Really Nerdy Webasto Questions

[henhullpilgrim]

Brother-in-law's 'used' Webasto now fitted and in situ. Suspect it may have been a truck/car unit rather than the marine version. However, brother-in-law got it for a song so worth the gamble versus the cost of a new, marine unit.

 

Switch it on and the unit kicks off (after some work on the main power supply cable) - water pump begins and everything appears promising except that the fuel pump does not start... no fuel and no combustion.

 

So, let's check the cabling loom to see if it's a wiring problem.

 

1. The main timer unit has only three cables (red, brown and black) and not the four shown in the wiring diagram. Where has the other black gone? No sign of it. Does anyone know what the two blacks are for and then we might know if the missing one is crucial for the fuel pump/combustion bit.

 

2. Let's check the fuel pump cables... both there (blue and brown)... okay, so

 

3. Let's go back to the six-pin data plug on the main unit. Strip back the sheath and discover:

 

3a). Pin No. 1 takes a black cable for the timer unit. Present and correct.

3b). Pin No. 2 takes a yellow cable that is not connected to anything. Worrying & puzzling.

3c). Pin No. 3 takes a black cable that is not connected to anything. Worrying & puzzling. Is this the missing timer unit black? If so, why is it not connected?

3d). Pin No. 4 takes a green/white cable that is connected to the relay unit. Present and correct.

3e). Pin No. 5 takes a lilac cable that is not connected to anything. Worrying & puzzling.

3f). Pin No. 6 takes a blue cable that is connected to the fuel pump. Present and correct.

 

Any observations or suggestions? I warned y'all it was just a tad nerdy!

 

Regards

 

Brent

[gazza]

from memory pin 4 is for connecting to a vehicles canbus system, this gives a signal to the vehicles HVAC system and starts interior fans etc when the webasto fires up.

 

1 is a switched live from timer

 

2 and 5 i think are for pc diagnostic of the unit.

 

6 is fuel pump.

 

3 can either be + 12v or 0v dependant on age of unit.

 

i had no wiring loom for mine, i used new plugs and simply used pin 1 switched live thru a battery powered timer, 12v permanent supply to main cables, job sorted.

 

as you are using webasto kit for your wiring have a look on this BMW website, it may  help you bmw webasto info

 

hope this helps!

[henhullpilgrim]

from memory pin 4 is for connecting to a vehicles canbus system, this gives a signal to the vehicles HVAC system and starts interior fans etc when the webasto fires up.

 

1 is a switched live from timer

 

2 and 5 i think are for pc diagnostic of the unit.

 

6 is fuel pump.

 

3 can either be + 12v or 0v dependant on age of unit.

 

i had no wiring loom for mine, i used new plugs and simply used pin 1 switched live thru a battery powered timer, 12v permanent supply to main cables, job sorted.

 

as you are using webasto kit for your wiring have a look on this BMW website, it may  help you bmw webasto info

 

hope this helps!

 

Thanks again gazza for your help. I still can't figure out why the fuel pump won't kick in though. I have power to the main unit and the circulation pump starts readily. Just no life in the fuel pump which actually looks pretty new.

 

From your notes above, I'm not sure that the disconnected pins would affect the fuel pump's performance so what's left to go wrong? Faulty cables to the fuel pump? Faulty fuel pump? Faulty internal circuitry on the main unit?

 

Any one had similar issues?

[mikevye]

Put a live and earth directly on the pump if it doesn't work it's a bin job!

[gazza]

Thanks again gazza for your help. I still can't figure out why the fuel pump won't kick in though. I have power to the main unit and the circulation pump starts readily. Just no life in the fuel pump which actually looks pretty new.

 

From your notes above, I'm not sure that the disconnected pins would affect the fuel pump's performance so what's left to go wrong? Faulty cables to the fuel pump? Faulty fuel pump? Faulty internal circuitry on the main unit?

 

Any one had similar issues?

 

i have wired flying leads to my coolant pump and fuel pump. i did this so i can run the pumps from a cable run to the battery with a couple of croc clips. it lets me run up the pumps independent of the burner controller. i used a couple of bullet connectors spliced into fuel pump and coolant pump wires.

 

 

the fuel pump needs priming before you start the burner, its a simple solenoid type pump, and works on a pulsed principle. to prime it simply disconnect fuel pipe at burner, connect wires to pump, run to battery clip + to + terminal (pin 6)  next touch - to - terminal then remove, repeat until fuel is present at the fuel pipe. reconnect to burner, give a couple more pulses then fire it up. a neater solution is to fit an inline switch, which i shall do next time i remove the burner for a service.

 

 

 

 

 

 

Put a live and earth directly on the pump if it doesn't work it's a bin job!

 

you would need to turn it on and off repeatedly to perform this test. the pump does not run all the time, it is a solenoid type pump

[smileypete]

the fuel pump needs priming before you start the burner, its a simple solenoid type pump, and works on a pulsed principle. to prime it simply disconnect fuel pipe at burner, connect wires to pump, run to battery clip + to + terminal (pin 6)  next touch - to - terminal then remove, repeat until fuel is present at the fuel pipe. reconnect to burner, give a couple more pulses then fire it up. a neater solution is to fit an inline switch, which i shall do next time i remove the burner for a service.

Maybe put a small 12v panel lamp or LED across the pump to check it's getting driven from the Webasto.

 

Connecting the pump to battery +/- while still connected to the Webasto may not be a good thing.

 

cheers,

Pete.

[gazza]

Maybe put a small 12v panel lamp or LED across the pump to check it's getting driven from the Webasto.

 

Connecting the pump to battery +/- while still connected to the Webasto may not be a good thing.

 

cheers,

Pete.

 

hence the bullet connectors spliced into the pump wires, i did omit to say do this with the unit switched off, though i did say it was done to operate the pumps independent of the webastos internal controller

 

 

clear as mud eh?!

[Phil Ambrose]

i have wired flying leads to my coolant pump and fuel pump. i did this so i can run the pumps from a cable run to the battery with a couple of croc clips. it lets me run up the pumps independent of the burner controller. i used a couple of bullet connectors spliced into fuel pump and coolant pump wires.

 

 

the fuel pump needs priming before you start the burner, its a simple solenoid type pump, and works on a pulsed principle. to prime it simply disconnect fuel pipe at burner, connect wires to pump, run to battery clip + to + terminal (pin 6)  next touch - to - terminal then remove, repeat until fuel is present at the fuel pipe. reconnect to burner, give a couple more pulses then fire it up. a neater solution is to fit an inline switch, which i shall do next time i remove the burner for a service.

 

 

 

 

 

 

 

 

you would need to turn it on and off repeatedly to perform this test. the pump does not run all the time, it is a solenoid type pump

 

 

I'm puzzled here, my MIkuni in common with most other diesel heaters has a solenoid pump, when current is applied it will work thus, click energise which moves diaphram and breaks contact, spring returns it to start point, click energise etc etc. If it does not do the clicky thing continually then I suspect it may be a bin job

 

Phil

[gazza]

I'm puzzled here, my MIkuni in common with most other diesel heaters has a solenoid pump, when current is applied it will work thus, click energise which moves diaphram and breaks contact, spring returns it to start point, click energise etc etc. If it does not do the clicky thing continually then I suspect it may be a bin job

 

Phil

 

the webasto pump fitted to the heater on the elysian needs 12v pulsed to it. its how a solenoid works, its either on or off. the spring doesnt return it on its own, only when the coil is not energised will the pump return under the springs pressure.

 

 

the heater pulses the pump to meter the fuel as required. the pump also acts as a shut off valve.