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Pinto Efi Drops Power When Cornering


Guest weazel134

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i was thinking along the lines of fuel moving about in the tank and not reaching the pickup as the level drops?

I am sure you are right in your thinking. This problem (when going round a corner with a part empty tank) of the fuel pump sucking air rather than fuel and leading to a sharp drop in fuel pressure is common on fuel injected engines. Less of a problem on carburettors as they have a built in reservoir, the float chamber, which reduces it. There are two common ways to avoid it when injecting. Either you build a tank with baffles and or a pot which keeps fuel round the pickup or you add an external surge/swirl pot which is tall and slim and draw fuel from the bottom of that.

 

You could get a tank built(expensive) but simpler is adding a pump and swirlpot combo like Tractor suggests is one possibility(cheapish) or getting an external swirlpot which the high pressure (HP) pump draws from and is constantly filled by a low pressure (LP) pump (easiest but medium cost).

 

A typical design is shown below. The swirl pot is always full or nearly so and kept that way by the LP pump. The HP pump draws from the base of the swirlpot. Unused fuel returns from the fuel rail to the swirlpot. Air and excess fuel bleeds from the top of the swirlpot back to the tank. The positioning of the pipes on the swirlpot in the diagram below is as they should be. A pot of about 1 litre is fine.

 

Nigel

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Edited by Longboarder
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Guest weazel134

ok so had a look this eveing and i think things run as follows. i have a LP pump in the tank, out of tank to small filter, into some big box thing (technical term). this only has 1 in and & 1 out. from the box to a (what i assume is the HP pump. then to another larger filter and up to the rail. out of the rail and back to the tank. on the end of the HP pump is a, what i assume is a regultor, similar to what is on the end of the rail.

 

photos attached.

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The big blue box appears to be a poor idea for a swirl pot -- it would work better if the copper pipe to the injection pump came from the bottom of the blue box & the feed from tank went into the top; so try turning the blue box 90* clock-wise ( looking at the copper pipe end)

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First four pics are upside down. The round thing on the outlet of the HP pump is a flow damper not a pressure regulator. The blue box is probably intended as a reservoir but can't work with only two pipes.

You have most of the bits. Buy a proper four pipe swirlpot and some new hose and you should be able to alter the plumbing to work fine.

Still no sign of a pressure regulator but that is commonly on the return end of fuel injection rail in the engine compartment. The fact that the car goes well as long as the tank is full suggests there is one doing its job fine somewhere in the system.

 

Nigel

 

This would do. http://www.ebay.co.uk/itm/Bulk-Head-Mount-1-Ltr-Fuel-Swirl-Pot-Rally-Race-Performance-Track-OBPA025-/190998670386?epid=650732639&hash=item2c78686c32:g:G8QAAOxyRhBSpxLs

 

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Edited by Longboarder
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Guest mcramsay

I would reccomend fitting the pot in the boot and not the engine bay, I have my swirl pot fitted in the engine bay and the temperature is causing me fueling issues.

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  • 2 weeks later...
Guest 2BJacko

Injection pump needs to be gravity fed so swirl pot needs to be above injection pump, I believe.

Yes you ar right about gravity feed though I would say that the swirl pool needs to be gravity fed 1st and preferably lower than the bottom of the fuel tank so it's kept constantly full and can give an uninterrupted supply of fuel to the pump.

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Guest 2BJacko

 

The outlet of the regulator should return to the swirl pot, the swirl pot should then return to the tank, this ensures any air returns back to the tank.

 

 

 

Aah now that remark explains a lot ! when I bought my EFi 2B 5 years ago the previous owner said the car was on its 3 fuel pump ! car had done around 7000 miles so I figured the original donor Sierra 20is pump was probably on it’s last legs and then he’d fitted a second hand one which went the same way. It had a newish looking pump fitted when I bought it. Then 2 years later the fuel pump went on me!

 

That’s when I started looking at the fuel system more closely. I don’t have a swirl pot as such but have a mesh filter bowl fitted with the inlet at the top of the bowl which is level with the bottom of the fuel tank which is gravity fed from the bottom of the tank. I have a 16mm outlet from the bottom of the filter bowl connected to the 16mm inlet of the vertically mounted pump at the side of the bowl so the 16mm pipe connects them in a “U” actually it wasn’t quite as tidy as that initially but it is now.

 

The tank return had been blocked off and the fuel return line plumbed back into the filter bowl on the opposite side to the inlet so that fuel being returned was being directly pumped against the gravity fed inlet and probably also pressurising the pump inlet ? The pump had always been fairly noisy but didn’t think much of it as it’s not unusual to hear a fuel pump whirring away.

 

A new fuel pump fitted with a nice aluminium pump mount and the fuel return going into the fuel tank and I can hardly hear the fuel pump and no fuel pump problems in almost 3 years.

 

I couldn’t understand why anyone would plumb the fuel return into the pre pump filter bowl. I guess the builder thought he had a swirl pot arrangement !!! after reading what you’ve said.

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Guest mcramsay

The swirl pot is not gravity fed, and does not need to be fitted lower than the tank. The swirl pot in most applications ( unless it's internal to the tank) is fed via a low pressure pump, ( google facet pump) these are generally self priming pumps. So you can fit them close to the fuel tank and they will pull fuel through them if needed. This low pressure pump feeds the swirl pot, it will run constantly and once the swirl pot is full it will simply rerun the excess fuel back to the main fuel tank.

 

The swirl pot now becomes a 1 litre reservoir of fuel which will not allow fuel to slosh around and cause the injection pump to lose prime.

 

The injection pump should be fed directly from the swirl pot.

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