Slow to start
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Junior Member
Joined: Sep 2000
Posts: 16
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From: Hampton, Va, USA
Slow to start
My 89 formula 305 TBI is still starting very slow (not until oil pressure has built up to 10psi which takes some cranking).I have repaced the fuel pump relay and the wireing harness that leads up to the relay. I still have the same problem the ses light is coming up with the code 54 and 32 the 32 Im not to worried about yet. Please help me I dont want to take it to the shop.IAC I really have no idea what it does will someone help me.
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Joined: Sep 1999
Posts: 352
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From: Southern MD, USA
It's possible that your IAC is not working properly and not opening at start up. It's supposed to open up at start up giving the engine a burst of air and raising the idle speed for a couple of seconds. It's like a choke. Eventually, when your car does start, does it have a burst up to about 1300rpms and then settle down or does it start at a slow rpm and build up?
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88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
Eats LS1's with a 2.73 open rear and 2 1/4 stock catback
My Formula
------------------
88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
Eats LS1's with a 2.73 open rear and 2 1/4 stock catback
My Formula
Supreme Member
Joined: Jul 2000
Posts: 1,445
Likes: 0
The IAC has nothing to do with acting like a choke. The IAC opens up a little controlled air passage to let air in to try to keep the required idle sped. It actually acts OPPOSITE to a choke in that it lets air in, wheras a choke restricts it. The ECU does the CHOKE (not the IAC) function by increasing the fuel content on demand.
On initial startup, when the idele speed will be higher, the IAC is open more but as engine warms, the iAC closes to a more normal level..
There are ways to check the IAC function and hopefully someone ele can add to this to help you with that. or Chilton's/Haynes can help, I'm sure.
On initial startup, when the idele speed will be higher, the IAC is open more but as engine warms, the iAC closes to a more normal level..
There are ways to check the IAC function and hopefully someone ele can add to this to help you with that. or Chilton's/Haynes can help, I'm sure.
i had this exact same problem
the ecm fuel pump relay power is not working or its not getting to the relay
the ecm should prime the pump for two seconds when you turn the key to the ON position, you can test this by putting a DMM on the wire from the ecm to the fuel pump relay (i forgot the colors but its in the chiltons manual)
you should see like 2 volts or something for two seconds and while its in crank that voltage should be constant, this is what activates the relay to give you fuel
right now, your oil pressure sending switch is the only thing powering the pump, once pressure gets above 5 psi the fuel pump kicks on
Like i said i had the same problem and it turned out to be a faulty ecm which i believe was damaged by a bad relay but it could be a short in the wire
the ecm fuel pump relay power is not working or its not getting to the relay
the ecm should prime the pump for two seconds when you turn the key to the ON position, you can test this by putting a DMM on the wire from the ecm to the fuel pump relay (i forgot the colors but its in the chiltons manual)
you should see like 2 volts or something for two seconds and while its in crank that voltage should be constant, this is what activates the relay to give you fuel
right now, your oil pressure sending switch is the only thing powering the pump, once pressure gets above 5 psi the fuel pump kicks on
Like i said i had the same problem and it turned out to be a faulty ecm which i believe was damaged by a bad relay but it could be a short in the wire
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