I have a 99 Trailblazer 4X4 4.3L engine. I am a new to this forum and this is my first experience with a Chevy so I need some help!! I was driving the car and all of a sudden it seemed to try and stall out on me. I had to pump the gas all the way home just to keep it running. It acted like it was going to stall out especially when I had to slow down or stop for a light. While driving and pumping the gas on the way home, the temperature gauge started fluctuating and then the gauge quit working. It went from roughly 180 degree then dropped to zero in a matter of a few minutes. When that happened the car just quit. I was able to get it restarted using starter fluid. Now, I am trying to figure out what happened. It is difficult to start, but once running it will run smooth and now the temperature gauge works fine. I did some research and saw when someone had a similar (although not exact) problem and they suggested relocating the temperature sensor from the drivers side to the thermostat housing so I did that. When I checked the oil, it has the strong smell of gas. So, I am not sure what to do next. Is it recommended to relocate the temperature sensor to the thermostat housing? Does anyone have any advice or suggestions on what to do next?

 

Odd set of symptoms, and may involve more than one thing acting up.
The location of the coolant temperature sensor shouldn't make any difference as long as it's in contact with coolant. Operating temp of 180F is low, should be ~195F. Low coolant temp will cause the PCM to apply a richer fuel mixture which may be why the oil has a fuel odor. Using starting fluid is not recommended, use carb cleaner instead, much safer and will not damage the engine. This could indicate a lack of fuel to the injectors.
Here are a couple of things to check:

If the Service Engine Soon light is on, most auto parts stores will retrieve trouble codes, (free). Post them here in the order that they are retrieved.

Fuel pressure and leakdown: Key ON, Engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for 10 minutes after the pump shuts off.

Coolant level with the engine at operating temp. Top off if necessary.

Battery voltage with the engine idling at normal operating temp and all accessories turned off.

Post your results.

 

I put a scope on the car and one code popped up and it was 118. The running temp was 2 slashes before the 210 midway point. I checked the fuel pressure and it spiked at 62 then it dropped to 55 and after 10 minutes it dropped to 42. I did change the fuel filter. When I tried to blow through it to see if it was clogged, it was difficult to do. What does this mean? Is the fuel pump going bad? Right now the car starts and runs good but I don't know if I fixed the problem. Suggestions or ideas.

 

The P0118 could have been set while you were relocating the coolant temp sensor. I wouldn't worry about it unless it sets again.

Key on engine off, pump running pressure of 62psi is normal. The initial drop to 55psi might be a bit much and may be a result of the 10 minute drop to 42psi, which is too much. Next step is to figure out what's causing the excessive drop. The fuel pressure tester will need to be modified to connect directly to the fuel filter so fuel flow ends at the tester. Basically the same test as before, fuel pump running pressure should be 73psi to 108psi and must remain above 55psi for at least 10 minutes. If pressure is out of spec, or drops below 55psi, the pump will need replacement. If it's within specs, further testing is required to locate the problem.

 

I did the fuel pressure test at the fuel filter. The results are that it peaked at 80 psi and after 10 minutes it was at 60psi. Is it plausible that my fuel pump is good?

Dan

 

Your reading of 80psi is low, but it's still within specs. 60psi after 10 minutes is well within specs. Probably be a good idea to run the test a few times to make sure the test is accurate. If the results remain the same, or better, yes, your pump is within specs.

The drop you experienced in post #3 to 42psi is a problem though. The pump holds 60psi which means there's a leak forward of the fuel filter. If there are no external fuel leaks, it could be an leaky injector, spider line, or fuel pressure regulator, all of which are inside the plenum.