Losing engines at idle????????

lobsta1 · Post by **lobsta1** » Mon Jul 05, 2010 8:53 pm

I've had an on going problem for some time now. More on the port than stb. What happens is at idle speed I can watch the gauges at both helms & watch the volts drop. Even at the dock on the charger both helms & both engines read under 12 volts. Last night was out to watch the fireworks. Other than nav lights & depthfinder everything was off. (no genny) After all the crazies left, started up & pulled the hook with the windlass. Did not notice volt reading but started off & lost port motor. Would then crank, start & then die. Came back on stb motor only while holding the parallel switch to try & get a charge into the port battery.(These are two year old 4 D batteries) Coming down the no-wake zone noticed stb temp gauge not reading & the voltage was down to 10v. Made it to the fairway to my slip & was able to control the boat enough to make it to the front of my slip & the stb motor died. When in my slip I turned on the 12v halogen deck lights to plug in shore power & they were nice & bright. Two minutes after plugging in I was able to start up both motors no problem. Started chasing the problem today. Specific gravity on all cells on both batteries was 1300. Concentrated only on port motor. At idle I read 13.24 volts at the battery, battery switch & at the 12v distribution panel. At 2000rpm these are all reading about 13.54v.At lower helm start switch I was reading 11.94v.Tried to by-pass the lower helm by direct connecting upper helm harness to engine harness. Won't work with out the wye in place. Everything back to original & volts at lower helm start are now reading 13.10v. Eureka!!! Go to upper helm & reading OK. Leave engine at idle & monitor volts. Slowly drop to about 12.91 at both helms. Turned on depthfinder & volts slooowly started to drop. Put motor in gear & after a while engine started fluctuating & volts were dropping down to under 12v. Out of gear & shut off depth finder. Engine stabilized & I left it running like that for another 45 minutes. Revved it to 2000rpm for about two minutes & volts back up to 12.94. I'm assuming I have a bad ground somewhere. All the grd cables were replaced two years ago. The lugs are the bronze plated ones. All gauges at upper helm were replaced 7 years ago. In the past I ran dedicated #6 wires to a new breaker panel on the bridge. I think the next thing is to jumper a new grd from there to the back of the bridge instrument panel. Any other ideas? Al

Post by **dougl33** » Tue Jul 06, 2010 4:45 am

Could it be an alternator issue? When did you get back in? How'd the work come out?

Rick · Post by **Rick** » Tue Jul 06, 2010 5:48 am

I'd start by measuring and observing the AC component of the charge coming from the Alternator(s). You'll have to hook up an oscilloscope to the battery and if you don't have one....guess who does. Could be a bad ground, bad connection, old wire or whatever. It sounds as though you've got a heating problem, when the wiring is getting warm, resistance goes up and so does current. But you've got to start with a good known state of your charging system and batteries. Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

lobsta1 · Post by **lobsta1** » Tue Jul 06, 2010 6:23 am

Doug Replaced alternator two years ago on port & stb about 5 years ago. Came in two weeks ago, but still have to go back for a few small things. Enclosure will be another 1 or 2 weeks. Rick, Both engines are exhibiting same symptoms, just port is worse. The alternators ARE putting out. The juice is just having a hard time making the round trip. Could be a combination of grounds & the old harnesses. Al

Post by **dougl33** » Tue Jul 06, 2010 7:09 am

Did you start having the issues after you got the boat back? Could Manchester Marine have done something by accident?

Rick · Post by **Rick** » Tue Jul 06, 2010 7:27 am

Well Capt'n, you're in trouble. As far as I know, they kept the power wiring for both engines completely independent. The only thing common is the wire that connects both battery negatives together. So that means you've got the same exact problem on both sides of your batteries.....and the electronics on my boat anyway, are powered by the Starboard. Something's fishy and I'm not believing you've got two different problems. I might be able to help a little later this afternoon, will call you in a little while. Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

lobsta1 · Post by **lobsta1** » Tue Jul 06, 2010 7:42 am

This started a few years back. That is why I went around replacing grd cables & alternators. Took off all the cables at the battery shut offs & sanded them clean. The output of the shut offs goes to 60 amp buss fuses. Cleaned them off & sanded the contacts of the holders. Besides at the batteries the grds are tied together in back of the instruments. That is why I was thinking of running a new direct grd to there. Off to Mohegan to see Sting tonite. Will check back in tomorrow afternoon. Al

Post by **dougl33** » Tue Jul 06, 2010 8:05 am

I saw the Police when they were at Fenway a few years ago. It was a great show. Have fun.

Donmystic1 · Post by **Donmystic1** » Tue Jul 06, 2010 1:03 pm

I would make sure that both batteries are topped off with distilled water. We find that most boats that we service with dead batteries have let the water level drop to the plates.

Gunny · Post by **Gunny** » Wed Jul 07, 2010 5:47 am

Al, Change those 60 amp buss fuses! They are slow blow and can cause the problem you are describing

lobsta1 · Post by **lobsta1** » Wed Jul 07, 2010 11:05 am

Donny, Batteries are not dead. It takes very little to bump them back up & the specific gravity reading was up at 1300 on all cells on both batteries. Gunny, Thanks for the tip. I would never have considered it. Doug, It was a great concert! Al

Post by **dougl33** » Mon Jul 19, 2010 11:14 am

Al, Any updates? Went by your boat yesterday afternoon and you weren't to be seen.

lobsta1 · Post by **lobsta1** » Mon Jul 19, 2010 5:28 pm

Doug, We were anchored out at Sandy Bay in Rockport for the weekend. I think I have it fixed now. Port is still reading low at the upper helm. First I took Gunny's suggestion & installed these fuses.... http://shop.genuinedealz.com/Items/5178 ... 2060%20Amp mounted on these posts.....http://shop.genuinedealz.com/Items/2151 ... use%20Dual in place of the Buss cartridge fuses. Then I started tracing out the ignition circuit. There are a total of 8 harness connection points between the engine & the upper helm. The ignition ckt. is a 10 gauge wire from the ckt breaker to (with a slide on spade lug) to a terminal strip on the stb bulkhead under the lower helm. (All connections on these terminal strips are spade lugs, not ring terminals. Look at them sideways & they pop off) Lug out goes to Bertram harness to upper helm & the upper start switch. RED or PURPLE wire out of switch goes to all other gauges as well as the Merc harness to lower helm & ultimately to the coil. After recrimping new spade lugs every where I also ran a new 10 gauge wire direct from the lower helm to the coil. (My boat was changed to Mallory Unilite distributors, so I have a ballast resister before the coil) Also found on the port motor the outside of the coil was soaked with oil so I replaced it. Since my boat was in the hospital since early March, I wasn't able to do my normal maintenance. So I now replaced plugs, caps, rotors & fuel filters. While doing this I found one plug wire on the plug but the wire was not seated & pulling the plug it was obvious that plug was not firing. Upshot of all this is voltmeters are still not reading accurately, BUT I read 13.2 volts at idle at the input of upper helm start switch. Engines ran fine all weekend, including a lot of slow speed running as Gene in the old Uniflite did his shake down cruise with the new engines. He was doing a lot of shaking after wrapping a buoy leaving Rockport. THEN HE RAN OUT OF GAS 200 yards from the Jubilee fuel dock & had to anchor in the channel at 5 PM. So we then used my boat as the tow vessel to put him on the Port Marine fuel dock. That is enough unifinger typing for me now. Al

Post by **dougl33** » Mon Jul 19, 2010 6:46 pm

You're buddy Gene should buy a trailer. Glad to hear you're back in running shape. I knew you'd figure it out.

Rick · Post by **Rick** » Tue Jul 20, 2010 5:49 am

Good trouble shooting Capt'n, never a doubt in my mind either. I also saw a guy run right over a buoy at the entrance to Tashmoo over the weekend in a 30 something Pearson. Didn't seem to harm the boat one little bit and he continued like he meant to do that. Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA