adnanshah247 Posted September 23, 2021 Share Posted September 23, 2021 Gentleman, Thank you for reading. I have a a right pita issue with the suppy. This is issue the fuelling in the back. I have a brand new walbro 450 in tank connected to a swirl pot that then goes to 2 x Bosch 044 pumps externally to the engine. 1st issue is putting fuel in, the second I put nozzle in the fuel comes running back up and causes the handle to click. It bubbles up the spout immediately. 2nd issue, I have to brim the car slowly for ages right to the top of the spout/filler cap, literally to the point it wants to fall out. The car does 40-50 miles and then I can hear the external Bosch pumps making a lot of noise as if they are not getting any fuel and the car cuts out on me, Jerry can of fuel in and she fires right up then off to the petrol station we’re again she takes only £15-£20 max and is over flowing. What is going on here? Also worth mention when I go round a long bend I get hesitation from the car as if she wants to break down. Im running a big single and under boost she’s fine. But this tank is driving me insane. Mechanic and I are stumped so reaching to the geniuses here for help! Quote Link to comment Share on other sites More sharing options...
mattdavies Posted September 23, 2021 Share Posted September 23, 2021 Sounds like the fuel tank breather, it may not be the fact your filling it up it may be that you are opening the fuel cap. 1 Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted September 23, 2021 Share Posted September 23, 2021 First question is - Why do you need 2x 044 pumps? Thats a shit load of fuel, 1 would be plenty. Im saying its fuel starvation, you have a 450lph pump supplying 2 pumps shifting what, 600lph? Quote Link to comment Share on other sites More sharing options...
adnanshah247 Posted September 23, 2021 Author Share Posted September 23, 2021 7 hours ago, mattdavies said: Sounds like the fuel tank breather, it may not be the fact your filling it up it may be that you are opening the fuel cap. How do I dea with this issue? 2 hours ago, Swampy442 said: First question is - Why do you need 2x 044 pumps? Thats a shit load of fuel, 1 would be plenty. Im saying its fuel starvation, you have a 450lph pump supplying 2 pumps shifting what, 600lph? The cars over 1k hp. There is a big swirl pot in the back between the 450 and Bosch 044’s. Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted September 23, 2021 Share Posted September 23, 2021 (edited) Oh right haha, you didnt say that in the write up. Is the return big enough? Theres obviously some supply issue as you can hear it, so the in tank pump isnt filling the swirl pot fast enough or air cant get out of the swirl pot fast enough Id say Edited September 23, 2021 by Swampy442 (see edit history) Quote Link to comment Share on other sites More sharing options...
Burna Posted September 24, 2021 Share Posted September 24, 2021 Has the problem just suddenly appeared? Or is this a new build setup and it's never run right yet? If it's just started happening I'm inclined to go along with what Matt said, and the breather to the tank is blocked. Which would prevent you putting in fuel like you said, and also from pumping fuel out, and that's why you can hear the 450 pump labouring. Quote Link to comment Share on other sites More sharing options...
mattdavies Posted September 24, 2021 Share Posted September 24, 2021 The 450lph to supply the swirl pot and two 044s is going to be more then enough for street use, unless you are WOT for some substantial time I doubt that you will cavitate with fuel, also as soon as you let off the throttle you would be fine again because in 8 secs yoiu would have a litre of fuel back in your swirl pot. the difference in flow between the inlet and the outlet is less the 100ml a second Quote Link to comment Share on other sites More sharing options...
adnanshah247 Posted September 25, 2021 Author Share Posted September 25, 2021 On 9/24/2021 at 7:53 AM, Burna said: Has the problem just suddenly appeared? Or is this a new build setup and it's never run right yet? If it's just started happening I'm inclined to go along with what Matt said, and the breather to the tank is blocked. Which would prevent you putting in fuel like you said, and also from pumping fuel out, and that's why you can hear the 450 pump labouring. Have had 3 external people say this to me, how do I go about fixing the breather? Is there a ‘how to guide?’ Please??? Quote Link to comment Share on other sites More sharing options...
mattdavies Posted September 27, 2021 Share Posted September 27, 2021 I am not sure if there is a guide but if you go on a parts site like Amayama you will see how the fuel system is put together. the breather will be a pipe from the top of the fuel hangar to the filler neck some where. Is there a hissing when you undo the fuel cap after running it for a while ? Quote Link to comment Share on other sites More sharing options...
Burna Posted September 29, 2021 Share Posted September 29, 2021 On 9/25/2021 at 4:00 PM, adnanshah247 said: Have had 3 external people say this to me, how do I go about fixing the breather? Is there a ‘how to guide?’ Please??? http://www.japan-parts.eu/toyota/eu/1994/supra/jza80r-ajpvzw/3_291230_009_/body/7701_fuel-tank-tube/1 Quote Link to comment Share on other sites More sharing options...
mattdavies Posted September 29, 2021 Share Posted September 29, 2021 8 minutes ago, Burna said: http://www.japan-parts.eu/toyota/eu/1994/supra/jza80r-ajpvzw/3_291230_009_/body/7701_fuel-tank-tube/1 Using this and thinking logically, its probably going to be an issue with the rubber hoses or a blockage in the breather hole near the fuel cap Quote Link to comment Share on other sites More sharing options...
Burna Posted September 29, 2021 Share Posted September 29, 2021 16 minutes ago, mattdavies said: Using this and thinking logically, its probably going to be an issue with the rubber hoses or a blockage in the breather hole near the fuel cap Aren't there 2 breathers? Quote Link to comment Share on other sites More sharing options...
Burna Posted September 29, 2021 Share Posted September 29, 2021 Just checked with someone more knowledgeable than me, and he's confirmed that there are two breathers from the petrol tank. One goes to the top of the filler neck, the other to the charcoal canister in the engine bay. Check both the breathers are clear first, then go from there. Quote Link to comment Share on other sites More sharing options...
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