First Mystery with a Volvo 5.7 ...maybe a couple

[Pilotmike]

My first Cobalt (2002 - 246 - 5.7 - 285hrs)

Love it love it, but.... questions.

1 - Overheated in June, The boat got to around185-190 when the alarm sounded and I shut it down immediately. Replaced a cracked impeller. No big deal. Ran great June/July/August.
I'm gauge crazy, always have been. Always watching them and I noticed before and after impeller replacement (temp 120 / oil at 40 psi at load) and (temp 160 /oil 10 psi at idle). I know gauges can be temperamental and connections always need to be checked, but they seem to be consistent. Any concern here? More flow while running equates to more cooling IMO....all in range no alarms...move on? see pics

but yesterday....

2- Running to the dock, not WOT or even close, but around 3500 rpms. The motor started getting sluggish, surged and quit pulling. I pulled the power all the way off. Waited 30 secs. and listened . No alarms, abnormal sounds, smells, smoke.
The engine idled fine, then i noticed the gauges, all of them, acted as if the engine was turned off. Fuel gauge dropped to empty, temp, oil, voltage, everything. When I throttled back up to 2800 rpms and everything came back to life. Ran the last 1/4 mile with out issue.

I can't risk taking it back out until this is diagnosed. Feels electrical to me but I'm new to Volvo. Fuel pump or filter, is there a computer, sensor, or should I have reset something after changing the impeller? Thoughts?

Thanks for the forum, very useful!!

MIke Van Metre

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[rabiddawg]

Your boat, like mine is possessed. How about we try and get a deal on a double exorcism

My oil pressure gauge does the same thing. Old hot rodders rule of thumb was 1psi per 100 rpm so I’ve not worried about it. My Malibu’s Indmar engine read the same way.

There should be nothing to reset after any maintenance.

The only electrical issues I have had have been self inflicted I suppose.

I reattached mounting screws on the back of my instrument panel. To do this I disconnected all the harnesses. Everything worked fine after I reinstalled it.

Next morning I decided to figure out why two of my speakers wouldn’t work. I turn on the perko turn the key and almost nothing works.

I called my wife told her I need a priest and vented for a few minutes. Then I disconnect/reconnect everything and everything works again.

[Big Block Power]

Your Prob running 140 and that's got a 140 tstat in it. Volvo washed that changed to 160 just so the oil got warmer and got rid of moisture in the oil. I haven't changed mine yet. It lasted 17 years so I figure it will be fine. But if you over heated I would change it. Did you have pieces of impeller? Or was it still in 1 piece?
It sounds like you have a poor connection somewhere. Maybe start grabbing a harness and wiggling it and watch the guages. Check your wires going to the alternator check all of your grds.

[cmattj]

It sounds like you have a poor connection somewhere. Maybe start grabbing a harness and wiggling it and watch the guages. Check your wires going to the alternator check all of your grds.

Yes check and tighten as it apears your alternator isn’t working or it’s not being consistent.

Next to your perko switch you should have some jumper lugs ( red and black )
Let’s see our running voltage ( yes you need a volt meter) as once under 10.5 volts ecm and systems stop working.

[Big Block Power]

When I redid my stereo wiring the battery cables going into the back of the perko were loose and arching. Would have never seen it if I didn't rewire it.

[Bfun220]

Yes check and tighten as it apears your alternator isn’t working or it’s not being consistent.

Next to your perko switch you should have some jumper lugs ( red and black )
Let’s see our running voltage ( yes you need a volt meter) as once under 10.5 volts ecm and systems stop working.

What he said. I've have seen a bad battery do this in a car once .

[Pilotmike]

Mystery continues. The gauge issue doesn’t seem to be an issue after reading many posts. Low temp at speed, 155-160 idling or no wake zones. No alarms, feel good.

But the loss of power from last year that is still a gremlin I haven’t figured out yet. Tightened all connections, new batteries ETC. so far this season shes run good.

Last night leaving the marina, I took off and felt a lugging and hesitation as we headed back to the trailer. Applied more power it smoothed out and no issues at 3000 rpms. (Related or not, above 3000, I hear a whistling come from the engine bay. I’m the only one who notices it, no one else on board has a clue when I bring it up. I think I can hear, smell, and taste anything coming from that motor:) ))

My next step is plugs, wires, and distrib cap. I’ve seen some talk on here about a fuel pump, hard to fix or is that a dealer call?

Any other thoughts?

Thanks

[Big Block Power]

Your whistle could be your iac filter? Won't effect the way it runs though. Or just air getting sucked in the throttle body. Or worse a vacuum leak but I doubt that.

[Pilotmike]

Yeah I feel like the whistle is my nervous energy, but the lugging at power up is concerning. As seen in my initial post of this thread, the complete loss of power last season right as I put the boat up for the winter was never diagnosed. Major concern is fuel injector or pump, but hope that the plugs are the easy fix. 2002 Volvo 5.7 MPI C if that gives any insight. Thanks all