofirlevy1]

Looks like a costly ECM repairs is in my future.. All wires checked out good. All sensors checked out good. Tomorrow I'm going to install a borrowed ECM and see if this thing fires up.

Will update.

 

[Fun Times]

Looks like a costly ECM repairs is in my future.. All wires checked out good. All sensors checked out good. Tomorrow I'm going to install a borrowed ECM and see if this thing fires up.

Will update.

If at all possible, sometimes it's a better idea to first plug your ECM into a known good running engine to see if it keeps that engine from starting, running etc. due to the rare event that something is still wrong on your engine causing the ECM to short out internally.

Good luck.

 

[QBhoy]

Change the diz and rotor before anything else. Even if it is 6 months old. If it?s not getting used all the time it gets damp and messes it up.
My local Merc dealer recommends replacing every year to make sure...that?s how bad the problem is.

 

[ofirlevy1]

Well, sent the ECM to the life saver Simon Motorsports. $640 later- they found that my ECM was full of water ( I cannot figure out how). So that's that. I will receive it next week at some point. Will update.