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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 36077
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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97 Cobra, KOEO Fuel Pump and fan runs constantly, no comms

Customer Question

97 Cobra, KOEO Fuel Pump and fan runs constantly, no comms with ECU. This is intermittent, Drives fine and then black smoke with above symptoms until car shuts off. CCRM checked out. Highly modified, 3 tunes via chip. Trying to figure out whether it needs a new ECU or the chip could be bad.
JA: How many miles are on the car? Have you been losing oil or coolant?
Customer: 32,xxx miles. Not losing oil or coolant.
JA: What is the model of your '97 Ford?
Customer: Mustang Cobra
JA: Are you fixing your Mustang yourself? What have you tried so far?
Customer: My Brother is a Master Tech at ex. Mazda and Lexus, now Land Rover/Jaguar. Tested CCRM, everything ohms out correctly.
JA: Anything else you want the mechanic to know before I connect you?
Customer: 97 Cobra, Built/Forged motor. Tuned at JMS, supercharged, intercooled, 552 to the wheels. Big fuel system , 42 lb injectors.
Submitted: 11 months ago.
Category: Ford
Expert:  Ron replied 11 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 11 months ago.

The most common cause for this type of problem is in most cases cause by a failing PCM (computer) if the scanner will not communicate and the fan and the fuel pump runs continuously . Before you consider replacing the PCM run the test steps in the link below while the problem is occurring to verify if in fact the PCM is at fault.

Customer: replied 11 months ago.
I drive the car about 8 miles a day on occasion. Since this has started it has never thrown a code. No Comms when the above issue is happening. The other random symptom has been that the car will die while driving, Check engine light shows solid, then the car come back to life, with a couple of fast bucks as if you are rapidly cycling the ignition switch. Wiggling the ignition switch has no effect when the above problems as happening.
Expert:  Ron replied 11 months ago.

Read my above post, as well as the test steps I provided. The most common cause is a failing PCM.

Customer: replied 11 months ago.
Will do and get back to you. Thanks.
Expert:  Ron replied 11 months ago.

Your very welcome and thank you as well.