FBH The end of the SAGA ?

[mrdexter1]

Recently finished fitting a rover 75 fbh to my megane cc and got it all up and running off a remote switch for pre heating.... and then...


I discover webasto offer a kit to upgrade the system to direct all the heat to the heater matrix which offers very rapid interior warming and defrost, reduced fuel and electrical consumption... on contacting webasto uk they knew nothing about it.

I set about replicating the webasto kit and now have a fully working remote switchable -

heater matrix only - 9 minutes to defrost and warm car

heater priority.

standard engine and heater pre heat.

this is a video of before I fitted the remote switch.


https://www.youtube.com/results?sear...ebasto+defrost


get in you beauty , I love my hot early mornings....

[Jakg]

Originally Posted by FrenchMike

Hi Jack

To me, 5 minutes means PCB out of the picture

White smoke and coolant warm are good signs

Possible flame out



(if you start it by grounding pin3 ,it't the second type (kbus interfaced on pin 2)

Keep the connection ON while all the cycle

a nearly 6 years adventure !!!

Mike

Could you expand on what you mean by flameout?

Should it run indefinately in the test mode, or will it stop after a while anyway?

[FrenchMike]

Yes,it MUST run indefinately in the test mode as long as you maintain the connection.
BUT when the internal temp reaches 73 degrees,it passes in half load .
And if the temp arrive at 77 degrees,then shut down and idle .

At full load,you can hear in the cabin the click click of the pulsing pump at
the rate of 2.38 per sec .

If ,for one reason or another the flame extinguishes,it enter the mode described above.

After 3 trials ,you have to do a reset (engine ignition OFF,remove /reinsert fuse F8)

Mike

[Jakg]

Originally Posted by FrenchMike

Yes,it MUST run indefinately in the test mode as long as you maintain the connection.
BUT when the internal temp reaches 73 degrees,it passes in half load .
And if the temp arrive at 77 degrees,then shut down and idle .

At full load,you can hear in the cabin the click click of the pulsing pump at
the rate of 2.38 per sec .

If ,for one reason or another the flame extinguishes,it enter the mode described above.

After 3 trials ,you have to do a reset (engine ignition OFF,remove /reinsert fuse F8)

Mike

When I started the engine after the test, coolant temp was 18° C, so it sounds like a flameout.

What is likely to cause it?

[FrenchMike]

It's important to know if 30 sec after starting you can hear the clik click of the
fuel pump at least for a while .
then check for fuel pulsing at the end of the little plastic pipe

Typical cold start :

The blue line is the fuel pulsing rate
green =fan
red = glow plug

[HarryM1BYT]

Originally Posted by Jakg

When I started the engine after the test, coolant temp was 18° C, so it sounds like a flameout.

What is likely to cause it?

That is easy to answer...

Most likely cause is that it needs a service, if you are sure it is getting air (filter not blocked) and adequate fuel (plenty of fuel in the tank and the pump working properly, no air leaks on the pipe).

The fuel pick up point is I understand, set some way above the tank bottom, so the FBH will be deprived of fuel, whilst there is still fuel in the tank.

Hard carbon build up around the glow pin and the metal mesh, can cause the glow pin not to work as it should and the fuel to be not properly atomised. I detailed how to service the FBH properly, several years ago.

[Jakg]

Originally Posted by FrenchMike

It's important to know if 30 sec after starting you can hear the clik click of the
fuel pump at least for a while .
then check for fuel pulsing at the end of the little plastic pipe

Typical cold start :

The blue line is the fuel pulsing rate
green =fan
red = glow plug

Surely if it's getting no fuel, it wouldn't of fired up at all? But yes, I can test that.

Originally Posted by HarryM1BYT

That is easy to answer...

Most likely cause is that it needs a service, if you are sure it is getting air (filter not blocked) and adequate fuel (plenty of fuel in the tank and the pump working properly, no air leaks on the pipe).

The fuel pick up point is I understand, set some way above the tank bottom, so the FBH will be deprived of fuel, whilst there is still fuel in the tank.

Hard carbon build up around the glow pin and the metal mesh, can cause the glow pin not to work as it should and the fuel to be not properly atomised. I detailed how to service the FBH properly, several years ago.

I've not cleaned air intake specifically, but I did strip the unit down and give it a basic service last year.

I always have >1/4 tank of fuel. My pump was also brand new a few years back.

I've found a post from myself back in 2011 - http://www.the75andztclub.co.uk/foru...ad.php?t=73341 - which seems to suggest that I've already sent the PCB to Mike, who said it's ok, but that also it looks like I've had this problem all along (coming on, but then going off).

My next thought is to try servicing it again, but this time pay special attention to the combustion chamber, testing the glow pin, and also think about replacing the gaskets as I know all of mine have had it (nb I know this is a matter of debate!).

I do remember removing quite a bit of carbon last time, though.

[sln8458]

Just a thought which maybe those who know more can verify.

I think the glow pin doubles up as the flame failure sensor, so you may have a borderline glow pin. I seem to remember Mike having a trick to fool the system into thinking the glow pin is ok (21w bulb??)

As I say just a thought

SteveN

[FrenchMike]

Originally Posted by sln8458

Just a thought which maybe those who know more can verify.

I think the glow pin doubles up as the flame failure sensor, so you may have a borderline glow pin. I seem to remember Mike having a trick to fool the system into thinking the glow pin is ok (21w bulb??)

As I say just a thought

SteveN

How are you Steve ?
you are right ,here is what to do :

The goal is to lower the glow plug resistor at starting .

Glow plug test.jpg


Mike

[HarryM1BYT]

As said, the carbon is very hard and it can look as if you have it cleaned out and down to bare metal, but the cleaning the carbon out is the primary job when servicing. Any left in the mesh, or around the glow pin, will cause flame failures.

The glow pin acts initially as an ignition source for the fuel, then once lit, it acts as a combustion monitor. The PCB measures the varying resistance of the glow pin, to determine whether it is burning correctly or not. Carbon around the pin, will hamper its ability to both ignite the mixture and measure the combustion temperature.

As said in my How To, the best way to break up the carbon in the mesh, is using hard pressure with a blunt object, pressing on the mesh. Don't attempt to pick the carbon out of the mesh, or the mesh will be destroyed. You have to crumble it, to the point where it can fall out.