Help- Fuel pressure drop but no thrown codes
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From: Rochester NY
Help- Fuel pressure drop but no thrown codes
Any help or input is appreciated. I was driving home from my office today and while making a left hand turn the car felt like it was in reduced power mode. Being I was in traffic I got nervous gave it a little gas and she just took off normal. I was like what the :cuss . So as I went up the street further made another left to come home and it did it again. This time I glanced up at my fuel pressure gauge and noticed it was dipping. It was odd because it looked like it was moving with my turn signal for a second but it could have been coincidence. Then it would drop. I was about to shut her down when it jumped back up to 60 and got me home without a problem.
I then ran the IPC codes and got nothing. I had one history code from when my battery died I believe U1064H but that was it.
What am I looking at here? Fuel pump going bad with 6k on the odo?
thanks
[Modified by Rookiedyn, 12:27 PM 7/20/2003]
[Modified by Rookiedyn, 12:28 PM 7/20/2003]
I then ran the IPC codes and got nothing. I had one history code from when my battery died I believe U1064H but that was it.
What am I looking at here? Fuel pump going bad with 6k on the odo?
thanks
[Modified by Rookiedyn, 12:27 PM 7/20/2003]
[Modified by Rookiedyn, 12:28 PM 7/20/2003]
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
I should add.. The fuel gauge was between 1/4 and 1/2 when I left my office and 5 miles later its at less then 1/4. Is it possible that the gauge is not accurate and I am almost out of gas? Wishful thinking that it would be that simple. The Fuel range says 59 miles.
Again any help is appreciated I am scouring with the search function now but not finding much info.
Again any help is appreciated I am scouring with the search function now but not finding much info.
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St. Jude Donor '08
Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
Since there a 2 tanks and you said you were at 1/4 tank left, that doesn't leave that much in each tank. Additionally, as you go around a corner, the gas sloshes to one side. The SC also draws the fuel much faster then a normally asperated car. Add these all up and you get fuel starvation when the tank is low.
Keep on eye on your fuel pressure just in case. Heat also adversly affects pressure.
JB
Keep on eye on your fuel pressure just in case. Heat also adversly affects pressure.
JB
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes (jbsblownc5)
thanks JB. Im going to fill a 5 gallon can and bring it back before taking it out again. I have company so I haven't been able to try it yet. Its nagging at me so I snuck away to check to see if anyone here replied. I hope thats all it is. Thanks :cheers:
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St. Jude Donor '03-'04
Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
Low fuel can DEFINITELY lower fuel pressure!!!!!!!!! And being sporadic or erratic the way you explain....could mean you simply had low fuel.
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes (Buckmaster)
Hey Buckmaster how have you been? :)
Yes I just went to the gas station verrry slow and let the tank fill until the pump kicked off once (didnt top it off) and it took 16.3 gallons. Out of an 18.5 gallon tank I imagine that was my problem? Funny thing is the gauge said around 1/4. I will know not to trust that. I am going to take it for another ride now. I worked her a bit on the way home from the gas station but I am not 100% satisfied yet (im **** when worrying about something with the vette ).
Thanks for the help guys. Buckmaster are you still in WNY? We need to get together this year before the snow flys.
Yes I just went to the gas station verrry slow and let the tank fill until the pump kicked off once (didnt top it off) and it took 16.3 gallons. Out of an 18.5 gallon tank I imagine that was my problem? Funny thing is the gauge said around 1/4. I will know not to trust that. I am going to take it for another ride now. I worked her a bit on the way home from the gas station but I am not 100% satisfied yet (im **** when worrying about something with the vette ).
Thanks for the help guys. Buckmaster are you still in WNY? We need to get together this year before the snow flys.
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
I just took it for another ride and its still doing it :cuss Stumbling a bit and I can see the FP drop and jump back up very erradic. I ran the codes again and the RO-RFA U1064 H came back but I don't think that is related is it?
Any more input? Where should I look next?
I appreciate it.
Any more input? Where should I look next?
I appreciate it.
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St. Jude Donor '03-'04
Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
Yep still here. :D Damn I thought that would have sloved it :( RFA codes are remote control functions and 1064 is loss of communication. I wouldn't think related at all.
Damn....I wonder if there was some air in the fuel lines after the re-fill? It's a stretch but who knows. Did you do a check of ALL connections under the hood? MAF, air filter, etc? ALL the ATI connections? Should throw a code if unmetered air is in there but ya never know with these cars. Damn, that is frustrating.
Damn....I wonder if there was some air in the fuel lines after the re-fill? It's a stretch but who knows. Did you do a check of ALL connections under the hood? MAF, air filter, etc? ALL the ATI connections? Should throw a code if unmetered air is in there but ya never know with these cars. Damn, that is frustrating.
Hey Buckmaster how have you been? :)
Yes I just went to the gas station verrry slow and let the tank fill until the pump kicked off once (didnt top it off) and it took 16.3 gallons. Out of an 18.5 gallon tank I imagine that was my problem? Funny thing is the gauge said around 1/4. I will know not to trust that. I am going to take it for another ride now. I worked her a bit on the way home from the gas station but I am not 100% satisfied yet (im **** when worrying about something with the vette ).
Thanks for the help guys. Buckmaster are you still in WNY? We need to get together this year before the snow flys.
Yes I just went to the gas station verrry slow and let the tank fill until the pump kicked off once (didnt top it off) and it took 16.3 gallons. Out of an 18.5 gallon tank I imagine that was my problem? Funny thing is the gauge said around 1/4. I will know not to trust that. I am going to take it for another ride now. I worked her a bit on the way home from the gas station but I am not 100% satisfied yet (im **** when worrying about something with the vette ).
Thanks for the help guys. Buckmaster are you still in WNY? We need to get together this year before the snow flys.
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Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
A voltage drop will affect the fuel pump and case it to drop off in pressure. Check your wirring to the fuel pump. Did your fuel pump whine at all?
That may not have been your imagination on the blinker, may be a short.
Good luck,
JB
That may not have been your imagination on the blinker, may be a short.
Good luck,
JB
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From: Milpitas Ca
Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
Are you still running the stock fuel pump? If so, change to a Racetronics. BTW, these cars are known for faulty fuel sensors in either tank. If you have one going out, change both. That is why your fuel gauge is off. I just had both my fuel sensors changed. The gauge went from 1/2 full to empty.
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes (jbkvette)
Thanks for the additional input guys. I checked all my MAF wiring, battery etc. and didnt see a problem. I did clear that code and it came right back again but like Buckmaster said it shouldn't be related.
Anyway where is the fuel pump wiring that JB mentioned? Keep in mind Im a hacker type weekend mechanic :lol: I dont dare dig into anything to deep on this thing but I do want to avoid the dealer if I can.
I did not hear the pump whining but after taking it for another ride and watching the fuel pressure gauge real close the darn thing "flickers" at times. between 60-50 psi.. sometimes even more of a drop. Very fast. When it goes from 60-10 thats when the car obviously stumbles but recovers very quickly.
I dont have a problem having the stock pump replaced as jbkvette mentioned. I am sure its a good upgrade being I am on the edge with my RWHP for the stock system but I hate to replace it and still have the problem.
Not very mechanicaly inclined and irritated.. help! :)
Anyway where is the fuel pump wiring that JB mentioned? Keep in mind Im a hacker type weekend mechanic :lol: I dont dare dig into anything to deep on this thing but I do want to avoid the dealer if I can.
I did not hear the pump whining but after taking it for another ride and watching the fuel pressure gauge real close the darn thing "flickers" at times. between 60-50 psi.. sometimes even more of a drop. Very fast. When it goes from 60-10 thats when the car obviously stumbles but recovers very quickly.
I dont have a problem having the stock pump replaced as jbkvette mentioned. I am sure its a good upgrade being I am on the edge with my RWHP for the stock system but I hate to replace it and still have the problem.
Not very mechanicaly inclined and irritated.. help! :)
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Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
I would be frustrated as hell. SO, when you did the ATI....Bob Kennedy didn't replace the fuel pump? You have upgraded injectors, right? You are right, I bet you are at the upper limits of the stock pump IMO. Damn, I wish I had some solution for ya. I wonder if you have a bad injector? Too bad Kennedy's is 100 miles away for ya. Have you called Bob for possibly his input?
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes (Buckmaster)
*Bump* for any opinions from the weekday posters.
Buckmaster.. I dropped Bob an email late last nite. I am sure he will get back to me soon. The injectors were replaced but the pump remained stock with that package. I imagine a bad injector could be the culprit as well as you mentioned. It could be so many things that is what is so frustrating.
Without codes the dealer would have some tech driving the thing around trying to recreate the problem etc. Not something I feel like doing just yet. I will wait on Bobs response for now.
In the meantime if anyone else has any input as well I would appreciate it.
thanks
Buckmaster.. I dropped Bob an email late last nite. I am sure he will get back to me soon. The injectors were replaced but the pump remained stock with that package. I imagine a bad injector could be the culprit as well as you mentioned. It could be so many things that is what is so frustrating.
Without codes the dealer would have some tech driving the thing around trying to recreate the problem etc. Not something I feel like doing just yet. I will wait on Bobs response for now.
In the meantime if anyone else has any input as well I would appreciate it.
thanks
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From: Tx
Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
It could be a clogged fuel filter. They cost about $50 (pretty easy to change but you get a little messy with the gas spilling out).
I would then try upgrading the power wiring to the pump (it is not adequate stock anyway). The Racetronix pump comes with an upgraded harness, but you could build your own without spending much. Just get yourself some good 10 gauge copper wire and a 40 amp relay. Run the wire from the alternator output or the + batt terminal to the input side of the relay. Then wire the normal power connector to the coil side of the relay. Then the ouput side of the relay to the pump connector where the old power wire was. You will most likely see an increase in fuel pressure and stability with just this change.
Only attempt this if you generally know you way around under the car. Just get the Racetronix upgrade installed by a professional if you are not a DIY guy.
I would then try upgrading the power wiring to the pump (it is not adequate stock anyway). The Racetronix pump comes with an upgraded harness, but you could build your own without spending much. Just get yourself some good 10 gauge copper wire and a 40 amp relay. Run the wire from the alternator output or the + batt terminal to the input side of the relay. Then wire the normal power connector to the coil side of the relay. Then the ouput side of the relay to the pump connector where the old power wire was. You will most likely see an increase in fuel pressure and stability with just this change.
Only attempt this if you generally know you way around under the car. Just get the Racetronix upgrade installed by a professional if you are not a DIY guy.
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Re: Help- Fuel pressure drop but no thrown codes (Rookiedyn)
The fuel pump runs on electicity and you only have so much to go around... power drain will effect the fuel pumps ability to keep pressure at its peak. I have noticed this on my car as well... Maybe the cure would be to have our alternators rebuilt for more power output?? On second thought, that may cause massive computer problems...
vetterdstr :cheers:
vetterdstr :cheers:
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From: Fairfax Va
Re: Help- Fuel pressure drop but no thrown codes (vetterdstr)
I've got a similar problem to you with my '98 6 sp coupe. I've posted about this as well. The car will crank, but not run. I've changed the fuel filter and it still won't run. The pressure at the fuel rail is 12 psi, which is way too low. However, sometimes the pressure will go to 60 psi, where it should be and the car will start, but if I stop the car and try to start it again, the fuel rail pressure is once again 12 psi or so. I'm going to try and pull the fuel pump tomorrow and we'll see.
I had similar symptoms to you for a few days and then one day it just wouldn't run. I bet we have a similar problem. Please let me know if you solve it, I'll do the same for you.
I think maybe it's a fuel pump going dead. Which might explain the how the fuel pressure sometimes is at the right level. Anyone know the symptoms of a dying fuel pump?
I had similar symptoms to you for a few days and then one day it just wouldn't run. I bet we have a similar problem. Please let me know if you solve it, I'll do the same for you.
I think maybe it's a fuel pump going dead. Which might explain the how the fuel pressure sometimes is at the right level. Anyone know the symptoms of a dying fuel pump?
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes (sffish)
I've got a similar problem to you with my '98 6 sp coupe. I've posted about this as well. The car will crank, but not run. I've changed the fuel filter and it still won't run. The pressure at the fuel rail is 12 psi, which is way too low. However, sometimes the pressure will go to 60 psi, where it should be and the car will start, but if I stop the car and try to start it again, the fuel rail pressure is once again 12 psi or so. I'm going to try and pull the fuel pump tomorrow and we'll see.
I had similar symptoms to you for a few days and then one day it just wouldn't run. I bet we have a similar problem. Please let me know if you solve it, I'll do the same for you.
I think maybe it's a fuel pump going dead. Which might explain the how the fuel pressure sometimes is at the right level. Anyone know the symptoms of a dying fuel pump?
I had similar symptoms to you for a few days and then one day it just wouldn't run. I bet we have a similar problem. Please let me know if you solve it, I'll do the same for you.
I think maybe it's a fuel pump going dead. Which might explain the how the fuel pressure sometimes is at the right level. Anyone know the symptoms of a dying fuel pump?
As far as symptoms of a failing pump. Iv'e been told they make a lot of noise. My SCer is a bit on the loud side so I cant really hear my pump but maybe its just starting to fail. I dont know. I will let you know what I find out and if you could do the same I would appreciate it... thanks
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From: Rochester NY
Re: Help- Fuel pressure drop but no thrown codes
I am going to bump my own thread here in hope for more insite from any of the super trouble shooters on the board.
My Corvette is currently at my tuners which I had to drive 70+ miles to get to. With the exception of a small drop in FP in my driveway then 60-0 on one left turn leading to the thru-way I made it the entire 70 miles without a problem. Unfortunately this doesn't give my tuner much to work with as its been there a week and he can't seem to duplicate the problem.
They checked the voltage to the pump. Checked all grounds for voltage drops etc. with no problems in sight. The car is running great for them. Now its come to the point where I need to eliminate any hidden gremlins so I opted to upgrade the fuel pump and wiring with the Racetronix unit (thanks to Chris at speeddemonmotorsports.com a forum vendor) we should have that soon.
Can anyone think of anything else that could cause erratic fuel pressure drop. It has a full tank of gas but the problem started when it ran very low. It seems to do it mostly on left hand turns at granny speeds.
Any further input?
[Modified by Rookiedyn, 2:17 PM 8/6/2003]
My Corvette is currently at my tuners which I had to drive 70+ miles to get to. With the exception of a small drop in FP in my driveway then 60-0 on one left turn leading to the thru-way I made it the entire 70 miles without a problem. Unfortunately this doesn't give my tuner much to work with as its been there a week and he can't seem to duplicate the problem.
They checked the voltage to the pump. Checked all grounds for voltage drops etc. with no problems in sight. The car is running great for them. Now its come to the point where I need to eliminate any hidden gremlins so I opted to upgrade the fuel pump and wiring with the Racetronix unit (thanks to Chris at speeddemonmotorsports.com a forum vendor) we should have that soon.
Can anyone think of anything else that could cause erratic fuel pressure drop. It has a full tank of gas but the problem started when it ran very low. It seems to do it mostly on left hand turns at granny speeds.
Any further input?
[Modified by Rookiedyn, 2:17 PM 8/6/2003]
