Vapour Canister Purge Valve/how does it work
07-24-2009, 07:36 PM
#16
Symptoms in your other thread seem to me to be a little too screwy for this to FPR failure alone. Any other signs of bad FPR - groaning fuel pump, longer hot starts...I guess you'll be measuring fuel pressure and leakdown soon so we'll know about the FPR
According to Clarks my symptoms are right in line with what I am experiencing regarding a failed FPR. Here is what they say about possible electrical interactions:
One of the most common failure modes for the FPR is to fail closed to the point that fuel rail pressure is extremely high. The high differential pressure across the injectors causes them to draw excessive current
That may explain the erratic drop in voltage and why the purge valve starts to sound off (it's actually vibrating). As soon as the car sits for an hour it's back to normal.
A failed FPR would be sweet. I'm going to install a guage permanently. It's coming in a week. The FPR should be here by Saturday.
According to Clarks my symptoms are right in line with what I am experiencing regarding a failed FPR. Here is what they say about possible electrical interactions:
One of the most common failure modes for the FPR is to fail closed to the point that fuel rail pressure is extremely high. The high differential pressure across the injectors causes them to draw excessive current
That may explain the erratic drop in voltage and why the purge valve starts to sound off (it's actually vibrating). As soon as the car sits for an hour it's back to normal.
A failed FPR would be sweet. I'm going to install a guage permanently. It's coming in a week. The FPR should be here by Saturday.
You know, you could just get any old fuel pressure meter and hose clamp it to the rail and have your answer tomorrow.
08-12-2009, 04:01 AM
#17
Instructor
Thread Starter
Just to conclude this thread for anyone that may have a similar problem, the culprit ended up to be a split in the sheathing of the negative battery cable very near where it bolts to the bell housing above the reference sensor.
This caused the vapour canister purge valve to make a racket, the DME fuel relay to make a racket, the fuel pressure to drop to 0 psi and back up, and the volts to drop down to 12.25 v. Now idling voltage is 13.8 v.
Only found the problem because my son noticed a spark coming from the reference sensor area when I was cranking it over. Previously I had checked that ground for tightness, but didn't/couldn't see the split. Whole thing totally sucked, but I'm now back in action. However, not after installing a new fuel pressure regulator, fuel pump, and a new toy; a pauertuning.com fuel pressure gauge.
This caused the vapour canister purge valve to make a racket, the DME fuel relay to make a racket, the fuel pressure to drop to 0 psi and back up, and the volts to drop down to 12.25 v. Now idling voltage is 13.8 v.
Only found the problem because my son noticed a spark coming from the reference sensor area when I was cranking it over. Previously I had checked that ground for tightness, but didn't/couldn't see the split. Whole thing totally sucked, but I'm now back in action. However, not after installing a new fuel pressure regulator, fuel pump, and a new toy; a pauertuning.com fuel pressure gauge.
