Fuel system heat failure

I have a 1993 ford taurus 3.8L V6 automatic GL. My problem is when the weather gets very hot and huimid my car will stall. It did this last week and I hooked up a fuel pressure gauge when it stalled and the fuel pressure was below 20. After letting it sit and cool off for about an hour the fuel pressure was around 35-40. My question is what is failing in my fuel system because of the heat? Is it the fuel pump, fuel pressure regulator, fuel injectors or what?

The temp and humidity should not affect the fuel pump at all. Your problem more than likely lies with the ignition module.
A net search for TFI-IV Settlement will provide info about the TFI modules which are prone to heat failure.

The lawsuit only applied to distributor mounted modules but the non-distributor mounted ones can also fail as these modules become scalding hot after only a few minutes with the key on. Summertime heat makes the problem even worse and the symptoms resemble running out of gas basically.

The module provides a pulse which the ECM uses to determine fuel pump operation so that is just one way in which the modules can fail. Testing the modules is often a waste of time because they may test fine and fail again 10 minutes after reinstalling them. Hope that helps.

So if it is the “ignition control module” like you say then it is going to fail everytime it is very hot and humid. So to put this to the test the only way to find out if it is failing because of the heat would be to place it in “cold” water to cool it off the next time it stalls on me. Is this the best test I could perform?

You could try carrying along a spray bottle of water and hose it down a bit to see what happens. These modules become very, very hot within a couple of minutes of turning the key on, even if the engine is stone cold. The early TFI modules were mounted on the distributors and the theory was that the module heat would be dissipated into the distributor body. Since the dist. is also hot as a firecracker that logic is a bit flawed. The later TFIs were mounted away from the engine on a separate heat sink.

The problem with testing is that in the few minutes it takes to run the test the module may have cooled enough to test fine; although the module would still be hot to the touch.

I had several module failures on one of my old Fords until I attached it to a piece of aircraft heat sink and mounted it inside of the air cleaner housing. That way the module was constantly being cooled by the incoming air when the engine was running.
There was even a class action suit brought against Ford over these module failures and it covered almost all Ford products from around 1985 up to the mid 90s.

Would buying a “new” module solve the problem? Would a new one be better than the one I have now assuming the one I have is the old type? Did ford fix the problem? My module mounts on the right side of the firewall.

I’m not guaranteeing the module is even your problem; only saying that the fuel pump will not be dependent on outside temperatures and the modules are a known problem and are affected by heat and humidity.

The symptoms vary a bit but often mimic running out of gas. The last one that failed on my car would seem to act up the most when stopping at a traffic light after a straight highway run. Sometimes they just cause bucking and jerking at all speeds and sometimes they cause the engine to shudder and die followed by no restarting for a while.
The only reliable test on one of them is when it quits completely and stays that way.

Ford “fixed” the module problem by doing completely away with it around 1995? I think.

So, if I conclude that it is the module and decide to go buy a new one, then this new one will also fail on me when it gets to hot?

The ignition module is not connected to the fuel pump. There could still be a problem with the ignition module.

There is a 30 page Service Bulletin Article No. 93-13B-1, dated 06/30/1993, named Fuel Delivery System Diagnostics. You could download it if your public library has an online site ARRC (Automotive Repair Research Center).

There are other TSBs (Technical Service Bulletins), for other makes and models, for those people who want to read one for their car.

I know the “ignition module” is not connected to the “fuel pump.” The “ignition module” is part of the “ignition system” and the “fuel pump” is part of the “fuel system.” So, if I conclude that the problem is coming from the “ignition module” and decide to buy a new one, then will the new one also “fail” because of the heat? What I saying is if the old “ignition module” I have now “fails” because of the heat won’t the new one that I decide to buy do the same thing?

The new one may go for years before it breaks down and starts to fail too. Be sure to clean the area it mounts to and apply new heat-sink grease.

The ignition module, whether it’s good, or bad, doesn’t address the low fuel pressure problem. Curing one, won’t cure the other,

I did a KOEO test with the fuel pressure gauge right after the car had stalled from the heat. It read below 20. When the car cooled off for about a hour then it read 35-40 with the same KOEO test. I concluded that something in my “fuel system” was failing because of the heat. Their could be no other conclusion. All I am trying to figure out is what in my “fuel system” is failing?