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The mkiv Supra Owners Club

FCD causes over fueling then stalling - why?


mawby

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Edit - Unless you meant the pump? I have one but it's been in a dusty shed for 4 years, so might well take you up on the offer, nice one :)
Yeah a pump. It came off my car a few months back at about 26k miles when I fitted the Walbro.

 

Sounds like you're getting to know to the Supra electrics/wiring well. You can have the pump if you can find out why fitting a Thor FCD to my car causes it to massively over fuel on startup and then stall. I bought a second FCD thinking the first one was faulty but they both do the same, so it looks like a wiring fault. Any clues?

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Yeah a pump. It came off my car a few months back at about 26k miles when I fitted the Walbro.

 

Sounds like you're getting to know to the Supra electrics/wiring well. You can have the pump if you can find out why fitting a Thor FCD to my car causes it to massively over fuel on startup and then stall. I bought a second FCD thinking the first one was faulty but they both do the same, so it looks like a wiring fault. Any clues?

 

Thanks Lee. One of the local members had the same issue and we solved it after a bit of tinkering, stick a thread up in tech and I'll post some details. It could be a couple of things.

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Now thats just lazy :D

 

Okay, the local guy that had an issue with his old Thor FCD found that the adjuster on it was wound the wrong way, turned back the other way and it was solved.

 

The other guy had a greddy unit that had the same issue, but this was caused by a faulty unit.

 

I'm looking at the TT wiring diagrams tomorrow so will take a look at what the FCD is cutting into as it should reveal a few clues.

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Well the full story goes like this...

 

Previous owner had a FCD fitted with no problems.

One day there was a problem with the car (not sure what) but it was tracked down to the FCD, which was removed.

Upon opening the FCD it was discovered that the cable had become disconnected from the circuit board, presumably accidentally by a passenger in the car.

I bought the car, with the FCD device unfitted.

I had Interpro fit the FCD. It overfuled and stalled. We concluded it was duff.

I bougth a known working one from Terminator, and had Interpro fit that one when it was next in. The same problem occurred and Jody suggested that either I was unluckly and had two duff FCDs, or there was a wiring problem somewhere. I didn't have time for them to investigate that day so they disconnected the FCD again.

 

It's not a problem in the summer, the restrictor ring stops me hitting fuel cut, but last winter I hit it several times and I'd rather not have the car lose all power whilst I'm trying to overtake a convoy of Micras on the A4! So any assistance greatly appreciated. :)

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I'm sure of nothing because I've not tried fitting either of these myself. I will try and have a look and see what's going on though.

 

P.S. The original FCD was supplied and fitted by a Mr Chris Wilson, so I'm sure originally it would have been 110% wired correctly. :D

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  • 2 weeks later...

Right then, Lazarus and I (mainly Laz) looked at this yesterday and came to the following conclusions...

 

Are you sure, 110% SURE it's wired into the CORRECT (yellow / black) ecu wire?
Yes

 

Earth to a proper clean chassis ground.
Yes

 

Ensure it is connected to the correct switched 12v ignition feed to the ECU.
Yes

 

Are you 110% sure it's wired with the CORRECT wire to the ecu and the CORRECT wire to the MAP sensor?
No! It looks like they wired it the wrong way around. Laz wired in as per the instructions on here and it worked fine.
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