89 351w Efi Help!
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Freshman User
Joined: Apr 2006
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89 351w Efi Help!
Whats up guys! Yes I am a newbie, but have been reading these post for sometime now.. Where to begin. well lets start with the fuel injection. This 89 f250 ext. cab long bed has 33 inch x 12.5 inch tires. with some sort of low gear ratio. To make a long story short this truck is being a kind of a pig at 6-7 mpg. I have replaced all sensors and the fuel regulator. could the injectors be messed up. and how can i check them. Then i have another issue with a low Diesel sounding noise around 2200 rpms ,with out a load after the truck has been driven for awhile. I have been told by someone it is my crank berrings??
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
Welcome to FTE!
What gears are in the truck now? Were they changed when the tires were put on?
A number of things can cause bad gas mileage. A clogged exhaust can do it, or any one of the sensors can also cause problems. Have you ever pulled the codes? It's very easy to do, all you need is a paperclip and the directions at www.fordfuelinjection.com. That will at least give you a good starting point.
What gears are in the truck now? Were they changed when the tires were put on?
A number of things can cause bad gas mileage. A clogged exhaust can do it, or any one of the sensors can also cause problems. Have you ever pulled the codes? It's very easy to do, all you need is a paperclip and the directions at www.fordfuelinjection.com. That will at least give you a good starting point.
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Freshman User
Joined: Apr 2006
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Hey Andy!
I am not sure what gears are in the truck now.
I know im pulling 3k at 60 though. All the exhaust has been redone up to the heads.. i bought a code reader from advanced, because my light was on. all that came up at the time, was something with the egr and throttle potioning sensor. I replaced the tps, reset the computer, and drove it around for awhile. the light has gone out and the reader blinks all fine.. so i dont know what was up with the egr. except i know i have disconnected the air pump, capped off the bottom of the egr, But also still have it hooked to the throttle body along with the sensor???
I am not sure what gears are in the truck now.
I know im pulling 3k at 60 though. All the exhaust has been redone up to the heads.. i bought a code reader from advanced, because my light was on. all that came up at the time, was something with the egr and throttle potioning sensor. I replaced the tps, reset the computer, and drove it around for awhile. the light has gone out and the reader blinks all fine.. so i dont know what was up with the egr. except i know i have disconnected the air pump, capped off the bottom of the egr, But also still have it hooked to the throttle body along with the sensor???
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Hey guys.
My first post.. but I saw something there I recognized. You have disconnected your air pump, and you are getting diesel sounds at cruising speed. That could be lean engine knock. The EFI system is calibrated to see the air from that air pump at the O2 sensor, and without it the ECU thinks the engine is running rich and leans out the mixture. I went through all this with my 89 when I installed aftermarket exhaust and removed the air pump because I didn't think it was really necessary. Truck ran like *** and displayed some of the same traits yours is.
My current truck has stock gearing(3:55) with 30" tires, and turns under 2k at 60mph. If you are spinning at 3k.. that might explain the lousy gas milage. I know mine goes south once I get over 2000rpm.
My first post.. but I saw something there I recognized. You have disconnected your air pump, and you are getting diesel sounds at cruising speed. That could be lean engine knock. The EFI system is calibrated to see the air from that air pump at the O2 sensor, and without it the ECU thinks the engine is running rich and leans out the mixture. I went through all this with my 89 when I installed aftermarket exhaust and removed the air pump because I didn't think it was really necessary. Truck ran like *** and displayed some of the same traits yours is.
My current truck has stock gearing(3:55) with 30" tires, and turns under 2k at 60mph. If you are spinning at 3k.. that might explain the lousy gas milage. I know mine goes south once I get over 2000rpm.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
I'm thinking your 2 problems are not related. The knocking at lower RPMs could also be ignition advance related.. what is this set at?
Your truck is probably close to 6000lbs, and has a stock 351 from what I gather. I bet you are heavy into the pedal all the time just to get it to go. I can get 15+mpg on the highway with my truck if I keep it under 2000rpm.. but it drops to probably half that around town when I'm standing on the floorboard blasting Honda Civics off stoplights.
Your truck is probably close to 6000lbs, and has a stock 351 from what I gather. I bet you are heavy into the pedal all the time just to get it to go. I can get 15+mpg on the highway with my truck if I keep it under 2000rpm.. but it drops to probably half that around town when I'm standing on the floorboard blasting Honda Civics off stoplights.
