fuel pump electrical help

[elk]

Recently I've been hearing my fuel pump power up when turning on the DC battery switch, the one that powers the engine, not the 1/2/ALL. This happens with no key in the ignition and the ignition in the off position. The only other indication is that the low oil press.(LOPS) lamp glows on the instrument panel, no other gauges or lamps activate.
Doing some research I find the pump is powered through the LOPS, which is normally open with no oil press., but also through the glow plug solenoid and maybe the starter solenoid.
I'm thinking its not the ignition switch because no other gauges power up, but maybe the glow plug momentary on part of the ignition switch? Don't know if that makes sense for only that part of the ignition switch to fail in the on position against spring pressure.
I'm thinking it's not a failed LOPS because there's no power to it with the ignition off. Maybe a stuck glow plug solenoid? Which I'd like to know the location of, if anyone knows.

Any clues would be helpful, and thanks in advance.

[TBOT422]

My guess is that it is the preheat solenoid. I replaced ours that failed such that the fuel lift pump did not operate as designed with the switch in the 'glow' position. Yours could have failed in the opposite direction so that it applies power as soon as there is power to the starter. Referring to wiring diagram #200360 on page 96 of the M35B Service Manual, you will see that the preheat solenoid is connected to the starter solenoid via wire #15 which would apply power to the preheat solenoid as soon as the engine start switch behind the settee is turned on. If stuck in a closed position, it would apply power to the fuel lift pump through the 10amp circuit breaker attached to the lug of the preheat solenoid and wire #16. The LOP light is likely glowing as the oil pressure switch is getting power through the fuel lift pump via wire #17.

However, it could be the ignition switch failed such that it always seems to be in the 'glow' position. From the above wiring diagram, you can see that wire #5 goes from the ignition switch to the small lug on the preheat solenoid that does not have the 10amp circuit breaker. I believe this should only have voltage if the ignition switch is in the 'glow' position to activate the preheat solenoid. To check, I think you would need to disconnect this wire from the preheat solenoid and check the voltage at the solenoid lug and also at the wire. If there is voltage at the solenoid lug, I would suspect the solenoid is failed in a closed position. If disconnecting this wire causes the fuel lift pump to stop running and there is voltage at the wire coming from the ignition switch, then I would suspect the ignition switch.

As to where it is located, it is right on top of the engine above the heat exchanger. It is a small phenolic cylinder about 1-1/2 in diameter and a couple of inches long with 4 lugs and a mounting bracket on it. Actually the wiring diagram mentioned above shows a pretty clear depiction of what it looks like. Very easy to get to and replace.

Good Luck

[elk]

Thanks for that detailed information, my thinking is along the same lines. i'm just having a problem believing that a solenoid would fail against spring pressure, same for the ignition switch.

As you point out, it should be easy enough to check out, and I'll post my results when I do.

My guess is that it is the preheat solenoid. I replaced ours that failed such that the fuel lift pump did not operate as designed with the switch in the 'glow' position. Yours could have failed in the opposite direction so that it applies power as soon as there is power to the starter. Referring to wiring diagram #200360 on page 96 of the M35B Service Manual, you will see that the preheat solenoid is connected to the starter solenoid via wire #15 which would apply power to the preheat solenoid as soon as the engine start switch behind the settee is turned on. If stuck in a closed position, it would apply power to the fuel lift pump through the 10amp circuit breaker attached to the lug of the preheat solenoid and wire #16. The LOP light is likely glowing as the oil pressure switch is getting power through the fuel lift pump via wire #17.

However, it could be the ignition switch failed such that it always seems to be in the 'glow' position. From the above wiring diagram, you can see that wire #5 goes from the ignition switch to the small lug on the preheat solenoid that does not have the 10amp circuit breaker. I believe this should only have voltage if the ignition switch is in the 'glow' position to activate the preheat solenoid. To check, I think you would need to disconnect this wire from the preheat solenoid and check the voltage at the solenoid lug and also at the wire. If there is voltage at the solenoid lug, I would suspect the solenoid is failed in a closed position. If disconnecting this wire causes the fuel lift pump to stop running and there is voltage at the wire coming from the ignition switch, then I would suspect the ignition switch.

As to where it is located, it is right on top of the engine above the heat exchanger. It is a small phenolic cylinder about 1-1/2 in diameter and a couple of inches long with 4 lugs and a mounting bracket on it. Actually the wiring diagram mentioned above shows a pretty clear depiction of what it looks like. Very easy to get to and replace.

Good Luck

[elk]

Replaced the preheat solenoid, it was the culprit. All is normal now, until the next failure.
Cost ~$40 shipped.

Thanks for all your help.

[JohnForr]

Does anybody know what the little square box is on the preheat solenoid is. See my the picture.

[TBOT422]

Does anyone know the part number for the preheat solenoid? Mine died again, and I can't find the part number of what I bought last time.

Thanks

[leigh weiss]

the preheat solenoid has an attached fuse (square unit) mounted, make sure the fuse has not blown. The fuse is an automotive part Look for it on ebay.
You can find a replacement for the solenoid from ebay STARTER SOLENOID RELAY SW-3 Ford Jeep Lincoln Mercury 1958-1991 for under $9.
Let us know how you make out.

[TBOT422]

Thanks Leigh. My solenoid is clearly dead, it has black goo oozing out of the bottom of it. I ordered the 'black' solenoid from ebay for $7.99, then discovered there was a 'heavy duty' red version for $8.36. If it fails again, I will pay the extra $0.37. Much better than the $35 Westerbeke version.

[wolfe10]

Yes, any relay MUST be sized (at a minimum) for the load it will be passing through. And, it doesn't hurt to oversize it (so for a 20 amp max load, a 30 amp relay will be better, as the contacts will be larger and less prone to burning/pitting).

It is fuses that must not be oversized, as they protect the wiring and in some cases the devices.

Brett

[TBOT422]

Leigh,

Have you actually used the solenoid you suggested? I installed one today and think something is wrong as it's mounting bracket become quite hot (about 160 - 170 degrees) after a few minutes. Possibly it is not sized large enough as Brett suggested. Nothing in the specs I see say anything about rated current. Or possibly whatever caused the previous solenoid to blow is still there causing the new one to overheat as well.

My problems all started with some maintenance work done at the local yard. Apparently when they dropped the boat in the water and started it to test for leaks, they damaged the ignition switch. At first I thought it was just loose in its mounting, but after getting back to our dock I found the ignition switch was broken internally and the key could just go round and round. I am assuming that somewhere on the trip home the ignition switch shorted and caused the pre-heat solenoid to blow and trip the 20 amp breaker between the solenoid and the ignition switch. The entire trip back is a long story. I replaced the ignition switch and was able to get the boat started again and back in our slip.

Time to do some more diagnostics and get to the root of the problem. Does anyone know how the solenoid is supposed to work? It appears the main 12V comes from the batteries through the Engine On/Off switch behind the settee and then goes to the B terminal of the ignition switch through the 20 amp circuit breaker. The S terminal of the ignition switch goes to the S terminal of the solenoid. Of course neither the new solenoid or the original Westerbeke one has the lugs labeled. I am assuming the S terminal on the solenoid is the small one near the 12V input lug. With the switch in the ON position, I would assume that there should only be 12V at the input lug of the solenoid and none of the other lugs. Turning the Key to the spring loaded preheat position should provide 12V to the S lug of the solenoid which should activate it and provide power to the heavy lug across the solenoid and the glow plugs, and also to the I terminal of the solenoid that provides power to the fuel lift pump. The oil pressure switch appears to be open when there is no oil pressure (engine not running). The oil pressure switch gets 12V from the ignition switch I terminal when the key switch is in the ON position. Once the engine starts and oil pressure comes up the switch closes and provides 12 V to the fuel lift pump irrespective of the key switch position or preheat solenoid. Does anyone know where the oil pressure switch is located? I want to verify that it is open when the engine is off and closed when running.

If I figure this out, I will then tackle the buzzer circuit and see if I can make that more reliable as well.

Thanks

[leigh weiss]

The oil pressure switch is located on the engine block forward and below the starter motor.
The solenoid should not get that hot. I think you might want to also check the glow plugs. They should be about 2 ohms each when disconnected from the power buss. Sounds like the solenoid was on continuously and the pull in coil is heating the unit rather than excess glow plug current.
I found glow plugs for our Kubota engine on ebay (15521-65511 Glow Plug for Kubota D1402 V1702 ) for about $8 each. The oil pressure switch is also on ebay for under $14, (New Kubota D1402 Oil Pressure Switch )
Let us know how it turns out.

Cheers,
Leigh

[TBOT422]

I finally worked my way through the problem. Leigh, you were right, the overheating was being caused by the glow plug circuit being energized all the time. Partially my fault, partially the fault of the original installation. When I replaced the ignition switch I referred to the schematic from the M-35B manual for Catalina Yachts. It shows one purple wire connected to the S terminal of the ignition switch and one red wire with white tracer connected to the I terminal. Of course, my old broken ignition switch had 3 purple wires all connected to the I terminal and one white wire connected to the S terminal. After tracing the 3 purple wires down I could tell one of them was powering all the panel instruments and one was going to the push start button. The third one entered a wiring harness that went below. Since it was the only purple wire going below, I assumed it was the one that was supposed to be connected to the S lug of the pre-heat solenoid, and should have been connected to the S terminal of the ignition switch, which is what I did. As the white wire as the only non-purple wire connect to the switch I assumed it was the wire that was supposed to go to the alternator and on to the oil pressure switch. Wrong on both counts.

I started out by disconnecting all the wires from the solenoid other than the 12V supply, and checking continuity and voltages at the solenoid lugs and disconnected wires. I found that with the key switch in the ON position I had 12V on the purple wire that was supposed to be connected to the S lug of the solenoid, and about 10V on the pair of light blue wires that were connected to the lug of the 10 amp circuit breaker. There shouldn't be 12V on the purple wire with the switch in that position, so I disconnected it from the key switch. Still showed 12V when I thought both ends of it were disconnected. So I made a 30 foot jumper wire to allow me to check continuity from the engine compartment to the helm with a multi-meter, and lo and behold found that the purple wire at the pre-heat solenoid was actually connected to the white wire at the key switch which I had incorrectly connected to the I lug of the key switch providing 12V to pre-heat circuit all the time.

Further tracing of the white wire into the wire harness found it connected to a terminal strip dangling loose deep inside the helm pedestal. Surprise, it was connected to a purple wire on the opposite side of the terminal strip. Tracing one of the purple wires at the ignition switch to the terminal strip found it connected to a red wire with a white tracer. Viola! Now that I could determine which wire was which I connected them up per the schematic and nearly everything started working as it was supposed to. I ran the engine for several minutes and the solenoid bracket no longer got hot.

The only remaining problem is that the glow plug circuit and fuel lift pump do not function as designed with the key switch in the spring loaded pre-heat position. I suspect the new solenoid was damaged when it overheated due to continuous load from being wired incorrectly. At least it was a $8 part instead of a $35 part. Which brings me to an understanding about the pre-heat solenoid. It really has very little real function in normal operation in a warm climate. In a warm climate, there is no need to pre-heat the cylinders with the glow plugs in order to start the engine. And as long as there is sufficient fuel in the system to start the engine, there is no need to activate the fuel lift pump to get the engine started. Once the engine starts and oil pressure comes up, the fuel lift pump gets power through the oil pressure switch for continued operation. Now there could be circumstances where the fuel is not in the system to start the engine such as after changing fuel filters. But, if the fuel disappears between engine starts that requires the fuel lift pump, something else is wrong somewhere. I'll probably order another solenoid, most likely the 'heavy duty' one, just so the boat operates the way it is supposed to even though it is not necessary.

[leigh weiss]

G&J

Looks like the oil pressure switch has a control over the fuel pump continued operation. This appears to be a safety feature ie. loss of oil pressure = loss of fuel pressure and this may stop the engine. The starter circuit and the glow plug circuit override the oil pressure switch to run the fuel pump to facilitate start up with no oil pressure.
You might want to restore OEM specs for these circuits.
Good luck and keep us posted.

[TBOT422]

Leigh,

I already ordered another solenoid to get things back to the way they are supposed to be. I did disconnect the wires from the oil pressure switch and confirm that it did not have any continuity when the engine was not running, so it is working properly.

And thanks for the lead to all the Kubota part numbers earlier. Ever since we have owned the boat there has been a small leak of coolant from the Kubota fresh water pump weep hole. I priced the Westerbeke part number a long time ago at somewhere around $400. Instead of replacing it, I install a small piece of paper towel just below the weep hole to catch the drips and change it every now and then. Anyway with the data you gave me about Kubota parts, I googled water pump for Kubota D1402 and found replacement pumps for $30-$100. Much more like I would expect for a normal standard engine water pump.

Thanks again. I don't know what I would do without all the help from the members of this association.