I've been trying to find the cause of my poor gas mileage for a while now. I keep getting a service engine soon light for oxygen sensor reading lean. The sensor is about 1 1/2 years old. I spoke with KingTalon a while ago, and he told me to try to run the car and pull one of the injector fuses out. The car should still continue to run. Well, when I pull the first fuse out, it idles poorly, but it continues to run. When I pull out the second fuse (with the first fuse installed) the car turns off immediately. Is this a bad fuel injector for sure? or could it be some other fuel related problem? The fuel filter is about a month old.

 

Each injector fuse powers half of the injectors. Removing both fuses means you have no working injectors.

TBIs are sensitive to fuel pressure. It probably would be a good idea to connect a pressure gauge and verify correct pressure before you get too deep into other possibilities.

 

I never removed both fuses at the same time. When I removed one, the other fuse was in, and vice versa. What I find odd is that depending on which fuse I pull, the car acts very differently. With one it stalls instantly, with the other it continues to run. I'll see if I can borrow a fuel pressure gauge to check fuel pressure. It should be around 9 to 13psi correct?

 

One way to look at TBI spray pattern is to use a timing light. Connect the pickup of the timing light to the coil wire and watch the spray pattern. With an HEI you have to play with the connection to one of the eight spark plugs wire to "catch" the spray pattern.