Eberspacher D2 fuel pump problem

[gary3029]

Have taken a perfectly working eberspacher unit out of one boat and put into a simliar boat so did not need to make any alterations to setup. Powered unit up and the and the fan tried to run but then stopped. On checking fuel gets to pump but no further. Have put a meter across terminal of pump and it is getting power. Did put pump directly to batteryand it would eject very small amounts of fuel each time I touched terminal, but not run constantly. Do I need to bleed pump or unit. Could it be a case of sods law in that the unit has gone defective because I moved it.

 

[Searush]

I'm no expert, but aren't these impulse pumps, requiring a series of pulses to supply constant fuel?

 

[fluffc]

Searush is correct, these are impulse units. The eberspacher control circuits 'pulse' the 12V to the pump (in time with the fan speed) to generate many spurts of fuel; which by the time it reaches the combustion chamber is fairly constant.

It sounds like you have an electricery problem. The characteristic you described would be symptomatic of maybe a flat battery, too long a cable run (too much voltage drop), or a dodgy electrical connection.

FYI, the start up sequence is as follows:

1-3sec System check. Nothing starts.

next 15 seconds - fan starts (~3 Amps), and quite soon after, the preheat (~16 Amps)kicks in.

next 90 seconds - ignition attempt, pump (not much constant current, but quite high current surges on each pumping pulse).

once heated up, glow plug turns off, leaving a current draw of only 3A or so.


The unit is quite fussy in having decent power, and will shut off if the voltage at the heater falls below a certain value (10.4V i think).

You will see that the pre-heat coil draws quite a lot of current, and this can cause enough voltage drop for the unit to shut down. Typically the fan will run for a second or so then cut out if this is the case.

The other point at which it may shut down is when it is trying to run the pump. Due to the large current surges that this causes, it is sometimes enough to cause the voltage to drop enough that it cuts out.


So, check that your battery is healthy, and fully charged. Also check all your terminations are sound, and that there is a decent sized piece of cable running to the heater.

FWIW one time my heater wasn't starting, I discovered that the Eberspacher-supplied fuse holder had melted (poor design).