Symptoms of bad fuel pressure regulator?
06-19-2016, 08:16 PM
#1
TECH Resident
Thread Starter
iTrader: (7)
Join Date: Apr 2005
Location: Houston, TX
Posts: 762
Likes: 0
Received 0 Likes
on
0 Posts
Symptoms of bad fuel pressure regulator? 0 psi fuel pressure when car is off.
Turned ignition on, psi went to 40 and then immediately back down to 10, then slowly down to zero. Did this numerous times.
Took 1.5-2 seconds to start. Psi went to 56 psi and held there. Took rpms slowly up to 4k, psi held steady.
Turned car off, psi immediately went back down to 10, then slowly to zero.
Are these the symptoms of a bad regulator? Fuel pump is a brand new Racetronix unit. Fuel filter is also brand new.
Turned ignition on, psi went to 40 and then immediately back down to 10, then slowly down to zero. Did this numerous times.
Took 1.5-2 seconds to start. Psi went to 56 psi and held there. Took rpms slowly up to 4k, psi held steady.
Turned car off, psi immediately went back down to 10, then slowly to zero.
Are these the symptoms of a bad regulator? Fuel pump is a brand new Racetronix unit. Fuel filter is also brand new.
06-19-2016, 10:03 PM
#2
On The Tree
Join Date: Jun 2016
Location: Central MN
Posts: 166
Likes: 0
Received 0 Likes
on
0 Posts
Very well could be a bad regulator, a nice way to tell is after the engines been off for 5 minutes or so pull the vacuum line off the regulator and see if there is fuel in it, if so the regulator is shot.
06-21-2016, 08:22 AM
#7
On The Tree
Join Date: Jun 2016
Location: Central MN
Posts: 166
Likes: 0
Received 0 Likes
on
0 Posts
As Supra said I believe your FPR is part of the fuel pump, but you do have a fuel pressure damper that is built very much like a regulator with a rubber diaphragm but I don't know where the dampers are located.
Trending Topics
06-23-2016, 07:29 AM
#9
It's not the regulator, as mentioned on an LS1 fbody it's in the tank at the fuel pump bucket, no vacuum line - what 67lark is referring to is a return line setup with the reg at the fuel rail, which is not applicable to these cars.
Since this is a Racetronix, 2 possibilities. First I noticed you are seeing 56 psi, which is a bit low, these tend to run a bit higher pressure than stock due to the higher volume and limitations of that in tank regulator, usually 62-64 psi. So it sounds like you're short on pressure, which could be the plastic flex tubing from the pump outlet could either have a small leak in it, or the clamps you had to tighten to hold it on could be loose. That would also bleed off the pressure in the line and cause your hard start and missing pressure.
Alternatively it could be a bad check valve on the pump itself, which will cause the pressure to bleed off quickly after shut down.
Since this is a Racetronix, 2 possibilities. First I noticed you are seeing 56 psi, which is a bit low, these tend to run a bit higher pressure than stock due to the higher volume and limitations of that in tank regulator, usually 62-64 psi. So it sounds like you're short on pressure, which could be the plastic flex tubing from the pump outlet could either have a small leak in it, or the clamps you had to tighten to hold it on could be loose. That would also bleed off the pressure in the line and cause your hard start and missing pressure.
Alternatively it could be a bad check valve on the pump itself, which will cause the pressure to bleed off quickly after shut down.