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Electric fuel pump- what psi do I need?


LarryH57

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Which millions were those, Ron? Mechanical pumps driven off the engine stop when the engine does and most of the rest were fitted with tachometric relays or other safety devices, to the best of my knowledge. There may well have been a transitional period in the 50s or 60s where this was not the case, but the electric fuel pump didn't go mainstream until close to the widespread adoption of EFI.

 

Ah, you are not familiar with the SU electric pump then, was widely used since the 1930's, still popular with classic enthusiasts.

 

Think Morris Minor and Mini for starters and that is just the tip of the iceberg.

Edited by Richard Farrant
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Ah, you are not familiar with the SU electric pump then, was widely used since the 1930's, still popular with classic enthusiasts.

 

Think Morris Minor and Mini for starters and that is just the tip of the iceberg.

 

Yes indeed Richard, pump of choice for me if required ;).

Does the job,.... reliable......well as long as the contacts are in good condition...... but a sharp tap with a medium sized spanner will fix most problems :cool2:

 

Pete

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Yes indeed Richard, pump of choice for me if required ;).

Does the job,.... reliable......well as long as the contacts are in good condition...... but a sharp tap with a medium sized spanner will fix most problems :cool2:

 

Pete

 

Pete, you can dispense with the spanner or hammer now as there is an electronic mod to replace the points ;)

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Yes as Richard says The Morris Minor and Mini for starters, not to mention 1000's and 1000's of Jags. I can well remember the Lilac coloured Morris Minors that were badged as Morris Minor 1,000,000 when that number was reached......Showing my age!!

 

Ron

Edited by Ron
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Yes as Richard says The Morris Minor and Mini for starters, not to mention 1000's and 1000's of Jags. I can well remember the Lilac coloured Morris Minors that were badged as Morris Minor 1,000,000 when that number was reached......Showing my age!!

 

Ron

 

 

Not just you showing your age Ron, my father bought a new Minor 1000 around 1959 and was a bit peeved when the Minor 1,000,000 came out a bit later on (1960?), he should have hung on to the MM a bit longer!

Back to SU pumps, without exaggerating, there were millions of vehicles using them.

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This thread seems to run and run, since I posted thread no. 7..!! a few bright sparks have given the correct simple answer, other,s wan't a computerised fully engineered NASA solution. 6volt neg/pos earth SU pumps are readily available new or used on E-bay...with filters built in 1.5-5 psi. Buy a pump fit it. End of problem .simples... If the engine stops switch off the ignition, SU pumps stop if there is no demand anyway.

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Sorry guys, I wasn't familiar with the SU pump; old British cars aren't exactly my forte and the majority of old cars I have dealt with (mostly Japanese and Australian) have run mechanical pumps.

 

As for my concerns about a safety cut-out on an electric pump, that is because I have a slight allergy to fire :P

 

Cheers,

Terry

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When I bought my Morris PU back in the 80's, it came with a Morris Minor SU pump mounted in the engine bay. I assumed that the original Autovac system (disconnected but still mounted in the cab ) must have been unserviceable. I ran it like that for years. Then one day I decided to reconnect the Autovac, and it's worked fine ever since. However I've still retained the SU pump in the system as an emergency back up (now hidden though). Ron

Morris PU 84 060.jpg

Morris PU 84 010.jpg

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An electric pump has been sourced from Southern Carburettors and is I think a Huco Suction Pump 133010 (I don't have it yet) but its said to be for either positive and negative earth on SC's website. So how would it be connected up if the vehicle is positive earth? Surely if it can be connected either way then it could potentially run either way i.e. in reverse? Any thoughts on this anyone?

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An electric pump has been sourced from Southern Carburettors and is I think a Huco Suction Pump 133010 (I don't have it yet) but its said to be for either positive and negative earth on SC's website. So how would it be connected up if the vehicle is positive earth? Surely if it can be connected either way then it could potentially run either way i.e. in reverse? Any thoughts on this anyone?

I'd suggest that simply means it comes with a red and a black wire poking out of the side rather than relying on the body of the unit to earth. Therefore it can be used on either a +ve or -ve earth vehicle. And yes, if you wire it the wrong way it will pump the wrong way, so don't :).

 

- MG

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Many thanks all

 

When in our haste to fit a pump last time (which we discovered was a negative earth pump) it did nothing when it was connected other than get hot before we quickly disconnected it. Now this time round I'm proposing that as it is a positive earth vehicle and a pump to suit that we attach the brown lead to the chassis earthing point and have the black one attached to the negative terminal on the coil. Fingers crossed!

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Pete, you can dispense with the spanner or hammer now as there is an electronic mod to replace the points ;)

 

Am deeply disappointed, Richard, I thought that lying on one's back on a wet road trying to hit the SU pump with a spanner was surely part of the pleasure of early Mini ownership?

 

Saying that, the fuel pipe did one day spring a leak and sprayed fuel onto the exhaust manifold, in the middle of Loughborough, setting light to the insulation I had rashly installed under the bonnet to aid me in listening to my tape player whine as it played. It taught me to always carry an extinguisher - which later proved its worth when my Dyane caught fire in Sutton Coldfield...

 

I would hesitate in connecting a fuel pump feed anywhere close to the coil, the last thing one surely needs is to replace a fuel issue with an ignition related one. ;)

 

trevor

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There must be a neat way of building in a safety cut-out.

 

For example what if we had a time-out relay (load circuit opens after set time) of say 10 seconds in the feed from ignition switch to fuel pump, with a running feed via an oil pressure switch or dyno / alt charge circuit?

 

During initial start-up the pump is only required to fill the carb bowl - which takes maybe 3 - 5 seconds. So a feed via the ignition switch and relay initially to fill bowl, then the feed can be taken over by something related to oil pressure or alternator / dynamo charge. Don't think the existing oil press switch be used without another relay as they usually close with no oil pressure thereby putting on a warning light, so another switch would be required, with a tee fitting.

 

Come on then - who is good on electrical puzzles then? Not too many relays please :cool2:

 

P.S. if we can land a rocket on the moon, why can't we make a decent quality rubber fuel hose? Another thing about those Filter King units is the fittings are designed for rubber hose - difficult to adapt for metal pipes.

Edited by N.O.S.
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There must be a neat way of building in a safety cut-out.

 

For example what if we had a time-out relay (load circuit opens after set time) of say 10 seconds in the feed from ignition switch to fuel pump, with a running feed via an oil pressure switch or dyno / alt charge circuit?

 

During initial start-up the pump is only required to fill the carb bowl - which takes maybe 3 - 5 seconds. So a feed via the ignition switch and relay initially to fill bowl, then the feed can be taken over by something related to oil pressure or alternator / dynamo charge. Don't think the existing oil press switch be used without another relay as they usually close with no oil pressure thereby putting on a warning light, so another switch would be required, with a tee fitting.

 

Come on then - who is good on electrical puzzles then? Not too many relays please :cool2:

 

P.S. if we can land a rocket on the moon, why can't we make a decent quality rubber fuel hose? Another thing about those Filter King units is the fittings are designed for rubber hose - difficult to adapt for metal pipes.

 

A fuel pump inertia switch is the answer if cutting off the fuel in the event of an accident is the main concern:-

 

http://en.wikipedia.org/wiki/Inertial_switch

 

Wiring diagram to stop the fuel pump when there is no oil pressure:-

 

http://www.how-to-build-hotrods.com/electric-fuel-pump.html

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Ok folks the Huco Suction Pump 133010 from Southern Carburettors was fitted this morning and works very well.

 

It seems that Southern Carburettors were the only people to point out that this pump works with negative or positive earth, so in the case of the Tilly the red wire was attached to earth and the black to -ve on the coil. All the other searches I did for this item suggest negative earth use only.

 

Anyway that's the good news - there is slight leak from the carb around the inlet pipe!

 

I know what your thinking the fuel pressure must be so high, it forced its way out but at 1.4psi its not that much and similar to the AC engine driven pump! Does anyone know what the rating is for the original AC pump?

 

Hopefully a new fibre washer (part 56 on the exploded diagram in the parts list) will stop the drip.

Edited by LarryH57
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Ok folks the Huco Suction Pump 133010 from Southern Carburettors was fitted this morning and works very well.

 

It seems that Southern Carburettors were the only people to point out that this pump works with negative or positive earth, so in the case of the Tilly the red wire was attached to earth and the black to -ve on the coil. All the other searches I did for this item suggest negative earth use only.

 

Anyway that's the good news - there is slight leak from the carb around the inlet pipe!

 

I know what your thinking the fuel pressure must be so high, it forced its way out but at 1.4psi its not that much and similar to the AC engine driven pump! Does anyone know what the rating is for the original AC pump?

 

Hopefully a new fibre washer (part 56 on the exploded diagram in the parts list) will stop the drip.

 

I am glad this thread is nearing resolution, I suggested an electromechanical fuel pump way back on thread no.7 would work fine, I thought we had already decided a mechanical fuel pump works at 1.5-3.0 psi depending on the type and condition of the pump. Fit the new washer and that should be cure the leak...

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