Quick FBH question. F5 or FL5

Hi,

My FBH has stopped working, which is annoying as I've just moved north and it's freezing.

In the fuse box under the bonnet, is it FL5 which is 80amps or F5 which is 20 (and has a picture of an engine and lightning bolt on the sticker).

Thanks.

underbonnet fusebox f5 - 20amps

Thanks Dave, pulled that fuse for 5 mins (ignition off) and it still didn't fire up. Didn't make a sound in fact.

Engine was warm though, does anyone know if it doesn't bother to fire if the engine/coolant is already warm?

Was working fine until a few days ago.

mine only works with engine running td4 auto i pull f5 fuse out then back in and it starts the fbh .

It will only run when the engine is running, and the ambient temp outside is cold enough.
It will decide how much heat to produce from the coolant temp passing through it, but you will hear it start up... after hours of running our FBH is still running, just in standby, I think it will heat to about 70degC, and the engine takes it to 90deg.
If you PM me your email address I can send you a great word doc that I found on how to service it..

My FBH doesn't appear to work... Ever since I've had the vehicle (October last year) it has made an awful 'banshee' noise which fades out after a few minutes of driving, but there's no heat. I can smell fuel though.

Apologies for hijacking the thread slightly!

RichStone said:

My FBH doesn't appear to work... Ever since I've had the vehicle (October last year) it has made an awful 'banshee' noise which fades out after a few minutes of driving, but there's no heat. I can smell fuel though.

Apologies for hijacking the thread slightly!

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Can you feel any warmth in the air coming from the little exhaust under the nsf, its normal for it to howl for a few secs while it starts up, then turns to a blowpipe kinda sound..

Do I pull the fuse with the engine running?

I've pulled it out for a couple of mins without the keys in the ignition - nothing, didn't even try to start when I started the car up, can't hear the pump or anything. It's dead.

Was working perfectly until a few days ago. Any ideas?

It will only fire up when less than 5 DegC and will then run until engine temp reaches approx 80DegC. Mine is always running lately because the thermostat is buggered and the temp remains lower than that. Try pulling fuse 5 when engine is cold, turning the ignition to pos 2 supplies the power to the FBH. So when the fuse is fitted the FBH should start up even without the engine running when outside temp is cold.

There are other threads which tell you how to short the Temp sensor that controls the FBH start up. The service document is in one of these threads, though dont ask me which one.

drturbo said:

It will only run when the engine is running, and the ambient temp outside is cold enough.

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Is that right? I though the whole point was that it would warm up the coolant and the interior without the engine running.

Well I know you can get a remote unit that fires it up with engine off to warm the cabin up. And I'm sure that it fired up when I was working on it with Ignition on one cold day a few months back....

Thanks for the fuse info, the FBH tried to fire this morning - made the banshee howl, but I think failed to light, as the car struggled to get to temperature, I also didn't hear the clicking FBH pump.

Any ideas what to try next?

Tried another reset. This time I could feel cold air coming out of the exhaust, but there was no banshee howl.

Any ideas of my next thing to try?

Thanks.

Look for a thread posted by me...."how I repaired and modified my FBH." there are details of how I got mine running again after a few years inaction.

Thanks Dave, been looking at that thread.

I have the rear wheel arch liner off and have checked the pump works by applying 12v to it, all seems OK it clicks quite happily with power applied.

When I put fuse 5 back in, the FBH fan comes on and blows cold air from the exhaust... it does this for about a minute, stops for a couple of seconds and then does it again a couple of times before it gives up - at this point only a reset will make it try again.

At no point the FBH fuel pump being engaged during this sequence. Doesn't seem right. Any ideas?

Does anyone know if, following a reset the FBH fan will come on even if the temp sensor is telling it it's above the activation temperature? I don't know whether the fan coming on rules out the temp sensor or not?

I've been searching a lot, but there's lots of threads where people ask questions, and never talk about the resolution.

Thanks.

The fan only comes on when it tries to light.

I would get the front wheel arch liner off to get at the FBH and check that the multi-plug is not corroded. This has the feed to the wee fuel pump in it, so if the contacts are oxidised there is perhaps no power getting to the pump. Use a 12v test lamp and see if it flashes.... iirc my multimeter was too slow to react the the FBH sending pulses to the pump.

Then try disconnecting the fuel hose from the fbh - its at the top and a real arse to reach. Pulse the pump and get someone to see if fuel comes through to eliminate a blockage in the pipe.

Thanks Dave, I'll try that tomorrow.

sijwhite said:

Is that right? I though the whole point was that it would warm up the coolant and the interior without the engine running.

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Can be made too, don't know if that was an option from new or not, not much hassle if you do want it too, keep thinking about modding ours to do that.. great in the winter, fire it up and go have a cuppa, 10 mins later nice and toasty..

Think their main purpose is to aid warming of the interior and engine during cold times, as the M47 engine amongst others is very efficient and produces little heat, disable it and see how much longer the temp gauge takes to get up when its below freezing... we had a vauxhall at work once that would take over 10 miles to get hot.. not a bad motor but slow at warming your feet!

drturbo said:

Can be made too, don't know if that was an option from new or not, not much hassle if you do want it too, keep thinking about modding ours to do that.. great in the winter, fire it up and go have a cuppa, 10 mins later nice and toasty..

Think their main purpose is to aid warming of the interior and engine during cold times, as the M47 engine amongst others is very efficient and produces little heat, disable it and see how much longer the temp gauge takes to get up when its below freezing... we had a vauxhall at work once that would take over 10 miles to get hot.. not a bad motor but slow at warming your feet!

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I haven't got one sadly. I don't find the TD4 to be that slow in warming up though, certainly not 10 miles.

sijwhite said:

I haven't got one sadly. I don't find the TD4 to be that slow in warming up though, certainly not 10 miles.

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Think that was a bit of Vauxhall there maybe..
The FBH will have it up to 90deg in about 2 miles max..