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Car Forum / Pontiac / Pontiac Firebird / January 2005Quadrajet
I have a '78 T/A and I want to put the standard Quadrajet back on it but I can't get it to stop flooding. I put a pressure gauge on the pump outlet and at cranking it gives peak pressures of slightly over 10psi, it is a new standard pump. I have connected an airline to the fuel inlet of the carb (on the bench) and the needle valve will not seal at 10psi, it will only work up to about 7. I have tried combinations of 2 seats and 2 valves, all new, and none of them will seal. There is no mention of a pressure regulator in the books and I have never seen a caburetted car with one. Please can someone tell me what I am doing wrong. TIA,  SignatureDavid Toft >I have a '78 T/A and I want to put the standard Quadrajet back on it but >I can't get it to stop flooding. I put a pressure gauge on the pump [quoted text clipped - 8 lines] > >TIA, Yes, there is too much pressure going to the carb. The pressure is overcoming the float seat. You need to get the pressure below 7psi for it to operate correctly. A pressure regulator or a replacement fuel pump is in order. ...Ron -- 68' Camaro RS 88' Firebird Formula 00' Mustang GT Vert >>I have a '78 T/A and I want to put the standard Quadrajet back on it but >>I can't get it to stop flooding. I put a pressure gauge on the pump [quoted text clipped - 18 lines] > ...Ron >-- It's a new pump done less than 100 miles, what is its output pressure supposed to be? SignatureDavid Toft >>Yes, there is too much pressure going to the carb. The pressure is >>overcoming the float seat. You need to get the pressure below 7psi [quoted text clipped - 5 lines] >It's a new pump done less than 100 miles, what is its output pressure >supposed to be? No more than 7 psi for a carb. ...Ron -- 68' Camaro RS 88' Firebird Formula 00' Mustang GT Vert > I have a '78 T/A and I want to put the standard Quadrajet back on it but > I can't get it to stop flooding. I put a pressure gauge on the pump [quoted text clipped - 6 lines] > never seen a caburetted car with one. > Please can someone tell me what I am doing wrong. > TIA, Hi david, Just a few thoughts (not teaching you to suck eggs etc ). Does it seal at 7 when holding it upside down but not at ten ? (that would appear to be the seat). Also, is the float at the correct height .I've seen carbs where the hinged plate is slightly bent and the float hits the underside of the carb stopping it from sealing firmly. If the level is too high, this can also allow them to flood(even though the seat might be OK ) HTH SignatureMitch - 1995 Z28 LT1 terminal_crazy@sand-hill.freeserve.co.uk Lancashire England >Subject: Quadrajet >From: David Toft david@burgoyne.demon.co.uk [quoted text clipped - 13 lines] > >TIA, How are your return lines going to the tank? If they are clogged/bypassed/screwed up, you could be getting a flooding condition. What brand of fuel pump did you use? A Delco 41382 (depending on certain conditions) is the stock GM pump that engine uses. Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 27k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going.... >>Subject: Quadrajet >>From: David Toft david@burgoyne.demon.co.uk [quoted text clipped - 18 lines] >How are your return lines going to the tank? If they are >clogged/bypassed/screwed up, you could be getting a flooding condition. I checked the valve seal on the bench with compressed air with the top off the carb (with a plate holding the float hinge in place) to eliminate as many of the variables as possible. >What brand of fuel pump did you use? A Delco 41382 (depending on certain >conditions) is the stock GM pump that engine uses. It came from Autozone or someone like that. SignatureDavid Toft >It came from Autozone or someone like that. I would try to get either a New Old Stock Delco pump or a replacement Delco from a dealer. A lot of the auto parts stores sell generic one-size-fits-all pumps. When the original pump popped on my 84 T/A it had a restrictor in the return line port. The auto parts store replacement had no restrictor and caused a thumping sound from the pump. Went to the Pontiac dealer and got a Delco pump, which had the restrictor, and solved the problem. Learned my lesson there. Signature_________________________________________________________________ Dennis Smith -1971 Trans Am - 455 H.O. - M21 4speed - Cameo white/blue stripe- -1973 Trans Am - 455 - TH400 auto - Buccaneer red- -1984 Trans Am - 5.0 L - TH700R4 auto - Royal blue/silver aero- _________________________________________________________________ |
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