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350matt, Engineer
Category: Mazda
Satisfied Customers: 21989
Experience:  Mechanical Engineer BEng Hons22 years experience
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Mazda MX-5 Miata: my 97 miata had a bad fuel pump which

Customer Question

hello my 97 miata had a bad fuel pump which I replaced
then it ran badly because of 1/4 tank of bad old gas
so I put 2 gallons of new gas in tank
miata ran perfectly then
idle good everything
so I decided to run the motor until most of the gas was burned up
but the car ran completely out of gas
I did not stop it in time
now there is a check engine light
but NO codes
after I by passed the fuel pump relay the gas pumped up
but car will not run
the fuel pump relay will not turn on for 3 sec when key is turned on
pump does run when cranking motor
now the car tries to fire but will no run
do you think the bad gas got to the O2 sensor or cat ?
there are NO codes
Submitted: 1 year ago.
Category: Mazda
Customer: replied 1 year ago.
the motor has bright blue spark on plugs
I tried to check fuel pressure
and or vent some gas, but I can hear the gas
flowing when I by pass the fuel pump relay
I believe there are 4 things that will kill
the fuel pump relay and I suspect the O2 sensor
or Cat, but there are NO codes when I check
I disconnected the battery but no change
Customer: replied 1 year ago.
this car was running perfectly
until I ran it completely out of gas
Customer: replied 1 year ago.
when i turn on the key i DO NOT hear the relay click on and i do not hear the fuel pump running when i crank the motor, then stop i do hear the fuel pump running then, and i do hear the relay click when it releases, motor tries to fire but will not run.
Expert:  350matt replied 1 year ago.
hello if the bad gas was very dirty then its possible that you've clogged up the fuel filter so the fuel reaching the rail isn't at sufficient pressure I'd say the next step is to get a pressure gauge onto the fuel rail and check that you have the correct 3.0Bar with the ignition on if its lower than this then replace the filterif this is OK then I'd next consider removing the injectors and have them flow tested as they too can be damaged by bad fuel