Let me first start this by saying i am not nor to i claim to be a know it all, i am here asking for help because i am at my witts end,

I have a 1995 ford f150 flare side, when i bought it, there was a 5.0 with a hole in the block, i then proceeded to buy myself a motor from a gental man a few towns away turns out the engine i bought was out of a late 80,s van, so i changed the intake and all that good stuff on the front over to the serpentine setup and slapped it into the truck, when it fired for the first time it was missing and spitting and backfiring so i proceeded to do research on firing order differances from the 80's to the 90's turns out 3 plug wires are off, so i switched them and started driving the truck it runs okish it has a miss but not bad at all defintly drivable it doesnt start hard it doesnt spark knock nothing too abnormal untill you get to the fuel milage, it LITERALLY uses so much fuel it took me 3 months to convince myself it wasn't leaking its just burning (or not burning) that much fuel (to drive about 10-15 miles and then back burns roughly a quarter tank) and thats not me with a heavy foot i have made it a point to drive it like a 900 year old person would and it does not seem to get any better, i have been told by some people that its because i didnt change the cam to the newer style to the valves are opening and closing at the wrong time, and some people have said something about the crank being differnt i am looking for a VERY FAST AND VERY CHEAP way to make this truck run right and increase the fuel economy back to what its should be ANY ADVISE OR KNOWLEDGE WOULD BE APPRECIATED

 

welcome to fte. im not up on the differences on the engines. but my buddy was having a problem of what he thought was using to much fuel but it turned out to be it was going into his other gas tank.

 

You know what i didnt even think to check that thank you i will go outside on my next smoke break and check and see if there is a unexplained amount of fuel in my second tank thanks very much for the input


Edit: i checked that possibilty and my second tank is bone dry the truck tries to die as soon as i switch tanks and thinking perhaps the fuel pump was no good back there i also banged on the tank and it is empty as can be

 

Some other items to consider when using the older 5.0L engine with your 1995 truck that is most likely using a Mass Airflow (MAF) control system. Not only is the spark timing different you will need to swap around the injector wiring as well to accommodate the older firing order. If your truck was using Speed Density (SD) the injector firing is not much of an issue, the PCM fires 4 injectors, then the other 4 (batch mode). MAF uses sequential firing for the injectors.

 

Thank you very much for the advise i will defintly be looking into this thanks again

 

Getting a newer (than yours) used engine could be a cheap and less complicated way to solve you problems, droping in a 90's engine and selling yours I think would save you a lot of trouble (and gas).