Digifant Fuel Pump Problems.

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   Greetings. I'm hoping that someone has an in-depth knowledge about the digifant fuel injection system built on the later T3 2.1's. I have a problem with the fuel pump relay system in as much as I seem to have two burned ECU's, neither of which will give the earth signal to the fuel pump relay. (terminal 3 on the ECU). When the first ECU didn't fire up the fuel pump relay,(system was 2nd hand, so no history on it)  I earthed the relay manually and the system ran perfectly. Everything ran perfectly, accept no 'auto shut off' of the fuel pump. After checking all the usual tricks, relays etc, it seemed to come down to the earthing system through the ECU not working. I got hold of another Digifant ECU, plugged it in and then the fuel pump relay worked perfectly. Switch the ignition on, a short burst of fuel pump, then start the engine. The new ECU worked perfectly for a few days, nothing to report. Then suddenly the engine stalled, so I switched OFF the ignition only to hear the fuel pump start up! I then put the ignition on, the pump stopped, off again and the pump started!.... Yup, double dutch. Disconnected the battery, had a dig around, everything looked perfect and tidy. Swapped the fuel pump relay (right hand relay) for a new one, same number etc, this cured the 'running' on with ignition off, but, now the pump won't start with the ignition on via the ECU. Again if I jump the relay to earth, the pump runs and the engine runs perfectly. The only thing I have noted that 'might' have been wrong is that the relay terminals were loose and maybe there was an internal short in the relay sending voltage to the ECU through the earth terminal. 

I've checked Bently's thoroughly, run all the tests and it seems to come down to the ECU. 

My question is, is this a known problem... and before I decide what to do next, is there a simple fix (other than simply bridging the fuel pump relay to earth). 

Thanks in advance. I hope I explained it well enough to understand. 

Mark

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Mark-Hans Members Profile Send Private Message Find Members Posts Add to Buddy List Yardie turkey drummer Joined: 22 Jul 12 Location: Netherlands Status: Offline Points: 332	Post Options Post Reply Quote Mark-Hans Report Post Thanks(0) Quote Reply Topic: Digifant Fuel Pump Problems. Posted: 17 Oct 16 at 21:46
	Greetings. I'm hoping that someone has an in-depth knowledge about the digifant fuel injection system built on the later T3 2.1's. I have a problem with the fuel pump relay system in as much as I seem to have two burned ECU's, neither of which will give the earth signal to the fuel pump relay. (terminal 3 on the ECU). When the first ECU didn't fire up the fuel pump relay,(system was 2nd hand, so no history on it) I earthed the relay manually and the system ran perfectly. Everything ran perfectly, accept no 'auto shut off' of the fuel pump. After checking all the usual tricks, relays etc, it seemed to come down to the earthing system through the ECU not working. I got hold of another Digifant ECU, plugged it in and then the fuel pump relay worked perfectly. Switch the ignition on, a short burst of fuel pump, then start the engine. The new ECU worked perfectly for a few days, nothing to report. Then suddenly the engine stalled, so I switched OFF the ignition only to hear the fuel pump start up! I then put the ignition on, the pump stopped, off again and the pump started!.... Yup, double dutch. Disconnected the battery, had a dig around, everything looked perfect and tidy. Swapped the fuel pump relay (right hand relay) for a new one, same number etc, this cured the 'running' on with ignition off, but, now the pump won't start with the ignition on via the ECU. Again if I jump the relay to earth, the pump runs and the engine runs perfectly. The only thing I have noted that 'might' have been wrong is that the relay terminals were loose and maybe there was an internal short in the relay sending voltage to the ECU through the earth terminal. I've checked Bently's thoroughly, run all the tests and it seems to come down to the ECU. My question is, is this a known problem... and before I decide what to do next, is there a simple fix (other than simply bridging the fuel pump relay to earth). Thanks in advance. I hope I explained it well enough to understand. Mark

rowlesy Members Profile Send Private Message Find Members Posts Add to Buddy List Vanorak murdered the murderwagen Joined: 09 Oct 05 Location: up unit! Status: Offline Points: 6466	Post Options Post Reply Quote rowlesy Report Post Thanks(0) Quote Reply Posted: 18 Oct 16 at 19:50
	sound like all t3 problems to me. bad earths. if you have a bentley trace the wires back through the fuse box and over to earths to make sure all is right and working well. although as i type this im thinking the tracks in the fuse box might be your problem? any of the other relays terminals gone green? leaky screen above it at some point may be the culprit. google ce2 fusebox and see what comes up. could even get a second hand one of a similar age vw to swap over....... might solve your problem
	UberFukz broke another! sucky sucky five dollah! always out numbered never out gunned! RWS welding 07846 380 467 (worcs)

Aidan Members Profile Send Private Message Find Members Posts Add to Buddy List Vanorak Joined: 25 Sep 04 Location: Llanfyllin Status: Offline Points: 1081	Post Options Post Reply Quote Aidan Report Post Thanks(0) Quote Reply Posted: 21 Oct 16 at 07:46
	or a poor connection on the alternator 12v live so when you start the voltage at the stud in the black box that supplies power to the relays 'disappears'
	Aidan Talbot, gearboxes for watercooled engines, 4, 5 speed and syncro front and rear rebuilt. 01691 648011, 07817 377938....www.aidantalbot.co.uk

jp1 Members Profile Send Private Message Find Members Posts Add to Buddy List Not Quite Newbie Joined: 10 Aug 10 Location: S E Hants. Status: Offline Points: 19	Post Options Post Reply Quote jp1 Report Post Thanks(0) Quote Reply Posted: 25 Oct 16 at 18:46
	Definitely check all the earths. On mine the problem was the 1cm wide earth braid between block and body: although it looked fine, it had intermittent high resistance - the braid itself not the end connections! Took a couple of trips home behind an RAC van before I sussed that one.
	jp 1986 Westfalia Joker DJ 2.1 5-speed mine from new

Mark-Hans Members Profile Send Private Message Find Members Posts Add to Buddy List Yardie turkey drummer Joined: 22 Jul 12 Location: Netherlands Status: Offline Points: 332	Post Options Post Reply Quote Mark-Hans Report Post Thanks(0) Quote Reply Posted: 06 Nov 16 at 06:50
	Thank you guys. Sorry for the very late reply. The + stud in the black box, I'll take a look at him. As for the mulitple earths, I'll check them out too. Thank you.