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BOSCH PUMP - Leak Around Electrical Connector


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The spec says, the operating pressure is only 4 Bar if that is the case its NBG

Thats exactly the question. Otherwise the Bosch 996 produces officially also only 5 bars.

I would try it.  

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1 hour ago, c.hydes said:

Do we have a definitive specification for our fuel pump for a TR6 PI, ie the most important "must haves", pressure/flow/current/ etc?

Colin.

 

1 hour ago, c.hydes said:

Do we have a definitive specification for our fuel pump for a TR6 PI, ie the most important "must haves", pressure/flow/current/ etc?

Colin.

This info I got  in the early 80's from Bosch engineering here in the UK The Bosch 0-580-254-952 pump requires 2.6 L per min free flow from the tank but preferably 5 L/PM using a 3/8" bore fuel hose to avoid cavitation. This means a mod to the fuel supply tank off, I did do this! The pump s/b mounted via a simple s/s gauze filter. The pump s/b mounted as low as possible on a special bracket with a shock absorbing mounting. Electrical supply: the above pump draws 9 amps but I have checked mine and it only draws 5 amps? I think that this is the difference between petrol and diesel fuel as the 952 is a diesel pump via 30 amp rated cable and a relay. The Bosch will not deliver full flow if the voltage falls below 10 volts and for correct operation battery voltage must not be less than 11.5 volts. When my 17 ACR alternator failed I went for an 18ACR rated at 45 amps. I noticed the difference straight away with the extra current. Hope this helps?

Bruce.

Bruce.

 

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22 hours ago, astontr6 said:

2.6 L per min free flow from the tank but preferably 5 L/PM using a 3/8" bore fuel hose to avoid cavitation

I suspect not doing this is the cause of at least some of the Bosch issues. Poor inlet flow will cause cavitation, and thus wear. I wonder (and I'm speculating here) if it also exacerbates the resonance problem, perhaps by generating a little vibration from cavitation which starts the whole thing off?

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11 minutes ago, JohnC said:

I suspect not doing this is the cause of at least some of the Bosch issues. Poor inlet flow will cause cavitation, and thus wear. I wonder (and I'm speculating here) if it also exacerbates the resonance problem, perhaps by generating a little vibration from cavitation which starts the whole thing off?

I worked in the Aerospace hose Industry years ago and harmonic hammering was a known problem! There was a PI specialist in North Wales here in the UK who would insist on using PTFE smooth bore hose with s/s braid on the o/d which was rated at 1000psi working pressure. In other words it was as stiff as a rod. Bosch pumps pulsate and they have to have a hose with flexible walls If they don't you get the dreaded harmonic hammering! To over come this problem he then offered his diaphragm PRV which cured the problem. All I can say it was a good earner for him. I use a Gates Green Shield Barricade Flexible hose material rated 225psi no problems including using the Lucas PRV Type. This hose type is  available in Australia?

Bruce.

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2 hours ago, astontr6 said:

I use a Gates Green Shield Barricade Flexible hose material rated 225psi no problems including using the Lucas PRV Type. This hose type is  available in Australia?

No idea. I use a bog-standard high pressure fuel hose from my local hydraulics supplier. By careful tweaking of the lengths between tank/wheel arch and wheel arch/pump I have eliminated resonance. I figured that resonance is a frequency thing, and so playing with lengths might mess with the available wavelengths. Of course I was probably lucky, as I expect the wavelengths are very small (and so my adjustments very coarse in comparison),  but better lucky than good!

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9 minutes ago, JohnC said:

No idea. I use a bog-standard high pressure fuel hose from my local hydraulics supplier. By careful tweaking of the lengths between tank/wheel arch and wheel arch/pump I have eliminated resonance. I figured that resonance is a frequency thing, and so playing with lengths might mess with the available wavelengths. Of course I was probably lucky, as I expect the wavelengths are very small (and so my adjustments very coarse in comparison),  but better lucky than good!

I  get high pressure Gates Barricade in Australia from Repco. To avoid resonance I just put a loop in the line from the PRV to the tank, and I'm fairly generous when cutting the lengths of Barricade around the rest of the PI components  in the boot.

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Maybe I take it too simple but I get a feeling, more and more, that a simple issue will transfer into a mater of sience because of... Mmh, yes, because of what? My car is a full standard PI with a standard Lucas incection system. Just the Lucas pump is a Bosch one. Since nearly 40 years. Standard drain, standard prv, hose, standard, standard, standard. And it runs. In the south, in the mountains, in the arctic north, just everywhere. And I am not the only one with that setup. I had plenty of breakdowns like a broken clutch plate, cracked spokes, electrical worms, nearly everything. But never ever any problems with the Lucas system. 

Hammering? Cavitation?  Vapor bubbles? Not with a fine, well handled TR with a well serviced Lucas Petrol injection system. With a exactly fitted Bosch. Or a original fine Lucas pump. A wrong selected pump leads to all the well known problems mentioned above.

 

 

 

 

 

 

 

 

 

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10 hours ago, Casar66 said:

Maybe I take it too simple but I get a feeling, more and more, that a simple issue will transfer into a mater of sience because of... Mmh, yes, because of what? My car is a full standard PI with a standard Lucas incection system. Just the Lucas pump is a Bosch one. Since nearly 40 years. Standard drain, standard prv, hose, standard, standard, standard. And it runs. In the south, in the mountains, in the arctic north, just everywhere. And I am not the only one with that setup. I had plenty of breakdowns like a broken clutch plate, cracked spokes, electrical worms, nearly everything. But never ever any problems with the Lucas system. 

Hammering? Cavitation?  Vapor bubbles? Not with a fine, well handled TR with a well serviced Lucas Petrol injection system. With a exactly fitted Bosch. Or a original fine Lucas pump. A wrong selected pump leads to all the well known problems mentioned above.

Same here.

My TR6 was converted to a Bosch 996 sometime in the 1990s

when i bought it in 2012 some of the injectors were past their best so i had Neil F recondition them and they have worked perfectly ever since ( 20K+miles)

I did add a relay fed larger gauge power and earth setup to help, but not sure it makes any difference !

when one came up on ebay i bought a second 'spare' 996 pump and a couple of years ago swapped this in with new rubber piping.

It too works perfectly.

I love the PI system !

Steve

PS, on my last car i 'upgraded' from a similar 996 setup to a kit from one of the usual suspects, it resonated like a bansheee....

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7 hours ago, DaveN said:

Just been out and measured the current draw on my pump. Which is a Sytec  OTP020.

The max. draw on start up is 7.93 amps and settles at 7.92 amps.

Thanks Dave, 7.92 A is reasonable, but I thought you said you had a Sytec OTP044 pump not an OTP044?

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My mistake it is an OTP020. It works just fine! As long as stamping on the loud pedal there’s no hesitation and it goes flat out... and at 50 quid I’m happy!:D

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Thanks to all who responded. I'm still considering which pump to purchase, but in the meantime a question on the outlet from the bottom of the petrol tank.

Consensus suggests that a larger bore than my existing copper, approx. ie 8 mm OD, is beneficial. This provides a better "free flow" to the pump. Some suppliers say they have an adaptor that simply screws into the existing small bore nut, (without any drilling/soldering/modification,) that provides this larger outlet pipe to be interfaced? However, my physics is telling me that although this may provide a larger outlet, it still has to flow through a small tube however short. 

Am I missing something here or will it make a difference?

Regards, Colin.  

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Hi Colin, just ask what ID the nipple is, original tubing (elbow) is 6.5 mm iirc.

A friend machined me a new ferrule from a 1/2” UNF bolt, this works ok. Think my current ID is 8.5 mm.

Waldi

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You need a larger bore if you go for a pump with delivers more fuel into the system. And that is the starting point when one thing leads to the next. I think it is worth to try a pump that does not more than 100 liters per hour like the Bosch 996.

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Might be worth testing to see what free flow you get from the tank at the pump inlet position (see a post further up). If that's insufficient, then consider enlarging the outlet. If not, press on!

John

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 If that's insufficient, then consider enlarging the outlet. If not, press on!

But why should it be insufficient? When I got it right, the system worked pretty well until the pump got a leak. only a too strong (=wrong) pump needs a larger bore. And after that you will get trouble. After the bore and the pump you get problems with the standard prv. But still then:problems. then the right hose for the wrong setup, then at a certain point when nothing helped, the question will pop up, if your tank has a swrll pot or not, then ...tbc...

 

 

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4 hours ago, Casar66 said:

But why should it be insufficient?

It's all relative to the pump. Fit a pump with too large a capacity and you'll starve it. They don't suck well. If your pump is well-suited then no problem, as you have already pointed out. I was responding to the various posts about different pumps. As I said, find what in flow the pump requires, and make sure you have it. If so, all good.

John

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On 12/15/2020 at 5:58 PM, Waldi said:

Hi Colin, just ask what ID the nipple is, original tubing (elbow) is 6.5 mm iirc.

A friend machined me a new ferrule from a 1/2” UNF bolt, this works ok. Think my current ID is 8.5 mm.

Waldi

Waldi don`t know what size nipple in as still have 1/4 tank of fuel, but it looks like the original.

Do you have any more spares of these that you had made up, and did this work? 

 

post-13554-0-06269600-1535034212_thumb.jpg.d67d2dbba438a73ac825fef94318a67e.jpg

 

Colin

 

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On 12/15/2020 at 4:19 PM, c.hydes said:

Thanks to all who responded. I'm still considering which pump to purchase, but in the meantime a question on the outlet from the bottom of the petrol tank.

Consensus suggests that a larger bore than my existing copper, approx. ie 8 mm OD, is beneficial. This provides a better "free flow" to the pump. Some suppliers say they have an adaptor that simply screws into the existing small bore nut, (without any drilling/soldering/modification,) that provides this larger outlet pipe to be interfaced? However, my physics is telling me that although this may provide a larger outlet, it still has to flow through a small tube however short. 

Am I missing something here or will it make a difference?

Regards, Colin.  

Hi Colin! 

The key issue is the flow rate into a container. It has to meet 5 l/m through a 3/8" bore hose at the pump? In my view the tank take off has to be modified?

Bruce.

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Hii Colin,

I do not have a spare. My friend used a long 1/2” UNF bolt , 3 strips on the head, this is a high tensile steel basically, which allowed me (my friend) to drill a large hole, think 8.5 mm. I may still have a copy of the nipple sketch I made somewhere.

As Bruce says, It would be better to simply increase the tank outlet nipple size (the welded boss), but this is more work off course. The Bosch pump has a 12 mm nipple on the inlet (for a 12 mm ID hose), so I made sure your filter matches that, if you have a pre-filter. In a previous thread I explained what I have, maybe this is where you have the picture from? 

Cheers,

Waldi

 

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On 12/17/2020 at 5:51 PM, Waldi said:

Hii Colin,

I do not have a spare. My friend used a long 1/2” UNF bolt , 3 strips on the head, this is a high tensile steel basically, which allowed me (my friend) to drill a large hole, think 8.5 mm. I may still have a copy of the nipple sketch I made somewhere.

As Bruce says, It would be better to simply increase the tank outlet nipple size (the welded boss), but this is more work off course. The Bosch pump has a 12 mm nipple on the inlet (for a 12 mm ID hose), so I made sure your filter matches that, if you have a pre-filter. In a previous thread I explained what I have, maybe this is where you have the picture from? 

Cheers,

Waldi

 

OK Waldi, thanks. Yes, saw your new larger manufactured tank pipe outlet on a previous thread. Thought this might be possible with a simple re-manufactured part that simply screws in without any major/dangerous (explosive atmosphere) modifications.

There are some traders  that seem to have these, but are reluctant to sell them unless you purchase an expensive "whole new Bosch type conversion kit" from them, and all I need is a suitable new pump and some minor modifications.

Thanks all for the useful/helpful and informative comments so far.

Best regards, Colin.

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3 hours ago, Rogcastle said:

Hi Colin

Try TRGB they have the large bore outlet for £8.94.

https://www.trgb.co.uk/search?q=large+bore+fuel+tank+outlet

regards

Roger

Thanks for the link Roger, have ordered one of those for next time i replace the fuel filter on my 6.

 

steve

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