1994 Ford Ranger rough/no start when hot

My Ford Ranger has an intermittent problem with rough or no starts (usually when hot) for 2 years now. Numerous mechanics and no one can solve the issue - the CEL is on, sometimes engine will sputter, run rough and go really slow if I try to press on gas (almost like flooding out) but then it will lurch, CEL goes off, and runs great. Worse when hot outside or after driving - sometimes no start at all, but after many attempts, or once cool it will turn over. Had crank sensor replaced, still have issue - could it be failing fuel pump?

If the Check Engine light is on, you need to pull any codes from the computer to determine what’s causing the problem.

Here’s how you pull the codes on your OBDI Ford and the code definitions.



Thanks, but I’ve taken it to about 5 different mechanics, no one has been able to pull a code from the computer. One mechanic thought it could be a bad computer. Even tho the CEL is on while running rough, it goes off and doesn’t store a code.

Any one out there able to help me? This is going on more than 2 years now - I just replaced the fuel pump, that didn’t solve the issue. There is NO CODE thrown even tho CEL light does come on when rough start. Recent mechanic tried to replace ground wire from relay box - did not help. Engine either no starts, or rough starts, idles rough, must give gas very slowly and stay in 1st gear, otherwise stalls - then engine jerks like I popped clutch, backfires, etc, and if it doesn’t stall out, the CEL will eventually go off and truck runs great. If it stalls, sometimes it will crank just fine on the next try. I replaced the coils b/c I read they will drive you crazy, and truck has this problem when engine hot, or ambient air temp is hot (sun baking on hood) - never first thing in AM. I replaced coils myself, maybe I didn’t go it right?

94 was before diagnostics were standardized in 96 so who knows what that computer stores. It may even require a special reader, for some vehicles.

It could be the temperature sensor that the ECM uses to decide fuel/air mixture. If it thinks the car is cool while it is actually hot, it will run horribly. The same could happen when the car is actually hot but the temperature sensor says it is cool.
Temperature sensors are usually cheap and often easily replaced. Worth a shot, with nobody having been able to figure out what’s going on.

Sounds like the computer is failing.

What engine do you have in this truck? The 3.0 V-6? If so, you should strongly consider the possibility of the TFI ignition module being the cause of this problem.

These modules are known headaches, failures are related to heat, and there may be no codes set when they act up. Testing the module may show that it’s good when in fact it’s not.

I have an extremely hard time believing that there wasn’t even a code when the engine was running like crap and the MIL was on

My last car was also an OBD 1 car. When the MIL was on, you can bet your life that there was a code, which I was able to retrieve.

Absolutely a problem with that year truck. It’s going to be a ground somewhere. Whether a wire is not grounding, a relay has failed or etc etc etc.

I’ve replaced relays. Worked for weeks, then not.

I’ve replaced grounds, fuel pump, computers, pressure regulators, fuel hoses, fuses, you name it - 35 year diesel mechanic.

Way too much of a problem to pay someone to “fix”.

Either take the time to learn how to test electrical “stuff”…or scrap the truck and start with something else.

I can’t believe that FORD doesn’t KNOW why this is happening.

This is a “lemon” issue, but FORD has gotten away with it.

And for the guy who is “extremely” suprised there are no “codes”? I’ll stand behind that guys post. :wink:

Lemon issue ??? You have to be kidding This is a 1994 Ranger and this thread is 6 years old so the truck has either been fixed or scrapped.

Incorrect in stating that a very aged anything is a Lemon. Too many people make the erroneous assumption that a problem with a vehicle no matter the year or miles makes it a Lemon. Not so.
Even a 20 year old vehicle that is absolutely plagued with problems from front to rear does not make it a Lemon.

You’re a diesel mechanic of 35 years. Does this mean if a Kenworth comes in with 300k miles and suffering from a problem that it is also a Lemon?
Or a dozer that has been used out the muck for 8 years is a Lemon if it breaks?

We will never know the outcome of the Ranger problem but failure to start when hot is the sign of a bad TFI ignition module which is a very common fault. Whether the owner of the Ranger took that advice will never be known.


The simple fact that the truck MADE it to 20 years and was still running defines it as “not a lemon”

I agree with @ok4450, not a lemon, just an old truck (17 years old when posted!) with problems all vehicles suffer with age. Some random, some issues suffered by specific models.

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Thanks everyone - I was the owner, and fixed the problem with a rebuilt computer! I had been told that was the issue years earlier but was afraid of replacing it, I finally ordered one, it was a very easy fix to this nagging problem that hounded me for years. The truck wasn’t a lemon, it was great and I sold it a few months after fixing the computer. I wish I’d known that replacing the computer wasn’t all that “risky” - at the time I feared I would lose all transportation if replacement failed. I guess it’s true computers don’t do well in the heat, and the truck was 20 years old…no complaints, it served me well. Hopefully posting this may help others.


Thank You for following up! It isn’t just heat that kills computers, it is age as well.

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