here's what you do. go to the auto parts store, and get a set of spark plug anti foulers. they are a brand called motormite, and come 2 in a package. make sure you get the same size/thread pitch as the sensors, which i think are 18mm. then, drill out the hole to about half inch. unscrew both post cat sensors, screw in the anti foulers, reinstall both sensors, and erase the codes. the codes will never come back. now go and drive the car, making sure it gets good a hot. if it dies, you may actually have clogged precats. also, you need to somehow check fuel pressure. you need to know what the pressure is when it dies. the fuel pump might be on its last legs. here's another curve. i used to work for a bmw dealer. there was a rash of fuel tanks imploding. what happened is that spiders were building webs in the air tubes to the fuel tank. when fuel is used, something has to displace the fuel, so some air is sucked back into the tank. if no air comes back in, the car will quit, because the fuel pump cannot pull the fuel and overcome the partial vacuum, too. you would be amazed at what the fuel tanks looked like. again, the best place to tap into the fuel line is back where the filter is. btw, you HAVE changed the fuel filter, right? because that is way back around step 1.

 

Yes, I changed out the fuel filter after it was first suggested.

The car started so I idled it this morning and took various OBD live reads on it as it warmed up to see if oxygen sensor voltages and / or short term or long term fuel trim would point to any conclusions. I still have no CEL but in a half an hour of run time (readings taken at idle 700 RPM)I recorded STFT readings of 3.1 to 0.0 on bank 1 and negative (-1.7) to positive 3.9 on bank 2. The LTFT on Bank 1 was always the same at 3.1 and on bank 2 it was always consisitent at 2.3. Bank 1 Ox sensor 1 voltages ranged .79 high to .46 while Bank 2 Ox sensor 1 ranged from .065 to .74. Bank 1 Ox sensor 2 voltages ranged from .785 low to .825 high then last reading before car died was .455. Bank 2 Ox sensor 2 voltages ranged between .075 to .14 then 2 readings before it died it went to .455 then .54 volts. In reading the fuel system 1 & 2 live readings it says "Closed loop" while running but "open loop" when it will not start.

Reading the I /M status monitors from the OBD II I now have "NO" have for CAtalyst, Evap system, O2 sensor, O2S heater, and EGR system. Previously (days ago) these all said "OK" .

After stalling this morning car will not start. I bought a fuel pressure gage and installed it with a "T" on the high pressure side of the fuel filter. I tried jumpering the FP and Grnd terminals in the data link connector terminals ( as suggested in the manual) to check pressure and saw none. I tired starting the car and did not see any pressure either. I did also notice that when i disconnected the fuel filter hoses there was not alot of pressure. I am assuming at this point that it is the fuel pump that is bad.

Am I missing anything here???

 

it sure looks like the fuel pump. they are not cheap, either. i have never done it, but i spoke to another person who did, and he said dropping the fuel tank is no big deal. there is a brand new fuel TANK on ebay, but they want 700 for it. dream on. i was very lucky to get a brand new genuine fuel pump on ebay for a killer price. since we have 2 99s', i dont mind getting something i think will die for a good price. i have seen some walbro pumps on ebay, dunno if i can recommend it, tho. if the pump is not quite correct, it can overrun the pressure regulator, and then you get more problems, and you will have to get the correct pump anyway.

 

I'm concerned that I don't hear any sound from the fuel pump relay or fuel pump resistor and relay located in the engine compartment and was wondering if this could be a problem.


The manual I have for A 1999 suggests listening to these and if you don't hear sound when the ignition is turned on to remove them and check for continuity between certain terminals. These are both supposedly found under the cruise actuator. I removed the cruise actuator and saw two relays but was not sure which was the main and which was the fuel pump. I never found the "fuel pump resistor and relay connector that had a 6 pin terminal. In any case, I heard no sound.

Does anyone else with a 2000 S hear these relays when the ignition is turned ?
Does anyone have any experience with the relays going bad and causing a fuel issue?

 

Update 3/08/2009-After sitting for a week with the fuel pressure gage still installed on the high pressure side of the fuel line the car started again this afternoon. Pressure was about at 35 PSI at idle, when reved the highest it went was 40 PSI. It ran this way for a good 20 minutes. Eventually it started to bounce 2 to 3 psi then gradually over about 10 seconds went to 10 PSI and stalled. At restart right away it barely idled and pressure finally went down to 5 psi and quit.


Fuel line pressure spec says 30 to 48 psi.
If I can get it to start again I will check pressure regulator vaccuum at the regulator vaccuum line.

 

it sure is looking like it is the fuel pump. even if the pump quits, pressure in the lines should stay above 35 for hours. sounds like when it gets hot, it quits, which is common in fuel pump failure. bummer that it is in the tank, double bummer that it is so expensive. watch out for the ebay pumps, while the price is attractive, you will have to reengineer it to make it fit. also, if the fuel pressure is not right, it may overrun the pressure regulator.
KJ14-13-35Z-423.77/292.34 from tasca mazda