mpg problem, take 2
Posting Guru
Joined: Jun 1999
Posts: 1,083
Likes: 1
mpg problem, take 2
Well, bought vacuum pump/gauge test kit and ran some checks today. MAP sensor is okay, Throttle position sensor okay, EGR okay, Air bypass valve okay, fuel pressure regulator okay. BUT, truck did fail the intake manifold vacuum test (vacuum drops more than 3 Hg as rpms rise from 1000 to 2500), so guess I'll bite the bullet and replace the Cat as failure of this test indicates exhaust restriction. If that doesn't improve mpg, guess I'll try fuel system options. Truck is running rich, ie. black soot inside tail pipe and on plugs, too. Would a toasted fuel filter cause excess fuel consumption? Wouldn't a toasted fuel filter make it gasp for fuel rather than burn too much? Gotta be a way to put this truck back up to 17-19 mpg from the 12 mpg it recently sunk to. Sorry for the long post, been a long day without firm answers. Any replies appreciated.
New User
Joined: Jul 1999
Posts: 19
Likes: 0
mpg problem, take 2
An overly rich fuel mixt. causes the cat to over heat thus destroying the cat (causes internal meltdown). If detected soon enough, the cat can be saved. I have seen cats glowing red as a result of over-rich. It's a prolonged state of serious over-rich that will destroy a cat.
