Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Chevrolet Silverado truck will not start the first time the key is turned. It usually takes up to three times of turning the key before it starts.
I have replaced the fuel pump, fuel filter, spark plugs, spark plug wires and the fuel pressure regulator.
What is causing this?
Does the starter engage and turn the engine over or just not starting?
Yes it turns the engine over but it may take a lot of cranking before it actually turns on. The very first time you turn the key it will crank but not start. When you let off of the key and turn it again is usually when the motor will start but if you just hold on to the in the on position, it will just crank and crank but wont start
With a new fuel pump and regulator, we will assume fuel pressure is okay. This would normally be the cause of a hard starting problem such as the one you have. Testing fuel pressure would still be a good idea. When turning the key on, the pump should run for 2 seconds to prime the system. You should get 55-62 psi fuel pressure with the key on, engine off.If fuel pressure is okay then there are a few more things that could cause a hard start.A possible problem is a vacuum leak at the intake manifold gaskets, this would cause a lean condition and hard start.Another possibility is a weak crankshaft position sensor. If the crank sensor signal is weak, the PCM may not signal spark and injector pulse. The fix would be to replace the crankshaft position sensor. It is located on the passenger side of the block, the starter must be removed to access this sensor.If you would like any additional information or have more questions please don’t hesitate to ask!
Has the intake been checked for vacuum leaks?
Has fuel pressure been tested since the fuel pump replacement?
The fuel pressure was checked the same day the fuel pump was installed and a local mechanic has checked the intake for leaks but no one knows why it is doing this.
I have read both your posts. I would like you to try a test for me. When you believe the engine will not start, get a spray can of Berrymans carb cleaner, spray two seconds in to the intake just in front of the throttle body. Open the throttle and spray into the intake. If it starts right up, you will most likely have a fuel problem. If it does not, then you will need to test for spark.
That is harder so please post back your results .
Okay it started when i sprayer the carb cleaner into intake
Now you will need a fuel pressure gauge. It should be installed and left over night to see if the fuel system is losing pressure and will not build up enough to start. The system should not drop below 25 PSI. If it does lose pressure fast enough to see on the gauge then you will want to pinch off the fuel and return line to see if you can stop the pressure loss.
1. If it stops from the fuel line pinch then its the fuel pump.
2. If it stops from the return line pinch then it the pressure regulator.
3. If you can pinch both and still lose pressure then its a fuel injector.
This all assumes there is no external fuel leaks.
New parts fail, that's why there are warranties. Try the testing you may have a leaking injector.
Testing is the way. If you can get the engine to start by adding fuel or carb cleanse, the engine must not be getting fuel. First you need to know that the pressure is not dropping the only way I know to do that is with a fuel gauge.
It is possible but you are jumping to a very technical issue to diagnose. You must start with the basic first. If you prove there is no pressure loss over the time it takes for the no start then you should test the electronics to start that you will need a light and a spark tester.
i like this spark tester
Yes it can. Try unplugging it when you think it will not start. It will not drive but it should start.
Not until I did the pressure test but if it runs ruff on start up try removing the spark plugs and look to see if any are fuel fouled. Just after a failed start attempt the one or ones that look rich. It may be a leaking injector.
Thats bad it must maintain some pressure. Now you need to do the fuel line pinch test. at the rear of the engine you will see two fuel lines one goes to the rail the other is the return line it comes out of the fuel pressure regulator. Find where the plastic pipe is with a pair of big needle noise pliers clamp down on each line as you watch the gauge. You may need to cycle the key to get the pressure up. If the pressure still goes down after pinching off both lines you have an injector leak.