Jump to content

Fuel pump - replace duff Bosch or refurb Lucas?


Recommended Posts

 

It does not look very safe at the Mercedes, the connection between the pumps, already working

under 3 bars, looks a little bit small but anyway, its Mercedes and it works for 25 years!

 

What I would do is to buy original BOSCH pumps and not the cheap Charlys to be on the safe side.

The original Bosch pump recommended by Bosch UK engineering dept. 40 years ago was their part number 0-580-254-952. This pump is still made but on 15 weeks delivery as per 3 weeks ago, another member has one on order! But it needs a 10m/m minimum bore fuel supply from tank to pump and must be sited below the fuel tank. I use a Mahle in line filter KL158 before the pump using a coil clamp to mount it to the body work. All my fittings are screw except the spigot for the feed into the pump from the filter.

 

Bruce.

Link to post
Share on other sites

Hi Bruce, you may get them from SANDTLER, German motorsport supplier.

He offers a list to transfer the hundreds of Bosch numbers to about 10 pumps.

They have most of them on stock.

Maybe the above is one of them

Link to post
Share on other sites

Yes, more manufacturers than you might expect used the Lucas Pi system. This thread on Sideways talks of Jaguar (D- and E-types), McLaren (M7A, possibly others), Ford and Cosworth using both the pump and the metering unit, but as said above, electric versions of the pump for starting, mechanical for running.

 

http://sideways-technologies.co.uk/forums/index.php/topic/6876-lucas-pi-on-new-jagaur-e-types/

 

John

Link to post
Share on other sites

I think I'm right in saying that in the racing application the MU didn't rely on manifold vacuum but it had a mechanical connection to the throttle slides.

Link to post
Share on other sites

Hi Bruce, you may get them from SANDTLER, German motorsport supplier.

He offers a list to transfer the hundreds of Bosch numbers to about 10 pumps.

They have most of them on stock.

Maybe the above is one of them

Thanks, I will look!

 

Bruce.

Link to post
Share on other sites

Do nt know a out others, but Kastner had a mechanical mod that translated throttle position into M/u action. He had a box of cams that would 'tune' the M/u for any conditions.

John

Link to post
Share on other sites

 

Yes, you have to find someone who can weld motor cycle fuel tanks which I did. They have the know how in my experience to do this type of work. My original BL welded fitting was cut out after purging my fuel tank with an inert gas. Sometimes it is done using Argon or Co2 then a new larger turned up female boss brazed in, some people will use a type of silver solder. Female/male bosses are available from some hose fitting suppliers usually with a AN thread..

 

Bruce.

Link to post
Share on other sites

 

Rhis is my 1st "quote reply", see above:)

 

Hi Bruce,

Thanks for your reply about increasing the pump suction line ID.

I gave it some additional thought, would it be possible to use the larger drain connection on the RHS of the tank, this would avoid brazing-in a larger nozzle. It would also allow a straight run from tank-outlet to pump.

Pump and PRV would remain on their current location on the LHS of the tank.

Thanks,

Waldi

Link to post
Share on other sites

Do nt know a out others, but Kastner had a mechanical mod that translated throttle position into M/u action. He had a box of cams that would 'tune' the M/u for any conditions.

John

 

Normally the metering is done what we call "speed density"

That is according to air pressure and air temp and manifold pressure

metering the proper amount of fuel. As we know PI does not have air pressure and air temp.

They assume it is always the same. For high altitude a second box was added to take that

lower air pressure into calculation because larger differences can not be tolerated.

 

What Kas did is called "alpha-n" where the throttle position and rpm is taken to

meter the fuel that is needed. Unfortunately the rpm is not measured with this solution.

The estimation is that fuel amount does not change over rpm.

I wrote a comparison between this modification and how this is done with EFI

on the Kas pages.

 

What was the reason to do so?

For hotter cams there will be problems with manifold pressure and pulsation.

That makes it difficult to get things perfect from 290 degree cam on.

Alpha-n does not need that "dirty" manifold-pressure-signal.

Modern EFIs can use both systems as required and some also offer a hybrid.

It starts with speed-density and with opening throttle is swapped to alpha-n

to take the best of both ways to meter the fuel amount.

Link to post
Share on other sites

Rhis is my 1st "quote reply", see above:)

 

Hi Bruce,

Thanks for your reply about increasing the pump suction line ID.

I gave it some additional thought, would it be possible to use the larger drain connection on the RHS of the tank, this would avoid brazing-in a larger nozzle. It would also allow a straight run from tank-outlet to pump.

Pump and PRV would remain on their current location on the LHS of the tank.

Thanks,

Waldi

I have to say that my tank which is original does not have a separate drain off, very useful! Yes I do nor see why not, I assume that it has a larger thread size than the fuel hose supply one?

 

Bruce.

Link to post
Share on other sites

I have to say that my tank which is original does not have a separate drain off, very useful! Yes I do nor see why not, I assume that it has a larger thread size than the fuel hose supply one?

 

Bruce.

 

One of my TRs uses that plug. Thread is very similar to M16x1,5.

I cutted that thread and used all that stuff from oil cooler.

 

Unfortunately a normal banjo does not fit because the tank is a little bit

to high above the rear hole.

But there is a so called double banjo availiable that I could use,

making a cylinder as a spacer instead of the upper banjo.

 

So I ended under the rear trunk with a 1/2" banjo where a 12mm fuel hose fits.

This is much bigger (more than double) compared to the original 8mm hose.

Link to post
Share on other sites

Thanks Bruce and Andreas,

I will (TRy) to fit the suction line from the large drain to the filter and next to the pump.

I note the Mahle KL158 has M16x1,5 mm thread, to that should all fit nicely.

Regards,

Waldi

Link to post
Share on other sites

Bosch any day. A Bosch equivalent can even be viewed as a service item and changed at the time of the fuel filter. The pumps supplied for TRs are not bespoke items so buy from a motor factor. (rather than an overpriced Bosch from a TR dealer)

 

Hi, have you a part number or recommended supplier? I've just been out and mines started making an awful noise. .

Link to post
Share on other sites

 

Bosch any day. A Bosch equivalent can even be viewed as a service item and changed at the time of the fuel filter. The pumps supplied for TRs are not bespoke items so buy from a motor factor. (rather than an overpriced Bosch from a TR dealer)

 

Hi, have you a part number or recommended supplier? I've just been out and mines started making an awful noise. .

 

Look at my response #27 part number given by me! Bosch pumps making a nose is often due to fuel starvation on low fuel in tank and poor sighting of pump? Or bore size of fuel pipe too small? Or a combination.

 

Bruce.

Link to post
Share on other sites

Look at my response #27 part number given by me! Bosch pumps making a nose is often due to fuel starvation on low fuel in tank and poor sighting of pump? Or bore size of fuel pipe too small? Or a combination.

 

Bruce.

Thank you. It's been ok up until today. Tank was low, less than 1/4 full and very hot weather. The pump is under the rear wheel arch and was very warm to touch so could be that but fancy getting a spare just in case.

Link to post
Share on other sites

How far away is it from the exhaust pipes / silencer box and is that a stainless steel type? If too close this could be down to heat radiation and affecting the m/s fuel line. It is very easy to get fuel vaporisation with modern fuel! That is why s/s exhaust manifolds are not liked by the racers!

 

Bruce.

 

Thank you. It's been ok up until today. Tank was low, less than 1/4 full and very hot weather. The pump is under the rear wheel arch and was very warm to touch so could be that but fancy getting a spare just in case.

 

Thank you. It's been ok up until today. Tank was low, less than 1/4 full and very hot weather. The pump is under the rear wheel arch and was very warm to touch so could be that but fancy getting a spare just in case.ave

Link to post
Share on other sites

" If it was good enough to run the Lucas injection on DFV engines "

 

Yes, but . . . . . on competition installations the Lucas pump was generally only there to provide initial starting impetus, thereafter the engine-driven mechanical pump took over . . . . .

 

Cheers,

 

Alec

And probably serviced/checked or replaced after every outing.....not what you want to be doing!

Link to post
Share on other sites

It is a stainless pipe and the pump is positioned right in the wheel arch along the chassis. It was a very hot day and we weren't at speed cruising in traffic which didn't help.

It does sound like cavitation to me what is the bore size of your fuel pipe from tank to pump?

 

Bruce

Link to post
Share on other sites

The pipe is 7.5mm. I recently renewed the rubber pipe and the original filter metal pipe was the same bore so didn't see the point of fitting larger rubber pipe unless I replaced the filter with a large bore version.

 

I think it was definately cavitation due tolls tank and weather. Just been out with a full tank now it's cooler and it ran perfect.

Link to post
Share on other sites

Interesting chat!

 

I swapped back to a Lucas pump and filter under the tank... The Bosch unit failed and left me stranded. It didn't seem any more reliable to me than the Lucas set up and had pipes and tubes in and out of the boot to the wheel arch. Went back to the original Lucas set up with all the mountings in the right place but driven by new positive and negative wires to the battery (with fuse!) and switched via a relay from the old wiring (relay also in the boot next to pump)

 

In hindsight, I wish I had fitted a fuel tap at the same time so I could drain/shut off fuel and work on the system.

 

I also fitted a coil over pump to try to keep it cool but it doesn't seem to get that warm! It's not let me down yet and puts the car back to original design. In my view, it is the Lucas PI system that makes the TR6 stand out from the crowd. So if it works why change it?

 

Neil

Link to post
Share on other sites

The pipe is 7.5mm. I recently renewed the rubber pipe and the original filter metal pipe was the same bore so didn't see the point of fitting larger rubber pipe unless I replaced the filter with a large bore version.

 

I think it was definately cavitation due tolls tank and weather. Just been out with a full tank now it's cooler and it ran perfect.

7.5 m/m bore pipe in my view based upon experience and Bosch Technical advice is far too small??? As you have now indicated that your car is running OK with a full tank! This is because the head of petrol in the tank increases the flow rate to the pump! Until it gets low again and the flow rate slows down!

 

Bruce.

Link to post
Share on other sites

7.5 m/m bore pipe in my view based upon experience and Bosch Technical advice is far too small??? As you have now indicated that your car is running OK with a full tank! This is because the head of petrol in the tank increases the flow rate to the pump! Until it gets low again and the flow rate slows down!

 

Bruce.

Yes, good point re the flow rate. I will renew the pipe work at some point but for the time being keep it topped up.

Link to post
Share on other sites

Yes, good point re the flow rate. I will renew the pipe work at some point but for the time being keep it topped up.

Remember that a Bosch pump suitable for TR6 pressure, requires a minimum of 2.6 l/m at the pump flow rate at the pump, preferably 5 l/m on a full tank. This takes into account the head of fuel pressure drop as the petrol falls below a 1/4 tank. Hence the 10 m/m bore size pipe work or larger! To further highlight this point if you do this test on the original Lucas/CAV system at a Lucas TR6 pump you will get around 1 l/m on a 1/2 tank Not good enough in hot weather! .That's why CAV came out with a 3/8" bore mod kit for the 2.5 Saloons fitted by CAV service centres around where I live.

 

Bruce.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.