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 Post subject: Pi Fuel Pumps
PostPosted: Sun Mar 26, 2017 9:22 pm 
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What are people running on their Pi's?

I've been trying to keep to the original Lucas pump on my Mk1 Pi, but reliability & performance issues are tempting me to look elsewhere.

Has any one used any other pumps that can provide the high pressure required?

I know that Malcolm at Prestige does a conversion, but I want to see if there are any other options available before I commit to that amount of money. :?

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1968 Mk1 2600 Saloon in Slate Grey. (the infamous 'Gertie')
1969 Mk1 2.5 Pi in White

http://kingratracing.blogspot.com/


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 Post subject: Re: Pi Fuel Pumps
PostPosted: Tue Mar 28, 2017 9:16 am 
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If wanting to migrate away from Lucas, I think that your options are largely restricted to Bosch or one of the generic replacements (Sytec?). Some research a few years back found suggestions of a Pierburg unit capable of maintaining the pressures and flow rates demanded by the Lucas PI system, but I was never able to identify a definite part number or fitment application, so unsure whether it was a series production unit or a competition 'special'.

One thing to bear in mind is that to do a proper job on a Bosch conversion, you really need to uprate the electrical feed and earth and ideally the internal diameter of the fuel supply pipe as well, all measures that will benefit the original Lucas pump. Also, the set-up fitted to the earlier (late '68 - early '69) Mk1 PI saloons with the small in-line filter and large round surge tank in the boot is apparently not altogether ideal, as the filter is prone to premature clogging-up and the surge tank can sometimes draw air through the return pipe to the fuel tank inlet (i.e. breathing the wrong way). There was an excellent article on the PI system published in Six Appeal close on 30 years ago (but, I think, reprinted a few years back) which I seem to remember suggested replacing the small in-line filter with one of the larger CAV assemblies fitted to late Mk1 and all Mk2 PIs, and restricting the bore of the surge-tank-to-fuel-tank return pipe to discourage it from allowing the pump to suck air.

Another possibility is fitting a low-pressure high-volume booster pump between tank outlet and filter to help ensure that the CAV filter head and pump inlet are always fully primed with fuel. A heat shield above the exhaust box to keep temperatures down is also a good idea (or even resituating the pump to the cooler right-hand side of the boot, though the latter obviously requires the use of proper high-pressure lines with nut-and-nipple unions in the interests of safety).


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 Post subject: Pi Fuel Pumps
PostPosted: Tue Mar 28, 2017 9:32 am 
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If you have the Service Notes provided by the 2000register on a DVD (SIXappeal), you will find excellent articles in fixing the PI system (including fuel pump fault finding). Run through those before buying.


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 Post subject: Re: Pi Fuel Pumps
PostPosted: Tue Mar 28, 2017 9:48 pm 
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Location: South Oxfordshire, UK
I've had 2 Mk2 PIs, both of which were changed to run on Bosch pumps before I got them. The earlier one (which had a tuned TR6 engine) ran very well with no apparent fuel starvation issues. The current PI also runs well (without the tuned TR6 engine!).

Interestingly, the Bosch pumps were different! The current PI has a high current power feed from the battery (fused) which powers relays for both the pump and rear screen heater.

Cheers,
Mike.

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1967 Herald 1200 Convertible rust should be white
1971 2.5PI Saloon Sapphire blue
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1973 Stag French blue
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 Post subject: Re: Pi Fuel Pumps
PostPosted: Tue Mar 28, 2017 11:05 pm 
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[quote="Jonathan Lewis"]If wanting to migrate away from Lucas, I think that your options are largely restricted to Bosch or one of the generic replacements (Sytec?). Some research a few years back found suggestions of a Pierburg unit capable of maintaining the pressures and flow rates demanded by the Lucas PI system, but I was never able to identify a definite part number or fitment application, so unsure whether it was a series production unit or a competition 'special'.

One thing to bear in mind is that to do a proper job on a Bosch conversion, you really need to uprate the electrical feed and earth and ideally the internal diameter of the fuel supply pipe as well, all measures that will benefit the original Lucas pump. Also, the set-up fitted to the earlier (late '68 - early '69) Mk1 PI saloons with the small in-line filter and large round surge tank in the boot is apparently not altogether ideal, as the filter is prone to premature clogging-up and the surge tank can sometimes draw air through the return pipe to the fuel tank inlet (i.e. breathing the wrong way). There was an excellent article on the PI system published in Six Appeal close on 30 years ago (but, I think, reprinted a few years back) which I seem to remember suggested replacing the small in-line filter with one of the larger CAV assemblies fitted to late Mk1 and all Mk2 PIs, and restricting the bore of the surge-tank-to-fuel-tank return pipe to discourage it from allowing the pump to suck air.

Another possibility is fitting a low-pressure high-volume booster pump between tank outlet and filter to help ensure that the CAV filter head and pump inlet are always fully primed with fuel. A heat shield above the exhaust box to keep temperatures down is also a good idea (or even resituating the pump to the cooler right-hand side of the boot, though the latter obviously requires the use of proper high-pressure lines with nut-and-nipple unions in the interests of safety).[/quote

Thanks Jonathan for a very helpful reply. My Mk1 Pi is an early one with the surge tank (or swirl pot as most people seem to call them?) and the inline filter mounted up on the inside of the rear wing. (although is soon to be changed)

After test driving the car for a few days now, my issues seem to be solely with my refurbed Lucas pump. Since changing to another one things have been fine.

However, I will still be looking at possible alternatives in the mean time. :)

_________________
1968 Mk1 2600 Saloon in Slate Grey. (the infamous 'Gertie')
1969 Mk1 2.5 Pi in White

http://kingratracing.blogspot.com/


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 Post subject: Re: Pi Fuel Pumps
PostPosted: Wed Mar 29, 2017 7:30 am 
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You're most welcome - and glad to hear that you seem to have got your problems sorted :D

FWIW, I'm still running a Lucas pump and quite happy with it, albeit with a few mods to the installation layout to address some of the known weaknesses.

And yes, 'swirl pot' is the terminology I was looking for yesterday but couldn't think of at the time :wink:


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