Poor Mileage
11-30-2003, 12:32 AM
#1
Race Car
Thread Starter
Poor Mileage
I am getting approx 400km to the tank ATM, this is terrible in my opinion. I have checked a couple things (been a while, so I forget), but tonight I checked my fuel pressure. 36-38psi at idle, 40psi jumpered, and 20 min leakdown is only down 4 psi (32, it was after the idle test). When it was jumpered, I could hear a LOT of fuel pouring through the line to the damper, and from the sound of it, it sounded like it was pouring on something, but alas, I cannot find it, or smell it. Anyways, there seemed to be next to no fuel coming back from teh regulator. Is this normal?
How does the regulator work, at 36 or 40psi does it just pop open? Or is it gradual? Perhaps mine is getting sticky or something.
What else should I check?
This may be unrelated, but I don't know, when I fill it up, the auto-shutoff on the pump will not work on my car, if I put it in all the way, it will either shut off after every 0.1 seconds, or never shut off, causing gas to pour all over (only once before I caught on). Is it possible there is a problem with the gas tank? Fuel lines? I do not know what or where to check, any help would be appreciated.
How does the regulator work, at 36 or 40psi does it just pop open? Or is it gradual? Perhaps mine is getting sticky or something.
What else should I check?
This may be unrelated, but I don't know, when I fill it up, the auto-shutoff on the pump will not work on my car, if I put it in all the way, it will either shut off after every 0.1 seconds, or never shut off, causing gas to pour all over (only once before I caught on). Is it possible there is a problem with the gas tank? Fuel lines? I do not know what or where to check, any help would be appreciated.
12-02-2003, 11:00 PM
#4
Race Car
Thread Starter
Hmm, think I found the culprit. I checked the vacuum at the FPR, and it's 14" Hg, so I believe my FPR is bad, because the rail pressure is still 36psi (Will check it one last time before I replace it, but I think it's f'ed). Have I found the problem, or is there something else I should check first?
12-03-2003, 01:05 AM
#6
Race Car
Thread Starter
Er.... I don't know if that answers my questions. I had it emissions tested this past summer (it's not law here), and it was 7-9% CO, and 1-2% CO2, with the HC at about 750-1000. Absolutely terrible, already had the surprise. That's why I'm tracking down what's causing my bad mileage. It's probably the same problem.
Very few shops here will test emissions, and where they do, it's quite expensive, so I'm just gonna keep fixing broken things until my mileage gets better.
Very few shops here will test emissions, and where they do, it's quite expensive, so I'm just gonna keep fixing broken things until my mileage gets better.
12-03-2003, 01:13 AM
#7
Instructor
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Wow, your HydroCarbons are through the roof! Have you checked the basics like leaky ignition wires, worn spark plugs, cracked/carbon tracked distributor cap, faulty/disabled O2 sensor, etc.?
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12-03-2003, 01:20 AM
#8
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Might be worth adjusting your fuel mixture as well. Most cars from areas which do not have mandatory emissions testing are usually way out of spec due to age, wear and neglect.
12-03-2003, 10:04 AM
#9
Race Car
Thread Starter
I know, I couldn't believe my emissions either! I have done a basic tune-up, and I'm going to do the cap and rotor soon. The rotor has some nicks in it about 1/8" deep, I'm sure that's not good, and if the rotor is that bad, then the cap is proly shot too.
I can't adjust the fuel mixture until I have the proper fuel pressure, otherwise when I fix the presure, I'll have to adjust it again.
I changed the plugs, the wires are good, changed the O2 (made things worse, but the idle got better), cleaned the air filter (K&N reusable), fuel filter (worse mileage again, but that's to be expected). I think the FPR is either the wrong one, or shot, because it doesn't seem to respond to vacuum, it just opens at 40psi...
I can't adjust the fuel mixture until I have the proper fuel pressure, otherwise when I fix the presure, I'll have to adjust it again.
I changed the plugs, the wires are good, changed the O2 (made things worse, but the idle got better), cleaned the air filter (K&N reusable), fuel filter (worse mileage again, but that's to be expected). I think the FPR is either the wrong one, or shot, because it doesn't seem to respond to vacuum, it just opens at 40psi...
12-03-2003, 12:48 PM
#10
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"I can't adjust the fuel mixture until I have the proper fuel pressure, otherwise when I fix the presure, I'll have to adjust it again"
Let me know how you adjust the fuel mixture past just the idle at the AFS using the stock components.
Let me know how you adjust the fuel mixture past just the idle at the AFS using the stock components.
12-03-2003, 11:50 PM
#12
Race Car
Thread Starter
Hmm, Partsource - "The parts, the pro's the price!" MY ***!!
jeez, takes me 3 days to get a FPR, and it's the wrong freakin one.... gonna give the manager a piece of my mind tomorrow, it's for a 911 I was told, after I told them 3 times it was a 944.... morons, absolute morons.
Well, I'll be shopping around for another place to buy a FPR, I no longer trust partsource, I'll post once I find one and see if it's what was wrong on my car.
jeez, takes me 3 days to get a FPR, and it's the wrong freakin one.... gonna give the manager a piece of my mind tomorrow, it's for a 911 I was told, after I told them 3 times it was a 944.... morons, absolute morons.
Well, I'll be shopping around for another place to buy a FPR, I no longer trust partsource, I'll post once I find one and see if it's what was wrong on my car.
12-04-2003, 12:38 AM
#13
Burning Brakes
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check those emission numbers, the CO% should be around 1% ahead of the cat, CO2 should be 14-15% with a decent running engine. Co is an indicator of air fuel mix, high numbers mean rich mixture, 7-9% mean very rich mixture. A missfire is not going to give you those sorts of CO readings. Have you checked the connection at the colant temp sensor? Try wiggling the blue connector and see if there is any difference in the way the eng. runs. Does the air-flow sensor look like it has been opened up? If it has, someone may have screwed up the calibration. If your fuel pressure is 40 psi it is not causing the richness you are experiencing. Look elsewhere for your answers. Good luck
12-04-2003, 09:49 AM
#14
Rennlist Member
One inexpensive thing to try is to run a bottle of Chevron "Techron" fuel system cleaner in your next tank of fuel.
I recently did this in my 1983 944, and the mileage has improved noticeably.
I recently did this in my 1983 944, and the mileage has improved noticeably.
12-04-2003, 09:55 AM
#15
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Re: Poor Mileage
Originally posted by Zero10
I could hear a LOT of fuel pouring through the line to the damper, and from the sound of it, it sounded like it was pouring on something, but alas, I cannot find it, or smell it.
I could hear a LOT of fuel pouring through the line to the damper, and from the sound of it, it sounded like it was pouring on something, but alas, I cannot find it, or smell it.