Odd gage behavior 1990 BFN
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=50623
Printed Date: September-28-2024 at 6:41pm
Topic: Odd gage behavior 1990 BFN
Posted By: woodyjumps
Subject: Odd gage behavior 1990 BFN
Date Posted: May-16-2022 at 12:52pm
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My Oil Pressure and Temerature gages rise when I turn on running lights. Interestingly, a friend with the same boat has the same issue. I've checked engine ground. Has anybody had and solved this already? ------------- Happy are those who find a lifestyle that they enjoy and the courage to live it. |
Replies:
Posted By: KENO
Date Posted: May-16-2022 at 6:55pm
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That's pretty much normal gauge behavior for anybody with that era Correct Craft, some more than others depending on the condition of your wiring and connections. It gets blamed on dash wiring, both the positive wires and the ground wires and old corroded and maybe loose connections. There's a lot of daisy chaining of power and ground wires under there and the wire size is small too, so energizing a load causes a voltage drop and the gauges are affected. Depending on which gauge you're looking at, some go up and some go down. People's improvements usually involve rewiring the positive and grounds under the dash with heavier wiring and a positive and negative bus with individual supplies from the buses to each load and instrument. You can search here on CCF for things like "dash wiring" "daisy chain" "dash grounds" etc. to get some reading on improvements
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Posted By: woodyjumps
Date Posted: May-18-2022 at 9:04am
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Keno, Thank you for the response. What caught me by surprise was that any gage would increase due to a drop in voltage or current due to resistance. I hadn't expected it was possible for the opposite reaction. I guess I have to study up. Yes, there is a lot of daisy chaining. I did a lot of wiggling of spade terminals to no avail. ------------- Happy are those who find a lifestyle that they enjoy and the courage to live it. |
Posted By: Jonny Quest
Date Posted: May-18-2022 at 10:15pm
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Some have had good success by using positive and negative bus bars to eliminate the daisy-chain problems. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: NCH20SKIER
Date Posted: May-19-2022 at 6:56am
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The PO of my '88 added the buss bars and so far so good for me ------------- '05 206 Limited '88 BFN |
Posted By: Gary S
Date Posted: May-19-2022 at 7:09am
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It's just easier not to use your lights during the day and focus where your going rather than looking at the gauges at night 😀
------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: KENO
Date Posted: May-19-2022 at 8:25am
I'd figure that some LED bulbs for the running lights and instrumentation lights would make a pretty good difference in the gauge reaction when the lights are turned on  |
Posted By: woodyjumps
Date Posted: May-19-2022 at 11:00am
We often ski late into the twilight on the Niagara River, and return under the stars, so not using the running lights is not an option  .I was baffled how a corrosion in power or ground could result in the gage reading increasing, so I did some research on VDO instruments that settled that bafflement. The instrument sends supply power "two ways". Through one coil and a resistor to ground, and through another coil towards the "sending unit", which is actually a path to ground, the resistance of which varies as the temperature changes. The two coils both act on the needle in opposite direction, the first one to pull the needle to zero, the other to pull the needle higher. If the first coil... let's call it the reference coil, does not have a free and easy path to ground, the current through it will reduce, allowing the needle to be pulled higher. Thinking of the ground buss like the drains in the house: All the things in service are using that drain. It might be fine when the sink is on, or you are flushing a single toilet, but if the main line has some resistance because of a diaper blocking half of the pipe, when the sink, washer, and a draining tube are all trying to drain through it at once it can back up. In electrical terms, the ground voltage rises. So, when the running lights are turned on, and the ground has resistance, the voltage in that ground leg rises... the current in the reference coils of the temperature gage and the oil pressure gage is reduced, so the balance within those instruments is affected in a way that results in the gages rising. It's that simple.   ------------- Happy are those who find a lifestyle that they enjoy and the courage to live it. |
Posted By: woodyjumps
Date Posted: May-19-2022 at 11:02am
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Now I can sleep. I can't sleep when I don't understand a problem. ------------- Happy are those who find a lifestyle that they enjoy and the courage to live it. |
Posted By: Jonny Quest
Date Posted: May-19-2022 at 11:20am
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Nighty night. ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: Hollywood
Date Posted: May-19-2022 at 1:12pm
| Not at all following that logic but it’s OK as long as we can both get some sleep. |
Posted By: KENO
Date Posted: May-19-2022 at 8:00pm
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Don't forget that there's a small voltage drop to the gauges too when the lights are turned on. I guess that would be like partially flushing the toilet
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Posted By: woodyjumps
Date Posted: May-20-2022 at 12:56pm
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Understood, a small voltage drop in the supply line will occur with each additional load. This is why the VDO gages have a balancing circuit, so the changes in supply voltage don't normally result in changes in engine temp and oil pressure meter readings (When the ground wires are sufficient...not 30yrs old and corroded). The changes in those meter reading are occurring due to the added resistance in the dashboard ground wiring. ------------- Happy are those who find a lifestyle that they enjoy and the courage to live it. |