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Ask Ron Your Own Question
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 34776
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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The engine will not start if i let it set for several hours,

Customer Question

the engine will not start if i let it set for several hours, pulled the DTC 542, tested the relay, has 12 vdc ignition pin 30 and 12 vdc pin 85 i think, the side pin to energize the relay, with a fuel gauge it builds 40 psig with just the key on, and 33 running, now and again the engine light will come on and the will not take fuel, lost
JA: Do you have a backup key? Maybe the emergency kind that fits in your wallet?
Customer: i used the new key that i use to make all my other key, ( the one i got when i bought the truck new
JA: What is the model of your '12 Ford?
Customer: 1995 bronco 5.8 eddie bower
JA: Are you fixing your Bronco yourself? What have you tried so far?
Customer: yes, im a diesel mech, gas engine are a bit differant cleaned the powers and ground at the battery and gound at the fender by the battery, replaced the fuel filter
JA: Anything else you want the mechanic to know before I connect you?
Customer: after it start in the morning runs bad, then clears up and repets
Submitted: 7 months ago.
Category: Ford
Expert:  Ron replied 7 months ago.

Hello. My name is ***** ***** I am happy to assist you today. Give me just a moment to review your post, and I'll be right back with the help you need.

Expert:  Ron replied 7 months ago.

The code 542 is indicating that the Powertrain Control Module (PCM) is not detecting a ground through the fuel pump monitor circuit. When it will not start do you here the fuel pump cycle on when you turn the key on?

Customer: replied 7 months ago.
i here a buzzing, hopefully its the pump, i didn't put the guage on the rail for presure, so not really sure
Customer: replied 7 months ago.
if you let the ignition stay on for about 5 minutes it will start
Expert:  Ron replied 7 months ago.

Okay I would tart with checking the orange wire at the fuel pump to make sure your getting a good ground when it dose not want to start. If you have power and ground (key on engine cranking) and it still dose not want to start then you may be dealing with bad windings in the fuel pump. Start with checking the power and ground at the pump and if they look then you going to need to run the full pinpoint test steps for this code. I have enclosed them in the link below. Have a look and post back if you have more questions and or need more information.

Customer: replied 7 months ago.
lol, the fuel tank is just above a skid plate, so it might take me a few minutes to access the pump
Expert:  Ron replied 7 months ago.

Yes I know that and its a real pain to access for sure. There is no rush. I have enclosed the complete systems wiring diagrams for testing reference in the link as well.

Customer: replied 7 months ago.
if you could, give me what the acronyms mean and the placement of the modules
Expert:  Ron replied 7 months ago.

Your Bronco uses a fuel pump relay located next to the PCM (computer) relay in the under hood fuse panel . The PCM controls the relay through a ground switch signal from it to the relay. Which other acronyms are you not familiar with?

Customer: replied 7 months ago.
n SIG RTN circuit in the Data Link Connector, this is the ATA connector, or the house shaped one, lol
Customer: replied 7 months ago.
where do i get a break out box?
Expert:  Ron replied 7 months ago.

SIS RTN stands for signal return. The data link connector is located out under the hood in the drivers side corner near the hood hinge. If you do not have a break out box and can not borrow one then your going to need to back probe the wires instead.

Customer: replied 7 months ago.
tools for back probing i do have
Expert:  Ron replied 7 months ago.

That will work. Hardly anyone besides the dealer have a break out box these days.