Have to pump gas to start when my car is cold?????
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Junior Member
Joined: Jul 2011
Posts: 68
Likes: 1
From: Cullman, AL
Car: 1988 Firebird Formula
Engine: 5.0L 305 TBI
Have to pump gas to start when my car is cold?????
Its weird.
When I try to cold start my car, I have to pump the gas, or else it won't start?
I thought with TBI fuel injection you shouldn't have to pump the gas to start it?
When I try to cold start my car, I have to pump the gas, or else it won't start?
I thought with TBI fuel injection you shouldn't have to pump the gas to start it?
Supreme Member
Joined: Sep 2002
Posts: 9,192
Likes: 19
From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: Have to pump gas to start when my car is cold?????
I doubt pumping it is making any difference. Check your fuel pump relay.
If the fuel pump relay isn't working, the pump won't "prime" for 2 seconds before startup. Unless primed, the injectors have no fuel. What's happening, is that the OIl Pressure Sending Unit (OPSU) is taking over as a backup circuit to operate the fuel pump - but this takes a few seconds of cranking ... and this is happening while you are "pumping".
If the fuel pump relay isn't working, the pump won't "prime" for 2 seconds before startup. Unless primed, the injectors have no fuel. What's happening, is that the OIl Pressure Sending Unit (OPSU) is taking over as a backup circuit to operate the fuel pump - but this takes a few seconds of cranking ... and this is happening while you are "pumping".
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Joined: Feb 2006
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From: Manteca,California. Nor Cal.
Car: SOLD IT. Mopar guy only now.
Engine: gone
Transmission: gone
Axle/Gears: gone
Re: Have to pump gas to start when my car is cold?????
I pretty much agree with what camaronewbie said.
Also another thing to note is that a bad Coolant temp. sensor will cause a weird cold no start condition. But I think your's is more what newbie said.
Also another thing to note is that a bad Coolant temp. sensor will cause a weird cold no start condition. But I think your's is more what newbie said.
Supreme Member
Joined: Sep 2002
Posts: 9,192
Likes: 19
From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: Have to pump gas to start when my car is cold?????
So glad you chimed in - maybe someday I'll remember that some TBI cars did have a CTS (but don't hold your breath).
Supreme Member
iTrader: (25)
Joined: Feb 2006
Posts: 7,260
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From: Manteca,California. Nor Cal.
Car: SOLD IT. Mopar guy only now.
Engine: gone
Transmission: gone
Axle/Gears: gone
Re: Have to pump gas to start when my car is cold?????
Yeah I feel ya. And on my car the CTS has nothing to do with the radiator fan. haha. it is located on the intake manifold, by the thermostat housing. sometimes it isnt even the sensor going bad it's a bad connector. they used to sell the connector with the sensor but have since stopped from what I have seen. It would not suprise me if that was this guy's problem.
Thread Starter
Junior Member
Joined: Jul 2011
Posts: 68
Likes: 1
From: Cullman, AL
Car: 1988 Firebird Formula
Engine: 5.0L 305 TBI
Re: Have to pump gas to start when my car is cold?????
It has everything to do with pumping.
If you don't pump it, it won't start at all.
If you don't pump it, it won't start at all.
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Supreme Member
iTrader: (25)
Joined: Feb 2006
Posts: 7,260
Likes: 5
From: Manteca,California. Nor Cal.
Car: SOLD IT. Mopar guy only now.
Engine: gone
Transmission: gone
Axle/Gears: gone
Re: Have to pump gas to start when my car is cold?????
Its weird because pumping should have no implications before key on. Now I can see when your trying to start and you pump it, the TPS sensor reads different and says more fuel. But not with key off. Did you change that sensor yet?
Joined: Sep 2004
Posts: 2,777
Likes: 7
From: Casselberry, FLA
Car: 88 V6 'bird/89TBI bird/85 T/A
Engine: 2.8/TBI/TPI
Transmission: V8 T-5/700R4 x2
Axle/Gears: 3.42 open/2.73 open/ 3.27 9 bolt
Re: Have to pump gas to start when my car is cold?????
Rather than pumping, which really doesn't do anything but move stuff (no fuel gets shot in like a carburetor does), just hold the pedal at 1/2 the travel. Try it once at halfway and once at full throttle.
Apparently, your TPS is not telling the ECM what it wants to know in order to give you enough fuel to start. You are running lean at idle probably after you get it started as well.
You need to check your fuel pressure. You will need an adapter to do this. I bought mine from eBay and it allows me to use a regular fuel pressure gauge like the TPI and V6 guys use.
1. Your fuel pump is probably shot. They are junk brand new, and replacements are not any better. Go to the parts store and buy the fuel pump for the 89 Turbo Trans Am and use that one. Its better than the TPI pump, too. It was a good enough pump that GM used it up to the late 90's in pickup trucks with the vin code R Vortec engines.
2. You may have a clogged fuel filter, change this first.
I just went through something similar with my 89 'bird before I left. One new vortec pump later, it runs like a million bucks.
Apparently, your TPS is not telling the ECM what it wants to know in order to give you enough fuel to start. You are running lean at idle probably after you get it started as well.
You need to check your fuel pressure. You will need an adapter to do this. I bought mine from eBay and it allows me to use a regular fuel pressure gauge like the TPI and V6 guys use.
1. Your fuel pump is probably shot. They are junk brand new, and replacements are not any better. Go to the parts store and buy the fuel pump for the 89 Turbo Trans Am and use that one. Its better than the TPI pump, too. It was a good enough pump that GM used it up to the late 90's in pickup trucks with the vin code R Vortec engines.
2. You may have a clogged fuel filter, change this first.
I just went through something similar with my 89 'bird before I left. One new vortec pump later, it runs like a million bucks.
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