1997 Chevrolet Silverado starting engine

PASQUALECALCAGNO

MEMBER
1997 CHEVROLET SILVERADO
5.7L
V8
2WD
AUTOMATIC
154 MILES

Engine always started right up, this last two weeks, starts right up, when I shut down, will not start unless I press pedal to floor, then it will start, but not as smooth as should be, I put in new plugs, also complete fuel pump assembly, still has same problem, truck has $154,000 miles and ran like new until recently

No engine light on or codes showing

On my evap purge vacuum switch, the vent hose is missing, what does this vent hose do, do I have to replace this Hose?

6 Replies

JACOBANDNICKOLAS

MECHANIC
109,779 POSTS

As far as the purge solenoid valve, it allows gas fumes to get burned through the intake manifold. Its part of the emissions control system. This system's goal is to prevent gas fumes from entering the atmosphere. I hope that answers that question for you. And yes, the hose should be replaced. Has it been missing for a long time?

As far as the hard start, it could be the result of several things. The first thing I need you to check is fuel pump pressure. If the pressure is too low, it can cause a problem. However, if it is too high due to a bad regulator, that can cause issues with the injectors.

If that checks okay, then the idle air control valve (IAC) needs to be checked for operation. The IAC is responsible for maintaining the engine idle speed. On a fuel injected engine like yours, air is regulated by the IAC that enters the intake and engine. If the valve isn't opening properly, that may be the reason you have to press on the gas pedal.

If that isn't the issue, we will need to check injectors for leaking, compression, coolant temp sensor. All of which can cause this problem.

NOTE: Let me know if you see any black or white smoke when it finally starts for you. That can be helpful.

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Wednesday, September 2nd, 2020 AT 5:55 PM

PASQUALECALCAGNO

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4 POSTS

Before I sent you question, changed compete fuel pump assembly, new fuel filter, new plugs, spark plug wires, new distributor

Just a repeat, on first morning starting, truck starts up normal, when I shut off, will be hard start, until I press pedal to floor

After all I have done, I would gladly replace the Idle control valve--please advise and I will go to auto parts store and buy right now

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Wednesday, September 2nd, 2020 AT 5:55 PM

PASQUALECALCAGNO

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Well--I changed the idle control as you suggested--it was not that--I made the trip to Autozone and bought the Coolant Sensor and installed, cost me $13.00--I started up and from the hum of the engine, I knew that was it--shut off and restarted no problem, I drove around an restarted many times and started right--I hope this does it, I am running out of parts to replace--Thanks--Pat Cal

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Wednesday, September 2nd, 2020 AT 5:55 PM

JACOBANDNICKOLAS

MECHANIC
109,779 POSTS

Glad it's running good now. The coolant temp sensor can be a tricky thing. Based on the temp of the engine coolant, the sensor tells the computer how rich or lean to make the fuel mixture to the engine. I had a 97 Chevy van that ran perfect one minute and really bad the next. Like you, it was hard to start once it warmed up. I live scanned the computer and found the sensor was telling the computer the coolant temp was -40 degrees F. As a result, once the engine was warm, the computer was dumping fuel thinking it was still cold. Like you, a 15 dollar part and all was fixed.

Let me know if you have other questions.

Take care,
Joe

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Wednesday, September 2nd, 2020 AT 5:55 PM

PASQUALECALCAGNO

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Joe--I will be back--I am a 73 year old rodder and have 5 rods, all running, I had 13 up until 6 months ago, but lost storage and had to sell--I will be back--satisfied with answer--Pat Cal