Webasto Thermo top E fuel problem ...

[dccruiser]

I repair a lot of Eberspachers but yesterday I was asked to take a look at a faulty Webasto which refuses to start, I checked all the obvious things , battery voltage, fuse holders etc. ... I then removed the fuel pipe at the unit and tried firing it to see if i had a fuel supply as at no point was there any smoke from the unit, the fuel pipe was dry.

I then checked the voltage at the fuel pump and it was only 10.1 volts whereas at the unit it was 13.6 .... 

I put 12 volts directly from the battery to the pump , each time i touched the battery positive it clicked once and squirted a few drops of fuel ... I blew through the pipe between the fuel pump and unit and it appears to be clear.... on removal of the pump I have diesel spewing out the pipe from the pre filter/isolator.

I also tried a spare eberspacher pump direct to the pre filter but although it was spinning it didnt pull fuel through, which leads me to believe the pre filter needs changing which i will do tomorrow when the guy returns...

The thing that is totally foxing me though is the pump voltage from the unit ... do these pumps run at a lower voltage , or do i still have a high resistance somewhere in the circuit i need to find? 

Any help or advice would be much appreciated.

Rick

[WotEver]

6 minutes ago, dccruiser said:

The thing that is totally foxing me though is the pump voltage from the unit ... do these pumps run at a lower voltage , or do i still have a high resistance somewhere in the circuit i need to find? 

Any help or advice would be much appreciated.

I seem to remember NMEA saying something like ‘don’t test the pump direct from the battery or you’ll kill it’. Maybe I’m dreaming that but if I’m not then it would explain your findings. 

[dccruiser]

4 minutes ago, WotEver said:

I seem to remember NMEA saying something like ‘don’t test the pump direct from the battery or you’ll kill it’. Maybe I’m dreaming that but if I’m not then it would explain your findings. 

Now you tell me! ... if thats the case maybe it explains why the voltage through the pump connector is only 10.1 volts ... 

[Tony Brooks]

maybe it is PWM for speed and thus output so you are only seeing an average value.

[dccruiser]

1 minute ago, Tony Brooks said:

maybe it is PWM for speed and thus output so you are only seeing an average value.

Possibly Tony as it is a "metered" fuel pump .... I will get back to it tomorrow and change the filter then go from there, although as i said there is a lot of fuel coming through the pipe it may well still be a restricted flow and not allowing the fuel pump to build up any pressure

[Tonka]

2 hours ago, dccruiser said:

Possibly Tony as it is a "metered" fuel pump .... I will get back to it tomorrow and change the filter then go from there, although as i said there is a lot of fuel coming through the pipe it may well still be a restricted flow and not allowing the fuel pump to build up any pressure

As the forum is fixing this problem hope it gets a donation from what you are getting paid

[dccruiser]

18 minutes ago, Tonka said:

As the forum is fixing this problem hope it gets a donation from what you are getting paid

And you thought you would point that out to me as a patron of this site when you have neglected to become one?  

[dccruiser]

3 hours ago, Tonka said:

As the forum is fixing this problem hope it gets a donation from what you are getting paid

I also do not and never have charged a fellow boater for any work i have done on their boats just as many on here dont, and over the 12 years i have been on the site i am sure the advice and knowledge i have shared has helped many folk just as i hope this thead will!

Rick