fuel pressure dropping
Thread Starter
Burning Brakes
Joined: Feb 2012
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From: Palm City Fl
fuel pressure dropping
I have noticed over the last couple months that my fuel pressure has been dropping by about a pound every few weeks. I used to run a steady 50#s, even under full boost. Now it is only at 47 and will drop to 45 under heavy acceleration, then recover to 47#. I just replaced the filter/regulator, hoping that was the problem, it wasn't. I don't know if the sender to my gauge is going bad, the gauge is losing its calibration or if this is a true reading and my pump is on its way out. I am running a boost-a-pump with original pump. My concern is, am I running lean due to the pressure drop? If I have to replace the pump I would like to do away with the BAP. Anyone else had this problem? Any ideas? Thanks for the help. 
Last edited by Lt. Dan M.; Nov 10, 2014 at 01:20 PM.
Drifting
Joined: Sep 2009
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From: cinnaminson n.j.
St. Jude Donor '14
you could be heading for a meltdown. I suggest you connect a reliable mechanical fp test gauge and see what it reads.Do you have a wideband afr gauge in the car already? What does it read?
Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
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From: Palm City Fl
I do not have a wideband afr, so wish I did. Just such a HUGE job to pull the headers to have bungs welded in, not to mention they are ceramic coated. Anyone know if fuel pressure is an input to the OBDll port? I am thinking of installing an aeroforce intercepter gauge that reads out all inputs to the port. I just don't know how to find what is input to the port??? For now I guess I will be looking for a mechanical gauge to hook up to the fuel rail.
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it depends how the car was tuned, if it was tuned with the pressure drop taken into account you may be fine but if not you could toast your motor... you really should have a wideband in the car... do you also have a hotwire kit?... alternator/battery in good shape?... you could be losing voltage to the pump and that could cause a decrease in pressure
Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
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From: Palm City Fl
I bought a fuel pressure tester from Harbor Freight yesterday, $16 and change. Like some of the people who reviewed this tool on the website, it didn't open the schrader valve. No big deal, I will just take the valve out. I brought the gauge to work and ran a calibration on the guage. It was only off by 1/2 a pound all the way to 70#. I didn't take it up to the 100# it is rated for, as I won't be using for that pressure. I am VERY inpresed with the accuracy and repeatability of this guage. I have seen new guages we pay hundreds of dollars for that are not near as good. Just thought I would pass this along. Hopefully, tomorrow I will get the chance to hook it up and see what the fuel pressure is doing. I will also check voltage. I would think with a BAP, if it was a voltage problem, that under boost with the BAP working it would show a pressure increase but, it doesn't. I will post results. Thanks for the help. 
Le Mans Master
Joined: Apr 2001
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From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
What year corvette, and what fuel system mods do you have? Did the problem occur after you changed the filter or before? It could just be the pump going out. How many miles are on the car?
Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
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From: Palm City Fl
It is an 02 Z06, stock fuel system except for BAP, with 40K on the car. Had TVS2300 installed just over 2 years ago. Never had a fuel pressure gauge till then. It has been a steady 50# since the install. I changed the filter after the problem, hoping to solve the problem. Just surprised at the pump going out with so few miles on it.
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stock fuel pump, that is probably the culprit especially if it's the original pump it is probably tired... but I would check all the other things just to make sure... check the bap to make sure it's working... is the bap wire looped or are you using the controller?... if you don't have a fuel pump hotwire harness I highly suggest you get one
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Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
Likes: 2
From: Palm City Fl
stock fuel pump, that is probably the culprit especially if it's the original pump it is probably tired... but I would check all the other things just to make sure... check the bap to make sure it's working... is the bap wire looped or are you using the controller?... if you don't have a fuel pump hotwire harness I highly suggest you get one
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basically it's a heavy gauge wire that is run straight off the alternator and it ties into your stock fuel pump wiring to make sure you get proper voltage to the pump... you can even get one that will plug and play with a bap... I got mine from racetronix and they are fairly cheap, well built, and worth the money in my opinion... if you find that your pump is bad just get the walbro255 from racetronix as well... they come already assembled in the bucket and have upgraded wiring, I think the whole kit with a fuel pump and hotwire harness is around $250
Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
Likes: 2
From: Palm City Fl
basically it's a heavy gauge wire that is run straight off the alternator and it ties into your stock fuel pump wiring to make sure you get proper voltage to the pump... you can even get one that will plug and play with a bap... I got mine from racetronix and they are fairly cheap, well built, and worth the money in my opinion... if you find that your pump is bad just get the walbro255 from racetronix as well... they come already assembled in the bucket and have upgraded wiring, I think the whole kit with a fuel pump and hotwire harness is around $250
That is most likely what I will do if I have to change the pump.
Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
Likes: 2
From: Palm City Fl
Good news, the fuel pressure gauge or sender is bad. The gauge has never read right since the installer sold it to me and installed it. I should have figured it would be crap, just like most of the install was. I am however glad my pump is fine and putting out a healthy 58# of fuel pressure. Now to figure out what to replace it with... Many thanks to all who commented on my post. I say again, Corvette Forum and specifically it's member base, are the most valuable tool I could ever have.
Burning Brakes
Joined: Oct 2013
Posts: 859
Likes: 1
Good news, the fuel pressure gauge or sender is bad. The gauge has never read right since the installer sold it to me and installed it. I should have figured it would be crap, just like most of the install was. I am however glad my pump is fine and putting out a healthy 58# of fuel pressure. Now to figure out what to replace it with... Many thanks to all who commented on my post. I say again, Corvette Forum and specifically it's member base, are the most valuable tool I could ever have.
Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
Likes: 2
From: Palm City Fl
Mine is an auto meter. I can't bad mouth them as the gauge was not new when I got it. I just expected more from an LPE dealer shop than to sell a gauge package that was 8# off to begin with. Live and learn, I do my own work now. I can't find where any of the manufacturers state accuracy of their gauges. I think I would like to try the aeroforce intercepter but, by the time I add the fuel pressure sender it will be around $300. I don't know much about them but, I love that it reads all info available at the OBDll port. I'm in no rush now that I know I'm not melting my pistons 
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I use speedhut revolution gauges and like them so far, you can also customize them to your liking... defi makes some really nice ones too for a little more money
Le Mans Master
Joined: Apr 2001
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From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
The racetronix stuff is good. I've had my harness and pump installed since 2007. I did have a bad pump at first but that was easy to figure out. As for gauges i like Dynotune. They have some good stuff and prices are not bad. I've run their fnp gauge since the pump install and no issues.
Thread Starter
Burning Brakes
Joined: Feb 2012
Posts: 901
Likes: 2
From: Palm City Fl