I've had a rich idle condition show up which figures now that I've got everything working right.

SYMPTOMS:
The car is easy to flood when starting. Fuel milage is so so. Idle hunts. I had to set the variable resistor at full LEAN and the air bypass screw all the way out to get best idle and it didn't used to need that. Scopeing the fresh and working O2 sensor's signal at idle shows a constant rich reading that took several vacuum leaks and clamping the fuel supply hose to lean out. Which by the way resulted in a better and faster idle speed. The Hydrocarbon fumes coming from the uncatted exhaust will burn your eyes and respitory tract. The engine runs better on the road with the air flow meter door clockspring set one notch leaner.

DIAGNOSIS:
But I'm getting good at this car I guess because I eventually figured out why. My fuel pressure is significantly higher than specs. I checked the usual suspects: igniton system, timing, O2, water temp. sensor, AFM circuts, throttle position sensor, vacuum lines and valves, etc. add nausia. I finally broke down and put the fuel pressure guage back on. Fuel pressure was always fine in the past so I checked it last after giving up. But now it's not, hey great something else to spend money on.

Running at operating temperature this is what I found.
Max pressure spec (vacuum line off regulator like WOT): 37 PSI
My current reading (vacuum line off regulator like WOT): 46.5 PSI

Standard value (vacuum line on regulator like normal idle): 28.4 PSI
My current reading (vacuum line on regulator like normal idle): 38.5 PSI

I've double checked the lines and they are routed correctly. I did find my AFM's closed vane switch was shorted, this causes my fuel pump to run any time the key is on. This is new and probably as a result of my last trip into the AFM to reset the clockspring. A tool slipped and I whacked it but it looked fine. The condition was there prior and it shouldn't effect the running pressure one bit so I don't believe it's relavent but I mention just in case someone else knows better.

QUESTIONS:
Is there anything else I should check before just replacing the reguator?

I got regulator prices from $80 at Autozoo (GP-Sorenson) to $160 at Napa (Beck Arnley), should I shop price or quality? Is anyones brand known to be crap?

My pulsation dampener doesn't leak, but hey it's old enough to buy beer, should I fork up the $140 MazdaTrix wants for a new one? Are they as trouble prone as the FC units? Does anyone else have a better price? I can't find anyone else but the dealer selling them.

Thanks for any help guys, and I searched like hell.
Vernon

 

Bump due to the SE gurus being off for the holiday. I didn't think a post could fall off page one without an answer here.

Vernon

 

I had a similar problem with my regulator. The fuel pressure was a bit high like yours. I ended up getting the Autozone one. The pressure is now much closer to specs, but is a bit higher still (like 30psi when it is supposed to be 28psi). That could be error in the fuel pressure tester as well.

Anyway, the fuel flow increases as the squareroot of pressure, so you are running sqrt(38.5/28.4)=1.16 (16% rich). I believe GavinJuice on here once had his reg totally stuck and was running a full 65psi to the injectors. I think the regulators just get gunked up over time and stop working well.

I would probably do the PD while you have it apart. I know it is expensive, but if it fails, you can burn down your car. There is a mod to replace the PD with a banjo bolt. That eliminates the possibility of failure, but is probably harder on the fuel pump and injectors.

 

Thanks, I guess that's next on the list.

Vernon

 

Vernon. Wanting to flood while starting is the AFM. You have stated that the Fuel pump is running when you turn the key on. The fuel pump is not supposed to energize until you start to crank. What you are doing is spraying fuel into the chambers before start up, this is flooding the engine. It is an inherent problem on the Se that the AFM gets out of adjustment over time.
You need to fix the AFM problem first or replace the AFM. Also when was the last time the injectors were tested and cleaned?
Alittle info on the Se O'2, if i remember correctly, the O'2 does not function until you are in 5th gear.
If after you fix your AFM you believe you need a fuel regulator, i have one.
Remember after you correct everything you will need to go back in and reset everything.

 

i don't think the injectors fire when you prop open the door, only the fuel pump runs.

 

They don't fire but residual fuel enters the chambers due to fuel pressure.