Noisy fuel pump
Discussion
Hello everyone!
I'm getting to the end of my tether with this issue (mainly because I usually solve anything with some common sense, but this one is escaping me.
Scenario is as follows. Citroen 2CV with a BMW R1100 1100cc flat twin bike engine, runs perfectly and has done thousands of miles with this issue present, with no effect on performance (that I can tell at least).
As the car was originally not fuel injected, I have a LP pump -> swirl pot -> HP pump setup to supply the 3 bar that the engine calls for. The fuel pressure regulator is the bike's original one, low pressure is supplied by a Facet Posiflo pump (nice and quiet) and high pressure is provided by a (genuine) Bosch 044 (wasp nest from hell) and now a Sytec 044 equivalent (also wasp nest from hell).
Pretty standard setup for an engine swap (as far as I know). As mentioned above, the car runs fine, fuel pressure is steady and has never cut out on me. But listen to this mess:
https://youtube.com/shorts/5o69_UCMd9Y (Why can't I embed this video?)
Things I've tried so far:
- Replace the original genuine 044, when I first put the car on the road I did manage (because reasons) to run it dry a couple of times. I assumed it was damaged from that so I tried replacing it. That original 044 took the car across Spain with no issue (but loudly). When I took it out there was no debris at all in the inlet gauze filter built into the pump.
- Restrict the return line from the swirl pot to the tank. The reason for this was two-fold... To provide the facet LP pump with some restriction to work against as it would in carb car, and secondly to provide a bit of backpressure in the swirl pot to improve the feed to the HP pump.
- Crack open the -6 line coming out the top of the swirl pot to the tank with the engine running to verify the pot is actually full (who knows, maybe the LP pump wasn't keeping up for some reason, or the 30 micron filter could have been clogged). Fuel comes out the top the moment it's cracked, so the pot is positively full.
- Turn the ignition on with the HP pump relay removed to check that the LP pump is actually working. (Clutching as straws, as I can't imagine the 044 would pull well from all the way up front on the bulkhead and would have probably failed by now).
Other symptoms:
- When the car is cold, the pump is still loud but sounds "healthier" for about 10 minutes until the car is up to temperature. At that point the buzzing gets like in the video.
Theories:
- Fuel heat/low restriction: I realise that the pump is way oversized for this application (1100cc flat twin), so I'm wondering whether it's working a full tilt against the 3 bar regulator, which means that at low rpm the vast majority of the fuel is coming back to the swirl pot. This constant cycling of fuel would probably introduce quite a lot of heat into it, reducing cooling of the pump. I don't know how plausible this is as the pump and the swirl pot don't feel particularly hot after a good drive (engine bay warm, but nothing I would consider HOT).
- Some kind of imbalance between the pumps? HP pump cavitating as it overpowers the LP pump? This doesn't make much sense to me as the pot is always full so I can't see where the pump could be cavitating from. Plus, a LP pump working with no restriction should far overdeliver what the HP pump needs at 3 bar surely?
I really am fed up with this issue, as the car goes like a dream apart from that. But that buzzing drives me nuts. I'm actually designig an in-tank single pump system in order to simplify the whole thing... but it bothers me that I can't figure this out. It shouldn't be this hard!
Any input is welcome...
Gratuitous photo!
I'm getting to the end of my tether with this issue (mainly because I usually solve anything with some common sense, but this one is escaping me.
Scenario is as follows. Citroen 2CV with a BMW R1100 1100cc flat twin bike engine, runs perfectly and has done thousands of miles with this issue present, with no effect on performance (that I can tell at least).
As the car was originally not fuel injected, I have a LP pump -> swirl pot -> HP pump setup to supply the 3 bar that the engine calls for. The fuel pressure regulator is the bike's original one, low pressure is supplied by a Facet Posiflo pump (nice and quiet) and high pressure is provided by a (genuine) Bosch 044 (wasp nest from hell) and now a Sytec 044 equivalent (also wasp nest from hell).
Pretty standard setup for an engine swap (as far as I know). As mentioned above, the car runs fine, fuel pressure is steady and has never cut out on me. But listen to this mess:
https://youtube.com/shorts/5o69_UCMd9Y (Why can't I embed this video?)
Things I've tried so far:
- Replace the original genuine 044, when I first put the car on the road I did manage (because reasons) to run it dry a couple of times. I assumed it was damaged from that so I tried replacing it. That original 044 took the car across Spain with no issue (but loudly). When I took it out there was no debris at all in the inlet gauze filter built into the pump.
- Restrict the return line from the swirl pot to the tank. The reason for this was two-fold... To provide the facet LP pump with some restriction to work against as it would in carb car, and secondly to provide a bit of backpressure in the swirl pot to improve the feed to the HP pump.
- Crack open the -6 line coming out the top of the swirl pot to the tank with the engine running to verify the pot is actually full (who knows, maybe the LP pump wasn't keeping up for some reason, or the 30 micron filter could have been clogged). Fuel comes out the top the moment it's cracked, so the pot is positively full.
- Turn the ignition on with the HP pump relay removed to check that the LP pump is actually working. (Clutching as straws, as I can't imagine the 044 would pull well from all the way up front on the bulkhead and would have probably failed by now).
Other symptoms:
- When the car is cold, the pump is still loud but sounds "healthier" for about 10 minutes until the car is up to temperature. At that point the buzzing gets like in the video.
Theories:
- Fuel heat/low restriction: I realise that the pump is way oversized for this application (1100cc flat twin), so I'm wondering whether it's working a full tilt against the 3 bar regulator, which means that at low rpm the vast majority of the fuel is coming back to the swirl pot. This constant cycling of fuel would probably introduce quite a lot of heat into it, reducing cooling of the pump. I don't know how plausible this is as the pump and the swirl pot don't feel particularly hot after a good drive (engine bay warm, but nothing I would consider HOT).
- Some kind of imbalance between the pumps? HP pump cavitating as it overpowers the LP pump? This doesn't make much sense to me as the pot is always full so I can't see where the pump could be cavitating from. Plus, a LP pump working with no restriction should far overdeliver what the HP pump needs at 3 bar surely?
I really am fed up with this issue, as the car goes like a dream apart from that. But that buzzing drives me nuts. I'm actually designig an in-tank single pump system in order to simplify the whole thing... but it bothers me that I can't figure this out. It shouldn't be this hard!
Any input is welcome...
Gratuitous photo!
Edited by carlosbeneto on Sunday 24th April 18:55
Sooo....
You've an engine that makes say 100hp ?
And you have chosen a HP pump that could flow for 700 hp ?? That seems utterly bonkers.
Then you choose to try and feed it with a little baby pump that if lucky might flow enough for 200hp. There seems to be no logic or common sense applied anywhere here.
Use properly sized pumps for the application, mount the pumps on rubber etc. There is every likelihood the 044 is screaming it's head off because you're strangling it.
And although this too is based around an 044...it can be a neater and quieter solution.
But DO NOT use any 044 type pump for an engine making such low power. It is just daft. And it's probably overpowering whatever FPR is on the engine too causing fuel pressure issues
I also would not have mounted the 044 or any EFI pump upside down as it may be unhappier this way if it does not have a solid supply of fuel.
Also, what is the actual filter being used ?
But yes, a system with a proper designed tank and a single in-tank pump would be the best and neatest solution all round. And there will be literally thousands of potential OEM pumps you could use and purchase very cheaply from almost any lowish powered car.
You've an engine that makes say 100hp ?
And you have chosen a HP pump that could flow for 700 hp ?? That seems utterly bonkers.
Then you choose to try and feed it with a little baby pump that if lucky might flow enough for 200hp. There seems to be no logic or common sense applied anywhere here.
Use properly sized pumps for the application, mount the pumps on rubber etc. There is every likelihood the 044 is screaming it's head off because you're strangling it.
And although this too is based around an 044...it can be a neater and quieter solution.
But DO NOT use any 044 type pump for an engine making such low power. It is just daft. And it's probably overpowering whatever FPR is on the engine too causing fuel pressure issues
I also would not have mounted the 044 or any EFI pump upside down as it may be unhappier this way if it does not have a solid supply of fuel.
Also, what is the actual filter being used ?
But yes, a system with a proper designed tank and a single in-tank pump would be the best and neatest solution all round. And there will be literally thousands of potential OEM pumps you could use and purchase very cheaply from almost any lowish powered car.
Edited by stevieturbo on Sunday 24th April 21:31
From EX Auto sparks [ retired now 79 ]......all i can say Fords used the High pressure 044 pump for many years with the Bosch "K" & "KE systems and Rollsl royce etc....etc.......all fitted the pump under the boot area..very close to the Fuel Tank.....and important on a steel bracket...held to the boot floor on Rubber cotton reel type Rubber insulaters... no noise in the car...a light "Hum " just about heard if you put your head under the boot...i dont see on the film any insulation rubber bushes ??....i feel the best thing is to move the pump...044 style pump is old school nowadays....as they now have pressure pump in the Tanks with the Fuel. never ever seen 044 pump bolted to the bulk-head under the bonnet. just my thoughts. Peter
Thanks for the replies. Stevieturbo, I appreciate that the 044 is way oversized, but that doesn’t really answer the question doesn’t it? The car has never cut out and the swirl pot is full at all times, so it’s not “overwhelming” the Facet.
This setup is very common on cars that didn’t have high pressure systems originally, and a low pressure pump will flow more than enough to supply the 044 at 3 bar and engine size; otherwise the car would cut out wouldn’t it? I’m happy to be educated though. Oversized? Yes, absolutely. But i struggle to see how you could possibly have a pump too big, as the fuel consumption is the same regardless?
This setup is very common on cars that didn’t have high pressure systems originally, and a low pressure pump will flow more than enough to supply the 044 at 3 bar and engine size; otherwise the car would cut out wouldn’t it? I’m happy to be educated though. Oversized? Yes, absolutely. But i struggle to see how you could possibly have a pump too big, as the fuel consumption is the same regardless?
carlosbeneto said:
Thanks for the replies. Stevieturbo, I appreciate that the 044 is way oversized, but that doesn’t really answer the question doesn’t it? The car has never cut out and the swirl pot is full at all times, so it’s not “overwhelming” the Facet.
This setup is very common on cars that didn’t have high pressure systems originally, and a low pressure pump will flow more than enough to supply the 044 at 3 bar and engine size; otherwise the car would cut out wouldn’t it? I’m happy to be educated though. Oversized? Yes, absolutely. But i struggle to see how you could possibly have a pump too big, as the fuel consumption is the same regardless?
There are many answers, and yes, incompatible pumps will lead to cavitation and excessive noise. As will poor mounting and orientation.This setup is very common on cars that didn’t have high pressure systems originally, and a low pressure pump will flow more than enough to supply the 044 at 3 bar and engine size; otherwise the car would cut out wouldn’t it? I’m happy to be educated though. Oversized? Yes, absolutely. But i struggle to see how you could possibly have a pump too big, as the fuel consumption is the same regardless?
There is not a hope in hell of that little Facet pump flowing enough to keep an 044 happy, even if it was running 100psi. An 044 even around 40-50psi will flow over 300LPH. That little Facet probably flows a little over 100LPH if you're lucky.
Now the only positive in that scenario is that you return from the main rails into the surge tank, but it still doesn't get around it being a badly implemented setup, even if the overall plan is sound.
And as others have mentioned, proper pump mounting makes a huge difference. At a minimum the torques bracket you used should also have rubber bobbins. The Torques bracket itself may look nice, but it is not in any way conducive to quiet running.
Cheapest options at the minute are a more sensible HP pump, mounted properly and IMO it needs to be mounted upright, not upside down ( although I'm not sure on that one making a difference )
But yes if you could do a proper designed main tank with an in-tank pump, again suitably sized for the setup....it would be the quietest and neatest
You say it's a fairly standard setup, but I'd have thought the more obvious approach would be to keep the whole fuel system that came with the engine - with your swirl pot and lift pump in place of the bike fuel tank. This way all components are a suitable spec and working in their normal operating conditions.
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