MPG problem & solution
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Posting Guru
Joined: Jun 1999
Posts: 1,083
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MPG problem & solution
Just a tip to pass on:
When your truck's fuel efficiency goes into the toilet, proceed as follows 1) run code check to find and possibly isolate cause 2) check ignition and spark systems and sensors 3) check exhaust for blockage/restrictions and 4) check fuel pressure at fuel rail.
Recently went through this with my 90 F150 300-I6 and no. 4 was the problem...bad fuel pressure regulator. Test only cost $20 and total repair was about $150 (I let them do it), would have been about $50 if I still had the patience to do it myself. Gauges also available from parts stores to check fuel pressure yourself, just get one that screws onto the check valve and will read up to 100 psi. My truck was pumping gas at 85 psi and of course sending a lot of gas/soot through the tailpipe. If you encounter this, follow steps 1-4 in whatever order is convenient, as quickly as possible, and you'll save yourself some grief and $$$$. Also check out the Ford Forum at:
www.westecauto.com -- it's another good site for ford folks, but not truck specific.
When your truck's fuel efficiency goes into the toilet, proceed as follows 1) run code check to find and possibly isolate cause 2) check ignition and spark systems and sensors 3) check exhaust for blockage/restrictions and 4) check fuel pressure at fuel rail.
Recently went through this with my 90 F150 300-I6 and no. 4 was the problem...bad fuel pressure regulator. Test only cost $20 and total repair was about $150 (I let them do it), would have been about $50 if I still had the patience to do it myself. Gauges also available from parts stores to check fuel pressure yourself, just get one that screws onto the check valve and will read up to 100 psi. My truck was pumping gas at 85 psi and of course sending a lot of gas/soot through the tailpipe. If you encounter this, follow steps 1-4 in whatever order is convenient, as quickly as possible, and you'll save yourself some grief and $$$$. Also check out the Ford Forum at:
www.westecauto.com -- it's another good site for ford folks, but not truck specific.
Postmaster
Joined: Jul 1999
Posts: 3,172
Likes: 4
MPG problem & solution
TM ,
Im glad you got it nailed ... Good lord , 85psi is a lot ...Im surprised something didnt let go .I put new injectors in my 90 300 a few yrs ago , working there isnt really that bad , lots of room once the upper intake is off ,Hardest part is lining all the injectors back up in the fuel rail and then having them all line up in the intake holes . Just a note if anyone is interested , I got a good fuel pressure gauge set from Mac Tools that fits several different shrader vavles , its been very handy diagnosing fuel related problems .
Paul
Im glad you got it nailed ... Good lord , 85psi is a lot ...Im surprised something didnt let go .I put new injectors in my 90 300 a few yrs ago , working there isnt really that bad , lots of room once the upper intake is off ,Hardest part is lining all the injectors back up in the fuel rail and then having them all line up in the intake holes . Just a note if anyone is interested , I got a good fuel pressure gauge set from Mac Tools that fits several different shrader vavles , its been very handy diagnosing fuel related problems .
Paul
