T&T: westerbeke fuel shutoff solenoid

[Jim Gano via Trawlers-and-Trawlering]

 I have a 1980s vintage Westerbeke diesel BTD 8 KW generator.  The fuel shutoff solenoid is getting a little finicky.  SOMETIMES (after turning the generator circuit breaker switch to "on") when I depress the preheat button (counting 15-20 seconds before depressing the start button) the solenoid does not move/open (hence no fuel flow) and hence no generator engine start (only engine turning over with no start).  If I turn "on" the breaker to the generator and then manual (with my hand) depress the solenoid all the way open (and let it come back to closed via its spring action) and THEN depress the preheat, the solenoid moves/opens and generator starts via normal procedure.
Also, with the generator circuit breaker "on" if I have someone depress and hold the preheat button AND I manually move the solenoid to the open position, it stays/locks in the open position and the generator starts via normal start procedure...
I really don't want to buy a new solenoid (about 170 USD) only to find there is a simple fix.... Any ideas? 
Jim Gano
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[Steve Sipe via Trawlers-and-Trawlering]

Some of the Westerbeke's have relays that operate the fuel solenoid,
glow plugs and lift pump as well as provide the holding circuit that
bypasses the oil pressure switch for startup. The relay is energized
when you hold the momentary preheat switch. Once the engine is running
and builds oil pressure, the relay is de-energized when the switch is
released, and power is provided to the solenoid via the oil pressure
switch. There may also be an additional relay that powers the solenoid
rather than directly through the safety circuit- to reduce the load on
the oil pressure switch. AFAIK, some of the earlier units were not
equipped with this second relay. You'll find them in the junction box
mounted above the generator section.

I would look to those relays as a potential culprit. Check voltage at
the fuel solenoid when trying to start, if it's low, say <10.8 V, one of
the relays could be bad and creating a voltage drop to the solenoid. A
battery problem- low, bad connection could also be at fault. You'll
normally see a fair amount of voltage drop due to the glow plugs. Those
relays are readily available, about $10 or less, they're a Bosch style,
google it to match yours. You don't need a Westerbeke OEM, it'll be 4
prices. Cheap enough that you could swap out for a new one to
troubleshoot. You could also bypass the safety circuits by placing a
temporary jumper from the circuit breaker which is typically close by,
to the solenoid you should be able to easily trace the wiring to
determine which lead on the solenoid is the ground/power. Then see if
the problem persists.

You're referring to the CB switch, I presume this is the 12V breaker, it
wouldn' t make sense for the high voltage breaker to have any effect,
the controls are all 12VDC. In warm weather, it's unlikely that you need
to hold the preheat switch for any appreciable time, mine starts right
up after about 3-5 seconds.

Hope that helps.


On 8/6/2015 2:56 PM, Jim Gano via Trawlers-and-Trawlering wrote:
> I have a 1980s vintage Westerbeke diesel BTD 8 KW generator. The fuel shutoff solenoid is getting a little finicky. SOMETIMES (after turning the generator circuit breaker switch to "on") when I depress the preheat button (counting 15-20 seconds before depressing the start button) the solenoid <snip>
>
> --
> Steve Sipe
> Solo 4303 "Maerin"
> Middle River, MD

[TW Collins via Trawlers-and-Trawlering]

Jim,

More force is required to pull in a solenoid than is needed to hold it in.

Your problem could simply be low voltage due to a weak battery or bad
wire or relay contact. Check the voltage at the solenoid coil to see if
it is above something like 10.5 volts.

One other possibility is an open pull-in winding. Some solenoids have
two internal coils (windings). One is a pull-in coil and the other is
the hold-in coil. Because it takes so much more energy to pull-in the
solenoid than to hold it in, coils that remain energized for a period of
time such as a fuel turn-on solenoid, usually (but not always) have a
separate pull-in coil. It draws much more current than the hold in coil
but disconnects as soon as the solenoid is activated. To accomplish
this, there is a switch located inside the solenoid connected to the
pull-in coil that opens when the plunger is fully actuated thereby
disconnecting the higher current pull-in coil. If the pull-in winding
or switch are faulty, then the solenoid will hold-in but won't pull-in.

If the linkage from the solenoid to the fuel shutoff is misadjusted, the
plunger never fully retracts to actuate the switch which then doesn't
disconnect the pull-in coil. Because the pull-in coil is only rated for
intermittent operation, it soon burns out. So when installing a
replacement, be sure that the plunger is able to fully bottom out in the
coil or you will soon burn-out the new solenoid.

Externally, there is no way to determine if the solenoid has a pull-in
coil because there are only two terminals on the device with either
configuration. If the voltage is OK, then likely it will be necessary to
replace the solenoid.

Tom Collins - Misty Sea

[Steve Sipe via Trawlers-and-Trawlering]

Another thought, there may be a voltage drop through the safety shutoff
circuit, check voltage across the switches, e.g. oil pressure, temp
switch- while running. You should see -0- volts if the switch is
operating correctly. You'll only read voltage across a closed switch if
there is a problem with the switch. This would be indicated if there is
a significant voltage drop at the solenoid. I'd be inclined to do the
troubleshooting prior to replacing the solenoid to insure you're not
missing something.

Best of luck in finding the solution.

On 8/6/2015 2:56 PM, Jim Gano via Trawlers-and-Trawlering wrote:

> I have a 1980s vintage Westerbeke diesel BTD 8 KW generator. The fuel shutoff solenoid is getting a little finicky. SOMETIMES (after turning the generator circuit breaker switch to "on") when I depress the preheat button (counting 15-20 seconds before depressing the start button) the solenoid does <snip>

>
> --
> Steve Sipe
> Solo 4303 "Maerin"
> Middle River, MD
>

[Jim Healy via Trawlers-and-Trawlering]

Jim,

What you're describing could indeed be the solenoid. Do the relay swap that Steve mentioned as your first step. Also, if the plunger has a rubber boot to protect it, take that boot off and make sure the plunger operates freely and isn't corroded and/or full of "sticky gunk 'n stuff."

Fuel solenoids are compound devices that have two coils. Internally, they have a "pick" coil, the operation of which is normally intermittent, and a "hold" coil, which is always activated. The pick coil is used to ensure that the solenoid opens when battery terminal voltage is low, as when the glow plugs are activated and the starter motor is cranking the engine. I have had solenoid pick coils fail on both my Cummins main and my Onan genset. The genset symptoms are just as you report. That is, if you manually "help" the solenoid, it'll work and hold in it's operating position. You're "helping" the pick coil, but the hold coil handles ongoing operation just fine. And yes, the manufacturers are quite proud of their parts, but then again, they run reliably for many years, so $170 divided by 30 years isn't so bad. If the solenoid itself has a part number on it, you may be able to buy it from its manufacturer or one of the manufacturer's dealers. For both my Cummins and Onan engines, I was able to do that (Delphi for Cummins fuel system parts; I'd have to dig in my records for my Onan).

Jim

Peg and Jim Healy aboard Sanctuary, currently on the Erie Canal (Fairport, NY)
http://gilwellbear.wordpress.com <http://gilwellbear.wordpress.com/>
Monk 36 Hull #132
MMSI #367042570
AGLCA #3767
MTOA #3436

[MY ALLEZ via Trawlers-and-Trawlering]

I would spray the fuel solenoid rod with some silicone spray and work it a little bit back and forth.
I have a 1993 Genset and still humming with 3,200 Hours. Those solenoid rod might be dirty.
It happened to me a number of years ago and that is how I fixed it.

Bob Kovach .
Chief Engr Bob, Onboard ALLEZ! @Florence, AL on the Great Loop

MTOA 2631, AGLCA1979, USCG-ARC-KJ4UGE, USCG-CWOA, USPS Charleston, S.C., WRCC, DFC