bad gas milage =/

[llamaking122]

so i have been getting 8-9mpg city mad did plugs and wires and they were carbon fouled, most likely from seafoaming it after 300k miles XD. and the idle is a little better and it idles were it should it just every couple second it misses. but its just a slight miss. not one were it wantes to die. going to do 02 sensors this weekend. but im leaning more towards FPR(or something else?) but how do i go about chaging the Fuel presure regulator? No codes what so ever.

 

[llamaking122]

If it helps at all my new DPFE sensor (erg sensor) went bad after 3-4 months a.k.a its coding for it again. I have a code reader so I read codes as soon as they appear

 

[rhauf]

i had the "slight miss at idle" problem as well. turned out to be a small crack in the air intake duct (between the MAF and the TB). fixed the crack and it runs much better now. it was sucking in a little air and running lean.

changing the fuel pressure regulator is pretty easy. it's right on top of the intake manifold at the end of the fuel rail on the passenger side. IIRC there is one fuel line going to it, one vacuum line, and it has an O ring fuel fitting on the bottom. i think there is only one or two bolts holding it in place. have you tested fuel pressure?

 

[llamaking122]

i had the "slight miss at idle" problem as well. turned out to be a small crack in the air intake duct (between the MAF and the TB). fixed the crack and it runs much better now. it was sucking in a little air and running lean.

changing the fuel pressure regulator is pretty easy. it's right on top of the intake manifold at the end of the fuel rail on the passenger side. IIRC there is one fuel line going to it, one vacuum line, and it has an O ring fuel fitting on the bottom. i think there is only one or two bolts holding it in place. have you tested fuel pressure?

My dad has too find his fuel pressure tester. You know I never thought of that hmmmm im going too have to look into the small crack thing

 

[llamaking122]

So you got me thinking (someone had too haha) the rubber gasket that goes around the intake at the throttle body is missing so I bet that is it. Ima look in the classifieds for another =/

 

[rhauf]

So you got me thinking (someone had too haha) the rubber gasket that goes around the intake at the throttle body is missing so I bet that is it. Ima look in the classifieds for another =/

Looks like you found the problem. If you can't find one im sure you can make one out of something.. there are also after-market intake systems which replace that whole tube you could buy as well.

 

[llamaking122]

Looks like you found the problem. If you can't find one im sure you can make one out of something.. there are also after-market intake systems which replace that whole tube you could buy as well.

ok so that didnt work and my milage is slowly getting worse. tommorrow i will be replacing the O2 sensors and cleaning the maf sensor wish me luck. then next friday i wil buy a fuel pressure regulator tester 9or if anyone close has one i could stop buy please?) with gas prices going up im thinking im going too sell it here soon so i have too get her running good. i just wish my acura integra transmission hadnt gone bad.. that was GREAT on gas. it just wasnt great for big people haha

 

[Zolepup]

Thermostat?

 

[llamaking122]

Thermostat?

i dont think so but i may pull it off one day too check

 

[llamaking122]

i dont think so but i may pull it off one day too check

so i dont think thermostat. i drove my dads wich has a new theremostat and it heats up in the same time.

 

[llamaking122]

ok so i started her up today and got out too put on my coat and the idle was boucing but then it settled down areound 750 ish. i really hope i find this soon or im selling the truck =(

 

[1AJeremyD]

sounds like it could be an injector going bad. Does it miss under throttle at all or is it primarily while at idle? Trying cleaning them with either some fuel injector or run some seafoam through it.

I've had some issues with my truck not starting properly in the morning if I start it up and let it warm up without driving it immediately. My MPG is garbage right now. Luckily I don't live TOO far from work so I use only about maybe a gallon one way. Im doing some seafoam tomorrow. Might even post the fun online for everyone.

 

[llamaking122]

its JUST at idle. i am pretty sure. when i accelerate and hold the pedal it is steady. ive run alot of fuel injector cleaner so i do not think its a stuck injector but it could be

 

[llamaking122]

would this work? http://www.harborfreight.com/fuel-injection-pump-tester-92699.html

 

[llamaking122]

I think it may be the crank sensor because when I drove 30 minutes to my grandpas went inside then after 10 mins or so he asked me to go too the store and I started it up and it idled like **** then after a little driving it cleared up to just a slight miss. I drive about 10-15 miles total a day so it barely gets too operating temp

 

[1AJeremyD]

I still think it could be an injector isn't spraying properly. Might be time to pull the injectors and clean them out by hand. if the crank sensor wasn't working you wouldn't be able to start the truck at all. A single miss is either related to the fuel or the spark. Have you been able to pin point which cylinder is missing? Once you get that one figured out go from there. You may have to just put in new plugs and wire. I'm currently leaning more towards fuel related issue though.

 

[gmanpaint]

I just went thru this on a 94. Turned out the vac line to the FPR was off. I got lucky. Went from 8mpg to 16 mpg by simply returning that vac line back on.

Check the vac line coming off the FPR going to the vac tree. Pull it off and look for fuel in it. If it is dumping fuel in the intake, your MPG will go to crap, and the FPR needs replaced.

It could be as Jeremy says as well, just giving you something else to check into.

 

[1AJeremyD]

^^^forgot about that line lol. I remember writing in about that with someone else. Once I get stuck on an idea I stick with it but definitely good thought! Did yours stumble only at idle as well or was it under all conditions gman?

 

[gmanpaint]

Oddly enough, it ran just fine with that line off. It was hard to figure out because of that.

I was talking to Corkey, and he had just helped a friend with the exact same problem, same bad MPG, and no change to the running condition. Turned out to be a bad FPR. That lead me to the vac line on mine.

 

[1AJeremyD]

See thats the thing, if it just had a bad MPG deal then I would say for sure FPR on the rail. Since his stumbles at idle but not under load that just seems more towards fuel not getting to the engine. The FPR would as you said dump fuel into the system and richen everything out and create not just one but maybe multiple misfires if the engine could not compensate for the excess fuel. He could end up having a couple of related problems. Never hurts to rule out all possibilities though