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PI Fuel pump failure


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Went for a first start on my newly rebuilt engine today.     Initial fuel pressure of 120psi rapidly fll to only 40!   The injectors won't fire on that!

I had this before, after an over-winter .     Then I diagnosed a seized vane on the pump, due to corrosion from water in the fuel.     Ran the pump in a circle, with lots of injector cleaner in the fuel, for ages to no avail.    Needed new pump.

This time, I used fuel stabiliser in the fule, then drained the tank.   But now it seems I have a failed pump.   Again.   Is it me, or has anyone else had this?

John

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Hi John,

My old 996 pump was leaking fuel through the electrical connection point after 3 years of (dry) storage. But that is a different failure off course. I replaced it by a new (different, more current) Bosch pump.

Waldi

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ntc,  you may not have noticed the swirl pot, above the pump

Mike C,  cant win, can I?   If it's above the tank, the Curse of NTC will fall upon it, if it below, it's water in the fuel!  My Facet has no problem working as a lifter pump filling the swirl.

Must be just me, then.     Paranoia rules!

 

Edited by john.r.davies
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John, sorry not to get back sooner. Your set up looks very much like the Malcolm Jones/Prestige Bosch pump kit I fitted to my TR6 many years ago, which has worked well over many thousands of miles.

A critical part of the kit is a new tank outlet, with pipe diameter increased from 1/4 to 5/16", to feed the pump better. Apparently Bosch pumps don't suck fuel from the tank well, even though they push fuel well at high pressure.

Could it be that there is too much flow restriction on the inlet side of your pump?

Nigel

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You would have checked the PRV setting hasn't drifted? Maybe run the Bosch pump briefly against a closed head and compare the shut off head against the factory spec sheet.

But if you're getting water problems with the pump each winter  it's a problem with the fuel or piping. I assume you don't store the car outside over winter- in the past I've had that cause water problems  in the fuel tank due to condensation from the air  on cold nights.

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Nigel,

Thanks, but if you look again at the "Turkish distillery" in my boot, above, you'll see that the Bosch is fed from a swirlpot, fed by a facet lifter pump and higher than the main pump, to recognise just the point you make.   This has worked well previously.   And yes, I got the Bosch frm Malcolm.

Mike C, 

Since that pic, I've fitted one of Malcolm's easily adjustable PRV, and I've twiddled that, to no avail.    

It may be just some dirt in the pump.    I've  had three suggestions: Hit it Tap with a hammer - Done.   Run it in a loop with a good does of injecter cleaner in the fuel - it does so anyway, tank- swirlpot- main - PRV- tank when the engine's not running.    Tried that with previous fauilure to n avail.    And BRIEFLY, reverse the polarity on the pump.    I'll try the second again and the third.    Don't trust myself much with the first !

John

 

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How old (years) is your Bosch pump John?

Could it be dirt from the upstream pump, pot, filter? If I understand your lay out correctly, the blue filter is at the inlet of the Bosch pump to protect it from debris from Facet pump and Swirlpot; How coarse is it?

 

Edit: And I not know the quality of repro Bosch pumps, is this an original or cheap look-like?

Waldi

 

Edited by Waldi
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I purchased a pump set up from Malcolm of Prestige (now retired) a couple of years ago.... Working great but I understand not a Bosch pump anymore...Any ideas which pump should I ever need a replacement?

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Waldi, correct, the blue filter has a replaceable element, the canister after the pump is very fine, and is disposable.   I ought to replace the first, maybe the second.

Mike, I fear that it's not water as droplets that is the problem, that a coalescer could remove, but dissolved in the alcohol component of modern fuel.

jogger - thus is subject of many discussions  EG https://www.tr-register.co.uk/forums/index.php?/topic/62490-fuel-pump-replace-duff-bosch-or-refurb-lucas/page/3/

John

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4 hours ago, jogger321 said:

I purchased a pump set up from Malcolm of Prestige (now retired) a couple of years ago.... Working great but I understand not a Bosch pump anymore...Any ideas which pump should I ever need a replacement?

No idea Jogger. Any pictures?

I recently bought a Pierburg 7.21659.72.0 Fuel Pump for my PI. I had read that it was a possibly quieter alternative to Bosch which I have, and retails for about £120. Amazon had some sort of sale and when it hit £40 I bought one. Afterwards the price immediately jumped back up to £120. I see it's gone back down to £35 - what are they playing at? I haven't fitted the Pierburg yet - I'm waiting for warmer weather - and there'll be a bit of engineering as the in/outlets are different!

Check out http://www.w124performance.com/docs/general/Pierburg_fuel_pump_specs.pdf and look for the E3T variant. Do you think Malcolm might have used this one? The Pierburg claims a system pressure of 94psi but the performance graph goes up to 150psi. One of the advantages is that they claim it will prime up to 0.5-metres.

Cheers, Richard

81mpwGNeAPL._SX679_.jpg

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Thnak you, Spit2.5!   Most informative!

But that information says that the max pressure on an E3T, or any of these, is 94psi. 

When the specified pressure for Lucas Pi is 100psi, is that sufficient?

JOhn

Edited by john.r.davies
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19 minutes ago, john.r.davies said:

Thnak you, Spit2.5!   Most informative!

But that information says that the max pressure on an E3T, or any of these, is 94psi. 

When the specified pressure for Lucas Oi is 100psi, is that sufficient?

JOhn

This max output pressure from Bosch pumps was dealt with in the 1980's, when we first Sought a replacement pump, by KMI supplying a Lucas PRV set to a lower pressure specifically for use with Bosch replacement pumps when fitted to Lucas PI systems.  The injectors I think must crack at above 70 psi.  TR Workshop and KMI spent many hours fine tuning these replacement substitute pumps and we at Cox & Buckles retailed them as good working solutions to the aging Lucas pump.

I notice they still offer them.  https://www.kmipetrolinjection.co.uk/Lucas%20Mk%202%20Petrol%20Injection.htm

Cheers

Peter W

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Yes, quite right John. I believe the pump was OE on some early electro-mechanical Bosch systems, hence the 94psi rated pressure. However, it is characterised up to 150psi. Frustratingly, they don't quote the opening pressure of the integral pressure-limiting valve. But, for forty quid, I thought I'd take a punt on it being >> 110psi. And I fancied trying a different pump.

Thanks Waldi. If they are using the same Pierburg E3T pump then looks like it'll work for me too.

Cheers, Richard

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2 hours ago, john.r.davies said:

Thnak you, Spit2.5!   Most informative!

But that information says that the max pressure on an E3T, or any of these, is 94psi. 

When the specified pressure for Lucas Pi is 100psi, is that sufficient?

JOhn

If it helps, I set my PRV to operate at 680Kpag (98.6 psi) with air. The PI system has worked perfectly with this setting for years.

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I think it is Richard, I can check. If Jochem reads this, he will know for sure.

Waldi

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7 hours ago, Spit_2.5PI said:

No idea Jogger. Any pictures?

I recently bought a Pierburg 7.21659.72.0 Fuel Pump for my PI. I had read that it was a possibly quieter alternative to Bosch which I have, and retails for about £120. Amazon had some sort of sale and when it hit £40 I bought one. Afterwards the price immediately jumped back up to £120. I see it's gone back down to £35 - what are they playing at? I haven't fitted the Pierburg yet - I'm waiting for warmer weather - and there'll be a bit of engineering as the in/outlets are different!

Check out http://www.w124performance.com/docs/general/Pierburg_fuel_pump_specs.pdf and look for the E3T variant. Do you think Malcolm might have used this one? The Pierburg claims a system pressure of 94psi but the performance graph goes up to 150psi. One of the advantages is that they claim it will prime up to 0.5-metres.

Cheers, Richard

81mpwGNeAPL._SX679_.jpg

Richard ...This is what is shown on the now retired Malcolms web page relating to the "Bosch type" pump fitted alongside a picture of the arrangement

http://www.prestigeinjection.net/pumps.htm

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15 hours ago, BlueTR3A-5EKT said:

This max output pressure from Bosch pumps was dealt with in the 1980's, when we first Sought a replacement pump, by KMI supplying a Lucas PRV set to a lower pressure specifically for use with Bosch replacement pumps when fitted to Lucas PI systems.  The injectors I think must crack at above 70 psi.  TR Workshop and KMI spent many hours fine tuning these replacement substitute pumps and we at Cox & Buckles retailed them as good working solutions to the aging Lucas pump.

I notice they still offer them. https://www.kmipetrolinjection.co.uk/Lucas Mk 2 Petrol Injection.htm

Cheers

Peter W

Thank you, Peter!

However, that page doesn't include a non-Lucas fuel pump.    I previously asked KMI is they could replace the one I have, and they cannot, which made me more cautious about the Pierburg.

That you at C&B had to go to such trouble to make them fittable increases my caution, and I'm going to try again tio get this one working.   And I note Richard's point about "up to 150psi" whihc appears in the spec, without explanation.

John

Edited by john.r.davies
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