Increased fuel mileage
06-20-2017, 08:48 PM
#1
Junior Member
Thread Starter
Increased fuel mileage
1988 F-150, 302, 2wd, EFI, a/c, dual tanks. I bought this truck about three years ago and have had very good results with it. It has, as a guess, 280,000 miles on it and maybe more. Last December 2016 I had to replace the engine cooling system totally. I have an intake manifold vacuum leak I'm aware of. I have the gasket set ready to replace. Here's the quandary. Since I've owned it my fuel mileage has been around 12 to 13 mpg. As of this week I am now getting 21.6 mpg. Why, and more importantly, HOW can I keep this mileage? I've replaced the TPS two months ago and not much else. I like my truck. She (Efie) is a good girl.
06-20-2017, 09:25 PM
#2
If you have a vacuum leak, it could be running very lean, which would give better MPG, but is not doing the engine any good. bad for valves and pistons to run that lean.
06-21-2017, 02:35 PM
#3
Senior Member
1988 F-150, 302, 2wd, EFI, a/c, dual tanks. I bought this truck about three years ago and have had very good results with it. It has, as a guess, 280,000 miles on it and maybe more. Last December 2016 I had to replace the engine cooling system totally. I have an intake manifold vacuum leak I'm aware of. I have the gasket set ready to replace. Here's the quandary. Since I've owned it my fuel mileage has been around 12 to 13 mpg. As of this week I am now getting 21.6 mpg. Why, and more importantly, HOW can I keep this mileage? I've replaced the TPS two months ago and not much else. I like my truck. She (Efie) is a good girl.
06-28-2017, 08:01 PM
#4
Junior Member
Thread Starter
Apparent vacuum leak
Having owned one of those (86 5.0 EFI and a 96 5.0 EFI), if you're getting 21mpg, either your odometer is broken, or you are running DANGEROUSLY lean. Those trucks in their best running shape will never see anywhere near that. 12-15 is what I would expect. Anything more or less, and I would start looking for problems.
Just now getting back all and all say the same thing. So far have narrowed the leak to the intake manifold. Also noticed a device to the left of the ignition coil that has an electrical connector and a vacuum hose bundle to it. It is missing a "top cover" and I can see the phenolic boards (two) and the small springs now exposed. Sure that can't be good as well. Don't know what that is or what it's for.
06-28-2017, 08:07 PM
#5
Junior Member
1988 F-150, 302, 2wd, EFI, a/c, dual tanks. I bought this truck about three years ago and have had very good results with it. It has, as a guess, 280,000 miles on it and maybe more. Last December 2016 I had to replace the engine cooling system totally. I have an intake manifold vacuum leak I'm aware of. I have the gasket set ready to replace. Here's the quandary. Since I've owned it my fuel mileage has been around 12 to 13 mpg. As of this week I am now getting 21.6 mpg. Why, and more importantly, HOW can I keep this mileage? I've replaced the TPS two months ago and not much else. I like my truck. She (Efie) is a good girl.
and I'm a little surprised. I thought it would be worst. I suspect that once I put a bed cover it will get even better
...............
06-28-2017, 08:14 PM
#6
Just now getting back all and all say the same thing. So far have narrowed the leak to the intake manifold. Also noticed a device to the left of the ignition coil that has an electrical connector and a vacuum hose bundle to it. It is missing a "top cover" and I can see the phenolic boards (two) and the small springs now exposed. Sure that can't be good as well. Don't know what that is or what it's for.