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Old 07-11-2018, 06:18 PM   #1
randywa
Registered User
 
Join Date: Nov 2012
Location: Republic, Mo.
Posts: 34
Question fuel pump quits on hot days

I may be overlooking something simple and obvious. The fuel pump on my 93 5.7 with auto has been quitting me, but only when on and off throttle a lot (hills and curves), the air temp is above 90, and running the a/c. It doesn't surge, stumble, or give any warning. It apparently doesn't even care how deep the ditch is or if the road has a shoulder to park on. It will always start after 30 minutes or so. Sometimes I can switch out the relay and it starts right away, but not always. Today I noticed it threw a blink code 15 - Engine coolant temp sensor error (low temp indicated). The code went away as soon as the motor started back up. I've pulled the bed and repaired the frame ground at the pump and cleaned all the grounds I can find. While the bed was off I fought thru a very fast idle problem, replace the knock sensor, tps, and coolant sensor. I've also chased more wire than a truck should have, just looking for bad spots. I've read all the threads I could find about fuel pumps and can't seem to figure it out. The people with the big butterfly nets are going to come take me away soon if this keeps up. Any and all help is greatly appreciated.
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