Gas Guzzler
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Gas Guzzler
I've got an 87 F-150 4x4 with a bit of a drinking problem. It has an EFI but I'm not sure if it's a 302 or a 351 or if it's even the original motor. Either way, I can't seem to keep gas in the poor thing. It just doesn't seem right that my 78 supercab on 33" tires and a carbeurated 400 gets way better milage. I had problems with it flooding out and starting back up, so I put new plugs in which solved the starting problem. But then it would stall out driving down the road(good thing it's a 4-speed) so I put a new filter on and solved that. The thing has power galore, but also drinks more gas than it should. When I first got it the temp guage ran close to half way and then one day as I was driving it dropped down to a little over a quarter way up suddenly. Been running that low ever since. Is it true that the temp sending unit might have some affect on my milage? Or does it sound more like my injectors are bad? If anyone has any ideas I would really appreciate it, cause I can't stand having to drive my 78 down our salty MN roads.
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The temperature of the engine can affect the mileage. The computer will not go into "closed loop" and trim the fuel by the oxygen sensor if the engine never warms up. Make sure you get the factory 195 degree(or whatever it takes) thermostat.
It's hard to believe a 400 would get better mileage than even a poorly running EFI engine. And you say it has lots of power, so I am suspecting you also have a very low ratio rearend.
It's hard to believe a 400 would get better mileage than even a poorly running EFI engine. And you say it has lots of power, so I am suspecting you also have a very low ratio rearend.
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The tag on the front diff said 3.54. But it still runs almost 3000 at 65mph. The tranny seems pretty low geared. It's a 4-seed, but I usually only use 2-4 cause 1st is so low.
I just talked to another mechanic and he said it sounds more like the fuel pressure regulator, and maybe the engine temp switch or o2 sensor. I'll see what I can figure out. Thanks for the help.
I just talked to another mechanic and he said it sounds more like the fuel pressure regulator, and maybe the engine temp switch or o2 sensor. I'll see what I can figure out. Thanks for the help.
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From: Virginia
You can check the fuel pressure. It should be around 40 psi. The O2 sensor would be something good to change too. I believe I read they get covered with soot and contamination over time, and that can affect their ability to work correctly.
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Joined: Nov 2004
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From: Asheville, NC
Change the thermostat first, if you havent already done this. Use a 195 degree, probably, and get a STANT, if you can. I'm in no way advertising for this company, but in 35 years of driving, I have never had a 'stat by Stant to fail.
2 from Autozone have failed OPEN on me in the last year.
2 from Autozone have failed OPEN on me in the last year.
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