Fuel pump noise
Discussion
AndreasW said:
mt308 said:
This noise has been happening ever since the car was brand new - half way back from the factory the pump got much noisier
My car has also a Bosch 044 installed which is quite loud since it has been new.The pump sits inside of a surge tank (http://www.performancebyie.com/ie-submerged-044-billet-surge-tank) which is installed horizontally.
Its intake position is below the lower dash ports of the fuel tanks - so that the fuel runs into the surge tank by gravity.
Once the fuel tanks are half empty, the pump starts to be noisy.
By googling you can find a lot about noisy Bosch 044 that behave exactly the same way.
Obviously the Bosch 044 requires a certain amount of pressure on the suction side.
I used to think the noise increased as the tanks emptied but now I think it is actually just as the system has been running for a while - 25 mins or so seems to do it.
Mark
I have pressure readout in cab if you have laptop connected. Fuel pressure drops from 45 to a wildly fluctuating 0-25 when pump goes noisy. The more frightening thing is what happens to the A/F readout which goes mega lean!!!!
All pipe is -6 except swirl pot to hp pump which is -8 and v short. Problem 1st occurred after long driving in hot weather at low speeds and lowish fuel level. Swapping fuel tanks immediately stopped it only for it to reoccur after about 1/2 hour in town traffic. engine actually stopped. Fuel in surge pot was bubbling big time. Got going again after 2 hrs on side of road with hood up. Solution was to fit low pressure (5psi) reg to vent on swirl pot so maintaining a small amount of pressure in there. However system still vapour locks if I park up to fill up with fuel for instance. It is very very difficult to restart engine. My swirl pot is high up on bulkhead and so empties quite easily if fuel is hot.
Having spent a year researching what the big power manufacturers do to combat the problem i.e. corvette etc. I am fitting 2 in tank pumps with built in surge control and a speed control system for the pumps which only supplies the amount of fuel required to maintain the fuel pressure at whatever you set. total parts cost @£1200
pumps being £850 of that. No external swirl pot, Far less pipework, still have 2 separate tanks, less noise, All off the shelf.
All pipe is -6 except swirl pot to hp pump which is -8 and v short. Problem 1st occurred after long driving in hot weather at low speeds and lowish fuel level. Swapping fuel tanks immediately stopped it only for it to reoccur after about 1/2 hour in town traffic. engine actually stopped. Fuel in surge pot was bubbling big time. Got going again after 2 hrs on side of road with hood up. Solution was to fit low pressure (5psi) reg to vent on swirl pot so maintaining a small amount of pressure in there. However system still vapour locks if I park up to fill up with fuel for instance. It is very very difficult to restart engine. My swirl pot is high up on bulkhead and so empties quite easily if fuel is hot.
Having spent a year researching what the big power manufacturers do to combat the problem i.e. corvette etc. I am fitting 2 in tank pumps with built in surge control and a speed control system for the pumps which only supplies the amount of fuel required to maintain the fuel pressure at whatever you set. total parts cost @£1200
pumps being £850 of that. No external swirl pot, Far less pipework, still have 2 separate tanks, less noise, All off the shelf.
mt308 said:
I am not currently filled with confidence when planning a trip to France with my wife where it could be a lot hotter than today and where I plan to do 250 miles or so in one run. She is rapidly building a dislike to the car!
Does anyone else notice any changes in noises when their cars get warm/hot?
The noise of my pump does not change by temperature (my surge tank heats up barely).Does anyone else notice any changes in noises when their cars get warm/hot?
During the cold-start phase (rich mixture) of the engine the pump remains silent, even if the tanks are half empty.
Once the engine has operating temperature the pump gets progressively louder.
I think it is not as noisy while driving but only at idle (maybe I'm wrong because of the loud driving noises).
This led me to believe that the pressure regulator (in my case, original GM) at idle almost must lead the entire fuel the pump delivers (my pump is not controlled and runs on full power) back into the tank - and the bottleneck is in the return line of the regulator (which can not be changed) what leads to cavitation inside the pump.
So far I had no problems and I traveled distances of around 500km length in one piece.
AndreasW said:
mt308 said:
I am not currently filled with confidence when planning a trip to France with my wife where it could be a lot hotter than today and where I plan to do 250 miles or so in one run. She is rapidly building a dislike to the car!
Does anyone else notice any changes in noises when their cars get warm/hot?
The noise of my pump does not change by temperature (my surge tank heats up barely).Does anyone else notice any changes in noises when their cars get warm/hot?
During the cold-start phase (rich mixture) of the engine the pump remains silent, even if the tanks are half empty.
Once the engine has operating temperature the pump gets progressively louder.
I think it is not as noisy while driving but only at idle (maybe I'm wrong because of the loud driving noises).
This led me to believe that the pressure regulator (in my case, original GM) at idle almost must lead the entire fuel the pump delivers (my pump is not controlled and runs on full power) back into the tank - and the bottleneck is in the return line of the regulator (which can not be changed) what leads to cavitation inside the pump.
So far I had no problems and I traveled distances of around 500km length in one piece.
My pump also gets (VERY) loud when up to temperature, and sounds under quite severe strain - as discussed above many times it has actually cut out.
Can I check my understanding of the system is correct as follows:
1. Low pressure pump feed fuel, unfiltered, into the surge tank - bottom of the 3 side connectors (I have no filter pre-surge tank)
2. High pressure pump draws fuel from bottom of surge tank, through a line with an in-line 100 micron filter
3. High pressure pump delivers fuel, through a line with an in-line 10 micron filter to the fuel regulator, my pump runs full pelt the whole time, no speed controller
(1-3 above is statement of fact on my set up)
4. At the regulator, fuel is sent to the injector rails to maintain 60psi (or maybe 57psi) of pressure. The remaining fuel flows back into the return line into the swirl pot - middle of the 3 side connections.
5. (just edited!) The top of the 3 side connections on the surge tank flows back under gravity/pressure from the low pressure and high pressure feeds into the tanks. This has a 2mm or so restrictor fitted which creates a pressure inside the surge tank. But inherently this pressure surely makes the HP pump (and LP pump for that matter) push uphill against pressure as the fuel can only trickle back down the line to return to the tanks. So pressure inside the surge tank builds and builds, as LP and HP pumps both running at full pelt all the time and the only escape being through a 2mm hole back to the tanks, potentially explaining why at idle the noise seems to get worse (and also at idle where the system has cut out on me in the past).
Its 5 above that I don't understand. Why have a pump pushing fuel into a restricted line? Does this not put the pump under pressure? (an extreme would be to completely block the outlet to the HP pump so it can't pump at all). This is the observation AndreasW makes above.
When I turn off the engine I am getting at least 1-2 minutes of gurgling/bubbling inside the surge tank. What is this likely to be? (I am thinking either it is air from inside the system (cavitation) or there is a pressure imbalance (vacuum) being created).
Could a faulty regulator cause these symptoms?
Other than the surge tank itself, and the fuel lines, I am running out of things to change, other than perhaps changing this restrictor to a 3mm or 4mm restrictor? The factory assure me there are dozens of cars out there with exactly my set up (engine and fuel system) - so suggestions of throwing it all away and starting again is something I am holding off doing for now, if nothing else than due to costs and time.
I still am not sure the advantages of running huge volumes of fuel around the system when the car is not under load.
Should also note that when I just removed the top of the 3 mountings from the side of the surge tank to check the restrictor, as I undid it I got a hissing noise (pressure relief). Is that to be expected? No fuel at that level - no drips at all removing this top line.
HELP!!!
Thanks
Mark
Edited by mt308 on Monday 8th June 21:52
Edited by mt308 on Monday 8th June 21:56
mt308 said:
OK - still trying to work out what my issue is. Maybe someone can help explain how the system is designed (factory standard system with 2 tanks, low pressure pump, surge tank, high pressure pump (just renewed - Bosch 044)).
My pump also gets (VERY) loud when up to temperature, and sounds under quite severe strain - as discussed above many times it has actually cut out.
Can I check my understanding of the system is correct as follows:
1. Low pressure pump feed fuel, unfiltered, into the surge tank (I have no filter pre-surge tank)
2. High pressure pump draws fuel from bottom of surge tank, through a line with an in-line 100 micron filter
3. High pressure pump delivers fuel, through a line with an in-line 10 micron filter to the fuel regulator, my pump runs full pelt the whole time, no speed controller
(1-3 above is statement of fact on my set up)
4. At the regulator, fuel is sent to the injector rails to maintain 60psi (or maybe 57psi) of pressure. The remaining fuel flows back into the return line into the swirl pot.
5. (Here is where I am a bit confused) The return line has a restrictor within the pipe which is about 2mm diameter. I am told this is to create pressure in the surge tank. Why would it create pressure? And surely this restrictor means the HP pump is working hard to push fuel at full power into a restricted line which will create more stress than if no restrictor?
6. The top hose on the surge tank flows back under gravity/pressure from the low pressure and high pressure feeds into the tanks.
Its 5 above that I don't understand. Why have a pump pushing fuel into a restricted line? Does this not put the pump under pressure? (an extreme would be to completely block the outlet to the HP pump so it can't pump at all). This is the observation AndreasW makes above.
When I turn off the engine I am getting at least 1-2 minutes of gurgling/bubbling inside the surge tank. What is this likely to be? (I am thinking either it is air from inside the system (cavitation) or there is a pressure imbalance (vacuum) being created).
Could a faulty regulator cause these symptoms?
Other than the surge tank itself, and the fuel lines, I am running out of things to change. The factory assure me there are dozens of cars out there with exactly my set up (engine and fuel system) - so suggestions of throwing it all away and starting again is something I am holding off doing for now, if nothing else than due to costs and time.
HELP!!!
Thanks
Mark
Right let’s take things one at a time.My pump also gets (VERY) loud when up to temperature, and sounds under quite severe strain - as discussed above many times it has actually cut out.
Can I check my understanding of the system is correct as follows:
1. Low pressure pump feed fuel, unfiltered, into the surge tank (I have no filter pre-surge tank)
2. High pressure pump draws fuel from bottom of surge tank, through a line with an in-line 100 micron filter
3. High pressure pump delivers fuel, through a line with an in-line 10 micron filter to the fuel regulator, my pump runs full pelt the whole time, no speed controller
(1-3 above is statement of fact on my set up)
4. At the regulator, fuel is sent to the injector rails to maintain 60psi (or maybe 57psi) of pressure. The remaining fuel flows back into the return line into the swirl pot.
5. (Here is where I am a bit confused) The return line has a restrictor within the pipe which is about 2mm diameter. I am told this is to create pressure in the surge tank. Why would it create pressure? And surely this restrictor means the HP pump is working hard to push fuel at full power into a restricted line which will create more stress than if no restrictor?
6. The top hose on the surge tank flows back under gravity/pressure from the low pressure and high pressure feeds into the tanks.
Its 5 above that I don't understand. Why have a pump pushing fuel into a restricted line? Does this not put the pump under pressure? (an extreme would be to completely block the outlet to the HP pump so it can't pump at all). This is the observation AndreasW makes above.
When I turn off the engine I am getting at least 1-2 minutes of gurgling/bubbling inside the surge tank. What is this likely to be? (I am thinking either it is air from inside the system (cavitation) or there is a pressure imbalance (vacuum) being created).
Could a faulty regulator cause these symptoms?
Other than the surge tank itself, and the fuel lines, I am running out of things to change. The factory assure me there are dozens of cars out there with exactly my set up (engine and fuel system) - so suggestions of throwing it all away and starting again is something I am holding off doing for now, if nothing else than due to costs and time.
HELP!!!
Thanks
Mark
1. I would have the coarse filter in the line from LP pump to swirl. Reason HP pumps don’t like sucking so a restriction like the filter could cause cavitation. Which incidentally is where I think your problem lies.
2. HP pump should draw from the swirl with no restriction, should ideally be below the swirl and should have the largest bore practical.
3. This is as it should be.
4. This is as it should be.
5. Which return line has the restriction? If it is the line from regulator to swirl then that is wrong it should be in the line from the swirl back to the tank.
The reason is as you say to create a pressure in the swirl to help eliminate cavitation at the HP pump.
There are two fuel circuits in the system. The LP pump pushes fuel into the swirl pot but anything that does not get used would return to the tank if it were not for the restrictor. The LP pump is self-regulating to about 6 psi so there is actually no reason for the fuel to return to the tank. You do however want any air trapped or generated within the system to escape which it can do past the restrictor. Personally I think 2mm is too large
The second circuit is the HP starting at the swirl is drawn into the PH pump (assisted by the back pressure created by the restriction in the LP return) through the filter, regulator then either injectors or down the return line to the swirl. Don’t think of it returning to the tank just think of it going back round the HP circuit again.
6. If I’m reading this correctly then I believe this to be wrong. The HP return should go to the swirl. The LP should go from swirl to tank.
I suspect your gurgling is in fact air/vapour caused by cavitation and/or the drop in pressure causing the fuel to locally boil at the entry to the HP pump.
An experiment you could try would be to block off the return to the tank and see if it make a difference. As I said the only reason for a return is to let air/vapour escape but you can ignore that just for the duration of the test. I suspect also the 2mm restriction is not actually producing the required back pressure as it is too large.
Steve
ETA I have a couple of pdf files with diagrams of what I have just described which I could send you. I don't think you can attach them to a post although I have never tried.
Edited by Steve_D on Monday 8th June 22:16
Steve_D said:
Right let’s take things one at a time.
1. I would have the coarse filter in the line from LP pump to swirl. Reason HP pumps don’t like sucking so a restriction like the filter could cause cavitation. Which incidentally is where I think your problem lies.
2. HP pump should draw from the swirl with no restriction, should ideally be below the swirl and should have the largest bore practical.
3. This is as it should be.
4. This is as it should be.
5. Which return line has the restriction? If it is the line from regulator to swirl then that is wrong it should be in the line from the swirl back to the tank.
The reason is as you say to create a pressure in the swirl to help eliminate cavitation at the HP pump.
There are two fuel circuits in the system. The LP pump pushes fuel into the swirl pot but anything that does not get used would return to the tank if it were not for the restrictor. The LP pump is self-regulating to about 6 psi so there is actually no reason for the fuel to return to the tank. You do however want any air trapped or generated within the system to escape which it can do past the restrictor. Personally I think 2mm is too large
The second circuit is the HP starting at the swirl is drawn into the PH pump (assisted by the back pressure created by the restriction in the LP return) through the filter, regulator then either injectors or down the return line to the swirl. Don’t think of it returning to the tank just think of it going back round the HP circuit again.
6. If I’m reading this correctly then I believe this to be wrong. The HP return should go to the swirl. The LP should go from swirl to tank.
I suspect your gurgling is in fact air/vapour caused by cavitation and/or the drop in pressure causing the fuel to locally boil at the entry to the HP pump.
An experiment you could try would be to block off the return to the tank and see if it make a difference. As I said the only reason for a return is to let air/vapour escape but you can ignore that just for the duration of the test. I suspect also the 2mm restriction is not actually producing the required back pressure as it is too large.
Steve
ETA I have a couple of pdf files with diagrams of what I have just described which I could send you. I don't think you can attach them to a post although I have never tried.
Thanks Steve - I did edit my post as I had made a mistake. The restrictor is on the return line.1. I would have the coarse filter in the line from LP pump to swirl. Reason HP pumps don’t like sucking so a restriction like the filter could cause cavitation. Which incidentally is where I think your problem lies.
2. HP pump should draw from the swirl with no restriction, should ideally be below the swirl and should have the largest bore practical.
3. This is as it should be.
4. This is as it should be.
5. Which return line has the restriction? If it is the line from regulator to swirl then that is wrong it should be in the line from the swirl back to the tank.
The reason is as you say to create a pressure in the swirl to help eliminate cavitation at the HP pump.
There are two fuel circuits in the system. The LP pump pushes fuel into the swirl pot but anything that does not get used would return to the tank if it were not for the restrictor. The LP pump is self-regulating to about 6 psi so there is actually no reason for the fuel to return to the tank. You do however want any air trapped or generated within the system to escape which it can do past the restrictor. Personally I think 2mm is too large
The second circuit is the HP starting at the swirl is drawn into the PH pump (assisted by the back pressure created by the restriction in the LP return) through the filter, regulator then either injectors or down the return line to the swirl. Don’t think of it returning to the tank just think of it going back round the HP circuit again.
6. If I’m reading this correctly then I believe this to be wrong. The HP return should go to the swirl. The LP should go from swirl to tank.
I suspect your gurgling is in fact air/vapour caused by cavitation and/or the drop in pressure causing the fuel to locally boil at the entry to the HP pump.
An experiment you could try would be to block off the return to the tank and see if it make a difference. As I said the only reason for a return is to let air/vapour escape but you can ignore that just for the duration of the test. I suspect also the 2mm restriction is not actually producing the required back pressure as it is too large.
Steve
ETA I have a couple of pdf files with diagrams of what I have just described which I could send you. I don't think you can attach them to a post although I have never tried.
Edited by Steve_D on Monday 8th June 22:16
If your 100 micron filter is after your swirl pot then it will be worth checking the cleanliness of the filter AND the swirl pot. Possibly also the low pressure supply pipe to the pot and to the low pressure pump as there have been issues with the plastic tank filler getting into the fuel system.
I go along with everything else Steve has said.
Paul
I go along with everything else Steve has said.
Paul
Storer said:
If your 100 micron filter is after your swirl pot then it will be worth checking the cleanliness of the filter AND the swirl pot. Possibly also the low pressure supply pipe to the pot and to the low pressure pump as there have been issues with the plastic tank filler getting into the fuel system.
I go along with everything else Steve has said.
Paul
HiI go along with everything else Steve has said.
Paul
Yes I agree there could be stuff in the swirl pot. Might be a silly question - but how do I check the cleanliness of the swirl pot? I have cleaned the filter - not that much stuff in it but there was a bit.
Thanks
Mark
Noise Level Test Bosch 044:
https://www.youtube.com/watch?v=wgVwgy3Iapw
https://www.youtube.com/watch?v=0axkzeWXzgY
https://www.youtube.com/watch?v=wgVwgy3Iapw
https://www.youtube.com/watch?v=0axkzeWXzgY
Update following some work on the car.
I have replaced the fuel hoses from the swirl pot to my filter and from filter to HP pump from -6 to -8 bore (including welding on a new -8 fitting to the bottom of the swirl pot). -6 pipes remain elsewhere in the LP system and form the HP pump to the engine.
I have also fitted a Fuel on Demand unit to slow the HP pump down when not under load. This makes an amazing difference in the current draw of the Bosch pump. Where previously it ran at 10amps constantly whether at idle or during generally pretty brief moments of full accelaration, returning on low demand and at idle probably 80% of the fuel back into the system, the new system runs at around 2amps at idle and even when running constant low revs doesn't go much higher and hopefully now returns very little back into the system. So hot fuel should be mainly ending up in the engine and out the exhaust.
8 amps less demand sitting in traffic can't do any harm to the battery load either, especially in the heat with air con and cooling fans on full pelt for long periods (e.g. Silverstone I expect). Should also make the car at least a little quieter - the noise will now be a big V8 mainly!
Time will tell if this set up works. I will find out on run up to Silverstone next weekend in the convoy...
Mark
I have replaced the fuel hoses from the swirl pot to my filter and from filter to HP pump from -6 to -8 bore (including welding on a new -8 fitting to the bottom of the swirl pot). -6 pipes remain elsewhere in the LP system and form the HP pump to the engine.
I have also fitted a Fuel on Demand unit to slow the HP pump down when not under load. This makes an amazing difference in the current draw of the Bosch pump. Where previously it ran at 10amps constantly whether at idle or during generally pretty brief moments of full accelaration, returning on low demand and at idle probably 80% of the fuel back into the system, the new system runs at around 2amps at idle and even when running constant low revs doesn't go much higher and hopefully now returns very little back into the system. So hot fuel should be mainly ending up in the engine and out the exhaust.
8 amps less demand sitting in traffic can't do any harm to the battery load either, especially in the heat with air con and cooling fans on full pelt for long periods (e.g. Silverstone I expect). Should also make the car at least a little quieter - the noise will now be a big V8 mainly!
Time will tell if this set up works. I will find out on run up to Silverstone next weekend in the convoy...
Mark
I have just been testing my fuel on demand unit. Drove it with the laptop connected.
As stated before the Bosch 044 pump draws 10 amps when running at full rate. With the FOD fitted at idle it is around 2 amps. Cruising along at 80ish in top gear this goes up to around 2.5 amps. Even under quite hard acceleration it doesn't get much about 3.5 or so.
The best I managed was foot to the floor in 4th at 6,000rpm (briefly!) when I managed to get the current up to 5.5 amps or so for maybe 2 seconds before backing off (this was on the road!) and then it settling back down to 2.5 or so.
Silverstone will be a good test to see if my cavitation issues are resolved...looking forward to seeing some of you there.
Mark
As stated before the Bosch 044 pump draws 10 amps when running at full rate. With the FOD fitted at idle it is around 2 amps. Cruising along at 80ish in top gear this goes up to around 2.5 amps. Even under quite hard acceleration it doesn't get much about 3.5 or so.
The best I managed was foot to the floor in 4th at 6,000rpm (briefly!) when I managed to get the current up to 5.5 amps or so for maybe 2 seconds before backing off (this was on the road!) and then it settling back down to 2.5 or so.
Silverstone will be a good test to see if my cavitation issues are resolved...looking forward to seeing some of you there.
Mark
The advantage to the FOD controller as Mark (above) has installed is that it senses fuel pressure and controls the pump speed using PWM to maintain the fuel pressure at the set point. The only other production system that I can find is the aeromotive one. Apart from being more expensive it only has 2 speeds which are controlled by engine rpm. An adjustable rpm set point changes the pump from low to full speed. This means that it is only running at the correct speed once in the rpm range of the engine!! whereas FOD is always running at the correct speed.
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