Annoying Starting problem
Thread Starter
Joined: Aug 2001
Posts: 723
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From: Newfoundland, Canada
Car: 1987 Camaro IROC-Z
Engine: L98 bored .40 (357 ci)
Transmission: Race Ready 700R4
Axle/Gears: 9 bolt 3.70 posi
Annoying Starting problem
I have this annoying problem. I am wondering if other Camaro/Firebird/Trans Am owner have the same thing...
Cold start... fires right up, I barely have to bump the key and she comes to life.
Hot start... say the engine is all warmed up after a run, situation " Let the car sit for 5 minutes or less" .. starts right up, again I barely have to bump the starter...
Hot start.... different situation, the engine is all warmed up " Let the car sit for more than 5 minutes and she is cranky to start, will have to spin her over and over before she catches, strong smell of unburnt gas (most likely due to the fact that she has to crank over so many times)
I was thinking that since the gas lines on the 87 5.7 L run very close to the manifolf that after sitting for a longer time it would heat the gas in the line and vapor lock me....I am not sure if the 88-92 5.7L's have the gas lines ran this way or not (pretty sure they don't)
Anybody have this problem? Anyone know what the cause/cure could be??
Cold start... fires right up, I barely have to bump the key and she comes to life.
Hot start... say the engine is all warmed up after a run, situation " Let the car sit for 5 minutes or less" .. starts right up, again I barely have to bump the starter...
Hot start.... different situation, the engine is all warmed up " Let the car sit for more than 5 minutes and she is cranky to start, will have to spin her over and over before she catches, strong smell of unburnt gas (most likely due to the fact that she has to crank over so many times)
I was thinking that since the gas lines on the 87 5.7 L run very close to the manifolf that after sitting for a longer time it would heat the gas in the line and vapor lock me....I am not sure if the 88-92 5.7L's have the gas lines ran this way or not (pretty sure they don't)
Anybody have this problem? Anyone know what the cause/cure could be??
Junior Member
Joined: Jun 2002
Posts: 35
Likes: 0
From: Central Valley, CA
I have the same problem. I figure it is a mild form of vapor lock. I turn the key to run let the fuel pump run until it shuts off, and then crank the engine. I bump the starter and it fires right up.
Jeff
Jeff
Moderator
Joined: Jan 2000
Posts: 19,653
Likes: 309
ROC Z,
Your symptoms are classic for a leaking injector(s) or pressure regulator. You should monitor the fuel pressure after the car is turned off. Pressure that drops off within ½ hour after shutdown may indiacte a leaking injector. It is also possible that the diaphragm in the fuel pressure regulator has a small hole that is allowing fuel to relieve through the vacuum fitting and line on the regulator into the plenum.
Either of these situations would cause the plenum to flood with excess fuel after a short time. If the leakage rate is low, restarting within a few minutes would present no problems. But after a longer time the fuel volume leaked into the plenum would be enough to cause an excessively rich condition as you describe. After an extended period (like overnight), the excess fuel leaked into the plenum would have had an opportunity to evaporate, relieving the overly rich condition. Once you determine whether you have fuel pressure loss, the next step is to determine the cause.
For all of this diagnosis, a fuel pressure gauge would be necessary, so beg, borrow, or buy one when you're ready to start looking into it.
Your symptoms are classic for a leaking injector(s) or pressure regulator. You should monitor the fuel pressure after the car is turned off. Pressure that drops off within ½ hour after shutdown may indiacte a leaking injector. It is also possible that the diaphragm in the fuel pressure regulator has a small hole that is allowing fuel to relieve through the vacuum fitting and line on the regulator into the plenum.
Either of these situations would cause the plenum to flood with excess fuel after a short time. If the leakage rate is low, restarting within a few minutes would present no problems. But after a longer time the fuel volume leaked into the plenum would be enough to cause an excessively rich condition as you describe. After an extended period (like overnight), the excess fuel leaked into the plenum would have had an opportunity to evaporate, relieving the overly rich condition. Once you determine whether you have fuel pressure loss, the next step is to determine the cause.
For all of this diagnosis, a fuel pressure gauge would be necessary, so beg, borrow, or buy one when you're ready to start looking into it.
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92camaroJoe
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