I’ve been chasing the reason that my new Westerbeke 35D3 (400hrs) suddenly became difficult to start. I thought originally that the colder weather was causing some issues so I used more glow-plug time than normal (about 20 seconds). When this didn’t help I thought the glow plugs might be bad, but they have tested out OK.
I then spent some time looking at the wiring schematic for this engine and saw that when the key is turned on, and the glow plug button is depressed, 2 things acually happen, the glow plug solenoid clicks and the plugs begin to heat, but the electric diesel lift pump solenoid also activates the electric pump. This normally results in a continuous clicking of the fuel pump. Once the engine starts and the glow plug button is released, it is the oil pressure sensor that keeps the lift pump going.
I listened very carefully on Sunday evening as I went through the start up procedure, and noticed that there was not continuous clicking from the lift pump. I’m beginning to suspect (confirming is a 2-man operation…and I have no friends at times like this) that the lift pump solenoid or the lift pump itself isn’t working.
The lift pump pressurizes the fuel system immediately before the mechanical fuel pump (mechanically-driven). My research points to the fact that most engines will run without the electric lift pump, but are more prone to drawing air (and are obviously difficult to start). This makes sense in that if I attempt to start the engine, and let it crank over for 5-6 seconds without starting…then turn the key off and go through the process again, it starts instantly. In other words, cranking the engine over allows the mechanical fuel pump to draw fuel into the system, and on the second attempt (with a pressurized pump), it starts right away. If the lift pump were working it would start instantly the first time, without relying on the mechnical pump to bring fuel up.
Just a theory, but I can easily test it by putting my multimeter on the hot side of the lift pump when someone else presses the glow plug button.
I should clarify that there is only one solenoid, called the “pre-heat” solenoid. This send power to the lift pump. I have also read in a service manual that the first step to see if your electric fuel pump is faulty is to whack it with a mallet…they apparantly get stuck.
I hope it’s as easy as a bad connection or a bit of debris in the pump.
The electric fuel pump (lift pump) is always powered, as soon as you turn the key switch is ON / Start. The engine does not even have to be running to hear the lift pump churning away. That’s how the fuel system is designed to be self-priming. The electric lift pump supplies fuel to the injector pump fuel bowl. When the engine is cranked, or operating, the injector pump will pulse (squeeze at high pressure, is more descriptive) the regulated amount of fuel through the injectors, at the proper time as controlled by the injector pumps’ cam shaft and timing chains/gears.
The push button only activates the coil to supply power to the glow plugs.
Did the problem of hard starting begin after the filter changes? If it did it sounds like you have a bubble of air in the system. The manual says the Westerbeke is self purging but I still bleed the system. I even installed a hand squeeze fuel bulb which makes it easier to bleed the air out.
John Ferrero
Puffin 297 30U
Northport, NY
Is the cranking speed as good as before? According to Calder (1996), no diesel will start without a brisk cranking speed (Nigel Calder, Second Edition, Boatowner's Mechanical and Electrical Manual, p. 263, International Marine/Ragged Montain Press, McGraw-Hill, Blacklick ,OH).
I am pretty sure from the wiring diagram that the lift pump receives power from only 2 sources, the pre-heat solenoid (which is activated only by the glow plug button) and the alternator, which supplies direct 12v power once the engine is running. This way the lift pump is always running from the moment you depress the glow plug button until the engine is supplying its own energy. The ignition key provides power to the glow-plug button (and the starter button), but not directly to the lift pump.
I went down to the boat tonight and found the 12v lead to the top of the lift pump. It is one of only 2 wires on the pump, the other being the ground. When i put my mulitimeter on the wire and grounded the negative lead, then turned the ihnition key snd depressed the glow plug button i heard the solenoid click loudly but only got 3v at the leaf, not 12v. I am wondering if the lead itself is corroded so tomorrow Ill check the resistance across it and/ or jump it eith a new lead.
The W-27 is, indeed, self priming and any thing added to the system just makes for more connections to leak or suck in air. If it doesn’t self bleed in 30 seconds, something is wrong.
Joe Valinoti
S/V IL Gatto NS30U #221 (1984)
Sea Harbour Yacht Club
Oriental, NC
The “ignition” switch provides power directly to the lift pump when energized. If the alternator provided the power, it would cease to provide it if it stopped charging.
Joe Valinoti
S/V IL Gatto NS30U #221 (1984)
Sea Harbour Yacht Club
Oriental, NC
Looking at the wiring diagram it shows the oil pressure switch in the circuit. This is to shut the engine down if the oil pressure drops below the rated amount. I suggest that you rewire the pump to eliminate this as it will cause problems and overly complicates the system. If the pressure oil pressure drops too low, the buzzer should come on. Wire the pump directly to the ignition system at the “IGN” terminal. It doesn’t hurt to have the pump hot all the time with the key on. Normally a solenoid (Relay) is used to reduce the current through a switch. The lift pump does not draw a lot of current and is not a problem that necessitate having it’s own relay.
Joe Valinoti
S/V IL Gatto NS30U #221 (1984)
Sea Harbour Yacht Club
Oriental, NC
At the risk of sounding contradictory, I can say that at least on the 35D3, the lift pump is NOT energised until the glow plug button is pressed. The pump has two completely separate circuits, one is completed by pressing the glow plug button, the other is completed when the oil pressure switch is closed. For this reason you must continue holding the button AFTER the engine starts for a few seconds to allow the oil pressure to build. The glow plug circuit draws from the batteries and the oil pressure circuit from the alternator.
It's true...both on paper and in reality through observation.
I would definitely change it to the way I described. If your alternator belt breaks, the engine dies. Not such a great setup.
Joe Valinoti
S/V IL Gatto NS30U #221 (1984)
Sea Harbour Yacht Club
Oriental, NC
I verified with another Nonsuch that was equipped with a Westerbeke engine,
and we both can energize the electric fuel pump just by having the ignition
key set at the "ON" position.
Joe, I think you’re right. At least run a wire and spade terminal from the hot side of the solenoid (which IS powered by the ignition switch) to the vicinity of the pump, in a sudden failure situation I could then quickly get juice back to the pump. I sort of like the idea of the oil pressure switch shutting down the engine, could prevent some very expensive repairs if the alarm were to fail.
It was the pre-heat solenoid, which was clicking but not making good contact internally. As soon as I replaced it, the lift pump clicked away happily and the engine started instantly. I believe the solenoid must have been failing to provide the glow plugs with sufficient voltage as well, because when I press the glow-plug button now, the voltage gauge on the engine panel drops very noticeably.
It’s a bit odd that the set-up requires that you send power to the glow plugs as you crank the engine…it’s quite a draw on the battery.
Nevertheless…fixed…and I didn’t pay anyone to look at it…somewhat impressed with myself on this one.
You initially said that the engine was difficult to start. It can’t start if the pump isn’t working. I would certainly not have that pump running through that relay. It’s not necessary due to the pump being a low draw.
Joe Valinoti
S/V IL Gatto NS30U #221 (1984)
Sea Harbour Yacht Club
Oriental, NC