C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

90 wont start

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Old Aug 1, 2009 | 12:46 AM
  #1  
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Default 90 wont start

I know the pump is getting power. when I uses a test light on the grey wire (Ithink) and then key on it lights for a few seconds then goes out. It always seems to have spark. This happened after I pulled the heater core. All fuses look good a couple wires are disconnected under the dash but I believe they are for the CDM.

prior to this I was running the car on reserve trying to get bad fuel out of the tank. Could the pump have just died all of a sudden? I was going to do the fuel pump eventually anyways so no biggy if I did kill it running the car out of fuel.

I know the car has fuel because I just put 6 gallons in it and it's showing 1/2 a tank however it got dark and I didn't check the fuel rail for fuel either.

are you able to hear this pump run while you are in your cars? If mine is in fact running I sure don't hear it at all.

or could this be a vats issue? The car does crank over fine and that security light by the tachometer stops flashing when the key is turned on ...... what do you guys thing a dead pump or something else? also prior to this the car used to have to be turned over maybe 5-7 seconds all the time kinda like it wasn't getting enough fuel.
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Old Aug 1, 2009 | 07:29 AM
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Having the pump turn on is still not an indication that it is delivering fuel to the rail you need to verify pressure. If that checks out OK I would ohm the injectors for resistance.
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Old Aug 1, 2009 | 07:50 AM
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Originally Posted by floridamale
Having the pump turn on is still not an indication that it is delivering fuel to the rail you need to verify pressure. If that checks out OK I would ohm the injectors for resistance.
Has new injectors, this pretty much started when I was always running the car on reserve thats why I'm wondering if I killed a already weak fuel pump.
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Old Aug 1, 2009 | 07:57 AM
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Default pump

you should never let gas in tank get below 1/4, the gas keeps the fuel pump cool so that it does not get to hot. so I would think you killed your pump by running on reserve so many times
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Old Aug 1, 2009 | 08:10 AM
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Originally Posted by jeffp1167
Has new injectors, this pretty much started when I was always running the car on reserve thats why I'm wondering if I killed a already weak fuel pump.
If that is the case just check for pressure at the rail, no pressure could be the pump. Good Luck
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Old Aug 1, 2009 | 09:23 PM
  #6  
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Problem fixed .... thanks guys ... was the fact my ignition feed wire to the coil is missing its retainer clip and the wire slipped out a bit causing no power to the coil.

I still however have a very low volume of fuel coming out of the fuel rails when the shrader valve is depressed. I have a hillbilly adjustable pressure regulator cap on it though so maybe the pressure is set way down. .... But it does fire right up now.
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Old Aug 2, 2009 | 04:18 AM
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well I guess that wasn't the cause after all. Seems when the car is cold yes it starts but takes extended cranking to fire up. However after it is completely warmed up and I shut the car off it doesn't want to start, it tries periodically but just doesn't really catch.

I also hear it searching for an idle through the exhaust sound, sometimes my fuiel rails have fuel and other times they don't. sometimes theres a large spray out of the shrader valve other time very little.

A dead pump, or could this be a cranking circuit pronlem with the car?
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Old Aug 2, 2009 | 08:02 AM
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You still need to test for pressure at the rail only real way is with a gague, also check to see if you have gas in the vac line to the FPR.
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Old Aug 3, 2009 | 12:03 AM
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could my ignition module also cause these issues? I notice after engine gets hot it wants to crank multiple times before it fires up and other times it wont start till it cools down. these are normal operating temps not overheating conditions.
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Old Aug 3, 2009 | 12:16 AM
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Originally Posted by geogolf
you should never let gas in tank get below 1/4, the gas keeps the fuel pump cool so that it does not get to hot. so I would think you killed your pump by running on reserve so many times
you are correct sir.
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Old Aug 4, 2009 | 08:36 AM
  #11  
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another thing I found is when the car is warm and encountering this starting issue you can hear the right side of the engine clattering (pinging) so won't run it again till I am sure of fuel pressure and there are no issues with the distributor. I will let you all know what was the cause.

keep in mind this car sat for a long period of time and I have run about 2 tanks of fuel through it to try and clear out the fuel lines etc. thats why I never put a new pump in it to begin with, Guess it's time to pull the sending unit though and give the tank a looksie and replace pump and fuel filter. Maybe the car is just starving for fuel.
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Old Aug 4, 2009 | 11:33 AM
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Originally Posted by NitroNutt
you are correct sir.
That's a questionable statement.

The fuel that flows thru the pump internally provides enough cooling for the pump.

What will kill the pump quickly is if you run it with no fuel flowing thru it.

Last edited by Hooked on Vettes; Aug 4, 2009 at 11:35 AM.
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Old Aug 4, 2009 | 01:30 PM
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Originally Posted by Hooked on Vettes
That's a questionable statement.

The fuel that flows thru the pump internally provides enough cooling for the pump.

What will kill the pump quickly is if you run it with no fuel flowing thru it.
this one has been subjected to that. when it was on reserve I remember it cutting out and stuff and ever since now it wont run right. but prior it always started and ran right. So I probably killed it.
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