V6 Discussion and questions about the base carbureted or MPFI V6's and the rare SFI Turbo V6.

IAC question

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Old May 1, 2003 | 11:48 PM
  #1  
bes217's Avatar
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From: San Francisco,Ca area
IAC question

Well, my car has been starting really really hard lately. I adjusted the IAC to what the manual says, and that made it a little better. But, it still takes 2-3 tries of cranking the engine for about 4-5 seconds. So I was thinking that I would just replace my IAC valve. My question is, when I get a new IAC valve it is preadjusted and I can pop it in, or do I have to set it to the correct length myself? Please help
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Old May 2, 2003 | 12:07 AM
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From: Northwestern Pennsylvania
Car: 1985 Pontiac Trans Am
Engine: 355 with stuffs.
Transmission: 700R4
Axle/Gears: 4.10 Posi
try this link, it should have what you need.

https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

have you checked your fuel pressure and spark?
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Old May 2, 2003 | 02:04 AM
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Car: 1991 RS Camaro (Jet Black)
Engine: 95 383 CI (6.3) LT1
Transmission: 95 T-56
Make sure the length between the pindle and the IAC gasket is no longer than 1 inch 1/8. When you buy the new valve it should have instructions on installation I recently just replace mine.
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Old May 2, 2003 | 06:54 AM
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From: AR
Car: 1991 Camaro RS Vert
Engine: 350 S-TPI
Transmission: T5
Axle/Gears: GU5/G80/J65
In my book that would be spark or fuel.

Truely sounds like the injectors are leaking down over night.
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Old May 2, 2003 | 07:05 AM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Might be the fuel pump relay. At key on (don't crank) listen for the fuel pump whining. Should run for 2 secs then stop until you crnak. If not then the relay needs checking.

Before you dismiss this the cranking brings up the oil pressure which turns on the fuel pump via the oil pressure switch, it then starts.

RBob.
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Old May 2, 2003 | 10:28 AM
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From: Northwestern Pennsylvania
Car: 1985 Pontiac Trans Am
Engine: 355 with stuffs.
Transmission: 700R4
Axle/Gears: 4.10 Posi
if cranking the engine brings up pressure and turns the pump on, then why do we hear it at key "on" as soon as we turn the key? there's no pressure then....
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Old May 2, 2003 | 12:24 PM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Originally posted by Quick_Trans_Am
if cranking the engine brings up pressure and turns the pump on, then why do we hear it at key "on" as soon as we turn the key? there's no pressure then....
Uhh, the ECM turns teh fuel pump on for 2 secs at key on through the fuel pump relay? Else it won't start until it has been cranked enough to get some oil pressure. Just like the original poster stated.

RBob.
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Old May 2, 2003 | 12:52 PM
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From: Central NJ, USA
Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
Yep, that's the "fuel pump safety switch". It gives power to the fuel pump when it sees oil pressure, so if the relay dies, the car will still start.

The safety switch does NOT kill the engine if oil pressure drops to zero.

I think by "safety", GM meant "safety of the driver if the fuel pump relay dies when the car merges onto a 70mph interstate highway in front of a fully loaded tractor trailer."
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Old May 2, 2003 | 10:54 PM
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bes217's Avatar
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So... you think it might be the fuel pump relay circuit. I do hear it pumping for about 2 seconds before when I turn the key to the on position and then it stops. But, it is still hard to start and takes a couple tries. On about the 2nd or 3rd try the oil pressure goes up and then about 2 seconds after that the car will start.

If it is leaky injectors how do I fix that. Just put new O-ring seals on the injectors and pop em back in. (I know its more involved than that).
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Old May 3, 2003 | 06:26 AM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Originally posted by bes217
So... you think it might be the fuel pump relay circuit. I do hear it pumping for about 2 seconds before when I turn the key to the on position and then it stops. But, it is still hard to start and takes a couple tries. On about the 2nd or 3rd try the oil pressure goes up and then about 2 seconds after that the car will start.

If it is leaky injectors how do I fix that. Just put new O-ring seals on the injectors and pop em back in. (I know its more involved than that).
Not the fuel pump relay as the pump comes on for 2 secs at key on.

How does it run? Good power? Idle OK? Fuel mileage? Difficult to start both hot & cold? Did this difficult starting happen suddenly or gradually?

And last but not least, TomP's tuneup been done?

RBob.
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Old May 3, 2003 | 01:29 PM
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Yes, the tune up has been done. Once it starts it runs good, I get good power(well, for a V6 anyway), it idles good around 600-700 rpm's. It is hard to start both hot and cold. Like if I drive for a while and get it up to operating temp. then stop somewhere and shut it off for like ten minutes it is hard to start. But sometimes it will start right up when it is still warm. This problem has been there since I got it, but lately it has gotten worse.
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