88 1/2 Samurai that has been converted to EFI with a 89/90 ECU and wiring harness. Starts perfect and idles great. Idles down after a few minutes fine. Runs and drives great until it gets hot. Then it starts to stutter sporadically at highway speeds and sometimes (rarely) will backfire when you let off of the accelerator. It has died several times when pulling up to a stop sign and when taking off easy. To restart it takes several seconds of turning it over and when it finally starts it acts flooded. It never dies if I rev it up a bit on take off. My wife commented on the smell of fuel when we were tooling around in it with the top off. My first thought was either fuel pump or regulator. Put a fuel pressure gauge on the banjo fitting come off of the fuel filter and started the motor. Pressure stayed a constant 40 psi. Pinched off the return line for just a few seconds and the pump fluttered between 75-80 psi. No fuel leak from the regulator vacuum nipple. Allowed the motor to get hot and start to miss sporadically while setting in the driveway. Watched the fuel pressure while it was stuttering and it didn't fluctuate the needle even a little bit. So I'm confident in the fuel pump. New plugs, cap, rotor, coil. I'm I right in assuming since the problem occurs after it is up to temperature that it isn't likely anything to do with IAC, dash pot, etc? I'm almost positive that the TPS is not calibrated correctly since it has been moved. I marked it before I moved it but I only marked one side and it moves on both sides. ECU was rebuilt a few weeks ago by Speedometer Repair Guy in Winona, MN. Connected and disconnected the vacuum advance and it doesn't make a difference that I can detect. I'm 80% fabricator and 20% mechanic so any help would be appreciated. Also, FIXKICK refers to adjusting "duty cycle" but for the life of me I can't figure out what he is referring to.
Forgot to mention that the fuel pressure immediately drops to zero after the motor is shut off. Does not hold any residual pressure in the lines.
Forgot to mention that the fuel pressure immediately drops to zero after the motor is shut off. Does not hold any residual pressure in the lines.