sensor going bad

alanurt · **Posted:** Mon Aug 06, 2012 7:58 am

2004 Volvo Penta 5.7 GXi-F
I have a sensor that is going bad and throws the motor into safe mode, sometimes only for a split second. Any idea how many there are and which one might be the most likely culprit? Not sure if it's a complete coincidence, but it seemed to happen when I tried to raise the drive once on plane, although it did happen at other times as well. Thanks.

alanurt · **Posted:** Mon Aug 20, 2012 6:16 pm

Update: I have ruled out the outdrive as just a coincidence. It happens when the boat gets jolted hard from a wave and is only for a split second. All is fine when it's calm. Anyone? Bueller?

ric · **Posted:** Mon Aug 20, 2012 6:47 pm

If you don't have a friendly mechanic under your belt, maybe buy a scan tool?

alanurt · **Posted:** Mon Aug 20, 2012 7:00 pm

They are always tough to nail down. Burned two vacation days last week getting blown off. I'm not sure a computer will pick up on an intermittent issue, will it?

ric · **Posted:** Mon Aug 20, 2012 7:18 pm

Once an error is logged, it should stay logged but I'm not sure how long it's stored for.

Winter Sux · **Posted:** Mon Aug 20, 2012 7:33 pm

Yup, a diagnostic trouble code or DTC will be stored in the history.

I'd throw some methyl hydrate in her first and see what happens.

Technologic80 · **Posted:** Mon Aug 20, 2012 7:45 pm

Things that can put the boat in S.L.O.W. or guardian mode (or safe mode as you put it):
-Overheat (or faulty ECT)
-Oil Pressure (or faulty oil pressure sending unit)
-TPS on its way out
-IAC on its way out
-I think low drive oil (merc) too.

Just to name a few. IIRC, most problems point to the oil pressure sensor. But you really do need to read the codes. If you search the web, you might be able to use a paperclip and LED (I bought mine at Radio Shack) to read the codes out of the DLC connector on the engine. That method will work on MEFI 1 - MEFI 4. And I want to say you are MEFI 4.

ric · **Posted:** Mon Aug 20, 2012 7:48 pm

Yup, or pay $65 for a fancy paperclip
http://www.ebay.com/itm/CodeMate-Tester ... 5f&vxp=mtr

alanurt · **Posted:** Mon Aug 20, 2012 7:57 pm

TPS and IAC are relatively new. I noticed a corroded wire is completely off from what I believe to be a sensor. It is right where the oil filter would be if the motor were in a car (oil pressure sensor??). The problem is, my oil pressure gauge is working, so unless threre are two sensors (one for guage and one for the computer), this isn't it. I really don't think this is it anyway because the wire is completely off and could never send a signal to the computer. If a sensor is unplugged or the wire is broken, what happens? Will the boat function normally? This wire seems like it's been off for a while, so I think the problem is elsewhere. As I mentioned, it only happens when I hit a decent wave, as if a loose wire is jiggling.

Bliss36 · **Posted:** Mon Aug 20, 2012 8:40 pm

I purchased this in the spring to diagnose my VP Mefi-4 problems. I chose it over the generic code reader because it shows live data on a cool dashboard screen as well as dtc's. Not bad for $195.00
http://www.mefi4.com/sc/details.asp?item=mefiscan1

FWIW this company also had really good tech support when I called them for help installing the software

Beachbob · **Posted:** Tue Aug 21, 2012 7:39 pm

We had a similar problem with out 2008 VolvoPenta. We discovered that heat sensors in the exhaust mainfold as well as the one on the thermostate went bad. Volvo stopped putting them in the exhuast manifold becasue they were mre problems then they are worth. I now carry spares.

alanurt · **Posted:** Wed Aug 29, 2012 5:16 am

Update: I had a mechanic come down the other night and he hooked up his computer. We went for a ride and I was able to duplicate the problem. The motor showed no codes and all is perfect with the motor. What did happen was power to the laptop was cut each time I hit a wave, demonstrating a power interruption from the motor's computer. The mechanic believes it to be a bad ground, but we ran out of day light. He is going to come back to replace an oil pressure switch and will trace the power interruption at that point. I'll keep you posted. Thanks for all the hints.

alanurt · **Posted:** Mon Sep 10, 2012 2:53 pm

Update: The wire from a newly installed starter came loose. The previous mechanic didn't use a lock washer.

noexcuses · **Posted:** Mon Sep 10, 2012 3:26 pm

Here is another item you might want to keep an eye on for intermittent electrical problems.

http://www.marinepartsexpress.com/VP_Se ... placed.pdf

www.iFourWinns.com

sensor going bad

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