75ZT Community

MrB · Posted 08 Nov 2010, 12:57 #1

Russ has already ascertained on his T4 (Testbook version 4.Computer Diagnostic System) that my FBH (Fuel burning heater.) isn't working.

However, I want to check a few things before ripping it apart.

Having seen another member's FBH working whilst at Andy Willi's garage, I have noticed that there is no clicking sound after 30secs, from the dosing pump. I don't recall noticing this on my old 75, which had a fully working FBH.

So is my dosing pump not working? Also where is the dosing pump located, I know it is somewhere near the tank, but which side etc?

My FBH shuts down after a round 1 minute of trying. Is this significant?

Where is the glow plug located? Is it under the screwed on section?

Thanks in advance for all your help.

Rammie · Posted 08 Nov 2010, 14:44 #2

Hi Chris,
The Dosing pump should be located near the rear offside wheel arch. I believe these have been known to stick, which can be freed by a judical tap with a hammer!

PICT1783.jpg

I have a brand new one if this turns out to be the problem.

Cheers

Brian

MrB · Posted 08 Nov 2010, 15:09 #3

Cheers Brian

I will try and give mine a 'Tap' and see what happens.

James.uk · Posted 09 Nov 2010, 03:57 #4

Contact FrenchMike - he seems to be a bit of an expert on the FBH.. he fixed my PCB (Printed Circuit Board) for me recently and it now works.. :thumbsup:

...

MrB · Posted 09 Nov 2010, 13:48 #5

Cheers James

Russ seems to think the PCB in mine is fine and that it is either the Glow Plug or the Chamber that need replacement/cleaning.

However, I have since noticed that there is no clicking noise from my pump, so am starting from there and then I'll work my way through all the other possible causes.

He ran the FBH through a T4 check and it seemed to pass all of it's tests but not fire.

SpongeBob · Posted 09 Nov 2010, 21:39 #6

I seem to recall that if the FBH does not fire after so many attempts it defaults to a fail-safe mode and will not re-attempt to fire until either something has been reset or similar. I'm afraid I do not recall this information fully as I do not own a FBH but something is sticking in the back of my mind about this though.

MrB · Posted 10 Nov 2010, 10:25 #7

Cheers Simon

Yes, it tries to fire three times and then doesn't bother after that until re-set.

Mine didn't try fire this morning, despite it being 0.5C, so it needs re-setting.

Supposed to be dry but cold today, so I'll try get under it and give the pump a tap this evening, if I get the chance. Lots of Flat Packs to assemble......

Russ · Posted 20 Nov 2010, 14:03 #8

Chris, give the dosing pump a tap with a mallet and see if it then fires up mine stuck acouple of years ago and has worked well since doing the above.

It used to go through the trying 3 times sequence the same as yours, also check that it's getting power.

Russ

MrB · Posted 21 Nov 2010, 17:10 #9

Cheers Russ

Where exactly is the pump located??

I can't seem to spot it. Have tried lying at the side of the car with torch in hand and rubber mallet at the ready but can't see it.

James.uk · Posted 21 Nov 2010, 17:28 #10

It's tucked up against a chassis member in front of the fuel return radiator. It's only small..

...

Duncan · Posted 21 Nov 2010, 19:50 #11

Drivers side of the car. Lie on the floor, near the rear door. Look underneath, you should see the fuel tank, and in front of it is the metal panel that comes down just underneath the front edge of the rear seat. It's on the bottom corner of that. Look at the pfoto already posted to give you a clue what it looks like. It's easy to see, if you are looking in the right place. It's not tucked away, so if you can't see it you are just looking in the wrong place.

MrB · Posted 22 Nov 2010, 12:57 #12

Thanks James and Duncan.

If it's dry will try get under this evening and give the little blighter a tap. :whump:

MrB · Posted 27 Nov 2010, 21:10 #13

Gave it a good few taps this morning and nothing.

If there is a problem at the FBH end, and it knows it isn't going to fire, e.g. glow plug not heating, will this mean it doesn't send a signal to the pump? Or has my pump died?

Think the cost of having to replace my In Tank and Under Bonnet Pumps will mean anything that costs with regard repairing the FBH will have to wait til this time next year.

James.uk · Posted 28 Nov 2010, 00:39 #14

I think if any faults are found during the "test sequence" then the whole thing just shuts down again..
...

MrB · Posted 29 Nov 2010, 13:05 #15

Thanks James

So the pump could be OK but the system has realised something is up, for example the glow plug isn't heating up?

Might have a go at cleaning the Glow Plug and combustion chamber.

75ZT Community

75ZT Community

FBH Questions by MrB