aiKzo6

Hey guys, trying to work out an issue a mate is having with his evo 6 and it's killing me. I don't have another car to run comparison tests on for voltages, etc so i figured here would be the best place to start!

The turbo has been upgraded with an ATP Gold, injectors have been upgraded, fuel pump has been upgraded to a walbro 255, and the ECU has been flash tuned.

Basically, the car will start fine when cold. When it is at operating temperature, occasionally the fuel pump voltage will drop below 6v and the engine will hesitate. Occasionally the car will refuse to restart when switched off hot, and if it does start, revs will drop very low for a brief moment before raising back up to normal. At times, the idle will hunt and, at which point the fuel pump voltage will be reading around 7-10v. For this reason, i assumed the #3 fuel pump relay (firewall) was sticking intermittently, so i removed it and retested. The car started straight away without the rev drop and the idle was perfect, however, obviously the hi-voltage circuit is now incomplete.

I don't have another relay to test at the moment and all the stores are closed for today, so i was wondering if anyone else on here has ever had similar issues. If the relay doesnt fix, it my next thought would be the ECU trigger to #3 relay. If i believe the ECU to be shot i will more than likely be hardwiring the fuel pump at battery voltage instead of running the 3 relay hi/lo circuit and running an adjustable fuel pressure reg.

Is it normal for the fuel pump voltage to peak to 12v as the car is being started? With the #3 relay unplugged, the car starts perfectly on 6V.

Any input would be great as this car's got me pulling my hair out!!

Ev0six

iTrader: (7)

Bypass the 2nd relay. I've seen it fail on a few cars already

aiKzo6

Would the 2nd relay be the top or bottom on the fuse box?