bodilx6 Posted May 26, 2015 Share Posted May 26, 2015 (edited) So, all of a sudden I experience what seems very much like fuel cut in fifth and sixt gear only after a few seconds over 1 bar (j-spec, BPU). My FCD has been working for 7-8 years and there have been no messing around with the wireing in the passenger footwell. Checking out the solderings, all looked well, but I still got me a same brand FCD and replaced. Cut the wires and made new solderings on the signal cable, reused the 5v and '0'. Same result. All solderings look very nice and should be working nicely. Any ideas of what is going on?? Can ther be any other reason for this? It is not the speed limiter, as I can easily cruise past that and that is also much more violent to my recollection.. Really need this working as I'm going to the ring in 10 days time.. :-/ Edited May 27, 2015 by bodilx6 (see edit history) Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted May 29, 2015 Author Share Posted May 29, 2015 Nothing? Quote Link to comment Share on other sites More sharing options...
mattdavies Posted May 29, 2015 Share Posted May 29, 2015 Which FCD are you using ? Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted May 29, 2015 Author Share Posted May 29, 2015 A non-brand. But has been working for the last 9 years and just installed a new to be sure. I'm thinking the voltage to the FCD from the pressure sensor is bad. Quote Link to comment Share on other sites More sharing options...
Chris88 Posted May 29, 2015 Share Posted May 29, 2015 Are you sure that the problem is with the FCD. It could be with the fuel pump ECU or with the fuel pump itself. Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted May 29, 2015 Author Share Posted May 29, 2015 I was thinking that as well at some point. I changed from a walbro to a (used) EU spec Bosch 2 years back. Can you elaborate? Quote Link to comment Share on other sites More sharing options...
Chris88 Posted May 29, 2015 Share Posted May 29, 2015 (edited) I'm no Supra expert but if this was a Soarer I'd be saying bypass the fuel pump ECU in the diagnostic port by connecting B+ and FP which will make the fuel pump run at full voltage. If the problem goes away then it's the fuel pump ECU and either remove it to run at full voltage all of the time or replace it. If the problem does not go away with the fuel pump ECU bypass in then my next port of call would be the fuel pressure regulator and the vacuum piping connecting it to the intake plenum before finally considering a fuel pump change. Edited May 29, 2015 by Chris88 spelling (see edit history) Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted May 29, 2015 Author Share Posted May 29, 2015 Thanks for the alternative input. Much appreciated. I just had an indication of going over 1 bar for quite more than the 3 sec, but then hit the fuel cut again. It could be down to temp differences and boost pressure since I experienced it quite different than the other day, but I get the feeling that it is electrical or something way different, which is where your theory comes in. I will measure voltage on the signal wire to the FCD next and then go after proving/dismissing your theory. Thanks again Other insight would still be highly appreciated Quote Link to comment Share on other sites More sharing options...
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