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Been searching all over the internet with mixed results. I have been having a starting issue where my Vette cranks for around 7 seconds then fires, or crank for 2 then recrank with good results. I finally hooked up a fuel pressure gauge to the rail and found that while running, I am running around 59psi. When I shut the car off, the pressure drops instantly to 5psi. I replaced the fuel filter/fuel pressure regulator with a Wix 33737 to no avail. I am now looking at replacing the fuel pump with a Delphi replacement. Question being, I should only have to replace the left side as the right side only acts as a jet siphon? I do not know if the right side had anything to do with fuel pressure at the rail or not. Thanks!
Been searching all over the internet with mixed results. I have been having a starting issue where my Vette cranks for around 7 seconds then fires, or crank for 2 then recrank with good results. I finally hooked up a fuel pressure gauge to the rail and found that while running, I am running around 59psi. When I shut the car off, the pressure drops instantly to 5psi. I replaced the fuel filter/fuel pressure regulator with a Wix 33737 to no avail. I am now looking at replacing the fuel pump with a Delphi replacement. Question being, I should only have to replace the left side as the right side only acts as a jet siphon? I do not know if the right side had anything to do with fuel pressure at the rail or not. Thanks!
Aside from the 7 seconds to start thing all else sounds normal....My car drops in pressure quickly too...No issues though....I would not replace the pump. Try putting the car in the "on" position and listen for the fuel pump to prime for a couple of secs then it shuts off. Once it shuts try starting the car...See if it starts quicker or makes no difference...But, if the pump primes I fails to see an issue with the pump...
Been searching all over the internet with mixed results. I have been having a starting issue where my Vette cranks for around 7 seconds then fires, or crank for 2 then recrank with good results. I finally hooked up a fuel pressure gauge to the rail and found that while running, I am running around 59psi. When I shut the car off, the pressure drops instantly to 5psi. I replaced the fuel filter/fuel pressure regulator with a Wix 33737 to no avail. I am now looking at replacing the fuel pump with a Delphi replacement. Question being, I should only have to replace the left side as the right side only acts as a jet siphon? I do not know if the right side had anything to do with fuel pressure at the rail or not. Thanks!
One other thing..What year is the car? I believe the earlier ones 97-98 have a regulator at the rail where as the 99 and up have it in the fuel filter....
1999 is the year model and yes, fuel filter also contains pressure regulator. I started to notice this past weekend that when get on the throttle, I develop a "dead pedal". I also had both right and left bank O2 sensors code on me. Hard starting, dead pedal, both O2 sensors, and poor mileage kinda lead me to believe that a return line on the pump is failing. Back to starting, if I turn the ignition to "on" I can hear the pump prime, I think. It doesn't matter how many times I cycle the ignition, it will start hard. Now if I've been driving and shut the car off, it'll typically start with no problems for the first minute or so.
1999 is the year model and yes, fuel filter also contains pressure regulator. I started to notice this past weekend that when get on the throttle, I develop a "dead pedal". I also had both right and left bank O2 sensors code on me. Hard starting, dead pedal, both O2 sensors, and poor mileage kinda lead me to believe that a return line on the pump is failing. Back to starting, if I turn the ignition to "on" I can hear the pump prime, I think. It doesn't matter how many times I cycle the ignition, it will start hard. Now if I've been driving and shut the car off, it'll typically start with no problems for the first minute or so.
I have a 99 as well. I see your point now as you listed more issues. Are the 02 the only codes you are getting? And what are the codes?? If you watch the fuel pressure guage and step on the gas does the fuel pressure change or stay steady? I checked my this way with the wife stepping on the gas while I was looking at the fuel rail guage...That should at least rule out a pump...I would think....But then again, I have a friend with a 2000 that was on a dyno and the car flattened at high rpms.....The pump seemed fine at part throttle and there were no codes....He just replaced the pump so we will see if that was the issue...
But, i would think the codes you are getting should be somewhat helpful....
I was getting a p0137 and a p0157. The only test I haven't done is hook a pressure tester up in between the filter and pump to rule out anything downline.
Your fuel pressure should not be dropping from 59 to 5 with key off...my 2001 says with key ON I should be reading 55-62...when the key is turned off should NOT drop more than 5 psi in 1 minute !!...the areas of concern are a leaky fuel injector, bad fuel filter/FP regulator, fuel feed line check valve, or a bad fuel pump module check valve... you have already replaced the FP filter/ regulator so we can rule that out...basically to check the injectors would require pulling up the injector rails and putting a towel or something underneath to catch the fuel and see if they leak when the key is turned on then off...I don't think you have an injector PCM driver stuck on (grounding the injector and keeping it spraying with key on) and if so you would probably have rich codes...just for the heck of it you can pull off all the injector connectors and then see if the pressure holds....you can't buy the check valve as a separate part but you would have to purchase the whole fuel feed line...the DTC's are the REAR O2 sensor low voltage...the rears only monitor the CATS and are not involved in fuel scheduling during "closed loop" operation. Now an exhaust leak between the front O2 sensor and the rear sensor can set that DTC...more oxygen getting drawn into the exhaust stream leaning the sensor below 450Mv !!...the rear O2 voltage usually hang around 600-800 Mv !!...low voltage is LEAN...I have the factory fuel line adapters (I don't mess around...LOL !!) that block off the fuel lines in different sections...they make troubleshooting very easy...you can probably make your own with some fuel fittings and shut off valves...factory P/N is J37287-2 (5/16" line) and -1 (3/8" line) which is made by Kent-Moore !!
Your fuel pressure should not be dropping from 59 to 5 with key off...my 2001 says with key ON I should be reading 55-62...when the key is turned off should NOT drop more than 5 psi in 1 minute !!...the areas of concern are a leaky fuel injector, bad fuel filter/FP regulator, fuel feed line check valve, or a bad fuel pump module... you have already replaced the FP filter/ regulator so we can rule that out...basically to check the injectors would require pulling up the whole injector rails and putting a towel or something underneath to catch the fuel and see if they leak when the key is turned on then off...I don't think you have an injector PCM driver stuck on (grounding the injector and keeping it spraying with key on) and if so you would probably have rich codes...just for the heck of it you can pull off all the injector connectors and then see if the pressure holds....you can't buy the check valve as a separate part but you would have to purchase the whole fuel feed line...the DTC's are the REAR O2 sensor low voltage...the rears only monitor the CATS and are not involved in fuel scheduling during "closed loop" operation. Now an exhaust leak between the front O2 sensor and the rear sensor can set that DTC...more oxygen getting drawn into the exhaust stream leaning the sensor below 450Mv !!...the rear O2 voltage usually hang around 600-800 Mv !!...low voltage is LEAN...I have the factory fuel line adapters (I don't mess around...LOL !!) that block off the fuel lines in different sections...they make troubleshooting very easy...you can probably make your own with some fuel fittings and shut off valves...factory P/N is J37287-2 (5/16" line) and -1 (3/8" line) which is made by Kent-Moore !!
Q
Excuse my ignorance, but what exactly are the adapters hooking into?
Excuse my ignorance, but what exactly are the adapters hooking into?
The oval in the picture is where the feed line connects to the fuel rail...it has a male and female ends...the adapter hooks inline with these 2 with the yellow shut off valve in between !!
1999 is the year model and yes, fuel filter also contains pressure regulator. I started to notice this past weekend that when get on the throttle, I develop a "dead pedal". I also had both right and left bank O2 sensors code on me. Hard starting, dead pedal, both O2 sensors, and poor mileage kinda lead me to believe that a return line on the pump is failing. Back to starting, if I turn the ignition to "on" I can hear the pump prime, I think. It doesn't matter how many times I cycle the ignition, it will start hard. Now if I've been driving and shut the car off, it'll typically start with no problems for the first minute or so.
Could be a bad fuel pump...if you had a scan tool to look at fuel trims on acceleration you can nail it down !!….if your front O2 sensors are lean like the rear it may be the pump....if the front are rich but the rears lean it's a bad O2 sensor...the fronts are reporting a false rich (PCM will then "pull" fuel...car will fall flat on it's face) but to have 2 bad are pretty slim !!
Been searching all over the internet with mixed results. I have been having a starting issue where my Vette cranks for around 7 seconds then fires, or crank for 2 then recrank with good results. I finally hooked up a fuel pressure gauge to the rail and found that while running, I am running around 59psi. When I shut the car off, the pressure drops instantly to 5psi. I replaced the fuel filter/fuel pressure regulator with a Wix 33737 to no avail. I am now looking at replacing the fuel pump with a Delphi replacement. Question being, I should only have to replace the left side as the right side only acts as a jet siphon? I do not know if the right side had anything to do with fuel pressure at the rail or not. Thanks!
Sorry, I forgot to mention there is a way to check the check valve in the fuel pump without removing it...if you can get yourself a radiator pressure tester and remove the fuel pressure line going to the fuel rail (the pic I posted) and adapt it to the fuel line and pump around 15 psi into it ....if the pressure holds for around a minute or so the check valve is OK !!...remember to remove the fuel cap !!
PS...you can make your own adapter with an OTC 7628 and 7629 fuel line and also a 3/8 and 5/16 shut off valve...maybe $90.00 or less in parts !!
I decided to go with my gut instinct rather then keep testing the fuel system. I mean, it is a 20 year old car and I'm already finding stuff out that contradicts what the prior owner told me. Needless to say, I have a brand new Delphi fuel pump going in between this afternoon and Wednesday because of ambition. Hopefully that solves my issues, it not, back to testing the fuel system. Thank you to everyone that replied with valuable information!
Typical me, I'm lying in bed overthinking my fuel issues. I knuckled under and made an appointment for tomorrow, Wednesday, since I am involved way over my head. However, hypothetically speaking, my rear fuel feed line check valve is shot. GM doesn't manufacture that part anymore. Could my mechanic remove and replace the check valve rather than purchasing a recycled one?
It can possibly be something “easy” like a leaky injector !!...if you can change a fuel pump you can certainly check for that !!....like I said with a coolant pressure tester if adapted to the fuel line can easily check the feed line check valve for leakage !!...and NO, the check valve can’t be replaced separately...let us know how things work out...I would have Fedex’d my adapter kit to you if you really wanted to tackle this whole thing yourself !!
It can possibly be something “easy” like a leaky injector !!...if you can change a fuel pump you can certainly check for that !!....like I said with a coolant pressure tester if adapted to the fuel line can easily check the feed line check valve for leakage !!...and NO, the check valve can’t be replaced separately...let us know how things work out...I would have Fedex’d my adapter kit to you if you really wanted to tackle this whole thing yourself !!
I really do appreciate that offer, but like I said, I'm starting to get too involved without someone physically here just pointing and explaining the process. I am mechanically inclined, just uncomfortable doing something alone I have never done. I'll keep you updated as to what the mechanic finds. Thanks again for all of the tips and pointers. This forum really makes a person appreciate people a lot more.
No problem !!...instead of using a coolant pressure tester I'm sure the mechanic has a Mityvac which is a vacuum/pressure tester...mine on the pressure side goes up to 30 psi...all he would need to do is connect either a male or female 3/8" fuel line fitting to the Mityvac....I'm sure he has one laying around...now I've heard of other members plumbing in a seperate check valve in series with the fuel feed line instead of removing it...that could be an option instead of replacing the whole line...if the check valve is good I think the injector is your last component that may be faulty....he may even have the 3/8" inch shut off valve...that way he can confirm 100% it is an injector !!!....good luck !!
p.s. and oh BTW you did a great job so far...you could have EASILY handled it !!
Fuel pump issues
