95 4.9 F150 fuel issue
05-21-2017, 08:45 PM
#1
95 4.9 F150 fuel issue
Howdy everyone,
Been looking around at a lot of posts on this great forum and have found lots of help. I'm looking to get some insight on my recently purchased 95 straight six f150. First poster here so excuse my lacking in forum etiquette!
I bought it from a good friend who recently replaced both rear fuel pumps because they both weren't sending fuel levels.
it stumbled a bit at highway speeds and acts fuel deprived at startup. The front tank seems to run and start better than the rear but both give me issues.
Ive pulled the truck bed and removed nearly a pound of old pieces of rubber from the tanks and both tanks are very clean and spotless as well with cleaning and inspecting both socks. I did a full tune up on the truck in hopes to resolve the stumbling to no avail. After running the truck down the highway and swapping tanks mid drive, I've determined my issues are fuel related. New fuel filter didn't change the issue.
I tested fuel pressure and got about 40-45 from the front and about 35 from the rear. When increasing the revs, the gauge bounces and appears to drop about 10-15psi. Given these less than 4 month old fuel pumps are reading a minimum of 15psi lower, I'm assuming there's a chance the pumps are bad or cheap replacements (cheapest option from Rock Auto)
Does anyone think a new set of fuel pumps should be in the works or am I jumping the gun on this diagnosis?
Also noticed when the truck is cold, the diaphragm located on the air pump valve with a vacuum line run to it seems to make a weird duck call like sound.
Any thoughts or insight would be greatly appreciated! I'm in love with the pickup truck and I'm looking forward to getting her up and running strong.
Thanks!
Been looking around at a lot of posts on this great forum and have found lots of help. I'm looking to get some insight on my recently purchased 95 straight six f150. First poster here so excuse my lacking in forum etiquette!
I bought it from a good friend who recently replaced both rear fuel pumps because they both weren't sending fuel levels.
it stumbled a bit at highway speeds and acts fuel deprived at startup. The front tank seems to run and start better than the rear but both give me issues.
Ive pulled the truck bed and removed nearly a pound of old pieces of rubber from the tanks and both tanks are very clean and spotless as well with cleaning and inspecting both socks. I did a full tune up on the truck in hopes to resolve the stumbling to no avail. After running the truck down the highway and swapping tanks mid drive, I've determined my issues are fuel related. New fuel filter didn't change the issue.
I tested fuel pressure and got about 40-45 from the front and about 35 from the rear. When increasing the revs, the gauge bounces and appears to drop about 10-15psi. Given these less than 4 month old fuel pumps are reading a minimum of 15psi lower, I'm assuming there's a chance the pumps are bad or cheap replacements (cheapest option from Rock Auto)
Does anyone think a new set of fuel pumps should be in the works or am I jumping the gun on this diagnosis?
Also noticed when the truck is cold, the diaphragm located on the air pump valve with a vacuum line run to it seems to make a weird duck call like sound.
Any thoughts or insight would be greatly appreciated! I'm in love with the pickup truck and I'm looking forward to getting her up and running strong.
Thanks!
06-23-2017, 10:05 PM
#2
Senior Member
35 is way too low for the 4.9.
dropping psi when revved seems to be a weak or defective pump. yours may be clogged inside with what was in your tank. i wouldnt have much confidence in the cheapest option from rock auto. both tanks on mine jump 10 psi at idle if i rev it quickly. i have an adjustable regulator but i run about 45 psi. i i go lower there is reduced power.
dropping psi when revved seems to be a weak or defective pump. yours may be clogged inside with what was in your tank. i wouldnt have much confidence in the cheapest option from rock auto. both tanks on mine jump 10 psi at idle if i rev it quickly. i have an adjustable regulator but i run about 45 psi. i i go lower there is reduced power.
06-23-2017, 10:31 PM
#3
Hey, thanks for the reply! I pulled the bed and ran pressures on both tanks at the pumps. They never increased beyond 30psi. I did a warranty on both of the cheap fuel pumps through rock auto and they both put out 55psi and the truck runs like a charm now! I appreciate the feed back! Just got her buttoned up today.
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justintendo (06-27-2017)
