Start, die, turn off, start, runs.
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Registered User
Joined: Feb 2000
Posts: 74
From: Oroville, Ca
Start, die, turn off, start, runs.
Maybe someone can help me out, I hope. Car is a 95 Z28, m6, ~100k.
Sometimes (39% of the time) when I cold start it, it comes up to normal cold idle (~1000 rpm) then dies. If I try to start it without turning the key to "Off" it will crank fine but not start. When the key is turned to "Off" and then crank, it always starts immediately and runs fine.
Any ideas? Thanks!
Sometimes (39% of the time) when I cold start it, it comes up to normal cold idle (~1000 rpm) then dies. If I try to start it without turning the key to "Off" it will crank fine but not start. When the key is turned to "Off" and then crank, it always starts immediately and runs fine.
Any ideas? Thanks!
Registered User
Joined: Sep 2002
Posts: 2,193
From: High Ridge, MO
Fuel pump? Sounds like it is priming but not staying on for some reason. Is it the stock pump? Try to get it to repeat this with a fuel pressure gauge. Check and see how the pressure is looking when it shuts off (dies).
Thread Starter
Registered User
Joined: Feb 2000
Posts: 74
From: Oroville, Ca
It may be the fuel pump, except it dies right down like the key was literally turned off vs sputtering for fuel. And it doesn't matter if I wait awhile before starting with the ignition on (to give it longer to prime.)
Anyone else have thoughts?
Anyone else have thoughts?
Registered User
Joined: Mar 2004
Posts: 147
Fuel Pressure Testing
"A fuel pressure test gauge can be bought at your local auto supply for ~$35. Attach it to the schrader valve that is on the fuel rail. Schrader valve location on 1994-1997
"When you have a gauge connected and the pressure looks initially good and then bleeds off quickly when you shut the engine off, you can do a couple of tests to help you figure out where the pressure loss is.
What the factory manual says to temporarily install, is a set of "fuel line shut off adapters" (probably something the normal guy is not going to have available). You remove the fuel lines from the rail and connect these valves in between. This lets you shut off either side of the lines for testing.
You can do the same thing by pinching the flexible lines to shut them off, but risk breaking them. You might be able to do it (your risk) by using a needle nose vise grips and putting some scrap hose as cushions on the jaws. Then use that to clamp off the line just enough to seal it. Obviously, this is not the best way to shut off the lines and could result in breakage. Heat and age can make the hoses brittle. If you don't want to risk it, don't.
You can use the fuel pump prime connector for pressurizing the system (jumper 12v to it to run the pump).
Watch your gauge as you jumper the prime connector. When you have good pressure remove the jumper and clamp off (or use shut off valve) the fuel supply line (3/8 pipe). If pressure holds, you have a leak on the feed line somewhere before it gets to the clamp (or shut off valve) or at the check ball in the pump. If it still goes down, release your clamp (or open shut off valve). Pressurize the system again, then remove the jumper and this time clamp (or shut off) the return line (5/16 line). If pressure holds, then the regulator is faulty. If pressure does not hold, you need to locate leaky injector(s).
If you can't tell a leaky injector from reading the plugs, you can look and see if injectors are leaking by removing the fuel rail screws and pull the rail and all the injectors up, so you can see under them. Leave them over the injector ports. Pressurized the system and look under the injectors to see if any are dripping."
shbox.com edited 4/13/2004
"A fuel pressure test gauge can be bought at your local auto supply for ~$35. Attach it to the schrader valve that is on the fuel rail. Schrader valve location on 1994-1997
"When you have a gauge connected and the pressure looks initially good and then bleeds off quickly when you shut the engine off, you can do a couple of tests to help you figure out where the pressure loss is.
What the factory manual says to temporarily install, is a set of "fuel line shut off adapters" (probably something the normal guy is not going to have available). You remove the fuel lines from the rail and connect these valves in between. This lets you shut off either side of the lines for testing.
You can do the same thing by pinching the flexible lines to shut them off, but risk breaking them. You might be able to do it (your risk) by using a needle nose vise grips and putting some scrap hose as cushions on the jaws. Then use that to clamp off the line just enough to seal it. Obviously, this is not the best way to shut off the lines and could result in breakage. Heat and age can make the hoses brittle. If you don't want to risk it, don't.
You can use the fuel pump prime connector for pressurizing the system (jumper 12v to it to run the pump).
Watch your gauge as you jumper the prime connector. When you have good pressure remove the jumper and clamp off (or use shut off valve) the fuel supply line (3/8 pipe). If pressure holds, you have a leak on the feed line somewhere before it gets to the clamp (or shut off valve) or at the check ball in the pump. If it still goes down, release your clamp (or open shut off valve). Pressurize the system again, then remove the jumper and this time clamp (or shut off) the return line (5/16 line). If pressure holds, then the regulator is faulty. If pressure does not hold, you need to locate leaky injector(s).
If you can't tell a leaky injector from reading the plugs, you can look and see if injectors are leaking by removing the fuel rail screws and pull the rail and all the injectors up, so you can see under them. Leave them over the injector ports. Pressurized the system and look under the injectors to see if any are dripping."
shbox.com edited 4/13/2004
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