Injector Pump & the Alternator

[Maddog]

Ok here's what happened. I would appriciate any in sight.

I replaced the injector pump on my perkins 4-107. Everything went fine. Engine has never run better. In the process of bleeding the engine I used a remote starter switch across the selenoid to to crank the engine, so I could see that fuel was geting to the injectors.

With me so far?

While I was using the remote starter switch, I had the key in the "ON" position, not "START". The engine cranked, the pump pumped, tightened the nuts on the injectors, disconnected the remote starting switch, turn the key, Perky roars to life. All is good, happiness, lollipops and puppy dogs rain from the heavens.

2 days later I take the wife on a romantic trip to Catalina island for 3 days. We had a wonderful time at a Wine Festival, ate good food and you know the rest. Sunday morning I go to start the engine and I get nothing. I try all my tricks and the selenoid dosen't even click. I call Vessel Assist, they give me a jump, Perky roars to life and we can make it home again. Before the jump start I checked the voltage on the batteries, 12.4 on the start (Single 12v High CAA), 12.3 on the house side (x4 6v Trogan T-105). I obviouly had run them down. After the jump start my amp meter was showing 0, I was getting no charge from the alternator. I charge at the dock with a 20 Amp smart charger to keep the batteries up.

Here is what I suspect, I fried the diodes on the alternator with the remote switch and the key in the "ON" position. The key in the "ON" position provides power to the "EXCITE" wire to the alternator. Can anyone verify this theory? Should I have left it in the "OFF" position?

Should I throw the remote start switch overboard? Should I take up golf instead of trying to service my own boat because I have no training other than what I have read in books, magazines, internet forums or listened to the advice from the cranky old salt in the slip next to me who knows all but strangly his immaculate boat never leaves the slippp....

The batteries have been charging for 2.5 days now, I'll be checking tonight to see what their state is. I have a feeling I'll be buying x4 new 6v Golf Cart batteries this weekend and having my alternator re-built.


Maine Sail - If you read this, I would love to hear your thoughts.

 

[Stu Jackson]

Why should a remote switch

which should simply have been wired in parallel with the "normal" keyed cockpit panel switch do anything different to your alternator?

How come your reserve bank was so low on voltage? It is supposed to be a reserve bank for just that reason: to use when you run your house bank down too low.

Do you have a battery monitor?

If the solenoid didn't click and you had the voltages you noted on your banks, did you then check the fuse between the start switch (or button)? Whenever we hear about "nada, zip, zilch, nothing" when the key or switch or button is turned or pushed, it is almost always the fuse to the solenoid.

Your alternator output will almost always be 0 if your batteries are full because the regulator (regardless of internal or external regulation) is seeing a full bank and not requiring the alternator to provide any output. Since you mention an "excite" I assume you have an internally regulated alternator. No too much to go wrong there unless you disconnected the alternator output, which could be done by "adjusting" the 1-2-B switch (either by moving it when the engine was running or turning it off).

If your alternator output goes through the 1-2-B switch and it was off, there is a chance you've fried the diodes. Did you? Because you didn't explain that at all.

Most of us have learned from books, these boards and other sources. Usually NOT from the jerk who never takes his boat out.

At least you got a great trip out of it!

 

[Rich Stidger]

Here's my two cents, maybe only worth face value....

First, congrats on an apparently good job with the injection pump.

Second, when I have used a remote start switch, I have connected it between battery positive and the solenoid coil and left the ignition switch off. Operating the remote switch just applies 12V to the solenoid and subsequently to the starter.

Stu's question about defining "nothing" on Sunday morning is important. If there were solenoid clicks but nothing else, that points to just low batteries. If there were no clicks, then the solenoid fuse is suspect. However, if you can now start the engine, the fuse must be good, but it may have a bad connection that is corroded and not allowing full power to be drawn.

Regarding the start battery at 12.4V and the house batteries at 12.3V, I think that if your alternator had failed and was not charging the batteries on the way to Catalina, after three days of use of the house bank, I would expect them to be low. The start battery is a different matter. With my diesel, the only power drawn when running is for the engine panel. That is pretty minimal. So I can't explain why that battery is down.

Did you happen to notice if the alternator was charging on the way to Catalina? I have an alarm on my engine panel if the alternator is not charging. Do you?

Even after a jump, I would expect to see some alternator generation.

Does your 20A smart charger charge both the house and starting batteries? Or does it only charge the house bank? Perhaps the engine alternator had failed earlier and the starting battery just got too low to start the engine.

Did you loosen the alternator belt in the process of replacing the injection pump and perhaps it is not tight enough? A loose belt will cause the alternator not to charge the batteries for sure.

Assuming you have an internal regulator in the alternator, the excitation circuit that I am familiar with is as follows: There is a trio of diodes inside of the alternator that take a small amount of power from the three generation stator windings and feed that to the regulator. The regulator is powered from this diode trio and it adjusts the power to the excite winding in the alternator rotor through the brushes. An external connection to this excite winding is just used to "kick-start" the alternator. In most cases this isn't necessary because there is enough residual magnetic field to self start. I am not aware of the nature of the external excite power. The excite winding only draws 5A or less when running but that could be higher when stopped unless there is a resistor in the engine panel wiring to limit the current at start.

In any event, the alternator is easy to test and a rebuild if it has failed is not complex or terribly expensive.

I agree with Stu- at least you had a nice trip and it sounds like you got your own batteries recharged!

 

[Don12364]

Key in 'ON' position is how it normally runs so should not have caused alternator failure. Also, one assumes you had the engine start battery master switch ON else you wouldn't have been able to crank the engine - so once again the alternator would always have seen a battery so its output voltage would have been limited by the battery.

Then again 12.3 volts is hardly 'flat' for a battery so your solenoid should have at least clicked and I would have expected the engine to start. 10.5 volts is FLAT!
My guess is that whilst thrashing around with the spanners on the injector pump job something else in the wiring got displaced.
Look first for a wiring fault, or a dodgy start switch or a blown fuse as Stu has suggested.
Also keep the remote switch handy because its was just what you needed when the start switch didn't do the job.

I have read of so many problems with start switches on this forum that I am thinking of fitting a push button in the engine compartment to feed battery volts direct to the solenoid just in case the start switch goes on the blink.

 

[alexco38]

The ALT indicator light on the panel

Check the ALT indicator light. If it was blown (rarely), bad or corroded contacts, the alternator will not start charging. Residual magnetism may not be strong enough. After a couple of days, you'll have very little battery left. But 12.3-12.4 volts are not that bad. When the motor is running and you turn off the key, most likely the fuse is blown.

 

[Maddog]

Thanks guys, I'll check fuses tonight. I had this alternator built for me about about 5 years ago and I installed it myself along with the start switch. I don't believe I have a fuse from the start switch to the selenoid, sounds like I need one. How many amps would you suggest. Are you refering to a fuse that would be on the + cable from the start battery to the power side of the selenoid? I don't have one of those either, I have read arguements on both sides on that issue. I do have a fuse on the output from the alternator to the batteries, I'll check this one. It would explain why there is no power from the alt.

I have a Blue Sea e Switch that keeps the start and house circuits seperate. When the switch is on, both circuits are on. It also allows you to connect them together if one side is low. The house and the start are then connected with a BlueSea ACR + to + for charging. For the last 2 seasons, this setup has been ideal. The alt charges the house bank, the ACR senses the charging voltage and closes to charge the start battery. All has been good.

I did connect both banks together at the battery switch and I still had nothing. I did check and clean the neg terminals, didn't help. the Perky did jump to life with the jump start connected at the selenoid and started with the key. I also check my negative battery cables, I don't think there is a problem there. All the house electrics were working fine. If there is a fault on the neg side, its one the start circuit.

Again, I appriciate all your help. Am I making any sense?

 

[Maddog]

Final update, I took the alt to be tested. It was fine. That leaves the sense, excite and power wires to check. Turns out I had a break in the excite wire at an in-line resistor. Re crimped it and all was good. Plenty of output from the alternator.

Looks like I was looking for a more complex problem when it was all very simple.

I suspect that my charger was keeping the batteries up at the dock, but a few day sails, bleeding the engine while replacing the injector pump and dumb luck got me started on the day of my trip to Catalina. The alterenator had not been working for a while and I had no charging from the alt on the way to the island with a low start battery. 3 days on the mooring dragged the house too low and I was stuck.

It was time to replace both banks anyway. Right now I am installing a new Optima Blue Top marine starting battery and 4 new 6v Golf Cart batteries for the house. That will be another story for another time.