1997 Chevrolet truck with a 4.3 engine runs rough.

The owner has maintained the truck very well, but with 300,000+ miles on the clock you would think it would be all worn out, but it’s not. This is why maintenance is critical to the long life of your car or truck. This truck looks and drives great because the owner loves his ride. The rough running condition was not setting any codes.

(This was a No Code, Driveablity Condition) 

It was not related to the ignition system or engine compression. It was caused by a faulty fuel pressure regulator on the fuel injection unit. The only way to spot an issue like this is to know fuel delivery basics.

The failure was not computer related.

Some engine parts go bad slowly over time. The client did not know that anything was wrong. The client only said it felt rough at an idle and to check it out. This little monster below is the fuel injection unit from under the intake manifold. It is hidden from sight. So when it has a leak, you do not smell it or see it, but your fuel economy will drop when it is going bad.

The client may have noticed that the engine was using more fuel, but he does not check the fuel mileage regularly. The easy way to check fuel usage is to zero out your trip meter when you fill up the gas tank. Then at the next fill up, divide the miles traveled by the fuel used to re-fill the tank. Presto, you just found out what your fuel MPG is. Now, do this at every fill up and if you notice your mileage drop over 20% suddenly, you may need repairs or lighter feet.

It’s all good under the hood. Anthony Xavier ASE Master Technician

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