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Dan, Technician
Category: Ford
Satisfied Customers: 24006
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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1993 ford f-150: engine cranks..fuel (35 psi) and spark at spark plugs

Resolved Question:

have a 1993 ford f-150 engine cranks but will not start. there is fuel (35 psi) and spark at spark plugs, however, truck will not start!!!!
Submitted: 8 years ago.
Category: Ford
Expert:  Dan replied 8 years ago.

What size engine? Did it not start after work was done to it or just happen all of a sudden? Thanks

Customer: replied 8 years ago.
engine size is a 5.0L and it happen all of a sudden. I had previously had the truck where it would not start for some time but would let truck sit for a 1/2 hr or so then it start right up.
Expert:  Dan replied 8 years ago.

It sounds like your fuel pump has failed, do a fuel pressure test, it should be 35-45 psi with key on engine off. If low replace filter and try again. If still low replace fuel pump. Let me know if you need anything .Thanks



Customer: replied 8 years ago.
fuel pumps , fuel filter, and fuel pump relay have been replaced. truck will idle if I spray throttle body cleaner through vaccuum port
Expert:  Dan replied 8 years ago.

Check for a 5 volt reference voltage to the Brown/White wire at the Throttle Position (TP) sensor while the problem is occurring. If reference voltage is low (less than 4.5 volts) while the problem is occurring, disconnect all sensors on the circuit, and if reference voltage is still low, check for a short to ground in the reference voltage circuit. If reference voltage is OK, check the TP sensor output voltage on the Gray/White wire. With the sensor connected, key on, and accelerator pedal not depressed, voltage should be less than 1.1 volts. If voltage is significantly higher, (over 3 volts) this can cause the PCM to go into "clear flood" mode, and shut off the injectors while cranking. If TP sensor voltage is high, check the Gray/Red wire at the TP sensor for a good ground, and if OK, replace the TP sensor. If reference voltage and TP sensor voltage are OK, the PCM has likely failed. Let me know what you find out or if you need anything else. Thanks

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Customer: replied 8 years ago.
sorry forgot to tell you but I also replaced the TPS but did not check for voltage referance. Will do that and get back at you
Expert:  Dan replied 8 years ago.
Sounds good, let me know what you find. You can also check reference voltage at pcm to make sure it is not wiring problem. Thanks