Ok, I have been having an issue with my 98 blazer for awhile now, its just starting to become more noticeable. When I try to start the vehicle some times I have to rev the engine to get it to stay started and not turn off. But the initial start up can take awhile, sometimes the power completely dies (like the battery goes dead/ but then it comes back on), the battery is a year old. Sometimes all the gauges start spinning around and acting weird. And sometimes when after I try to turn the vehicle on and it is a couple moments later and it hasn't turned on and is at rest, it makes a weird little spin sound (this only happened a couple of times). The voltage meter when the car is on is just below 14 (1 or 2 hash marks). When I went to autozone they checked the alternator and it looks like it is starting to go. Wondering if it is just a alternator or maybe a fuel pump. The reason i ask is because i have to rev engine to keep it from turning off at start.

 

Low voltage/current will cause many strange problems.

Just after starting, the battery is a bit drained so if the alternator has a weak output, then the engine is running off of the battery which it is not going to do very well since the battery is a bit drained from starting.

Suggest replacing the alternator and cleaning the battery cable terminals including pealing-back the red and black covers to see the ends of the cable and clean if required.

 

To rule out your fuel system as your issue you must do a fuel pressure leak down test. Most auto part stores will loan you the gauge to do the test(auto zone for sure) for free. Just pay a deposit and get it back when you return it. First hook up the gauge at the service port on the fuel rail near the rear of the engine bay. Make sure there is no leaks and test with key on engine off the pressure should be 60-66psi and after 10 minutes should be no less than 55psi. If it fails either you have a problem in either your plenum (fuel spider assembly or regulator) or your gas tank (fuel pump). To determine if your problem is in the tank or the plenum you need to test the pressure at the fuel filter which is located inside the driver side frame rail. As captain hook says it takes some creative plumbing to get it connected just right and test again with key on engine off as well as after waiting ten minutes. If it passes then your problem is inside the plenum (spider assembly or regulator). If it fails its most likely your fuel pump. Also smart to check for 12 volts to the pump as well as continuity to ground.

 

Thanks for the input I appreciate the help.

 

thank you