Dear Car Talk; I have a 1994 Ford F-150 XLT with all the amenities, and with only 75,000 miles. Its red and white and looks great, but have a problem. I let it run out of gas about a year ago and when I filled it up it started missing. I have tried fuel boosters, replaced the fuel filter, twice, and even had it completely overhauled, meaning new plugs wires, distributor cap, twice., and it still misses.
At idle, you can feel a small but constant miss. When cruising along and I begin to give it a little gas, it shakes, or vibrates to the point that I have to feather the gas peddle. It acts as if it is starving for gas. I know it isn’t the transmission, because I have had to have that rebuilt recently and it works good. Once the truck is up to highway speed, it seems to smooth out some. Any suggestions?
I am not a mechanic but I wonder if letting it run dry might have messed up the fuel pump?
I guess it might be posable but my truck has two fuel tanks and when one tank runs out I switch to the other tank and the pump in the empty tank cuts of as apposed to the OPs the key would have to be turned of to stop the pump I wonder how long he went before turning the key t stop the pump running dry is not good for it.
Since you started with… I ran it out of fuel… that is what you should be focused on. Fuel, not ignition, not transmission, fuel.
Very likely trash got into the fuel system and into your fuel pump damaging it. I’d suggest your fuel pump needs replacement BUT have the pressure checked at idle and running down the road first to verify a bad pump before it is replaced.
Also some trash may have made it past the fuel filter to the fuel injectors and is now clogging them up. Replacement may be in order.
But your mechanic SHOULD have recommended this to you. If they did not, you may want to find a better mechanic.
If you are going into the shop telling them to replace the plugs, plug wires and distributor cap (that is NOT a “complete overhaul” by the way) hoping this will fix things, stop that. Let the mechanic diagnose the problem.
Being a 1994 model anything… I’d suspect the fuel pump(s).
If you have access to the fuel pressure regulator’s vacuum line, check to see if there’s fuel inside the line. There should be none. If that’s ok, ask your shop to verify the fuel pressure is correct. If that’s ok likely some sort of clog in the fuel system. Try a dose of fuel injector cleaner in the gas tank. Tom & Ray used to recommend a product called “Techron” as I recall. If it helps but doesn’t entirely resolve the problem, try another dose.
Have you checked for diagnostic codes? If you have any, post them here, may get some good ideas. By the symptoms I expect there is likely a lean code present.
Running a pump dry can certainly damage it. I believe your Ford is one of the last to use the TFI-IV ignition module.
Those modules run very hot and are prone to heat failure. The symptoms for a failing module can mimic a fuel problem. There was even a settlement on a class action suit over this but I am sure this is far to late to gain any reimbursement.
If you change the module you MUST use the special grease to coat the plate on the back of the module with and clean the surface it sits on. Failure to do so can kill the new module.