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Author Topic: Fuel pump  (Read 430 times)

stevesteve

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Fuel pump
« on: August 05, 2017, 05:00:21 AM »

Hi, there doesn't seem to be a engine section so I'm posting here.


Do any of you guys running 2 stroke petrol (not glow) use fuel pumps because of lack of tank height?


What I'm working on is not a boat, it's a giant RC truck, I ideally need to move the tank to a position where it will be level with or even slightly below the carbs fuel inlet.


To make this work I'm going to have to pump the fuel to the carb


I have no idea what any of the pump pressure ratings mean in real terms and obviously, if I provide too much pressure, the shut of valve in the float housing won't be able to stop it and I'll have fuel pouring out the overflow!


If anyone has experience in doing this, I'd be grateful for advice, I've found a couple of 12v mini fuel pumps but don't wanna buy and hope!


Thanks, Steve.

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MartinL

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Re: Fuel pump
« Reply #1 on: August 05, 2017, 07:49:54 AM »

Steve, forgive me if Im totally wrong but I was under the impression that nearly all petrol engines run a Walbro type carb which has a build in fuel pump.
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Jerry C

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Re: Fuel pump
« Reply #2 on: August 05, 2017, 08:50:21 AM »

In the old days we used a bleed nipple off the exhaust led to the fuel tank which pressurised the tank. We didn't have float chambers.
Jerry.

stevesteve

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Re: Fuel pump
« Reply #3 on: August 05, 2017, 12:39:09 PM »

Steve, forgive me if Im totally wrong but I was under the impression that nearly all petrol engines run a Walbro type carb which has a build in fuel pump.


Nope, no pulse pump here, a gravity fed float controlled carb.


I understand the engine and the carb Inside out but it's delivering the fuel to it if I move the tank low down that creates challenges
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MartinL

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Re: Fuel pump
« Reply #4 on: August 05, 2017, 01:46:50 PM »

In that case wouldn't it be best to add a fuel pressure regulator that way any excess fuel would be pumped back to tank. About 15 off eBay.
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stevesteve

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Re: Fuel pump
« Reply #5 on: August 05, 2017, 04:18:26 PM »

In that case wouldn't it be best to add a fuel pressure regulator that way any excess fuel would be pumped back to tank. About 15 off eBay.


Not thought of that, with a regulator the fuel wouldn't need to be sent back, it would just create pressure on the pump side and most fuel pumps are quite happy to pump away like that, I would just need to set the flow so it was slightly more than was needed to make the height to allow for full throttle drain
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MartinL

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Re: Fuel pump
« Reply #6 on: August 05, 2017, 04:35:19 PM »

I think it should solve your problem although the one I looked at had a return feed to tank and it was adjustable from 0 to 100 psi, which may be a excessive for a little needle valve. Good luck, how big is this truck of yours?
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stevesteve

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Re: Fuel pump
« Reply #7 on: August 06, 2017, 03:42:24 AM »

48.6cc (it's got the 44mm bore) and based off a mini quad bike chassis, it's been chopped and re welded to give the chassis a lower profile as there's no longer a need for the handlebars seat ect or there mounts and I needed to A, get the center of gravity as low as possible and B, get the frame low enough to fit totally Inside the pickup body I have.


At a guess, I'd put it at about 30kg,  you don't want heading your way at speed
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MartinL

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Re: Fuel pump
« Reply #8 on: August 06, 2017, 07:44:25 AM »

Thanks, it sounds like a real fun project. Good luck.
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stevesteve

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Re: Fuel pump
« Reply #9 on: August 06, 2017, 08:39:04 PM »

It's still a work in progress but I've run it around a field and it's a lot of fun but you wouldn't wanna get hit by it!!!

The body is not fitted to the frame properly in those pics, it sits about 2 or 3cm lower when properly secured

I have  a working brake light circuit fitted too, made from a hacked micro servo.

















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