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Bad gas mileage and P1105

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AK Maniak

10+ Year Contributor
2,073
18
Jul 9, 2009
Butte, Montana
Well i've been having really bad gas mileage lately (150 miles per tank) and today when I started my car I got a CEL so i had autozone scan it and it came back as a P1105 which i guess is the fuel pressure regulator. I don't know if this is related to it but I changed my spark plugs 3 days ago and when i pulled them they were a bit white, which I thought meant the car is running a bit lean. Either way the car still ran fairly well or atleast I didn't notice any difference while driving it with the CEL.

Another thing is that when i'm idling and i push my clutch in, the RPM's drop a bit:notgood:
 
yes its a fuel pressure regulator. its at the far corner of the engine bay on the driverside. there should be two vacuum lines going to it. check to see if there connected or something might be clogged in it or the solenoid might be just burned out. check the wire connections as well to see if there are any wires broken or anything unsual about the wiring. after you do all that and the code still pops up (after clearing the code of course :thumb: ) then your fuel pressure regulator is burned out. you can go to a junkyard and get a new one or you can go out and buy an aftermarket one like an aeromotive fuel pressure regulator. they work great too. i hope this helped! :cool:
 
It isnt the fuel pressure regulator, this check engine has to do with something else I believe it is related to a vacuum leak
 
i had this code pulled up in 98 talon tsi awd and replaced the the regulator and the vacuum lines and it never came back on again. i got the regulator at a junkyard for 10 bucks :thumb: but it could be something different tho. try doing that and let us know what happens. and yes that could effect your gas milage.
 
I believe P1105 is the code for Fuel Pressure Solenoid Malfunction. Try to check if that's problem.:D
 
What type of plugs are you running??? also do you use any fuel additives??? lucas fuel injector cleaner??? etc.
I'm using NGK BRPE7's or 6's I can't remember which but its not the colder of the two. I don't use any fuel additives (Should I be?) just the 91 pump gas.

I believe P1105 is the code for Fuel Pressure Solenoid Malfunction. Try to check if that's problem.:D

Sorry for the newb question but how would I go about doing that? Just replace the Solenoid?
 
no worries about the question, if your not sure about something, never hesitate to ask and yes just replace the solenoid and maybe the vacuum lines on it because they might have a tear in it or something. go to a junk yard or to your local parts store and tell them you need a fuel pressure solenoid, it should look a little something like this...

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all thats holding it on is a 10mm bolt and the vacuum lines and just unplug it and plug the new one in and you should be set. dont forget to clear the code.:thumb:
 
i believe that code is for the fuel pressure solenoid. make sure you reset the computer, ie. unplug the battery or clear the CEL with a scanner, after you install the new one. all the solenoid does is open and close. It allows more fuel when cold(43.5psi) and less when its warmed up(37-38psi). if its malfunctioning you could be dumping fuel hence your poor gas mileage. good luck keep us updated.
 
Fuel pressure solenoid. Helps out on hot starts. When my car threw this code and started dumping fuel it ended up being my o2 sensor. Get yourself a logger and check for proper sensor function.
 
Could you just hook the fpr straight to the manifold? I know it wouldnt help with the CEL but would it help with the issue of the car running rich?

Yea I bypassed the fuel pressure solenoid when I was trouble shooting and it had no ill effects. It wouldnt cause any extra fuel to be dumped either because it can only lower fuel pressure. To the OP I would again highly suggest using a logger and checking the front o2 sensor. Mine did the exact same thing and thats what it turned out to be.
 
I have this issue too I changed the fuel pressure solenoid cleared the ecu it was off, ran for over an hour never came back, got home hot started it and cel came back. Would it have anything to do with having a 190 wally with stock injectors and fuel regulator can i be overworking the stock system. and thowing a cel or should i look into the 02 sensors, the car had no cat on it, but I have a stock dp on it now for emmissions.
 
if the question above me could be answered that'd be great. i threw this p1105 code yesterday and was wondering the same thing, if i've got a wally 190 or 255 and stock injectors and fpr (which i do) could this overwork the solenoid and cause it to be damaged?

Also wondering if the solenoids are different between the turbo and non turbo 2g eclipses
 
The 190 will not over work the stock fpr or the fuel pressure solenoid however, the 255 is to much for your stock fpr and would be over working your fuel pressure solenoid. You can use the solenoid though with an afpr. Im not sure if the n/a's fuel pressure solenoid is compatible with our turbo'd one. i would assume not because our solenoid is reading boost when n/a's are not. That would be a completely different signal to our ecu if we miss matched them, but that's just my opinion though.



p.s. i noticed you were from milford 97 cavenne if you need anything or any help let me know im right down the road. im gonna be working down there soon too.
 
Hey guys! Sorry to bring this threat back to life, But I have a question. Does the Fuel Pressure Solenoid need to be hooked up to a vacuum at all times? If so is there a diagram or how do I hook it up. Mine is connected to the plug but not to the hoses, and I have code P1105 among others that Im trying to figure out.

Thanks for your time and help.
 
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