PI Fuel Pumps - RBRR Whinning Nightmares

[Pete PiEst]

Hi All,

I've got a DIY BOSCH 044 conversion on the estate, which has done well for over 10+ years but on this years RBRR it decided to give us a "challenge" towards the end. From just before Bude to just after Honiton it was cutting out with a lack of pressure and we wasn't too sure if we were going to make it back to Knebworth 🤦‍♂️🤦‍♂️

It was getting hot and making quite a racket !!

We got round this by removing the spare wheel in the estate and leaving it open along with the windows. This allowed it to keep cooler.

I've just checked the fuel filters both pre and post pump, both fine.

The problem with the estate is that it has to suck the fuel out through the top of the tank through a pipe with an ID of 6mm.

My new plan is to get a new outlet welded on to the tank in AN-8 the ID bore of the aluminium hard line is around  10mm the flexible tubing is around 11mm and 9.5 for the fittings.

The pressure side of the pump and post filter is already in AN-6 up to the distribution block of the PRV.

So my question to the Pump-ologists is:

1, Do you think AN-8 is large enough?

2, Is AN-6 OK for the pressure side or should that be increased to AN-8?

3, It has a diaphragm PRV and  the over pressure return is in ID 7mm. Should that be increased ?

Its not an electrical supply problem as the pump is fed with a direct line from the battery through a 30amp fused relay. The relay also has a direct earth back to the battety. All cables are rated at 30 amp. They were cool to the touch when the pump wasn't !

Views etc appreciated👍

Looking forward to the 2025 run !!

Cheers,

Pete

[thescrapman]

You could try fitting helper sucker pump to see if that helps, even better if it feeds a swirl pot, which ISTR is omitted on the estate.

That it has been fine for 10+ years, now playing up says perhaps pump is getting near EOL?

[Radders]

From what I've gathered so far, a lot of cars running Pi had pump issues. The list so far is:

Ian Iglis, Doug Thompson, Dave Harvey, myself, and now you as well Pete.

I'm wondering if it's the petrol that's causing these problems? (We couldn't always get E5, so had to resort to E10 in places) 

The other issue is that KMI are no longer interested in refurbishing the Lucas stuff, so our options regarding repairs, replacements or upgrades are quite limited. ☹️

[ferny]

I'm running a 5bar bosch copy supplied by a 10amp fuse and relay and its set to run at just below 3bar. My lines are 8mm copper. The return line is the original fuel line.

 

That's been supplying fuel for 7(ish) years to a turbo 1.6 engine running 200+bhp.

[Pete PiEst]

Thanks for the replies 👍

Colin, Many years ago I did try setting up a feed to a container but I just had 2 pumps making a lot of noise. There isn't enough room in the boot area as the spare wheel takes up most of it - otherwise that would be a way to go with a 1.5lt swirl pot. I don't really want the spare knocking about the inside and would prefer to keep it where it lives.

I've just checked my notes and it was fitted in 08.2007 at 49,000 miles - it's now on 42,000 miles so I think it could well be EOL !!

Pete, Apart from the pump it's still on the Lucas MU so needs 105 ish PSI (7.43 bar) at the MU.

Steve, I'm assuming KMI would still refurb the MU's, Is it just the pumps he's not doing anything with ?? Also Tim & Jason had issues with their pump in the TR6.

I think I'm going to go with the larger tank outlet as it would require less suction to get the fuel out of the tank and fed to the inlet of the pump.

A customer used to race off road quad bikes and knows of a guy in the Epping area that will weld on the required fittings - I just need to work out the best way of getting the new feeder pipe plumbed in.

If I look at the current feed pipe to the MU which is still the original size I think AN-6 from outlet should be OK as it's ID is larger ... I could redo the lines all the way up to the MU .... I think I'll do the supply side and see how it goes before reinventing the wheel !!

If you know anyone with a decent spare Estate tank knocking about let me know 👍

Once I get it out and done I may well upload some pictures but don't hold your breath 😂

Cheers,

Pete

[iani]

15 minutes ago, Pete PiEst said:

<snip>

I'm assuming KMI would still refurb the MU's, Is it just the pumps he's not doing anything with ?? Also Tim & Jason had issues with their pump in the TR6.

</snip>

Yes, KMI will refurb the MU's no problem, I even had them tap the blank boss on the top so I could fit a pressure gauge sender directly to the MU. I am interested the pipe bore question, my supply pipework is standard PI, feeding a Bosch type pump, I am sure my issues  were pressure related too.

Ian

[Pete PiEst]

As I'm going to need to empty the tank for the welding, I'll wire up the Bosch and use it to fill the jerry cans as a transfer pump. I'll put AN-8 inlets on it and see how it sounds - At the end of the run it was pretty loud !

I think I'm going to run everything in braided teflon AN-6 to the MU to save having various extra joins converting one to the other.

There's not a lot of space in the boot with the spare wheel, but I think I'm going to start from scratch - I was using the Lucas pump mounting plate and jiggling everything to fit. With a bit more thought I'll have more room and potentially a quieter set up !

Cheers,

Pete

[Nick Jones]

It’s all (mostly anyway) in the suction side. This is a system that operates on the edge and always has. The noise is cavitation, which crudely speaking, means that the fuel (or the most volatile components of it) is boiling at the entrance to the pump.  Factors that affect this are:

Fuel. Yes, modern fuel is more volatile than the old stuff. Ethanol content doesn’t help as although ethanol is less volatile than some of the other things in there, its overall effect is to increase the vapour pressure, which means it boils more easily. Whether E10 is  worse than E5 I don’t know offhand.

Temperature. We all know things boil when they get hot. It is mostly the temperature of the fuel itself that matters, though obviously ambient temperature contributes to this. One of the issues with Bosch pumps on a PI is that they are too big, so lots of fuel is continuously recirculating through the relief valve, which heats it up. The pumps draw about 100w and a big chunk of that ends up in the fuel. The less fuel in the tank, the faster it heats up.

Pressure at the pump inlet. This is influenced by two things.
1. Static head, which is the height of the fuel level above the pump. More is better. Therefore a full saloon tank is much better than a nearly empty estate one (Sorry Pete!).
2. Friction losses, or resistance to flow, influenced by pipe sizes, elbows, bends, Ts and filters. Basically you want the suction line to be as straight as possible, as large diameter as possible, as short as possible and any filters/strainers need to give minimal pressure drop - so either very large surface area or fairly coarse. Note that a suction filter doesn’t have to be blocked solid to cause problems. A “bit restricted” is enough, especially combined with warm weather.   The Bosch roller-cell pumps are not very fussy about particle size so you don’t need a fine filter in front of them. In fact, genuine Bosch pumps have a built-strainer and often have no additional pre-filter in OE applications, beyond a coarse “sock” on the pickup pipe. My own preference is to put a strainer on the inlet pipe (Baldwin do them with 10mm and 12mm tails) and a nice big, fine filter on the outlet where there’s plenty of pressure to spare.

Something else to consider is that there are other types of pump available. The Lucas pump is actually a better match for the job than the Bosch. But mostly now old/knackered/etc. However Pierburg make gear pumps and screw pumps in similar packages to the Bosch roller-cell ones and some of those are more suitable as they don’t flow so much but still have sufficient pressure ability.  I have previously posted details of these on the TRR forum, but years ago now so probably hard/impossible to find. I’ll have a proper look when sat at a computer.

Meanwhile, anything you can do to enlarge and simplify the suction run to the pump will be of benefit!

 

I also think you should compare notes on where you bought fuel….. ISTR a similar mass failure event on a 10CR where a whole bunch of cars had problems after buying fuel from the same place (altitude makes vapourisation problems worse too)

Edited October 11, 2023 by Nick Jones

[Clive]

Worth noting that some cars with the Bosch 0044 pumps fitted as OE had a 12mm feed from tank to pump. And below the tank. 

That ties with Nicks excellent response above. If there is a more suitable pump, it may well be worth seeking out.

[Pete PiEst]

Thanks for your input Nick 👍 .. I'd be interested in the Pierburg you mentioned. I did look at them but if I remember correctly they maxed out at around 90 psi but it was a while ago so I could be wrong.

As I've got to do some work on the tank would you go for AN-8 at 11mm ID or next size up AN-10 with an ID of 14mm ??

For the pre filter I've been using an aluminimum bullet type with the bronze element .. What are the Baldwin ones?

There's a Sytec on the pressure side.

Thanks everyone for your input !!

Cheers

Pete

 

[Pete PiEst]

After sleeping on it I think there's a better way forward!

I've been thinking about this for many years and collecting bits - I did have an abortive attempt at welding a sump on the bottom of a spare tank I had, it would've sat in the wheel well. I managed to fabricate the sump which was leak free, but I couldn't weld the tank to the bottom without holes being blown in the underside of the tank  - a good idea let down by my lack of skill !!

If the feed from the top was going to be enlarged it would require welding plus I'd then have to get the feed pipe and associated plumbing sorted.

So seeing as I need to get something welded to the tank I might as well get a boss welded to the bottom corner of the tank.

I've got a fullbore stop cock with AN-8 tails on it

I'm going to get a professional to weld an AN-8 fitting on the bottom corner. As you can see from the picture there's enough room for the stop cock.

The top of the tape is around a quater of the way up, so as long as that's as low as I allow the fuel to go the outlet will be covered

As there'll now be a head of fuel feeding the pump I think AN-8 will be big enough but will defer to experts advice seeing as nothing has been done yet and this is a once only job so I might as well do as right as it can be done!

Views etc appreciated.

Cheers,

Pete

[GT64fun]

Photo of fuel installation on a 2.5 PI GT6 currently under construction in Somerset.

Huco lift pump, fuel filter and then Lucas pump. If it fits in a GT6 !?!

As yet untested but looks well designed and executed.

Nick knows the car.

Ian

[Martins Stag]

Pete I think your idea may work re the fuel take off. Correct me if you are wrong but your tank is the same as a Stag one? I have put an Alloy one in my stag and I did wonder why it in effect sucked it out the top rather than use gravity to help as you suggested. I have mount a Hurco pump lower down under the fuel filler next to the tank so it is the same height at the tank but i am guessing a non PI pump is smaller than yours ? The other thing you could do is to to go almost straight out through the the bulkhead to the underneath of the car when it comes out of your new take off via the fuel pump so you get it "out in the fresh air" sooner?  Let us know how you get on? 

[Pete PiEst]

Mentioning Pierburg jogged my memory as I had a dim recollection that I got one years ago .. After a search through various boxes I found it ! .. It's an 7.21659.72.0 which has a 12mm ID  push on inlet so I might as well go for AN-10 that way I can fit any of the pumps I have and just make sure I have the relevant adapters to go from the prefilter to the pump.

I found this PDF on the web

[Pete PiEst]

GT6 is looking good 👍 - When will it be ready?

I think the tanks in the Stag & Estate are the same size and shape. I did see an ally one advertised by EJ Ward and they look great but I can't justify the cost - although the flat sides of it look a bit easier to weld a fitting to than the curves on the estate.

It would be nice to have a bit more room to fit a lift pump and a swirl pot but the spare wheel takes up most of it and I'm left with bit where the orginal equipment was located. I don't want to go on any events without one after I clipped a curb and punctured the tyre due to "over enthusiasm"

Will keep updating .. I think the next step is to drain the tank and get that bung welded on !

Cheers,

Pete

[GT64fun]

On 12/10/2023 at 13:36, Pete PiEst said:

GT6 is looking good 👍 - When will it be ready?

Pete

I'm afraid it's not my GT6. As to when it might be ready....who knows, the owner is a busy (and gifted) Engineer.

Nick Jones and I are providing moral support.

Ian

Edited October 18, 2023 by GT64fun

[iani]

5 hours ago, Pete PiEst said:

GT6 is looking good 👍 - When will it be ready?

I think the tanks in the Stag & Estate are the same size and shape. I did see an ally one advertised by EJ Ward and they look great but I can't justify the cost - although the flat sides of it look a bit easier to weld a fitting to than the curves on the estate.

It would be nice to have a bit more room to fit a lift pump and a swirl pot but the spare wheel takes up most of it and I'm left with bit where the orginal equipment was located. I don't want to go on any events without one after I clipped a curb and punctured the tyre due to "over enthusiasm"

Will keep updating .. I think the next step is to drain the tank and get that bung welded on !

Cheers,

Pete

Stag & FL Mk1/Mk2 Estate tanks are the same, the PFL Mk1 Estate tank is smaller, I intend fitting the larger tank to my PFL car when I convert to PI. Wards are looking at having the next batch of ali tanks ready for EFi, with a swirl pot and a return line stub, I am told that they might also have identified an in-tank pump that will fit too, I'll keep an eye out for that.

I looked up the Baldwin filter thread on the TRR forum (thanks Nick) and I have now ordered one of these https://inlinefilters.co.uk/Filters-Fuel/InLine/MetalStrainer/FIN-FF30145/ which is similar but with 12mm tails. I will fit this to my PI on its return from the RAC, hopefully this weekend. 

I'm interested to see how you get on with your mods Pete, I have a larger tank ready to go into my Estate but it's not too late for me to modify it. 

Ian

[Pete PiEst]

I'm waiting on some Jerry Cans to decant the tank - then I'll get the bung welded on.

I'll keep you updated.

Thanks for finding the part Ian - I've just ordered a couple !

More anon !!

This is nearly as exciting as the RBRR itself - getting it ready for the next one and events inbetween !! 😂

Cheers,

Pete

[Nick Jones]

8 hours ago, Pete PiEst said:

I found this PDF on the web

That’s the one. I know it says 94 psi in the table but the curve shows up to about 150 and looks fine for 105.

12mm is fine. Short section of 10mm is likely fine too. The OE tank exit is 8mm at best, possibly only 6mm - that’s what the narrowest bit measured on my PI tank exit.

 

[Pete PiEst]

I found the inlet and outlet from the spare tank earlier today and the ID is 6mm!

I think the various pumps I've tried have all had the same issue the tiny feed from the tank !! But no more it'll be 12mm ALL the way.

If the pump is still screeching I'll go to Plan B and crank the radio up to 11 !!🎵😂

Cheers

 

[JohnD]

Pete,

Nick's words on pumps  are, of course, as Holy Writ!     

When I converted the Silverback to Pi, I was very conscious of the effect of cornering and fuel slosh in the tank on mechanical fuel injection. A carburettor can reject bubbles in the fuel supply in the float chamber, but injectors cannot and early in the conversion, it would cut out just as you put your foot down on exit.  Triumph fitted a little gravity pot under the estate's fuel tank but it wasn't adequate.   So I added a swirl pot, fed by a Facet Red Top.     I thought that this would easily keep pace with the Bosch that the pot feeds, but in fact, and about ten years down the line, I actually checked, by running either into a measuring jug.      In fact, free-running (no pressure), they are about equal, and I suspect that sometimes, taking in the other factors that Nick mentions, the Facet isn't keeping up.  I've simplified the hose layout and installed new filters, which so far has done the job.   I'm sure that  maximising the hose and connnector sizes is  the way to go, and to mount the swirl pot as high above the Bosch as possible!

John

[Clive]

50 minutes ago, JohnD said:

Pete,

Nick's words on pumps  are, of course, as Holy Writ!     

When I converted the Silverback to Pi, I was very conscious of the effect of cornering and fuel slosh in the tank on mechanical fuel injection. A carburettor can reject bubbles in the fuel supply in the float chamber, but injectors cannot and early in the conversion, it would cut out just as you put your foot down on exit.  Triumph fitted a little gravity pot under the estate's fuel tank but it wasn't adequate.   So I added a swirl pot, fed by a Facet Red Top.     I thought that this would easily keep pace with the Bosch that the pot feeds, but in fact, and about ten years down the line, I actually checked, by running either into a measuring jug.      In fact, free-running (no pressure), they are about equal, and I suspect that sometimes, taking in the other factors that Nick mentions, the Facet isn't keeping up.  I've simplified the hose layout and installed new filters, which so far has done the job.   I'm sure that  maximising the hose and connnector sizes is  the way to go, and to mount the swirl pot as high above the Bosch as possible!

John

John, does the return from the engine bay not feed into the swirl pot? That is the "usual" way to do things so the lift pump only needs to keep up with the fuel used, as opposed to how much the injection pump wants. Downside is that the fuel can warm up, but with an "open" return from the swirl pot to the tank  it shouldn't be too much.

I really like the VW fuel pump I have used in my Spit tank. It has a built in swirl pot, and despite no extra baffles, and the pump being over on the RH side of the tank, it will run the tank almost dry. However, I doubt that pump is high enough a pressure for PI. My injection has the PRV set to 3.5bar. (std ford PRV)

[Pete PiEst]

Unfortunately there's no room to have a swirl pot anywhere in the "boot" of the Estate, not beside or above the tank.

I think me best bet is to keep an eye on the fuel level and not let it drop too low.

I think there is a swirl pot of sorts mounted inside the tank which is where the fuel pickup & return from the PRV extend in to.

Pete

[JohnD]

Pete Piest,

You have to think laterally - or in this case longitudinally!    I first used Pi in the Silverback, the one and only racing Vitesse Estate.    There was no room for pumps or anything in the boot, and I wasn't prepared to fit them under the floor, so they went in front of the rear axle hump.    For fire security, they were all enclosed in an alloy housing, as shown here:

This was before I realised the need for a swirl pot, but I used the Facet then as the Bosch was at the same level as the tank, and as Nick says, that needs at least a few inches of 'head' to work properly.   I subsequently fitted the swirl in there too!.

No need for rear seats in a race car, but some surgery to the seat base would have provided a normal looking, if firm, rear seat!

John

[Pete PiEst]

Turns out inline filters are out of stock of those but here's a cross- reference link ...

https://www.fuelfilter-crossreference.com/convert/BALDWIN/BF7693