Bob Marcho
12-14-2006, 05:56 PM
Because I helped my brother-in-law get ready for the Runoffs in FF, I am just now trying to diagnose a problem in my ITS 1986 Nissan 300ZX...
At the regional race at Texas Motor Speedway in September, the car ran ok during qualifying -- it would seem to miss occasionally, like it was flooded then it would clean out and run ok. But on the pace lap for the race the car would literally die completely, then pick up and run, then die completely again, then pick up and run only to die again. I was able to keep it running -- angering everyone behind me because I couldn't keep up with the pace car -- until they threw the green flag. The car then ran but would not pull beyond 3500 rpm no matter what I did. It never died again, but just would not pull beyond 3500rpm in any gear.
I needed to finish so I kept on motoring, staying out of everyone's way. Twice coming out of a sharp left-hand turn on to the back straight it would take off like a rocket in 2nd gear, running all the way up to 6000rpm, only to stop revving past 3500 when I shifted into 3rd, 4th, 5th, etc. Running great in 2nd gear out of that one particular corner only happened twice during the race. The rest of the time it would pull up to 3500, then just not rev anymore no matter what I did with the throttle, etc.
I just pulled all the plugs and found that all 3 of the plugs on the passenger side (1 - 3 - 5) are black, wet, and fouled with gas. The 3 on the driver's side (2 - 4 - 6) are fine. Obviously that is my problem. I checked the spark plug wires 1st, checking each one with a diagnostic tool and they are all firing perfectly. No difference in the voltage for 1 - 3 - 5 compared to 2 - 4 - 6. Both sides are getting spark.
Not electrics, must be fuel.
Obviously the passenger side is flooding the 1 - 3 - 5 plugs with fuel which leads me to wonder if all 3 injectors are stuck open (unlikely in my mind) or that the sensor at the front of the fuel rail is somehow faulty causing too much fuel to be sent to the passenger side.
Does this sound like a possibility? Any other ideas? I will be posting the same question to the SCCA production page and Z31.com, but I would appreciate your thoughts as well.
As always, thanks for your help,
Bob Marcho
At the regional race at Texas Motor Speedway in September, the car ran ok during qualifying -- it would seem to miss occasionally, like it was flooded then it would clean out and run ok. But on the pace lap for the race the car would literally die completely, then pick up and run, then die completely again, then pick up and run only to die again. I was able to keep it running -- angering everyone behind me because I couldn't keep up with the pace car -- until they threw the green flag. The car then ran but would not pull beyond 3500 rpm no matter what I did. It never died again, but just would not pull beyond 3500rpm in any gear.
I needed to finish so I kept on motoring, staying out of everyone's way. Twice coming out of a sharp left-hand turn on to the back straight it would take off like a rocket in 2nd gear, running all the way up to 6000rpm, only to stop revving past 3500 when I shifted into 3rd, 4th, 5th, etc. Running great in 2nd gear out of that one particular corner only happened twice during the race. The rest of the time it would pull up to 3500, then just not rev anymore no matter what I did with the throttle, etc.
I just pulled all the plugs and found that all 3 of the plugs on the passenger side (1 - 3 - 5) are black, wet, and fouled with gas. The 3 on the driver's side (2 - 4 - 6) are fine. Obviously that is my problem. I checked the spark plug wires 1st, checking each one with a diagnostic tool and they are all firing perfectly. No difference in the voltage for 1 - 3 - 5 compared to 2 - 4 - 6. Both sides are getting spark.
Not electrics, must be fuel.
Obviously the passenger side is flooding the 1 - 3 - 5 plugs with fuel which leads me to wonder if all 3 injectors are stuck open (unlikely in my mind) or that the sensor at the front of the fuel rail is somehow faulty causing too much fuel to be sent to the passenger side.
Does this sound like a possibility? Any other ideas? I will be posting the same question to the SCCA production page and Z31.com, but I would appreciate your thoughts as well.
As always, thanks for your help,
Bob Marcho