Westerbeke Fuel Solenoid Current Timer #46739

[R_C]

Twice in two years the fuel solenoid current timer (part #46739) has failed on my 7.6 kw genset. Last year the solenoid died and after replacing it I discovered the current timer was also bad. I bypassed the white pull wire of the current timer to start until I replaced the part. Recently, I've been having difficulty starting and the problem appears to be the current timer again. When I bypass the current timer with the white pull wire it starts right up.

Last year Westerbeke tech support told me the current timer's purpose is to "time out so glow plugs don't stay on" but I think that's wrong. I believe its purpose is to time out the solenoid's high current pull coil so it does not overheat. Can anyone confirm this part's purpose? Any idea why it fails? Is it acceptable to just eliminate the current timer? It's a $150 part and I'd rather not replace it until I know the cause of the failure. Thanks.

[Cheechako]

Sorry I dont know the answer, but a couple thoughts. Have you tried buying that solenoid elsewhere? (kubota etc) Also, are you located somewhere that needs glow plugs? Maybe just bypass the whole thing. The kubota 2 cyl I had, I added the shut off solenoid and it was very cheap. It just pulled on a lever that was already on the engine. Is that what this is? or is it an actual solenoid actuated fuel valve body?

[R_C]

The solenoid is not the problem. It works fine. It's a dual coil solenoid that enables the flow of fuel at the injection pump when activated. The high current pull coil retracts the solenoid's plunger and the low current hold coil holds it in this position. The problem is the $150 current timer connected to the solenoid. Right now it will not send any current to the solenoid's pull coil when the starter is engaged. I can bypass the current timer and the genset starts right up with little or no preheat. I'd like to learn the real purpose of the current timer and whether it is really necessary.

[Cheechako]

are you saying the solenoid and current timer are active only when you run the engine as opposed to shutting it off? seems pretty stupid to me... but then, the "Raison Detre" of many gen set makers now days seems to be to make them as complicated as humanly possible. then they dont run at all! Exhaust temp sensors, water flow sensors, current timers...... arghh! Just remove it all unless you have no mechanical sense.... then... welll... you better leave them on!

[Blue Stocking]

Originally Posted by Cheechako

Just remove it all unless you have no mechanical sense.... then... welll... you better leave them on!

LOL--so true.

Anyone pulled an '84 Onan, 2 cylinder gas gen apart lately?

More relays than a dog has fleas.

[R_C]

Originally Posted by Cheechako

are you saying the solenoid and current timer are active only when you run the engine as opposed to shutting it off?

That is correct. Unlike the main Ford Lehman in my trawler, which uses a solenoid to stop the fuel flow, the Westerbeke uses a solenoid to allow fuel flow by applying a voltage to pull in its plunger. I suppose this is because it is designed to run unattended and will shut itself down if any of its sensors (oil pressure, water temperature, exhaust temperature) detects a problem. If any of these sensor switches opens it stops the current to the solenoid's hold coil allowing the solenoid's plunger to reappear and stop the fuel.

I used the patent number listed on the current timer to retrieve the patent filing and I think I know the purpose of this part. Without the current timer, you risk burning out the solenoid if you engage the starter for prolonged periods. The current timer will allow current to the solenoid's pull coil for some predetermined period of time, presumably long enough to pull the plunger in but not long enough to overheat the solenoid. The hold coil is energized through the preheat switch while starting and the oil pressure switch after starting.

[daddle]

Solenoids can require a large current to move, but only a small current to hold position. The timer probably controls this. Most will overheat is left at the initial high power. The timer probably controls this. It would be unwise to bypass it.

However you could replace it with some kind of toggle switch. Perhaps a spring loaded two position switch like a auto ignition switch. Then you just have one more thing to get right when you start the generator.

I'd replace the timer and the solenoid and hope it's fixed. Make sure you are not using 12V parts in a 24V system, or whatever.

[R_C]

As I suspected, the current timer does limit the time high current flows to the solenoid's pull coil. I disconnected the current timer completely, connected a 12V light to the timer's pull output (white wire) then applied 12V to the input white wire. The bulb lights for one second then goes dark. I did this repeatedly with the same results, which indicates the current timer works properly. As I said earlier, the solenoid is fine. I can test it with a jumper lead by momentarily applying 12V to its pull coil and I can hear and feel the plunger retract.

I think the real problem is nothing more than vibration loosening the bullet quick disconnect on the white pull wire of the current timer. Bypassing the current timer and plugging the solenoid directly into the engine's wiring harness eliminated both connectors on the current timer allowing the engine to start.

I'm glad I did my homework and didn't waste $150 for another current timer when the real problem is just a couple of bullet connectors.