TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

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Old Mar 9, 2009 | 09:48 PM
  #1  
88ragtop's Avatar
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Joined: Jul 2003
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From: Baton Rouge, La
Car: 88 sport coupe convert
Engine: 305 tb
Transmission: auto
runs only a few seconds

my 88 305 tbi will start right up but only runs a few seconds. If I keep pumping the gas it will stay running but really rough. Also,by doing this after a few minutes the whole exhaust system gets really really hot. I looked at the two injectors while someone keep pumping the gas and it looked like they had a good spray pattern. Then I had them start it without pumping the gas. It ran for 2 or 3 seconds and died. In this scenario at idle the injectors had no spray pattern at all but there was a little fuel coming out the injectors. Now, Should I have a nice spray pattern even at idle also?
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Old Mar 10, 2009 | 06:05 PM
  #2  
bigd077770's Avatar
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Joined: Mar 2008
Posts: 79
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From: south attleboro mass
Car: 1998 Trans Am/1992 Camaro RS
Engine: LS1/5.0L TBI
Transmission: 4L60E700r4
Axle/Gears: 3.23/2.73
Re: runs only a few seconds

i had the same thing that happened, i put so much time and money int my 91 and found out it was just the fuel pump. good luck
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Old Mar 10, 2009 | 09:07 PM
  #3  
88ragtop's Avatar
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Joined: Jul 2003
Posts: 148
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From: Baton Rouge, La
Car: 88 sport coupe convert
Engine: 305 tb
Transmission: auto
Re: runs only a few seconds

If it is a bad fuel pump that still don't explain why the exhaust is getting so hot.
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Old Mar 10, 2009 | 09:47 PM
  #4  
Antguy90's Avatar
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Joined: Feb 2009
Posts: 9
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Car: 1991 Camaro RS
Engine: 5.0 305cid tbi
Transmission: 700r4
Re: runs only a few seconds

I had the same problem. But the car ran longer, by maybe 5 seconds, with the map sensor vacuum line unpluged. With it plugged in, it died immediatly. Check fuel pressure. My spray from the injectors looked a little weird at idle, with the throttle open it would run a little longer before stalling. I finally checked the fuel pressure it had like 2-4 psi. Thats not nearly enough to keep it running. Plus my fuel filter was old and had lots of contaminant, that didn't help. The spec for stock tbi 305 is 13-15 psi. You should deffenitly check you pressure. The car would only run for 15 seconds top. Changed the fuel pump, cost me $50 at auto zone, runs great. Good luck!
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Old Mar 11, 2009 | 12:36 AM
  #5  
UnderCover89TBI's Avatar
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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: runs only a few seconds

i would say the exhaust is getting so hot becaus eof the unburnt fuel igniting in the pipes causing them to get hot.
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Old Mar 11, 2009 | 07:03 PM
  #6  
bigd077770's Avatar
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Joined: Mar 2008
Posts: 79
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From: south attleboro mass
Car: 1998 Trans Am/1992 Camaro RS
Engine: LS1/5.0L TBI
Transmission: 4L60E700r4
Axle/Gears: 3.23/2.73
Re: runs only a few seconds

yeah, idk man that sucks. a word of advice is that it is a good idea to do the fuel pump because mine is a 91 and the little hose in the tank got rotted horribly and you should do it as a precautionary step. its best to pull the trim and carpet up in the hatch well and cut a hole in the hump behind the seat. thats wat i did and it was alooottt easier than pullin the rear end, suspension and exhaust. good luck
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