DTC code mystery
#1
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Where would you guys start? I know sometimes codes can come up because another problem sets off a chain effect.
So far I have replaced the fuel filter. I am thinking the knock sensor might be the actual issue. A mechanic friend told me
it is a bit strange that 2 oxygen sensors go at the same time, he suspects MAF sensor. I cleaned it with MAF spray, no change.
#2
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GoPhat, because you have a 2002, you have a schrader valve on your fuel lines. I would start with measuring the fuel rail pressure. Should be 50-60 psig with the car in RUN but the engine not running and with the engine running should be in the 40-50 psig range (closer to 50 psig). If you have pressures that are off from that, then I would do the fuel rail pressure sensor first, then see what is left.
Keep in mind you may have dual issues. But, the fuel issue seems to be a bigger thing at the moment.
Keep in mind you may have dual issues. But, the fuel issue seems to be a bigger thing at the moment.
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Gophat (01-02-2023)
#3
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I had a fuel gauge on the whole time and it never got higher than 27 psi while the engine is running. The first thing I replaced was the fuel rail sensor and nothing changed, the code didn't go away. I tried clearing them and they all came back in under a minute. I replaced the fuel filter next and no change. I went ahead and replaced the fuel pump this morning (I have an access hole so it was easy). I did notice the outer strainer for the fuel assembly was broken off. The inner fuel strainer on the actual pump was fine. I replaced the whole assembly anyway. No change at all, 27 psi nothing more. I thought my gauge was damaged and checked on another vehicle and it works fine. Is there anything else that may command the fuel pump? Possible a fuel module hidden somewhere? Or is the knock sensor causing the pump to act crazy?
#4
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A little research led me to check the fuel pump module under the rear driver side seat. I looks brand spanking new with no signs of corrosion at all. The research basically says if it is corroded it need to be cleaned and replaced.
Moving on to the actual fuel hose, might let it run just in case there is bad fuel in the line.
Moving on to the actual fuel hose, might let it run just in case there is bad fuel in the line.
Last edited by Gophat; 01-02-2023 at 12:20 PM.
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#6
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To the contrary Thermo, I actually replaced it yesterday night. The assembly body strainer was damaged but the inner strainer on the fuel pump was fine. Regardless I replaced the whole thing (hole cut under seat from years ago). And can you believe it, nothing changed the car starts up fine and sounds great, but then 30 secs later it starts stumbling and brick walls to its death. If I even feather the pedal it dies. I removed all the fuel from the tank and replaced with 93 octane just to see if it was bad gas. Nothing. I think it is electrical somehow. Almost like the pump is being commanded to die but the fuel pump module seems fine. I don't know if I should throw 80 bucks at a module if it is probably not the issue but I will if I have to.
Weird side note that might be important. My heated o2 sensor bank 2 (which is the front by the radiator?) had water in the connector, it may have dislodged from the connector tab under the battery. I blew it out and 1 pin was corroded. Would that affect a fuel pump?
I get a feeling the issue is unrelated to all these codes. Would a knock sensor cause all of these problems?
Weird side note that might be important. My heated o2 sensor bank 2 (which is the front by the radiator?) had water in the connector, it may have dislodged from the connector tab under the battery. I blew it out and 1 pin was corroded. Would that affect a fuel pump?
I get a feeling the issue is unrelated to all these codes. Would a knock sensor cause all of these problems?
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A knock sensor would not cause low fuel pressure. As my saying goes, "apples and volvos different". A knock has no effect on the fuel pressure. The fuel pressure sensor sends a signal to the fuel pump module and that is what commands the module to send an electrical signal to the fuel pump and tells the fuel pump how long to be on and off. By regulating the on and off time, you can control the fuel pressure. This is happening 100's of times a second. So, with a low fuel pressure, the fuel pump module should be commanding the pump to run more. So, if you measure the voltage doing to the motor, in the condition you have, you should be seeing the fuel pump getting 12.6 VDC or higher (ie, trying to raise pressure). If you are getting something in say the 8.0 VDC range, then your fuel pump is being told that it is at the right pressure and to maintain that pressure. This then leads back to etiher a bad fuel pressure sensor or a bad fuel pump module. Since you can get to the fuel pump module pretty easy, I would start with measuring the fuel pump voltage and then going from there.
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#9
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Well everything checked out. Out of curiosity I opened the locking ring for the tank and watched the fuel pump as I primed it with the key and I noticed the plastic hose coming from the transfer side of the tank is spraying inside the tank. It is close enough that I can repair it if it is possible. It's a small mist like leak. Is there a way to couple these pieces or is it a "replace it only" kind of thing?
It's called 'convoluted nylon fuel line'.
It's called 'convoluted nylon fuel line'.
Last edited by Gophat; 01-04-2023 at 11:59 AM.
#10
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Gophat (01-04-2023)
#11
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You might want to contact member Dr Dome who parts out X's. I would hazard a guess that seldom are the internal hoses a piece/part that is kept or requested. Pump, tank, yes but hoses not so much. http://www.radiumauto.com/Submersibl...bing-P672.aspx
Last edited by Dell Gailey; 01-04-2023 at 09:29 PM.
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Gophat (01-05-2023)
#12
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Long story short, I called the Jaguar vendor who sent the "new" pump and apparently they boxed a core as new by mistake, funny thing is it looked clean and no smell of fuel out the box. This pump was leaking through the assembly and the hoses were cracked. He is sending me another unit with the hoses brand new. It was supposed to already have the hoses attached that go to the sender on the driver side.
I went through all this, what a learning experience.
Thank you guys again for all the help. Sometimes it's not us but the actual parts store now. Wow.
I went through all this, what a learning experience.
Thank you guys again for all the help. Sometimes it's not us but the actual parts store now. Wow.
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Gophat (01-06-2023)
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