2.0 CDT - fuel pump failure and FBH

JohnFol · 7th November 2006, 10:53

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 · 7th November 2006, 11:04

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 · 7th November 2006, 11:26

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 · 7th November 2006, 12:02

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 · 7th November 2006, 12:58

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_ma...g%20diagram%22

SCOTTY1 · 7th November 2006, 14:48

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 · 7th November 2006, 15:18

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 · 11th November 2006, 10:14

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 · 11th November 2006, 11:50

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 · 11th November 2006, 12:01

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!

7th November 2006, 10:53	#1
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	2.0 CDT - fuel pump failure and FBH 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?

7th November 2006, 14:48	#6
SCOTTY1 Regular poster ROVER 75 CDT CONN SE (MANUAL) Join Date: Nov 2006 Location: Longbridge Posts: 50 Thanks: 0 Thanked 0 Times in 0 Posts	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 __________________ *Remember, a dog is not just for Christmas, if your lucky you'll have a bit left over for boxing day!* http://www.easyrider01.btinternet.co.uk/ [SIGPIC][/SIGPIC] ROVER 75 CDT CONN SE (MANUAL)

11th November 2006, 11:50	#9
SCOTTY1 Regular poster ROVER 75 CDT CONN SE (MANUAL) Join Date: Nov 2006 Location: Longbridge Posts: 50 Thanks: 0 Thanked 0 Times in 0 Posts	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 __________________ *Remember, a dog is not just for Christmas, if your lucky you'll have a bit left over for boxing day!* http://www.easyrider01.btinternet.co.uk/ [SIGPIC][/SIGPIC] ROVER 75 CDT CONN SE (MANUAL) Last edited by SCOTTY1; 11th November 2006 at 11:56..

7th November 2006, 11:04	#2
Keith This is my second home ZT400 Join Date: Oct 2006 Location: Ellesmere Posts: 5,948 Thanks: 0 Thanked 43 Times in 29 Posts	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.

7th November 2006, 11:26	#3
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	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

7th November 2006, 12:02	#4
Keith This is my second home ZT400 Join Date: Oct 2006 Location: Ellesmere Posts: 5,948 Thanks: 0 Thanked 43 Times in 29 Posts	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?

7th November 2006, 12:58	#5
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	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_ma...g%20diagram%22

7th November 2006, 15:18	#7
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	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.

11th November 2006, 10:14	#8
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	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 .. . .

11th November 2006, 12:01	#10
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	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!