changed plugs and cleaned butterfly to fuel injection still smelling unburnt fuel and very bad gs milage any ideas

 

Have you changed the cap/rotor and plug wires?

Is the Check Engine Light (CEL) on? Even without a CEL on you can still have codes, have you checked for codes?

What modifications have been done to the truck? taller tires?

Does the truck have two tanks? is the calculated MPGs the same on both?

What kind of mileage are you getting and under what driving conditions?

 

only getting like 6 miles per gallon no engine light tires r pretty much stock

 

What RLA said.

If you wanna check for one obvious problem, pull vacuum line on FPR and check for fuel. If its got gas leaking from it, then that's a problem. Try turning the key to start/run position and check to see if fuel starts leaking from it.

Everything else is gonna need some diagnosing and post back with your results from what RLA asked.

Other members will chime in soon, I'm sure.

 

Gonna have to check for stored codes. Bulb could be burned out.

Www.oldfuelinjection.com shows you how to pull codes for free. Or $35 for Equus code reader, which is a Gold mine when owning these vintage Ford's!

 

service engine light works not leaking fuel smell unburnt fuel in exhaust

 

cat been gutted?

 

Have you tried pulling codes yet? When was the O2 sensor last replaced? What about the cap, rotor, plugs, plug wires, fuel filter...all the usual tune up parts? Have you verified the timing? What method are you using to calculate your mileage?

To receive quality information, you need to provide quality information.

 

changed plugs will check codes after i change wires cap rotor oh i did change filter

 

And about the O2 sensor, ignition timing, and mileage calculation method?

 

don't know about o2 sensor only had truck 4 months as for milage went with gallons and miles drivin

 

havn't checked timing yet thought was timed by computer any idea what it should be at

 

Provided that a tuneup (plugs, wires, cap, rotor, etc) doesn't improve the mileage significantly, that the ignition timing is set at least 10* BTDC with the SPOUT removed, and that no codes are present, I'd certainly consider replacing the O2 sensor, as that is the sole means of feedback to the ECM in regards to AFR correction.


RockAuto has the NTK (which I'd suggest) for $27.79 plus shipping, before the easily obtained 5% discount.
www.rockauto.com/catalog/moreinfo.php?pk=1643146&cc=1122107

 

10 BTDC.....

Fuel Injection Technical Library » Setting the timing

 

Dual tanks?

These trucks are prone to pushing fuel from the tank in use to the one that is not. It's known as crossflow and it happens a lot. That is why we ask if you have two tanks. So if you are using only one of the two tanks, one tank may be filling the other. Sooner or later the unused tank will start to overflow. And it makes it look like the MPGs are in the toilet.....