How does an FMU go bad? We took my brother's car to the dyno recently and discovered that his car is leaning out very badly at 3000 + rpm's. We belive it is the FMU gone bad, but how? Any recomendations on a replacemeny? Thanks,

Kyle

 

were you monitoring fuel pressure at the time? Did you play around with the adjustment at all?

 

Yes. FP was at about 38psi at idle and only went up to about 40 psi, max. Car was 14.8/1 AFR at 3400 rpm and went up to 18.0/1 by 4100 rpm. RWHP was at 210 at 3400 rpm and went up to 258 at 4000 rpm. After that, car took a nose dive and would not gover 4900 rpm. Any ideas? Thanks,

Kyle

 

What fuel pump are you running, and was it operating properly?

 

It's running the stock in tank with the supplied in line from ATI. The in line was just checked a couple of weeks ago and a new relay was put in. When the key is put in the on position but not turned on, you can hear the inline pump cut on for a few seconds and then cut off like it should. When running, it is audible. Thanks,

Kyle

 

Sounds def like the FMU then. Has it worked before, or is this the firs time you've used it? I think i remember reading that a common mistake when installing it is wiring it in backwards. (fuel inlet & outlet reversed). I haven't really messed around with them, so i can't offer too much help.

 

It has worked fine in the past. we just recently put a new cam, 52 MM TB, and new Ed Wright tuning. Took it to the same Dyno where it made 350 rwhp a year or so ago and couldn't get any higher than 258 rwhp. We checked the inlet/outlet as well and it seems alright (that was our thinking as well). If anyone has a diagram or schematic of the routing, that would be greatly appreciated. Thanks,

Kyle

 

fyi, I have a FMU for sale if you are interested