Bad mileage
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Bad mileage
You guys have helped me immensely in the past so I hope you can again. I had a problem with my truck jerking badly and it turns out I had 100 psi of fuel pressure. They changed my fuel switching valve since I have dual fuel tanks and it was okay for a while. Now I can hear my fuel pump running loudly. It's brand new. It's the high pressure one on the frame rail. My mileage has dropped horribly. I use 1/4 tank to go 20 miles. I have no codes except for 63, which is TPS below minimum voltage. I have changed the TPS 3 times and I still get the 63. My idle is rough. It goes from 500 to 800 back and forth constantly. I have changed every sensor that can be changed. I have changed every part of the fuel delivery system as well. The only thing I can think of is the fuel pump relay switch. I'm not sure what it looks like though. It doesn't give a code for this on my code reader. Any thoughts?
Billy
Billy
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From: Durant, OK (SOSU)
What year, engine, all that? We need more info!
Ok...dual tanks...sounds older, perhaps carbed? Carbed at 100psi, I can't believe it would even run, but if it did it would suck gas like no other.
Ok...dual tanks...sounds older, perhaps carbed? Carbed at 100psi, I can't believe it would even run, but if it did it would suck gas like no other.
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From: Eastern WA
I think for now, and assuming that your fuel pressure is within spec (I assume you have checked), I'd focus on the cause of code 63. Have you gotten your hands on pinpoint diagnostics for this code and gone through it? One must remember, a code in itself is not always caused by a failed sensor. Could be things such as a bad connection, broken connection, or even a seemingly unrelated sensor (been there, done that). I don't know off hand on yours if idle equates to low or high voltage, but if the ECM is seeing a signal corresponding to a much higher throttle position than when it is actually at idle that it's possible for it to respond with fuel based on the higher than idle throttle position (ie, rich).
Last edited by CowboyBilly9Mile; Mar 13, 2006 at 07:01 PM.
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From: West Mansfield, Ohio
If you checked your pressure on the fuel rail (I assume you did) and you're getting 100 PSI, the FIRST thing you need to check is the fuel pressure regulator. There is no way on God's green acre your FPR can be in working function getting 100 PSI. The FPR is the piece connected to the fuel rail, in close proximity to the front of the engine. It has a vaccuum line attatched to the top of it. It's looks are hard to explain, but replace that because I can promise you that it's not in working order.
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From: West Mansfield, Ohio
Fuel Pressure Regulator...
That is the fuel pressure regulator. The nipple on the right side in the picture will actually be pointed towards the 1:00 position, if looking at the front of the engine.
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I replaced the fuel pressure regulator once and then when the garage fixed the fuel pressure problem I replaced it again. This is the 3rd TPS I have changed. I had the original one. I bought another one and it read too high. Now this one reads too low. I understand how it may think that it needs more fuel if it is reading low, but why would my fuel pump be so loud. You can really hear it working when sitting at idle.
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From: West Mansfield, Ohio
So let me get this straight.... you have a brand spanking new Fuel pressure regulator installed correct? And you have somewhere between 35-40 PSI correct?
As for the fuel pump, Ford's are known for some pretty noisy fuel pumps. Mine one day just became noisy on my Ranger, and that "one day" was about 2 years ago. Still crankin to this day.
As for the fuel pump, Ford's are known for some pretty noisy fuel pumps. Mine one day just became noisy on my Ranger, and that "one day" was about 2 years ago. Still crankin to this day.
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Yes, it is a brand new fuel pressure regulator. When I say noisy, I mean it sounds like it's working overtime. Much more than I ever heard before. When they fixed the fuel switching valve last week they pulled all the lines off. I suppose it could be clogged again though. What does everyone think of maybe the ECM going bad? Would that cause the pump to run incorrectly and the 3rd TPS to still read wrong. Also, could it cause my idle to swing back and forth? Thanks for everyones help so far.
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Each tank has a low-pressure pump and the one on the rail is the high-pressure pump. The high-pressure one is the one making the loud noise like its running overtime constantly. I did get a code for the TPS. It is 63. What's strange is this is the third one I have put on now. I took the original one off and put a new one on. It read too high. Now after I put this new one on it reads too low. I'm totally lost.
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Check the TPS connector. That year had problems with the wires corroding in the back side of the connector. Also make sure the pac-con seal is still in place in the connector, if its missing it can cause a loose/bad connection causing a low/erratic voltage reading . Are you back probing the TP sensor or using a break out box to read voltage? Sometimes back probing will not always give you an accurate reading. Disassemble the wires from the connector & check for corrosion or loose terminals. Resolder the wires to the terminals & clean the contacts.
Last edited by 03XLT4x4 Flareside; Mar 14, 2006 at 10:09 PM.
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I have another question. I have two vacuum lines that go into some type of sensor on the passenger side of the engine. I'm not even sure what it's called. It shows it under the hood on the decal as being egr and egr to a solenoid. It has a little disc on the bottom of one of the pieces and there is a block with a electrical connector and another block with another electrical connector that are connected together. There is a green and red vacuum line that goes into it. The green vacuum line comes from the egr and the red one comes from on top of the throttle body and they plug into this sensor thing. Right now it is running real rough and it idles from 400 to 800 back and forth almost dying. When I unplugged the red vacuum line that goes into the top of the throttle body to a larger vacuum line it idled perfectly and didn't try to die. Does this make sense to anyone? What could cause that?