Sudden (apparently) decline in gas mileage?

[BigSwede]

Bart, I'm not really experiencing a drop in gas milage like you are, but Vicki is slow on starting up lately. Like you, I used to just turn the key and she would fire right up, but recently she turns over, sometimes for quite a while, until she catches and then runs like always. I did notice that if I turn the key on and wait for a while she will start right up as she used to. To me, and to some other that I asked for help here on the board, it sounds like a fuel issue; specifically a fuel pressure issue. When you turn the key on the fuel pump in the tank starts up and prime's the system and that is why I think she starts up after the key has been on for a few seconds.

Some of the suggestions where to replace the fuel filter and fuel pressure regulator (which I haven't done yet), and to check the valve on the fuel rail to see if it is pressurized after the car has been off for a while.
http://www.vehicross.info/forums/sho...t=cranks+start
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Sure sounds like a fuel pressure regulator to me...

[89Vette]

Sure sounds like a fuel pressure regulator to me...

[Ldub]

mine always goes from 230-240 mptank, down to 200 mptank every winter.

[nfpgasmask]

Well, my fuel pressure regulator was changed out probably 35,000 miles ago. Same with my EGR. I replaced it, not cleaned it.

Now Mark, I think you are on to something, because I notice the same thing. If I put the key in and turn it but not start up, I wait until the beep, beep, beep, beep is over and then usually it fires right up. Meaning the fuel pump has activated and got the right amount of fuel pumped up front. I sometimes wonder if it could be a tired fuel pump. The start up issues may or may not be related to my fuel consumption woes, but who knows?

I suppose I could pull my FPR and see if the screen has any holes in it, but again, I changed it a couple summers ago. I'll have to look back in my log book and find out exactly how long ago it was. Same goes for my EGR.

I was thinking though, when you burn a lot of oil, you are pumping a lot of soot through the exhaust system. So wouldn't my O2 sensors and my cat be pretty dirty? I mean, you would think I would throw a code if there was an issue, or at least experience some performance issues, which I am not, so I am kinda stumped.

Anyway, thanks for the thoughts.

Bart

[Ldub]

Well, my fuel pressure regulator was changed out probably 35,000 miles ago. Same with my EGR. I replaced it, not cleaned it.

Now Mark, I think you are on to something, because I notice the same thing. If I put the key in and turn it but not start up, I wait until the beep, beep, beep, beep is over and then usually it fires right up. Meaning the fuel pump has activated and got the right amount of fuel pumped up front. I sometimes wonder if it could be a tired fuel pump. The start up issues may or may not be related to my fuel consumption woes, but who knows?

I suppose I could pull my FPR and see if the screen has any holes in it, but again, I changed it a couple summers ago. I'll have to look back in my log book and find out exactly how long ago it was. Same goes for my EGR.


Bart

How long since you changed the fuel filter? That helped mine light up quicker, & is the cheapest / easiest / & maybe least fun solution to try first...

[VX crazy]

I remember Tone and I replacing his fuel pump in his vx back in 2002.......huge PITA....thank goodness I have small hands! But I always thought fuel pumps just go, either work or don't?

[nfpgasmask]

OK, I guess time flies when you are having fun!!!

I just pulled my log book. My VX has 111,234 miles on it right now.

I replaced the EGR Valve at 80700 miles.

I replaced the FPR at 68708 miles.

And I replaced the fuel filter at 46180 miles!!!

I must be thinking of the last time I did the fuel filter on the Trooper!! So I know what I am doing this week! I'll start with the fuel filter and see if that helps with start up at least! And, its been roughly 43,000 miles since I changed the FPR. So how long are they supposed to last? I guess I need to check the manual. Maybe another new one is in order.

Thanks folks,

Bart

[89Vette]

OK, I guess time flies when you are having fun!!!

I just pulled my log book. My VX has 111,234 miles on it right now.

I replaced the EGR Valve at 80700 miles.

I replaced the FPR at 68708 miles.

And I replaced the fuel filter at 46180 miles!!!

I must be thinking of the last time I did the fuel filter on the Trooper!! So I know what I am doing this week! I'll start with the fuel filter and see if that helps with start up at least! And, its been roughly 43,000 miles since I changed the FPR. So how long are they supposed to last? I guess I need to check the manual. Maybe another new one is in order.

Thanks folks,

Bart

Have you tried another brand of fuel? Maybe something happened where you've gotten more moisture in your fuel. Or someone cutting gasoline.

[BigSwede]

And, its been roughly 43,000 miles since I changed the FPR. So how long are they supposed to last?

My old 99 Trooper FPR went out at around 50K. I'm sure they are supposed to last longer than that, but I believe the FPR is one of those fine GM parts that Isuzu used here and there, so whaddya gonna do?