Hello all, I just got this 93 FD, and I got it for a great price because when I went to see it, it wouldn't start



Here's what happened, Last owner replaced the fan belt, and from there on it woudln't start



since then, he's replaced the fuel pump and ECU, and tested the relays, however, here are the ECU codes I pull up..



51 - Fuel Pump relay open or shorted

25 - Pressure regulator solenoid open or shorted

09 - Water temp sensor open or shorted



I can plainly see the broken water temp sensor wire

Mechanical fuel pressure guage shows about 35 PSI, so it would lead me to believe the fuel pump does work

tested the fuel pump relay (the one by the rad) and it's fine

tested the EGI relay, it's fine

tested for spark (I haven't personally yet, will tomorrow) apparently it's fine

Cranked engine over with fuel relay out and pedal to the floor for a while to clear a possible flood, no luck



Engine has 15000 kms on a reputable shop's rebuild, including new turbos and sounds healthy





Given the trouble codes, would any of those alone prevent the car from starting?



Also, apparently there are two fuel pump relays, a main relay, and a pump speed relay, which one is the one in front of the car, and where is the other?



It's raining out and I have to go to work in the morning, hopefully I will have some nice weather when I get home so I can try and give you more information



thanks in advance

Update, Got it started, it was flooded, but it stumbles at boost from around 4-5000 rpm and up, seems to boost to 9 or 10 PSI, and then when it stumbles it drops down a pound, kinda feels a little like fuel cut, but isn't that a little low for fuel cut?

That hesitation you are feeling is the turbo transition. That is normal, boost pattern is 10 - 9 -10. At 4500 RPMs the second turbo kicks in.



Be sure to fix that water temp sensor, your fuel maps and ignition maps rely on the water temp for the timing and fuel, and over heating an rx7 is the LAST thing you ever want to do. If you ever see the gauge starting to go hot you need to shut the car off ASAP and figure out whats wrong.



The pressure regulator solenoid is probably for the Hot start system, it causes lower pressure at the injector rail to assist in hot starting, many people end up having this disabled without problems



As for the fuel pump i've read numerous articles on the mazda fuel pump wiring, but im personally not familiar with how its all setup. If i recall correctly it uses some sort of resistor to keep the fuel pump from working so hard all the time. Its possible that code you have means your fuel pump is just bypassing the resistor system and recieving full voltage. But u might look into it more as im no expert in that area.