1991 4.9 (300) i6 power loss, bad mpg, gassy startup
01-23-2019, 02:48 AM
#1
1991 4.9 (300) i6 power loss, bad mpg, gassy startup
Hey 8th gen crew. My 91 F-150 is having some trouble. Check engine light is on, idling around 1200 rpm so clunks really hard into gear, which is a recent occurrence. Been running pretty rich for a while based on the gassy smell and poor mpg’s (11/13.5 city/hwy). Hasn’t had as much oomf recently either. I’ve chalked this all up to being old, but something is obviously wrong. Any hints? I’m thinking clogged cat as of now but I’m not sure. Any feedback is appreciated!
01-23-2019, 05:12 AM
#2
Senior Member
I would start with a code scan, as primitive as it is may give some direction as far as troubleshooting. See what the CODE (S) are. There are many things to check, don't go guessing and start replacing everything under the sun. I would start with checking of fuel pressure, condition of the plugs and hang a vacuum gauge off the intake manifold to verify 18-22 inches of steady vacuum. The vacuum gauge can also be used to check the CAT but I do not think that is the cause for rich conditions. It may end up being a victim of your engine running rich if you are still driving it. Pull the vaccum line off the fuel pressure regulator regulator and look for raw gas or a smell of raw gas which would indicate a ruptured diaphram. The raw gas would get sucked into the intake and dramatically richen the mix.
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jdaum1222 (01-23-2019)
01-23-2019, 11:02 AM
#3
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---not appreciated---
Last edited by Steve83; 01-24-2019 at 11:59 PM.
01-23-2019, 12:07 PM
#4
"My engine has nearly a million miles of hard use, and runs like-new. There's no reason yours shouldn't, other than neglect & abuse."
alright big shot. go troll somewhere else.
alright big shot. go troll somewhere else.
Last edited by jdaum1222; 01-23-2019 at 12:10 PM.
01-24-2019, 11:59 PM
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Clearly, you don't understand what a forum "troll" is, or how to recognize when someone is trying to help you. Good luck.
01-25-2019, 01:16 AM
#6
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01-30-2019, 04:52 AM
#8
Senior Member
Thanks for the update. I did get a chuckle out of the "nearly a million miles of hard use, and runs like-new ". Maybe Ford will have Steve on one of their commercials.