2.0 CDT - fuel pump failure and FBH

[JohnFol]

I have a few symptoms relating to starting and I am now sure the in tank pump has failed. I've also noticed the Fuel Burning Heater (FBH) runs, but never has a hot exhaust. I've checked the small pump (under o/s rear jacking point) and can hear a slight hum that sounds like an electric motor that cannot turn.

I put 12v across the pump and can hear a click, and I can repeatedly do it until diesel coumes out the FBH exhaust. I'm therefore sure there is no blockage.

Now my question.

The fuel line for the FBH goes from what appears to be the in-tank pump, and through the small pump as described. If the in-tank pump has failed, will it prevent the small pump from working?

[Keith]

No I don't believe it will as the in tank pump does not need to be operating for the FBH to run.

Have you reset your FBH by pulling the power plug (two pin connector) or the fuse for a minute or so as they go into lock out after three failed starts and then all you will get is the thing spinning up without igniting to purge fuel in the burner, which is pretty much what you are describing.

[JohnFol]

Hi Keith, thanks for the quick reply.
Yes I have removed the plug, and get a very health fan noise from the FBH. I get a good flow of air out of the exhaust, but it's always cold.

I checked the voltage on the pump connector and get 10v, hence why I connected it to a separate 12v supply. Even with the correct voltage I don't get the clicking. I've tried the "give it a tap" approach incase it has siezed but no joy.

I've also mailed sarkblue who confirms the pump on eBay will work. Apparently Scotty has one on order and will give me an update once his has arrived.

Based on the tests I have done I'm fairly sure it is the motor, and you have confirmed the in-tank one has no effect.

I'll leave things as they are until I can replace the FBH pump and then try again.

Many thanks for your help

[Keith]

Have you read the stuff here
http://www.techwebasto.com/thermosystems_automotive.htm
specifically the one on troubleshooting

The pump is pulsed by the fbh to operate are you gettng pulses (bulb test)
maybe the fbh glow plug has failed and it can't fire up?

[JohnFol]

Hi keith, yes I had seen that document, however the troubleshooting section is sparse to say the least. Most symptoms result in "perform troblehsooting at workshop level"

I did however find this document that is a bit more thorough

http://www.techwebasto.com/heater_main/heater_technical_bulletins/TSB_T_Top_Troubleshooting_Tree.pdf#search=%22webas to%20thermo%20top%20wiring%20diagram%22

[SCOTTY1]

Hi John, I have tried everything you have done with the same results, my under car pump is dead, I even turned up the voltage gradually to 18V but still nothing!

As soon as the new pump arrives and its fitted I'll post an update.

Scotty1

[JohnFol]

Hi scotty1 I have 2 more tests as suggested by Keith

1) make sure I get a pulsing bulb across the pump contacts (I expect this to work)

2) disconnect the fuel line by the FBH to see if I get fuel delivered. I expect this to fail as I suspect the pump. However if I put a 12v across the pump, and off, and on, and off . . I get fuel out of the FBH exhaust. hmm . . . .

Please, if you could let me know as soon as you've tried it.

[JohnFol]

Hi all

A quick update. New fuel pump fitted and same problems as before with the FBH (as expected).

A bit more diagnosis. After 30 seconds I do get a pulsing voltage on the FBH fuel pump but it's only 10v. (Checked the +ve against chassis and same)

I then checked the circuit diagram and it looks like pin 6 is the other end of the wire. Tested pin 6 against the battery and again a little over 10v.

Next checked the 2 pin connector to the FBH against the earth on the battery and I get a healthy 12+v.

Based on my sticking 12v directly across the pump and getting fuel out of the FBH exhaust I think it is capable of pumping with 12v supplied.

So it seems that my pump probably is alright, but it's only getting 10V. I am thinking 1 of 3 things

1) There is a fault within the FBH as it only puts out 10v
2) The pump should work with 10v
3) I just stick a relay in to get 12V from a known good supply.


I'd prefer the option 1 route if anyone has any suggestions .. . .

[SCOTTY1]

Hi John, I have replaced my FBH pump thismorning but no luck in the heater firing up :( I've wired it to the battery and it pulses but it does'ent pulse when wired to the car loom (can't hear it or feel it when I switch on the FBH).

Cold air out the FBH exhaust too. I was wondering is there a fuse for the pump ? or if anyone has any idears I could try?

Scotty1

[JohnFol]

No fuse between the pin 6 on top of the FBH and the pump itself.

Might be worth checking the voltage coming out of pin 6, and then at the pump.

In the end I had a paper clip in pin 3 connected to earth to fire it up, and a paper clip in pin 6 (next to it) to check the voltage!

I might be looking into this further tomorrow, so keep posting!

[SCOTTY1]

My FBH is wired to a switch in the cabin from pin 3 to earth so that I can just switch it on. I'm going to try a few more things and have a mess so if i get it working i'll post here.

Scotty1

[Roverron]

My FBH is wired to a switch in the cabin from pin 3 to earth so that I can just switch it on. I'm going to try a few more things and have a mess so if i get it working i'll post here.

Scotty1

You can make it remote control by using one of Maplins (ready built) kits.
It just needs 3 wires, bat -v, bat + and wire to pin 3 of the fbh connector.
If mine worked I'd fit one!

Press the button to turn it on, and again to turn it off. Wire up aled in the cabin to remind you its on.
You could also buy one of their timer kits to turn it off after 20mins.

Ron

[simpsora]

Anybody had any success getting their FBH to fire up yet? .Mine has the same symptoms (can't hear any clicking of FBH pump- Where do you buy pumps from?)
Anyway, appears there may be other causes for non operating.

Thank's , Simpsora

[SCOTTY1]

You can make it remote control by using one of Maplins (ready built) kits.
It just needs 3 wires, bat -v, bat + and wire to pin 3 of the fbh connector.
If mine worked I'd fit one!

Press the button to turn it on, and again to turn it off. Wire up aled in the cabin to remind you its on.
You could also buy one of their timer kits to turn it off after 20mins.

Ron

Thanks Ron but first I've got to get the heater to fire up, It won't play ball at the moment. Fan comes on and everything but won't burn fuel.

[SCOTTY1]

Anybody had any success getting their FBH to fire up yet? .Mine has the same symptoms (can't hear any clicking of FBH pump- Where do you buy pumps from?)
Anyway, appears there may be other causes for non operating.

Thank's , Simpsora

You can get the pump here:- http://cgi.ebay.co.uk/NEW-WEBASTO-12-V-FUEL-PUMP-ALSO-EBERSPACHER_W0QQitemZ150057205566QQihZ005QQcategor yZ15263QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[simpsora]

Thanks for reply SCOTTY but may 'hang fire'on puchase (no pun intended) until I see if you have any luck getting your FBH to work.
Thanks , Simpsora.

[JohnFol]

Simpsora, it sounds like Scotty and I have similar, strange problems. It's still worth trying the basics like giving the pump a tap to see if it's just jammed through lack of use through the sommer .

[simpsora]

Hi Johnfol,
Have tried the 'tapping' routine etc (but no joy) .Can get it to run by shorting pin 3 ,but won't fire because it's not getting fuel.The main reason (I think ) is because the pulsed DC output from webasto to fuel pump is not there,
(SCOTTY1 can get his to click /pump by applying 12v on and off of pump ,simulating the pulsed DC that the webasto outputs) If anybody could get their hand's on webasto circuit diagram /component layout then it may be possible to trace where/why there is no pulsing volts to pump?
(Keith has held his hands up to having knowledge of webasto's )

Thank's, Simpsora

PS I think a lot more owner's may have webasto problem but just don't know it yet!

[JohnFol]

Agreed, however I do get a pulsing voltage it just happens to be 10V and not 12V needed to drive the pump.
I'm trying to solve the problem by using the 10v to switch a relay. Tried Halfords (Winnersh - name and shame) and got asked "wot's a relay?" followed by "wot carzit 4?"

Just popping over to Maplins to see if they can suggest a solution.


Scotty, any progress on checking the voltage you get?

[SCOTTY1]

Agreed, however I do get a pulsing voltage it just happens to be 10V and not 12V needed to drive the pump.
I'm trying to solve the problem by using the 10v to switch a relay. Tried Halfords (Winnersh - name and shame) and got asked "wot's a relay?" followed by "wot carzit 4?"

Just popping over to Maplins to see if they can suggest a solution.


Scotty, any progress on checking the voltage you get?

Hi John, I have 12v at the FBH 2 wire input. Not sure where else to put the meter to test other pins as I'm not good with electrics. I've given up for the time being as its getting on my nerves a bit:mad:

[Roverron]

Agreed, however I do get a pulsing voltage it just happens to be 10V and not 12V needed to drive the pump.
I'm trying to solve the problem by using the 10v to switch a relay. Tried Halfords (Winnersh - name and shame) and got asked "wot's a relay?" followed by "wot carzit 4?"

Just popping over to Maplins to see if they can suggest a solution.


Scotty, any progress on checking the voltage you get?


A relay is not a good idea - the contacts won't handle continuous on/off switching.
Its better to use a mosfet, protected by a flywheel diode.
Maplin sell them.
HUF75337P3 part no UE47B.

You also need a 3.9v diode from gate to ground and a 4k7 resistor in series with the 10v pulse lead from the fbh.
I'd recommend a 3amp diode across the mosfet as well.

Ron

[simpsora]

Hi
You probably have RAVE,but just in case you haven't then the following Quote may assist "After 20sec.the ECU starts to operate the 'dosing' pump at 0.7 Hz. The fuel entering the combustion chamber is ignited by the glowpin." If an analogue DC voltmeter is used on pulsing DC it may only register 10v or so. Needle may not be seen to pulse up and down .
Hope this info may be of some use.

Thanks , Simpsora

[JohnFol]

In fact, just got back from Maplins.

One comment that was made is the "driver" may be a problem. To explain, When I get the 10V and connect it under bonet to a relay, the voltage drops to zero and there is no click. The suspision is there is not enough current to drive the relay, or equally the solenoid.


Got a few more tests to try . .

Scotty, the pin I was testing is no.6 (just to the right of pin 3 that gets grounded).

It would be really usefull to know if anyone else gets 10V with a working pump . ..

[Roverron]

In fact, just got back from Maplins.

One comment that was made is the "driver" may be a problem. To explain, When I get the 10V and connect it under bonet to a relay, the voltage drops to zero and there is no click. The suspision is there is not enough current to drive the relay, or equally the solenoid.


Got a few more tests to try . .

Scotty, the pin I was testing is no.6 (just to the right of pin 3 that gets grounded).

It would be really usefull to know if anyone else gets 10V with a working pump . ..


There would enough to drive the mosfet, they need a a few microamps!

[simpsora]

Hi
if the ability to provide the required current to drive the pump is suspect (even if volts are there) then then this would throw suspicion on an internal circuit (ie the .7 Hz pulse circuit)of going wrong, ie high resistance,which may be pre-curser of failure.

[Roverron]

Hi
if the ability to provide the required current to drive the pump is suspect (even if volts are there) then then this would throw suspicion on an internal circuit (ie the .7 Hz pulse circuit)of going wrong, ie high resistance,which may be pre-curser of failure.


This is true, but rather than replacing the internals of the fbh, or even the whole fbh, if there is enough current available to drive a mosfet, then this would be much cheaper.

Ron

[simpsora]

Hi Roverron
what you are suggesting would work (as MOS FEt's have extremely high input impedence) However , this would be 'working around' problem rather than pinpointing the real cause, which may be as simple as 10 pence resistor going increasingly high resistance till it fails altogether .When this happens there would be no output to drive MOS FET solution.
That's why a copy of webasto circuit diagram/ component layout would be very usefull.

Thanks, Simpsora.

[JohnFol]

If I can delay or avoid the cost of replacing the internals of the FBH for a few pence then why not?

In fact Maplins suggested a Medium Power lenear transistor (TIP120)

Just need to remember my base collector emmoter stuff now to be able to use it!

[Roverron]

If I can delay or avoid the cost of replacing the internals of the FBH for a few pence then why not?

In fact Maplins suggested a Medium Power lenear transistor (TIP120)

Just need to remember my base collector emmoter stuff now to be able to use it!

Diagram attached.

Ron

[simpsora]

Hi There,
Yes, roverron's circuit suggestion should work ok for you Johnfol, go for it and let us know how you get on. However ,for those of us who have no remaining vestige of pump pulse (including mine )then restoring correct operation
of circuit within webasto remains the best way forward (possibly) .

Anybody ever successfully got a defunct webasto working again? (not including complete replacements or retro fits etc)

Also, as webasto's (fitted as standard) must all be coming on for 5+yrs . old approx. then it may be an age related fault!

Thank's,Simpsora

[simpsora]

Hi
Just as an afterthought , I see from RAVE operation description that the Glowpin has to pre-heat the combustion chamber for 20 sec.beforethe webasto starts to output 'dosing pulses' .If no pre-heat then no pulses. What would be best way to check if Glowpin is OK? and where could I purchase one?
Thank's Simpsora

[JohnFol]

Hi Ron, many thanks for this. Working away a bit this week so had to order the bits (delivery costs more than the parts!!).

I'll give it a try this weekend.

[JohnFol]

ok, some progress but my conclusion is the Webasto is itself the fault.

I get 10v from pin 6 (the one that energises the pump) even if the unit is off. Even if I remove the 2 pin connector I still get 10v. Whatever I do, including the bulb test I cannot get a pulsing

With Ron's curcuit I can get a 12v feed, and hooked up to a light bulb to eliminate the pump and associated wiring I still get no pulsing

So my conclusion is I really need to find someone who will either repair the circuit board, offer a replacement on a swap out or see if Webasto have service centres.

If anyone has been down this road, I'd appreciate any comments.

PS as longs as it;s not "gonna bench it 50 quid dun"

[simpsora]

Hi,
I am also in similar situation (circuit diagram would be invaluable). I removed centre cover on webasto to expose 'bank' of plugs /socket's. Pulling connector to glowpin and checking continuity proved it was intact ,
(ceramic -so should last!)However, no supply to it (pre-heat voltage for 20 seconds). Took cover off webasto control panel side to reveal a lot of chips but only one power 'transistor'( going on principle that this is probably to do with the supply to glowpin ,as it will draw a fair bit of current, then I need to check it for open circuit etc ) Will also need to check 'transistor' type etc, first.

Simpsora,

PS could be using it at moment, 3.5 deg in Aberdeenshire (and dropping).

[REMF]

Mine has never worked, so disconnected the plug for a couple of seconds and it only NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- works:D :D :D

Burnt my hand on the exhaust to be on the safe side:drool4:

Dont have a meter here today, but if anyone needs any voltages etc let me know, it may help

[simpsora]

Hi
Thank's REMF for your kind offer of voltage measurements , (may be taking you up on that) I went a little 'deeper' into Webasto this morning .The 'power transistor' (on control panel, that I suspect) is a BTS 141 with legs identified as
I , D ,S. . Can anybody identify what it is ? Also, when heat sink screw is removed and all plugs removed, the complete panel lifts out and would be easily replaced with an exchange / new one as 'John Fol' suggests. This may be a better / easier way forward.

Thank's Simpsora

[JohnFol]

Data sheet is here

http://www.chipdocs.com/datasheets/datasheet-pdf/Siemens/BTS141.html

However I have a final test to try before I make my next posting

[JohnFol]

REMF, could I take you up on your offer?

Firstly do you have FBH or do you have the timers etc to make it a parking heater? Reason I ask is I believe my problem may be because I have FBH and am testing without the iginition on. The FBH is fed 12v from the alternator, where as the Parking Heater has a relay in the circuit to feed 12v.


My 10v detected seems constant, irrespective of pin 3 being grounded. I've not had a chance to try it with engine running and cold coolant but would appreciate a reading from a known good system.

So, would you mind confirming if you have fbh/parking heater, and if the former, could you check to see if you have 10v or 12v on pin 6 with engine turned off? Any other variations such as engine on, with without pin 3 grounding would be usefull.

Many many thanks in advance

[REMF]

REMF, could I take you up on your offer?

Firstly do you have FBH or do you have the timers etc to make it a parking heater? Reason I ask is I believe my problem may be because I have FBH and am testing without the iginition on. The FBH is fed 12v from the alternator, where as the Parking Heater has a relay in the circuit to feed 12v.


My 10v detected seems constant, irrespective of pin 3 being grounded. I've not had a chance to try it with engine running and cold coolant but would appreciate a reading from a known good system.

So, would you mind confirming if you have fbh/parking heater, and if the former, could you check to see if you have 10v or 12v on pin 6 with engine turned off? Any other variations such as engine on, with without pin 3 grounding would be usefull.

Many many thanks in advance

Absolutely no problem at all, will do it tomorrow for you.

I just have the FBH, no timers or remote.

What colour wire is pin 6-just so I get it right:D

[pondweed]

johnfol - only just read this string so see the problem is deeper seated...

Another thought - I read on one of the landrover forums (cant remember which one) about same gnarly issues.. and there is obviously a lot of retrofit/rebuilding/restoration that has been going on over a far longer time frame than has been possible with the 75 yet. So we probably dont need to be reinventing any wheels...others will have been there before us?
Have any of you got any landie specialists near you.. as they might be a good source of down to earth renovation info. The thing I remember noting was "glowplugs are often the things that need doing".. some chap buying up them to sell on once done... may not be relevant here but obviously some units are being renovated by the initiated!

[JohnFol]

good idea. There is a 4x4 centre near by who specialise in old land rovers so worth a try.

I think I need to do the extra diagnostic first i,e, check the opperation with engine running. Hopefully tonoght as I have a lift to work so coolant will be cold when I get home.


REMF, from memory there are only 3 wires connected to the plug. I *think* it's the front right and from memory it's predominantly white

[Rufras]

My original Webasto failed this winter, at would not pulse the pump where a multimeter showed 11v and no pulsing, finally it went haywire where it was affecting the K-Bus circuit and making the alarm, air con, central locking, indicators go haywire.I got one from a breakers and guess what it was worse than the one I had, still no pulsing and a fan that could be heard for miles.
Webasto do not supply the PCB separately as they say they come with the combustion chamber as a part assembly at £334 (+VAT). Incidentally Rover charge £328.62 (+VAT) for the entire unit including coolant pump which is better than going to Webasto. Ebay has some but at prices higher than Rover!
I getting another one from the breakers but I am beginning to feel that it will just be as bad as the last, at least if you get it from Rover you have some assurance it will work. My nearest Webasto agent (Wolverhampton) gave me the impression that for them to service my original I would end up paying at least £334 (+VAT) for combustion part assy and labour which is more than a new unit from Rover.

[JohnFol]

I've just tested my car again with engine running
Wow 12v on the lead to the pump, however I put a bulb between the wire and the battery and no light . . certainly no pulsing . .

[REMF]

Apoloogies for delay, couldnt find my meter:confused:

Three wires

Green/White(pin1)
Red/White(pin2)
Brown/White(pin6)

Plug removed, ignition on, and off 12V to pin2

Let me know if you need anything else

HTH

[Roverron]

My FBH has never worked. It tries 3 times after being reset by removing fuse 9 and then gives up.

No noise from the solenoid pump.

I removed and checked this and found it was working okay.

Metering the connector, 10.7v is present but definitely non pulsating.

Looks like the heater pcb is going to have to come out. Probably a driver transistor.

BUT, there is another way!

Using the 10.7v to activate a replacement pulser!
Assuming there's a couple of ma available, I'd use a mosfet as a switch to turn on the supply to a timer IC.
This will generate a .7Hz pulse and drive the pump via another mosfet.

There is a problem however, the 10.7v does not return to zero as soon as the heater fan switches off. Its only when the cooling down stage has finished that the heater probably shuts down completely. So I'm not sure whether too much pressure will build up unless there is a pressure sensor in the heater which switches off the 10.7v.

Ron

I have now confirmed that the 10.7v is probably just leakage from a faulty transistor. With the fuel pump connected the voltage is zero, with a 10k resistor in series with it, the voltage drops to 5.8, so only about .5ma is available instead of 3 amps. This shows no signs of pulses and as I said above, does not switch off as soon as the heater does. So my an 'other way' won't work.

[JohnFol]

Sounds like you get exactly the same as me.

Any suggestions or cures, I'm your guinnea pig

[JohnFol]

how about a non-solenoid type pump? i.e. one that needs a constant 12V to run?

[Roverron]

Sounds like you get exactly the same as me.

Any suggestions or cures, I'm your guinnea pig

I hoping someone has taken their heater's pcb out so I can borrow it with a view to possible repair. I'd guess a power transistor has gone. There should be a 3 - water pump, blower, fuel pump..?

Ron

[Roverron]

how about a non-solenoid type pump? i.e. one that needs a constant 12V to run?

No good.

I could easily make a replacement circuit to pulse the pump.

The heater has to control the pump. Otherwise what's to stop the pressure building up and potentially spraying derv all over the place.

If I could locate the pump pulse on the pcb I could bypass any dud transistor and use my external circuit.

Ron

[baxlin]

Put this Q on .org forum as Parking heater switch wiring was being discussed, but I'm impatient for a reply!

Which is pin 3, if viewed from the front of the car?

TIA

Malcolm

[Roverron]

Put this Q on .org forum as Parking heater switch wiring was being discussed, but I'm impatient for a reply!

Which is pin 3, if viewed from the front of the car?

TIA

Malcolm

If its the one grounded to activate the heater, its the front lefthand one.

[baxlin]

Thanks once again Ron

Malcolm