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Klaatu55
05-31-2017, 07:25 AM
Suspected bad "NEW" fuel pump. Have to prime pump for start,pressure drops to zero immediately upon key off.(suspect bad anti-backflow valve in pump assembly) Removed fuel pump from tank and and blew into output nozzle.There was no resistance. You think this is an indication of anti-backflow failure?

prerunner1982
05-31-2017, 09:56 AM
Certainly sounds logical to me.

4.3LXJ
05-31-2017, 10:23 AM
Pressure bleeding down is generally a bad back flow valve. Better take it back

Klaatu55
06-01-2017, 06:48 AM
Thank You. Your rapid response is appreciated.

Klaatu55
06-08-2017, 07:29 PM
Removed old fuel pump serviced it and put it back in. Fuel pressure went from 50 to 15 so that was a bust.Bit the bullet and bought new pump again. This one is working fine. After original pump stopped holding pressure when off, I got a replacement that also did the same thing, i returned for exchange and the exchanged one showed same symptoms so i figured it was a different problem. I troubleshot for a year. then decided to take pump apart to find anti back flow valve, I screwed pump pressure up and had to get a new one. New one works fine. It was defective replacements all the time.