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Tim West
Tim West, ASE Certified Technician
Category: Ford
Satisfied Customers: 4638
Experience:  ASE Certified Service manager of Firestone
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1994 ford ranger: wont start..replaced the fuel pump and fuel filter.

Customer Question

I have a 1994 ford ranger that won't won't start when hot. Does fine when its cold. replaced the fuel pump and fuel filter.
could my starter be going out?
Replace spark plugs and wires. but since I did that it now is cutting out. i check gap twice.

This morning it didn't start when the engine was cold for the first time.
Submitted: 7 years ago.
Category: Ford
Expert:  Tim West replied 7 years ago.
Thanks for visiting Just Answer,
Is there a check engine light on?
When the problem is and isn't present compare spark from the wires. Using the engine as a ground check for spark to jump from the end of the wire to the ground. Compare to when the problem is present and not present. See if there is a noticabl difference in spark.
If spark is weak, you could have a bad coil. Also what kind of plugs did you use?

NExt, do you have access to a fuel pressure gauge? If possible check the fuel pressure and verify fuel pressure holds. 30-45psi is specification. Verify the fuel pressure isn't high or does not bleed off. This is important. If fuel pressure is too high, replace the fuel pressure reuglator for letting too much gas go to the injectors. This can cause a hard start. Also, if fuel pressure does not hold pressure, the regulator could be bad. You can also remove the return line from the fuel pressure regulator and smell for raw fuel.

If ok, let's move on to the PCM and some possible sensor issues.

First, unplug the mass air flow sensor and see if the problem goes away. The mass air flow sensor is the one located on the hose coming from the air filter box.
If no change, plug back it.

Next the coolant temp sensor, the coolant temp sensor and Mass air flow sensors both can affect how much fuel the pcm thinks the vehicle needs, so both can cause a rich condition. graphic

(Ohms) Max.
(Ohms) Temp F Temp C
31700 42900 68 20
13650 18650 104 40
6500 8900 140 60
3240 4440 176 80
1770 2370 212 100
980 1380 248 115
Customer: replied 7 years ago.
No check engine light on. I use motorcraft spark plugs And new wires but only after it started having problems.
fuel pressure on old pump i replace was 20.
I have already unplug the mass air flow sensor there was no change
I will check the fuel pressure reuglator like you said
and I will check the coolant temp sensor,
thank you
Expert:  Tim West replied 7 years ago.
Thanks, XXXXX XXXXX to me let me know how it goes. Thank you.
Customer: replied 7 years ago.
I replace the ingintion coil both of them
and the fuel pressure regulator
the fuel pump the fuel fiiter
the spark plugs and wire.
and the coolant temp sensor.
it still won't start hot or cold.
it trys to start but won't
is there anything else i should replace?