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1965 Impala SS Convertible
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Ive cleaned the IAC the mass air flow sensor,tried premium gas,temp. sensor.Hooked up a diagnostics machine and the maching says let the car warm up,this is when its fully warmed up and driven for 20 mins.Anyway it runs like crap when it warms up.when the engine is cold it runs beautiful.when it warms up it like stalls like its getting starved of gas and while going a steady speed it like will jerk like its not getting gas ,then it is,then its not,then it is.its a 92 lincoln towncar with a v8
 

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Save a horse, Ride a Cowboy.
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EazyDuzIt102 said:
Ive cleaned the IAC the mass air flow sensor,tried premium gas,temp. sensor.Hooked up a diagnostics machine and the maching says let the car warm up,this is when its fully warmed up and driven for 20 mins.Anyway it runs like crap when it warms up.when the engine is cold it runs beautiful.when it warms up it like stalls like its getting starved of gas and while going a steady speed it like will jerk like its not getting gas ,then it is,then its not,then it is.its a 92 lincoln towncar with a v8
The TownCars and Vics are notorious for having poor connections at the fuel pumps/fuel tank. Right where the harness plugs into the tank itself at the rear of the axle housing. The connector is semi-circular on the front side of the gas tank and the retainer snaps are poor. What you have is fluctuating voltage to the fuel pump.

If you want to confirm this problem, pull the FP relay and jump across so it has continuous run (with the engine off) and listen to the pump. Wiggle the pump connections and see if the pump changes pitch.

What happens is an intermittent or poor connection with high resistence, and the engine starves for fuel and misses like an ignition miss because the pressure is low. When you kick the throttle, the fuel pressure increases enough that usually the miss goes away. When the engine is cold, it is running in "choke" mode so it has enough fuel to run smoothly.

Best thing to do is carefully unplug the connector on the fuel tank, don't break the snaps on the ends (OHOH) and clean everything well. Then take an ice pick and close up each of the circular metal female wire ends that fit over the male pins on the tank. Glob it full of silicone grease to keep the water out, and reconnect. Be careful when you push the connector back on, it will seem tight but it might not be. I've seen them jump off in a few days. Visually check the retainer snaps for security. There is no way to put a zip tie on these, you will see why when you get down there.

This is the 4th time in the last year to see this problem.
First thing in the morning I have to do a 90 TownCar with the same problem.
NO kidding. :welcome:

By the way, I would bet 1/2 of the failed fuel pumps are just bad connections that get restored when a new pump is installed.

The diagnostic machine telling you to let it warm up might be reading a bad coolant temperature sensor for the fuel injection circuit. I am pretty sure, not 100% that if that fails completely the mixture will go to rich, not lean. An intermittent sensor MIGHT make it lean, but I don't know.
 

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This particular car the pump ran intermittent by wiggling the fp connector and the associated missing as described above. It has had 3 pumps installed.

I discovered that the post terminals on the fp/sending unit assembly that the connector plugs to are mounted in plastic and the ground terminal plastic was broken allowing the post to wiggle.

My guess is that at the first pump replacement the plastic was broken.

Removing the fp assembly, (5 minutes) I saw the internal eyelet to post knurled connection was loose due to the broken plastic. (Big Fords do not have to drop tank to pull fp)

I cut the internal wire, installed an eyelet terminal, ss screw to internal line support gusset.

Cut ground wire on external connector, installed eyelet terminal and ss screwed it to gusset supporting external fuel line.

Solid grounding accomplished. :thumbup: no more miss.
 
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