Catastrophic Engine Electronic Failure?!? Diagnosis Help!

[Jg.hughett]

Coming from three marine techs at my shop. We need some ideas before diving any deeper.

Volvo Penta 5.0 GXI-D
Original complaint: No crank

Starter tested bad and was replaced. Engine still did not crank. Key switch also ended up being bad. Test switch put in for confirmation. Engine now cranks consistently however only runs occasionally and if so not for long nor well.

Poked around and found alternator to also be bad only putting out .2 bolts at 2000 RPM(lucky to get that rpm)

Logical conclusion was since the system(injectors, ignition, etc) run largely off of the alternator, that it would solve the problem. Alternator that was already brand new got replaced. It did not solve running issue(However I do now have good Alt voltage).

Onto the unconfirmed. Keep in mind we do not have access to Volvo software(non dealer).

Ignition coil Ohmd out to 10-30 mOhms. Would seem to be a problem however here is the kV output for each spark lead by cylinder #:1-16kv
2-17kv
3- 6kv
4- 7kv to 9kv when Rev high. 12kv when idle
5- 16kv
6- 10.2kv
7- 16kv
8- 10kv to 14kv

Yes. I know. “Well there’s bad voltage on some so replace the coil, distributor, and rotor. Understood however I need some reasons. Multiple sensitive electronic failures and still rough running. Possible boat got struck by lightning and killed everything? All other grounds and positive cables have been cleaned and Ohm tested. All good.

One last detail: timing sitting at 0 Degrees. Normal is 8 BTDC however I can’t get engine to sit anywhere other than ~300RPM for more than 30seconds. Cant adjust timing like that very well.

Timing, Distributor cap, rotor, coil, CPS sensor, fuel pressure could all explain rough running but not as to why everything went… HELP!!!

 

[tpenfield]

What's the engine diagnostics tell you when you hook the computer up to it? Are you able to record engine data when the engine is running?

 

[Jg.hughett]

What's the engine diagnostics tell you when you hook the computer up to it? Are you able to record engine data when the engine is running?

Sadly that’s our one downfall. We do not have access to Volvo software. Non dealer.

 

[muc]

Rinda Technologies Inc.

Suggest Diacom for your shop. If you want to charge customers to repair EFI sterndrives ----- you NEED this.
The service manual that explains operation and troubleshooting can be found at;
https://www.volvopenta.com/en-us/service-and-support/your-engine/manuals-and-handbooks/

KVs are all over, possible lightning strike, if it is you really need a scantool.

First try a new rotor and distributor cap. Don't buy a cheap one!
While your replacing them take a close look at the distributor hold down bolt. This engine has non-adjustable timing. If someone has moved the distributor it will have to be put back to the correct position and you don't use a timing light to do it! Cap, rotor and making sure dist is correctly clocked might be all you need. All of these can cause your symptom's.
If not it will be time to buy a scanner.

 

[Donald0039]

Your either going to buy the Diacom to scan the engine codes now or latter.

If your going to DIY maintain your engine you need a Diacom.

 

[tpenfield]

Rinda Diacom or bust.

 

[Donald0039]

People can complain all they want about the engine electronics and EFI and the cost of a Diacom.

But I had a 1987 Mercruiser 5.7 L with carb and electronic ignition. And now a 2012 VP 5.7L with an ECM, EFI, etc. The 2012 starts and purrs like a kitten. Significantly better starting and running.

I will pay the cost of the Diacom to have a smoother running engine.

It would be nice if the boat engine and car engine could use the same code scanner. Too big a wish I guess.

 

[tpenfield]

With fuel injected engines, really comes down to this . . .

1) Parts Cannon . . .

.
or

2 ) Diacom