Does The Pug Fuel Pump Have A Non Return Valve?

[kyepan 291]

Just to break this off from the other thread and ask a specific question.

 

1) Does the Bosch fuel pump in the pug have a non return valve / check valve?

 

I have been looking at the Bosch site, specifically their spec sheets but can't get a straight answer, because they seem to have streamlined their range from 72 to 7 pumps and are using adapter kits.

 

2) If so is the check valve external to the pump or internal?

 

3) Has anyone here either got an FPR with a pressure gauge in it, or done a fuel pressure drop test? if so how long did it take for the pressure to drop from 40psi to nearly zero.

 

(its the test where you switch the engine off and watch how the residual pressure in the rail decays)

 

failing that

 

4)would someone fairly local to maidenhead with a 205 be kind enough to pop round so we can stick my gauge in line and run it up to test what happens when the engine is switched off.

 

Answers to these questions would be Most appreciated.

 

Cheers

 

j

Edited September 28, 2009 by kyepan

[Galifrey 1]

Don't quote me but i believe they have an electromagnetic non return valve that activates when the ignition is turned off to keep the fuel rail under pressure.

[James_R 3]

I thought the one way valve on the top of the pump meant the fuel rail would remain pressurised just under the FPR's max pressure (although does drop slowly) I'd happily swing past once mines running again next week sometime.

[Anthony 1,000]

Otherwise you're welcome to do the pressure test on mine if you want Justin if you're over this neck of the woods at all - I know mine holds fuel pressure pretty well, and starts pretty much first or second revolution of the engine even after sitting for days.

 

As said, there is definately a non-return valve of sorts in or near the pump, but I've never investigated to find out the finer details.

 

Edit: Thinking about it, mine might not be ideal, as there's not a particularly easy place to tap into the fuel line in the engine bay on an 8v unlike an Mi16, as the feed fuel pipe has a treaded nut fitting on the end of it - and whilst I'm happy to help, I'm understandably less happy to hack up my fuel pipe to do so!

Edited September 28, 2009 by Anthony

[kyepan 291]

I thought the one way valve on the top of the pump meant the fuel rail would remain pressurised just under the FPR's max pressure (although does drop slowly) I'd happily swing past once mines running again next week sometime.

 

Thanks for the replies guys, if anyone knows anything more about these electromechanical valves porka was talking about, i'm all ears.

 

James, your right, it should still be at more than 20psi after 10 mins, mine drops to zero almost immediately.

 

If you are local it would save a trip over to swindon (thanks though anthony as the offer is also much appreciated) is your car getting a new engine at the moment?

 

J

[kyepan 291]

Edit: Thinking about it, mine might not be ideal, as there's not a particularly easy place to tap into the fuel line in the engine bay on an 8v unlike an Mi16, as the feed fuel pipe has a treaded nut fitting on the end of it - and whilst I'm happy to help, I'm understandably less happy to hack up my fuel pipe to do so!

understood, i usually place the gauge just before the rail, which involves un-securing the pipe to the rail and placing the gauge in line. Have separate hose to allow this and then jubliee clip it together. Does the 8v not jubilee clip on to the rail.

 

 

 

arrangement without gauge

 

filter - hose - rail

 

arrangement with gauge

 

filter - hose - gauge - extra hose - rail.

 

[DrSarty 90 1 Cars]

Is this not worth a whip round of some sort J, getting a handful of GTI pumps and just swapping 1-for-1 until it works?

 

That would seem easier than this informative but time consuming testing to confirm something you probably know already.

 

Just trying to get you on the road sooner.

[Galifrey 1]

From bosch.au website

 

Many Bosch fuel pumps utilise an external threaded non-return valve most of M12 x 1.5mm specification (i.e. pump number 0 580 254 044). These pumps were originally applied to vehicles that use a “banjo” style fuel line connection system and hence have the threaded non-return valve connection used in conjunction with a banjo fitting, copper washer and cap nut. The purpose of this valve is to prevent fuel returning back to the fuel tank when the fuel pump is shut down.

 

This non-return valve must not be removed from the fuel pump, removal will result in fuel system pressure loss as soon as the fuel pump is shut down. If the fuel system cannot retain a certain amount of pressure after shutdown, fuel vapourisation may occur in the fuel lines and rail resulting in difficult hot start characteristics.

 

The non-return valve is a serviceable item in many older style fuel pumps and is therefore removable for this purpose only. Consult the Bosch Engine Management Components catalogue for a listing of relevant non-return valve to fuel pump applications.

 

So some pumps have an external non-return valve on the outside of the pump in the banjo fitting, others it seems have the non-return integrated in the outlet "neck"

 

I think the electromechanical one way valve may not apply to the bosch pumps, and it is merely a sprung valve?

[Anthony 1,000]

understood, i usually place the gauge just before the rail, which involves un-securing the pipe to the rail and placing the gauge in line. Have separate hose to allow this and then jubliee clip it together. Does the 8v not jubilee clip on to the rail.

Nope, it screws onto the rail, hence the comment that an 8v isn't ideal for the test.

[Galifrey 1]

The kit I used for fuel pressure "intercepted" the feed from the pump and had a dry break adaptor that fitted before the fuel rail.

[kyepan 291]

Is this not worth a whip round of some sort J, getting a handful of GTI pumps and just swapping 1-for-1 until it works?

 

That would seem easier than this informative but time consuming testing to confirm something you probably know already.

Yer that was my first reaction too, whack a new pump in, but I've already been through two pumps, so I'm not completely convinced it's the answer.

 

Plus it's a phase two pump, most seem to be the earlier type of connector on a leash, rather than connector on the fitting so finding one took a while (weeks). I'm not completely convinced it's the pump to be honest.

 

So after much messing about, I want to be sure I know what it should do both electrically and pressure wise, then i can sniff out the route cause.

 

chances are it will come down to a new valve, but if its a case that the car needs the tank cleaning or something and it's getting crud in the valve then i need to know, or another valve my get clogged in a short period. Alternativly it could be some dodgy electrical problem that fitting a new pump might not solve, or only solve temporarily if the electrical issue is damaging the pump somehow.

 

Don't want to bodge this, want to be sure i've fixed it and understood why it's fixed, as i need some kind of reliability in this car for a reasonable length of time.

 

a quick edit - just re-read this and if you can't tell i'm really frustrated about this issue, so any grumbling isn't directed at your sensible response,its the situation.

Edited September 28, 2009 by kyepan

[kyepan 291]

From bosch.au website

 

 

 

So some pumps have an external non-return valve on the outside of the pump in the banjo fitting, others it seems have the non-return integrated in the outlet "neck"

 

I think the electromechanical one way valve may not apply to the bosch pumps, and it is merely a sprung valve?

ok, good that's pretty much the conclusion i came to, they show the screw in types only, but i can't make head nor tail of their fitment charts as they have slimmed the range.

 

thanks mate.

[DrSarty 90 1 Cars]

they have slimmed the range.

 

72 down to 7 is a 'hack', not a 'slim'.

 

[kyepan 291]

Right.. so. This morning I took apart the spare pump housing to remove the pump, and managed to split the plastic housing in several places removing it from it's rubber ring, it's held in by four rubberised clips that are far too big. Perhaps some washing up liquid would have helped but hey ho.

 

The clipped exit to the pump, and rubber sleeved section did not contain any kind of valve, which answers the question, No the pug pump does not have an external non return valve.

here you can see the different filter sections and various components that go together to make up the pump

 

This could mean it has an electrically operated internal valve that opens when current is applied...

 

the pump does not appear to allow air to flow in it's off state, so either the internal workings are air tight when not rotating or it does have a valve.

 

So I'm going to do a couple of tests,

 

1) Check the voltage to the pump with the ignition off, there should not be any.

2) rig the pump up and disconnect the power to the pump whilst turning off the ignition, to see if this allows the pressure to be held.

 

3) possibly try to swap the pump itself from this housing to the other without breaking it. ha ha, yer right.

 

for your reference the serial number on the side of the pump is

 

BOSCH 0 580 464 993 MADE IN FRANCE

[DrSarty 90 1 Cars]

Good luck with this J. It certainly shows the commitment of an engineer to get to the root cause.

 

By the way, just to translate:

 

'Made in France' in English means 'Defo will break'.

[kyepan 291]

ok, a quick question,

 

Where is the earth for the fuel pump and sender unit?

 

My sender has been giving dodgy readings for quite some time.

Also there is a bypass wire for the fuel pump feed with 3, yes 3 different joins in it... this runs down the side of the passenger foot well and up behind into the fuseboard.

 

It's marked on the xu9ja wiring diagram in the haynes.

the pump has 0.15-0.07v going through it with the ignition off.

[DamirGTI 327]

No the pug pump does not have an external non return valve.

 

Im 95% sure that the non return valve is integrated within the pump , i.e. inside the outlet orifice (spring and steel ball ..) .. and possibly relief valve as well ...

 

Anyway , you haven't said , what's wrong with the car ? you can start the engine at all ? or is it hard to start from cold/hot ?! .. etc.

 

Damir

Edited October 3, 2009 by DamirGTI

[kyepan 291]

Im 95% sure that the non return valve is integrated within the pump , i.e. inside the outlet orifice (spring and steel ball ..) .. and possibly relief valve as well ...

 

Anyway , you haven't said , what's wrong with the car ? you can start the engine at all ? or is it hard to start from cold/hot ?! .. etc.

 

Damir

It's turning over and over when it's hot, taking a while to start, there is more information in this thread.

Basically when you turn the engine off, fuel pressure drops immediately to zero, it should be maintain pressure at approximately 20psi, ten minutes later.

 

Running the pump manually, it takes time to fill the rail with fuel, stop the pump and the fuel runs back into the tank leaving an air pocket at the rail, it would seem to loose pressure immediatly and then over time the rail will empty and fill with air.

I'm 1000000% sure the fuel rail, FPR, fuel lines etc are not the problem, because i've systematically tested everything with painstaking detail over the past few weeks. however the bit that really confused me was when manually pressurising the fuel line from rail to pump with a foot pump it held pressure. So i was thinking that it might be an electronic valve.

 

so if you're pretty sure that the valve is in the neck, and it's not electrical, then it looks like i need to change the pump... but i've done this once already, and it didn't make a difference.

 

confused.com

[Galifrey 1]

Entirely possible you have an injector stuck open

[kyepan 291]

Entirely possible you have an injector stuck open

Yes that was a possible cause, but I've had the rail out and there is no leaking their that i could detect, i've also changed the o-rings, on both ends of the injectors themselves.

 

But as previously stated, the system will hold pressure right up to the pump (tested with mole grips by the pump).

 

so i'm 100% sure it's the pump... in some capacity.

[DrSarty 90 1 Cars]

This is not a 'I told you so', because I admire(d) your tenacity.

 

But I do think one or several fuel pump swaps is the solution to fixing this. Blunt but effective.

[kyepan 291]

swapped the pump over on friday,

 

it has solved the following.

 

Taking up to 15 seconds of cranking after the engine has been run and then sat for over five mins.

 

Starting then firing on one cylinder then dying when you touch the throttle

 

Reving twice up to 2.5k rpm when you start it without any throttle

 

Kangerooing at low speeds when you've just started it.

 

Dead zone below 3krpm on part throttle

 

lack of crazy zone above 5k...

 

 

 

Pump must have been on it's absolute last legs, it actually looked tired when i pulled it out of the tank, and gave a little sigh as i let the fuel dribble out.. it's last gasp...

 

that is all.