"Low Fuel Exonomy" Light
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Senior User
Joined: Apr 2008
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From: Iowa
"Low Fuel Exonomy" Light
I recently bought a '75 F250 super cab 4x2. It has a 460, C6 and 3.55 gears. On the right side of the instrument cluster it has a light that says "low fuel economy". It comes on briefly when I floor it, unless the engine is actually working a bit- ex flooring while on a hill or when going 75+MPH
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It's definitely unique- anybody else's truck have one? I haven't seen one before. Was it a 460-only thing?
.It's definitely unique- anybody else's truck have one? I haven't seen one before. Was it a 460-only thing?
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
It wasn't a 460 thing, it was a 1975 only thing. Not all '75's have it so it must've been an option.
It works off a vacuum switch mounted on the firewall.
Under low vacuum situations (pulling heavy loads, hard acceleration, etc.) the light comes on alerting the driver to back off for better fuel economy.
Kind of ironic (and pointless!) to have something like this in trucks that get dismal fuel mileage under the best of situations.
It works off a vacuum switch mounted on the firewall.
Under low vacuum situations (pulling heavy loads, hard acceleration, etc.) the light comes on alerting the driver to back off for better fuel economy.
Kind of ironic (and pointless!) to have something like this in trucks that get dismal fuel mileage under the best of situations.
Senior User
Joined: Jul 2009
Posts: 377
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From: Canyon, TX
I've got one of those (disconnected, of course.) Yeah, it wasn't until recently looking at an old 75 brochure reprint that I saw the Low Fuel Economy light was an option. I don't know if that's funnier than it actually being useful! 
Save the old ones
Joined: Dec 2002
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From: Boyne Mich
If the light was calibrated to todays standards it would be on all the time!!!! Lol Even just Idling.
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Joined: Aug 2004
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Kinda like a guy I knew who bought his new Ford F-350 with the V-10. He was so proud of the engine. He went to show it off so he stomped on the throttle and the low fuel alarm started dinging at him.
Thing is, GM's 8.1L felt much quicker to me. All those cylinders to accomplish not much.
Thing is, GM's 8.1L felt much quicker to me. All those cylinders to accomplish not much.
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Senior User
Joined: Apr 2008
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From: Iowa
I don't know who would really order the light for that, LOL
It only comes on at full throttle if the truck is under a bit of load. I'll have to make a 0-60 vid sometime and watch the light.
Funny thing is my truck has a vacuum gage that looks about as old as the truck is. Somebody must've really been trying to get some MPG out of the old 460. It will get 12 on the highway, which aint bad.
It only comes on at full throttle if the truck is under a bit of load. I'll have to make a 0-60 vid sometime and watch the light.
Funny thing is my truck has a vacuum gage that looks about as old as the truck is. Somebody must've really been trying to get some MPG out of the old 460. It will get 12 on the highway, which aint bad.
Logistics Pro
Joined: Mar 2001
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Those babies eat gas when turned off by osmosis.
Elder User
Joined: Jan 2007
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From: Minnesota
When I was 17, I had a stock 460 in my 74 f100, and I drove it hard. I ended up cracking 2 pistons. I bought a wrecked f150 with a stock 390 and swapped in, which I drove equally as hard. I got considerable better gas mileage with the 460 then the 390. Years later I had an efi 460 in my 89 F350, which got considerably better gas mileage then the v10 I had in my 01 F350.
