ItsAllHype Posted February 13, 2005 Report Share Posted February 13, 2005 On a 96 STS I have a fuel pressure gauge hooked up. What would cause a fuel pressure gauge needle to flutter between 41 and 43 pounds of pressure with the car running at idle? (I have a new fuel pressure regulator and new fuel filter installed. With the updated fuel rail also.) Link to comment Share on other sites More sharing options...
JimD Posted February 13, 2005 Report Share Posted February 13, 2005 It probably means your fuel pressure gauge mechanism does not have enough damping. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 16, 2005 Author Report Share Posted February 16, 2005 I just took off the fuel gauge and I can still feel the pulsing in the rail. I just picked up my car from the dealer tonight. They changed the fuel pump and harness. Any ideas?? Link to comment Share on other sites More sharing options...
JimD Posted February 16, 2005 Report Share Posted February 16, 2005 Not sure what the question is. What was the key on - engine off pressure before the work was done? What is the key on - engine off pressure with the new pump? Likewise, what is the pressure with the engine running? I do not feel any pulsation on the fuel line on my '04; not sure about the '98. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 16, 2005 Author Report Share Posted February 16, 2005 My question is why is it still doing it? I am trying to find out if anyone has ever noticed this flutter while diagnosing a problem related to the fuel system. Injectors? I am not getting any codes, but my gas millage is at about 10MPG. I am thinking they may be related, but I want to know if it is normal for the pressure to cause the needle to flutter. Link to comment Share on other sites More sharing options...
Scotty Posted February 16, 2005 Report Share Posted February 16, 2005 Don't worry about the flutter mine does that also, 43 to 46..., 42 to 43 is hardly fluttering at all, don't give it a second thought! You may have stated this already this is a long thread, did you have the fuel rail replaced on the recall? Make sure your fuel rail is tight, my 96 has four studs, snug them down (10 mm deep socket or wrench), I don't see how you could feel anything, you are probably feeling the injectors doing their thing.... Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 16, 2005 Author Report Share Posted February 16, 2005 What do you think about the 10MPG Scotty? I drive normal in the suburbs. Link to comment Share on other sites More sharing options...
Ranger Posted February 16, 2005 Report Share Posted February 16, 2005 Have you checked for a stuck open injector? Link to comment Share on other sites More sharing options...
Scotty Posted February 16, 2005 Report Share Posted February 16, 2005 What do you think about the 10MPG Scotty? I drive normal in the suburbs. obviously it sounds low. you just had your fuel pump replaced recently? how did you determine the miles per gallon so quickly I am surprised. Did you clear everything when you did the MPG test? Check the air pressure in your tires. Do you have any drivability problems? Was the fuel rail replaced? Is is snapped in fully and tightened down, I am very surprised that you think you feel the 1 pound flutter...which to me is minor Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 16, 2005 Author Report Share Posted February 16, 2005 I put in a new battery before I brought it to the dealer, so the fuel mileage got reset. I drove it for about 15 miles around town after the repair, so I may be jumping the gun, but I am worried because I thought my millage would show up fast in the past to be at around 16. I am using the built in miles per gal estimater. tires are correct pressure. I have had the fuel rail updated. They did not put the plastic covers on the wires though. I plan on having them do it soon. I seem to feel more pulsing in the rail at the front of the engine, I recognize the frequency of it from feeling it much stronger in the fuel gauge when it was hooked up. It drives fine, no miss or hesitation. Just doesn't seem to idle as smooth as it used to, even though the tach doesn't move it feels like something isn't right to me because I am so in tuned to how my engine idles. Wouldn't an injector problem trigger a code? Link to comment Share on other sites More sharing options...
The_Raven Posted February 16, 2005 Report Share Posted February 16, 2005 Howyadoin, [wild_assed_guess] Fuel pressure regulator? [/wild_assed_guess] -Rav //oops, on preview I see in another thread that you changed that in January... Right then, carry on... -Mark P. Salem, MA "Refined Sugar" - '96 SLS, 175K "...the Caddy is dedicated to relentlessly -- and comfortably -- converting time into distance." -J.J. Gertler Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 16, 2005 Author Report Share Posted February 16, 2005 I should add that the reason I had the fuel pump changed was because I was running the car with a gauge on it trying to diagnose an intermitant complete loss of power problem. In the driveway, after waiting for weeks for it to happen again, it did it. The car ran really bad at idle and pressing the gas pedal would make the engine not increase rpm's. So I popped open the hood and jumped out of the car only to see the fuel pressure at 20PSI on the gauge. With a new FPR, fuel filter, fuel rail, and fuel pump.....am I forgetting something that could cause such a drop in fuel pressure to occur. I shut the car off and restarted and it was fine for weeks again until I got sick of worrying that the pump going out would strand me, so I changed it. Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 16, 2005 Author Report Share Posted February 16, 2005 Also have a new pump relay. Link to comment Share on other sites More sharing options...
Ranger Posted February 16, 2005 Report Share Posted February 16, 2005 I put in a new battery before I brought it to the dealer, so the fuel mileage got reset. I drove it for about 15 miles around town after the repair, so I may be jumping the gun, Yes, your jumping the gun. Give it a little time to average out and you should be back to your normal MPG. I am not positive, but an inoperative injector might set a DTC but I am pretty sure a leaky or stuck opened one wouldn't. Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 16, 2005 Author Report Share Posted February 16, 2005 So how would I go about diagnosing a stuck open or leaky injector? Especially if it only does it once every three weeks and then is fine? Link to comment Share on other sites More sharing options...
Ranger Posted February 16, 2005 Report Share Posted February 16, 2005 Well, intermittent is hard to diagnose and since it is intermittent I doubt that is the problem but the only way to do it is pull the fuel rail. Turn the key on (don't start) to pressurize the system and look at the injector tips to see if any are leaking. Link to comment Share on other sites More sharing options...
adallak Posted February 16, 2005 Report Share Posted February 16, 2005 So how would I go about diagnosing a stuck open or leaky injector? Especially if it only does it once every three weeks and then is fine? I think a bad injector would be bad all the time...Looks like fuel pressure has been changed by PCM getting some wrong intermittent input from sensors. Just my .02 The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Scotty Posted February 16, 2005 Report Share Posted February 16, 2005 Well, intermittent is hard to diagnose and since it is intermittent I doubt that is the problem but the only way to do it is pull the fuel rail. Turn the key on (don't start) to pressurize the system and look at the injector tips to see if any are leaking. Larry, when you put the fuel rail back in place do you think its prudent to lube the o-rings with silicone grease? I had my fuel rail replaced last week and when I pulled it to clean my EGR it appeared that the o-rings were coated with silicone grease... (I think I saw o-rings with my over 40 eyes) That was the first time I every pulled a fuel rail so I was a little apprehensive. The procedure went pretty easily however I was surprised. Mike Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 18, 2005 Author Report Share Posted February 18, 2005 So lets say it was a bad sensor. My question is what sensor would be capable of telling the pcm something that could drop the fuel pressure down to something drastic like 20 lbs? Also, I haven't had any experience with injector problems, but is it possible that a stuck open injector could drop my fuel pressure down to 20 lbs. And could the pcm not know that this is happening and not set a code. Link to comment Share on other sites More sharing options...
Ranger Posted February 19, 2005 Report Share Posted February 19, 2005 Well, intermittent is hard to diagnose and since it is intermittent I doubt that is the problem but the only way to do it is pull the fuel rail. Turn the key on (don't start) to pressurize the system and look at the injector tips to see if any are leaking. Larry, when you put the fuel rail back in place do you think its prudent to lube the o-rings with silicone grease? I had my fuel rail replaced last week and when I pulled it to clean my EGR it appeared that the o-rings were coated with silicone grease... (I think I saw o-rings with my over 40 eyes) That was the first time I every pulled a fuel rail so I was a little apprehensive. The procedure went pretty easily however I was surprised. Mike Mike, Sorry the reponse is so late but I was up snowmobiling in Northern Wisc. Just got back. I think the manual says lube the O rings with engine oil. That's what I used when I pull the rail to do the upper intake on my wifes 3800. I was going to say I don't think silicone grease would hurt anything but the more I think about it I seem to recall Guru once saying that nothing will kill an O2 sensor faster than silicone so I would tend to keep it away from any intake ports including injectors. Just my $0.02 Link to comment Share on other sites More sharing options...
Scotty Posted February 20, 2005 Report Share Posted February 20, 2005 Well, intermittent is hard to diagnose and since it is intermittent I doubt that is the problem but the only way to do it is pull the fuel rail. Turn the key on (don't start) to pressurize the system and look at the injector tips to see if any are leaking. Larry, when you put the fuel rail back in place do you think its prudent to lube the o-rings with silicone grease? I had my fuel rail replaced last week and when I pulled it to clean my EGR it appeared that the o-rings were coated with silicone grease... (I think I saw o-rings with my over 40 eyes) That was the first time I every pulled a fuel rail so I was a little apprehensive. The procedure went pretty easily however I was surprised. Mike Mike, Sorry the reponse is so late but I was up snowmobiling in Northern Wisc. Just got back. I think the manual says lube the O rings with engine oil. That's what I used when I pull the rail to do the upper intake on my wifes 3800. I was going to say I don't think silicone grease would hurt anything but the more I think about it I seem to recall Guru once saying that nothing will kill an O2 sensor faster than silicone so I would tend to keep it away from any intake ports including injectors. Just my $0.02 Thanks Larry, I will look into that with regard to the O2 sensors, it certainly appeared to be some sort of clear grease that they used on the fuel rail o-rings, Mike Link to comment Share on other sites More sharing options...
Scotty Posted February 20, 2005 Report Share Posted February 20, 2005 Lots of people use vasoline to install injectors....maybe that is what you saw. You do NOT want to use any sort of silicone grease on injectors as that will contaminate and kill the O2 sensors. Thanks bbobynski, I did not know that about silicone and O2 sensors, thanks. However, the thought would never cross my mind to use vasoline as its a petroleum based product wouldn't that swell the rubber o-rings? The dealer used this when they replaced my fuel rail under recall. Thanks again, Mike Link to comment Share on other sites More sharing options...
Scotty Posted February 20, 2005 Report Share Posted February 20, 2005 Lots of people use vasoline to install injectors....maybe that is what you saw. You do NOT want to use any sort of silicone grease on injectors as that will contaminate and kill the O2 sensors. Thanks bbobynski, I did not know that about silicone and O2 sensors, thanks. However, the thought would never cross my mind to use vasoline as its a petroleum based product wouldn't that swell the rubber o-rings? The dealer used this when they replaced my fuel rail under recall. Thanks again, Mike Well....oil is petroleum based....and so is the gas the o-rings are sealing into the intake manifold....LOL. You don't want to use vasoline on condoms but the o-rings on the injectors are made to work with petroleum products......LOL I will keep that in mind! but I'm a KY Gel man myself Hmm, I wonder how KY is with O2 sensors, it's water based Link to comment Share on other sites More sharing options...
ItsAllHype Posted February 27, 2005 Author Report Share Posted February 27, 2005 Hey bbobynski, thanks for the info. This is where I am at now. I haven't had any drop of fuel pressure since I changed the fuel pump. My mileage driving around the suburbs will not go over 11.7 MPG though. New fuel filter, new FPR, updated fuel rail. I have no drivability problems. Any thoughts on the mileage issue, I think it is way too low, but if I am wrong correct me. Link to comment Share on other sites More sharing options...
Scotty Posted February 27, 2005 Report Share Posted February 27, 2005 You know on another thread someone mentioned that if the VCC is acting up your gas mileage would drop. Have you checked for codes? Link to comment Share on other sites More sharing options...
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