84 SN2001 Voltage Drop
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=41982
Printed Date: April-27-2024 at 4:48pm
Topic: 84 SN2001 Voltage Drop
Posted By: maxibarker
Subject: 84 SN2001 Voltage Drop
Date Posted: September-24-2017 at 3:21pm
| Shouldn't my electrical system be able to overcome the load of a small Rule bilge pump, and the OEM blower? I have great hole shot with these loads off, and stumbling, and stammering when I stab it with these loads on. Nominal voltage is 12v, but when loads are on it drops to 10.5. Shouldn't the available voltage regulate to maintain nominal 12v? My solution is obvious, loads off generally. But seems to me that when this boat was new I didn't have to do this. Thoughts? |
Replies:
Posted By: Gary S
Date Posted: September-24-2017 at 3:39pm
|
Thoughts? do a search,common problem with all makes. You need new feeds to the dash,much like people needing a heart bypass ------------- 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: September-24-2017 at 4:09pm
|
Sounds to me like a nominal voltage of 12 is low and maybe your alternator/voltage regulator have issues. You should have 13 to 14 or so at the battery itself (measured with a multimeter) with the engine running and a little less at the dash. If that 12 is on your dash meter, it's too low What do you have for an ignition system? points or electronic. What brand if it's electronic? If it's electronic, depending on the brand, they can be finicky and do things like you describe if supply voltage is too low. It could be wiring related like Gary said or the alternator/regulator or a combination of both. |
Posted By: gt40KS
Date Posted: September-24-2017 at 5:27pm
|
* Failing alternator? * Ground or power cable corrosion and/ or short? * Voltage regulator? Regardless, I would verify the exact running voltage with loads off to eliminate the possibility of a failing battery and that the alternator is supplying the correct voltage while running. It's a good starting point anyway. ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: maxibarker
Date Posted: September-24-2017 at 6:12pm
| Thanks all. I did search the forum first but didn't come up with anything relevant. It's a new alternator with an integrated regulator as my "mechanic" suggested but no help. Also at his suggestion we changed out the loom resistor with a ballast resistor no help. And while we were at it we replaced the coil. Same result. It has points by the way, not EI. Will get the meter and check these suggestions and the battery is probably about 7 years old so will do a load test. |
Posted By: gt40KS
Date Posted: September-24-2017 at 6:45pm
|
Battery is not to be ruled out, you're correct - stranger things have happened. As with the alternator ... brand new out of the box has been known to be faulty. I'd still check it. ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: KENO
Date Posted: September-24-2017 at 7:08pm
|
I'm kinda wondering what you have for an engine, since you mention having a loom resistor originally and I haven't seen any mention of the brand, like PCM Ford, Mercruiser Chevy for example. The PCM Fords didn't have a resistor in the wire loom You could also check the big connector plug at the back of the engine, unplug it, clean the connectors and plug it back together. Power has to get thru that plug to get to the dash and back thru the plug to get back to the ignition system and corroded connectors can impact your voltage and current carrying capability. |
Posted By: maxibarker
Date Posted: September-24-2017 at 7:15pm
| It's a Ford 351 Commander and it did have a loom resistance wire. I will clean all connectors while I try to find the problem. Thanks. |
Posted By: KENO
Date Posted: September-24-2017 at 7:44pm
| I guess I won't put up Tim's PCM wiring diagram then, it may confuse things |
Posted By: 8122pbrainard
Date Posted: September-24-2017 at 8:38pm
Confirming what has already been said, clean all your connections check voltage at the alternator and then at the dash with a VOM. Up sizing both the - and + wire up to the dash is common. Also add up your amp draw and run it through http://www.calculator.net/voltage-drop-calculator.html" rel="nofollow - one of the on line calculators like this one. When sizing wire, take a look at the chart:   ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
maxibarker wrote:Posted By: maxibarker
Date Posted: September-24-2017 at 8:56pm
| Will do. Thanks all! |