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Gas tank rust causing lean. |
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Anderslober 
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Joined: 30-July-2019 Location: Denmark Status: Offline Points: 764 |
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 Topic: Gas tank rust causing lean.Posted: 14-February-2023 at 8:35AM |
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I have had my 72 GTS started a couple times now….it seems to run lean….pops through carb.
I have an inline (glass😵😵) filter before the fuel pump. It is filtering a LOT of debris/rust from the tank. Clogs up by the looks of it. Fuel does get to the carb…..accelerator pump pumps fine…..although it leaks terribly through the top at higher (about 2000) rpm. Its as if the carb cant ‘pass’ the fuel forward fast enough….. Mixture screws are dialled out 2 turns……too much? Carb is newly cleaned an’all. Ideas welcome. |
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handsofstone
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Posted: 14-February-2023 at 10:01AM |
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Lose the glass filter. That is a fire waiting to happen. Get some plastic filters and replace as needed. Wasn't your fuel tank restored inside? If the fuel line is original can you disconnect it and blow it out with a compressor?
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AUS GTS
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Posted: 14-February-2023 at 11:54AM |
Good thought ....did that with an old Edsel & quite a bit of gunk came out! |
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Al
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Anderslober
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Posted: 14-February-2023 at 7:19PM |
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Gas tank is not restored. I did shine a light down the filler-neck, and it didnt look to bad….I guess you cant see everything! I did blow out all fuel lines. Lines are free-flowing. I am waiting for new plastic filters to arrive.
I will try to snap a photo of the current (glass) filter.
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californiajohnny
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Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14609 |
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Posted: 14-February-2023 at 7:21PM |
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if the fuel cant get through as needed it will go into the carb but as youre using fuel if it cant fill fast enough it will be low on the bowl essentially be lean as if the float was set low... same theory here...
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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Anderslober
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Posted: 14-February-2023 at 7:26PM |
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How about the fuel coming out the top of the accelerator pump? (At higher rpm)
Picture from net..  |
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Anderslober
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Posted: 14-February-2023 at 7:28PM |
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It seems there is no lack of fuel going into carb. I slighty unscrewed the inlet and fuel came ‘gushing’ out.
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californiajohnny
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Posted: 14-February-2023 at 7:33PM |
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does it leak out when you move the accelerator pump or even when idling? float may be too high and overfilling the bowl???
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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Anderslober
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Posted: 14-February-2023 at 8:09PM |
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At idle there is no leak coming from the top of accelerator pump.
When I move the accelerator pump there is no leak…until about 2000 rpm…then it starts. I have not touched or adjusted the float. Only directly swapped the air horn from the spare carb(due stripped inlet threads on the original)
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Anderslober
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Posted: 14-February-2023 at 9:22PM |
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Car was idling at around 700rpm….that is to low for 72cj. I will adjust to 1000rpm at idle….
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72 RS 351
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Posted: 15-February-2023 at 2:55AM |
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That accelerator pump has a diaphragm in there made of rubber, which sound like is leaking. I would work on that and the float level, adjust it carefully and check the fuel pressure too.
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000+ rpm 351-4V &4R70W 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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whmitchell
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Posted: 15-February-2023 at 3:52AM |
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If you haven't set the float level or done a carb rebuild, you probably should look at doing that. Old rubber parts need to be replaced and all the carb passages should be cleaned. To rule out the gas tank, just run it off a gas can right to the pump. It sounds like your tank needs to be refurbished or replaced, regardless.
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Anderslober
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Posted: 15-February-2023 at 6:13AM |
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Carb is rebuilt an’all.
Idle is acting up now….up down up down…flame out…I think I better get to the tank!
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Anderslober
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Posted: 15-February-2023 at 8:00AM |
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New (f48a) gas tank has no filler neck……..how do you use the old neck? Can it be pulled right out of the tank? Install with a seal?
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Anderslober
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Posted: 18-February-2023 at 4:03AM |
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I just took a look at the filler neck today. It has a rubber grommet.
The tank may have been changed earlier….
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Anderslober
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Posted: 18-February-2023 at 8:38PM |
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Picture from the 72 manual…..filler neck looks grommeted….
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californiajohnny
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Posted: 18-February-2023 at 9:50PM |
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pretty sure they are all grommet-ted? the newer ford part # is posted on here somewhere??? iirc i got one for an 83 E150 van as they all used this same grommet for a lot of years...
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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Anderslober
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Posted: 25-February-2023 at 4:19AM |
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What was the factory 351cj jet size in the 4300D carburetor of 1972?
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Rockatansky
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Posted: 25-February-2023 at 4:31PM |
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750 cfm but that depends upon the depression factor they used during testing. pretty much all different the OEM manufacturers used a different depression factor and 4 bbls are different than 2 bbls. aftermarket uses a standard 28inches of water IIRC so you can't compare different carbs directly
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72 GT Ute
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Anderslober
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Posted: 25-February-2023 at 5:02PM |
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I mean the fuel main jets….what size were they in 72 4300D/4sp carburetor?
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handsofstone wrote: