Service Engine soon light is on and engine turns over but will not start. I have self diagnosed this problem as the fuel pump but I am no mechanic, just listenng to the symptoms which are: Engine turns over but will not start unless accelerator pedal is continuously pressed while turning ignition (still does not start everytime). Can hear engine flooding as if gas is not getting through. I codes being returned are 0420, 0725, 0335, and 1273

Does the Check Engine or Service Engine Soon light come on? If so, there is an error code stored in your car's onboard computer. This code can be read and interpreted to provide a starting point for troubleshooting the problem. If no light, I would suspect bad gasoline (water or contaminants in fuel), loose wiring to the fuel pump, clogged fuel injectors or fuel filter, or an ignition electrical problem. Without additional information, it is very difficult to diagnose. If the Check Engine or Service Engine Soon light illuminated, take your car to a larger auto parts store and ask the counterperson to read the error code with their diagnostic scanner. They can interpret any code and advise what corrective action(s) may be required. Good luck.

There is a diagnostic procedure in the factory service repair manual for engine light lit ,no codes . Did you take it to ford dealer ? MIL - is referring to check engine , service engine soon etc...

• MIL always on when engine is running (no DTCs):
• MIL circuits

• For Focus, Mustang, Town Car, Continental, LS6/LS8, Escape, Windstar, F-150, Expedition and Navigator/Blackwood:
• Instrument Cluster, Section 413-01 of the Workshop Manual.
• All Others:
• GO to NB1

SERVICE ENGINE SOON indicator After the engine is started, the SERVICE ENGINE SOON indicator will prove out for a duration of three seconds. If the instrument cluster does not receive a message from the PCM within five seconds, the instrument cluster will illuminate the SERVICE ENGINE SOON indicator and log a diagnostic trouble code (DTC).

• An indicator is inoperative/always on - SERVICE ENGINE SOON

• Circuitry.
• Bulb.
• Instrument cluster.
• PCM.

• GO to Pinpoint Test P .

PINPOINT TEST P: AN INDICATOR IS INOPERATIVE/ALWAYS ON - SERVICE ENGINE SOON CONDITIONS DETAILS/RESULTS/ACTIONS P1 CARRY OUT THE INSTRUMENT CLUSTER SERVICE ENGINE SOON INDICATOR ACTIVE COMMAND Trigger the HEC active command MIL.

• Did the SERVICE ENGINE SOON indicator illuminate?

Yes REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual.

No INSTALL a new instrument cluster; REFER to Instrument Cluster . CLEAR the DTCs. REPEAT the self-test.

you have an issue with vehicle. could be anything from loose fuel cap to failed catalyst/ cat convertor, which is very expensive. you need to know the code number to get started with diagnosing issue. get your self a small hand hels scanner from your local friendly auto parts store and scan for codes. some part stores may even scan it for you for FREE. nissan dealer will charge you arm and your leg to look at it. our dealership charges 1hr of labor to look at "service engine soon" light and diagnose it no matter if it takes 5 minutes to figure out or 45 minutes you will pay 1hr of labor which could be around $100 big ones. so get a scanner which goes for around $60 and scan it your self and this way you have a scanner for future if the light comes on again for something else. that light can copme on for number of reasons.

Sounds like you need to find another mechanic. A dirty throttle wont cause a loss of power. Sounds like fuel pump to me, but you need to have a competent mechanic check the codes, and check the fuel pressure when its acting up.

You need to get the fault codes read to determine where the problem is that set the SES light. Autozone will scan your car at no charge. At some point you will need to get a mechanic involved to further diagnose the codes.

Which one is it?... Elantra?... or Santa Fe? In either case, the problem could be fuel pressure (fuel pump), then again, it might be crank sensor, coolant temp snsr, Intake Air Temp snsr. Have you scanned it for any trouble codes? Did the 'Check Engine' Light come ON? Whenever the 'CHECK ENGINE' (Service Engine Soon) light comes on, the ECU (Engine Control Unit) sets a Diagnostic Trouble Code (DTC). These codes identify the particular engine management system which caused the light to come on.
You'll need to use/find an OBDII (On-Board Diagnostic) Scanner to retrieve any code which have been stored in the ECU computer. Afterward, we might be able to help you DIAGNOSE the problem and perhaps eventually fix the problem.

Your vehicle’s computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and you should have the car diagnosed and repaired. The shop owner should be able to diagnose this for you and give you a solution.

Turn key ignition forward but do not start engine. Pump gas pedal fully 3 times then engine light will start flashing. Do not pump gas pedal short quick pumps. After light is flashing turn ignition off then start engine. The check engine will reset it's self.

A fault code reader would be a huge help in diagnosing general problems. It plugs in under left side dash and gives specific failure codes (this is what mechanics use).
You can buy an OBD-I code reader (for cars before 96) online for $79.95 or a OBD-II which reads all cars from 1996 on. It will also reset faults or engine trouble lights.

You may want to check your fuel pressure with a gauge.

or do a simple Fuel pump test:

1. remove the gas cap.
2. have one person listen in the gas tank at the gas cap opening.
3. the other person turns the ignition switch to the ON position ONLY (so the dash lights come on.) Do NOT crank or start up the engine.
4. As soon as the ignition key is turned to the ON position, The person at the gas tank should hear the fuel pump run for TWO SECONDS and then it should STOP.

If it does NOT run for the 2 seconds every time, the fault is either the fuel pump or fuel pump relay