I've got a 1991 F-150 300cfi with approx. 190,000 miles on it. Over the last several months the fuel milage has gone from 17-19 mpg to around 13 mpg. This is occuring on both tanks. Compression checks are good, new plugs, cap and rotor, plug wires, fuel,air, crankcase filters. Does anyone know if the either the coil or the TFI system that bolts to the sude of the distributor will fade out or when they go do they die completely? Do I need a new distributor?

 

i'd maybe check for restrictions in the exhaust, if it is running ok otherwise. if you had ignition problems you would have a miss, hard starting or dying out, not just poor mileage.

 

Well, my 300-6 just up and died on me the other day. No sputter, just stopped.
Checked the coil: NO Spark.
Damn...
The troulbleshooting part in the Hayes manual didn't say anything about the TFI Module, but after taking the distributor apart to change the pick-up gizmo, I popped off the cover of the TFI Module to see the little computer chip in the gooey (thick film)stuff.
Figured I had me a Y2K problem...

Anyway, I did a search on the net for info, and it turns out that I wasn't alone, or the first.

Read an article and a law suit regarding the stupidest place to put the TFI module at the following two sites:
<a href="http://www.examiner.com/990502/0502ford.shtml">http://www.examiner.com/990502/0502ford.shtml</a>
<a href="http://www.autosafety.org/fordweb/Ditlowdec2.html">http://www.autosafety.org/fordweb/Ditlowdec2.html</a>

I popped a new one in ($62.00) from Pep Boys, and it fired right up. Mileage is better now also.
You need a 7/32" nut driver or thin wall deep socket to get the screws out.

Funny thing, while I was in Pep Boys, the guy behind me had the same problem. His on Jan 1, and mine on Jan 4. They guys in Pep Boys say they can barely keep these on the shelf.
I'm considering just running 4 wires to the distributor to keep the TFI Module away from all that heat. 3 wires for the terminals, and one for the case ground.

How many cases of this has occured to FORD owners?
I know I ain't alone
Regards,
Pete

 

TFI modules arent the greatest design in the world . Ive been told by Ford Techs to replace them any time after 70K miles or so ? They do fail with no warning . The best way to go with an older model that uses them is to keep a spare one in the glove box along w the little tool made to remove the recessed screws ...I got the tool from Lisle , very reasonable price . Also its a good idea to dab a layer of Dielectric gel on the back of the module , It helps disapate the heat .
Paul

 

 

IS there any way you can test this TFI module, ?
so you dont hve to shell out the $ for one if it is not your problemo ?

 

You can isolate your problem to the TFI module by following the checks in your Haynes manual. Section 5-10. When the module goes bad, your truck all of a sudden won't start one day. $30 for a Wells replacement at Autozone, $5 for the special tool, and 10 minutes to swap them.

Hope this helps....

TM

 

Do what I did. I scrapped my TFI ignition for the old points system. You can use a dura spark system or you can get an aftermarket distributer that is totally independent from your current system. The distributer comes complete all you need is a hot wire and you will eliminate your current system. It costs about $400.00.

 

This is a fix:
If everything seems to be working ok the next
venture is to(lone star beer case) take a piece of
cardboard with alumium sheet anchored to one side.

alumium>-----------___________<cardboard overlap.

cut to fit so there is at least 1/2" clearance or more
all around and slide it into the area below the TFF.
Try to fit it back against the manifold and out about
3? inches from the radiator fan. There isa gas line
(carb) to the right(driver view). Wire it(this heat shield)
and it will stay in place. The heat from the motor is
shielded away and the air from the fan helps keep
and even temp. Some revision for fuel will be necessary.