Swap Done, Loud Fuel Pump Question
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Swap Done, Loud Fuel Pump Question I'm complete with my 2006 5.3 with 46,000 miles into my 68 Camaro. Only engine modification was a Trick Flow cam. I'm extremely happy with the performance and drivability. There are two fuel system issues that I have questions on.
I bought a Tanks, Inc tank and fuel pump (Welbro) kit. First issue is the car takes a two fuel pump cycles (two key turns) to allow the pump to build enough fuel pressure to start the engine. Seems like I'm loosing fuel pressure after the car sits for a while. I asked Tanks, Inc about this and they said the pump does not have a check valve built into it and most of the time you don't need a check valve to hold fuel pressure. Is that true? They suggested installing an in-line check valve near the pump to fix the problem.
The other possible issue is the pump makes excessive noise (high pitch whine) that changes frequencies while driving. Tanks, Inc. suggested the pump pick-up may be pressed against the bottom of the tank, causing the pump to work harder to pull fuel, which would cause excessive noise. I was very **** about measuring and cutting the tubes to fit properly inside the tank so I doubt this is the issue. Also, I don't hear the whinning pump during warm-up, only when the engine is hot. Maybe this is normal and I'm just over thinking the noise? What have you experienced?
Thanks. Doug
I bought a Tanks, Inc tank and fuel pump (Welbro) kit. First issue is the car takes a two fuel pump cycles (two key turns) to allow the pump to build enough fuel pressure to start the engine. Seems like I'm loosing fuel pressure after the car sits for a while. I asked Tanks, Inc about this and they said the pump does not have a check valve built into it and most of the time you don't need a check valve to hold fuel pressure. Is that true? They suggested installing an in-line check valve near the pump to fix the problem.
The other possible issue is the pump makes excessive noise (high pitch whine) that changes frequencies while driving. Tanks, Inc. suggested the pump pick-up may be pressed against the bottom of the tank, causing the pump to work harder to pull fuel, which would cause excessive noise. I was very **** about measuring and cutting the tubes to fit properly inside the tank so I doubt this is the issue. Also, I don't hear the whinning pump during warm-up, only when the engine is hot. Maybe this is normal and I'm just over thinking the noise? What have you experienced?
Thanks. Doug
Check valve is a must if you want it to fire first go.
The pump whining could be multiple things, first that come to mind for me is the pump wired straight or do you have a good relay?
As far as being to close is very possible but it sounds like when the pump gets hot it starts to whine which could be caused by it being to close.
Don't know if that is really the answer your looking for
The pump whining could be multiple things, first that come to mind for me is the pump wired straight or do you have a good relay?
As far as being to close is very possible but it sounds like when the pump gets hot it starts to whine which could be caused by it being to close.
Don't know if that is really the answer your looking for
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Thanks for the input. The pump is direct wired from the wiring harness...no relay. Again, maybe I am over thinking the whine. Does others have the same sound or do I need to do something about it? There is no issue with fuel delivery. These engines flat get with the program.
I will plan to install a Russel in-line check valve in the near future.
I will plan to install a Russel in-line check valve in the near future.
I would suggest checking your pressure at the rail. I had an issue where the car didnt want to start on the first turn of the key. The hose from the pump to the outlet burst and I was only getting about 15 psi at the injectors. The car still ran and drove with no issues. As far as the whine my pump whines a little and does get louder with less fuel in the tank. It changes pitch a bit due to voltage fluctuation as well. It has done this since day one and i have about 15000 miles on my swap so I am not too concerned about it.
How is the rest of the fuel system (tubes, hose, filter and regulator) setup ?
would suggest checking the following:
- Checking how close the bottom of the pump/sock is to the bottom of the tank.. to close ?
- Reguator, what pressure are you getting at the fuel rail ?
- Return, is it block or restricted ? dead heading the pressure and causing the pump excessive pressure on trying to feed.
- on first start up.. what is the pressure at the rail ?. what is it running at idle and also at WOT ? needs to be 58psi regulated.
would suggest checking the following:
- Checking how close the bottom of the pump/sock is to the bottom of the tank.. to close ?
- Reguator, what pressure are you getting at the fuel rail ?
- Return, is it block or restricted ? dead heading the pressure and causing the pump excessive pressure on trying to feed.
- on first start up.. what is the pressure at the rail ?. what is it running at idle and also at WOT ? needs to be 58psi regulated.
Thread Starter
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How is the rest of the fuel system (tubes, hose, filter and regulator) setup ?
would suggest checking the following:
- Checking how close the bottom of the pump/sock is to the bottom of the tank.. to close ?
- Reguator, what pressure are you getting at the fuel rail ?
- Return, is it block or restricted ? dead heading the pressure and causing the pump excessive pressure on trying to feed.
- on first start up.. what is the pressure at the rail ?. what is it running at idle and also at WOT ? needs to be 58psi regulated.
would suggest checking the following:
- Checking how close the bottom of the pump/sock is to the bottom of the tank.. to close ?
- Reguator, what pressure are you getting at the fuel rail ?
- Return, is it block or restricted ? dead heading the pressure and causing the pump excessive pressure on trying to feed.
- on first start up.. what is the pressure at the rail ?. what is it running at idle and also at WOT ? needs to be 58psi regulated.
Last edited by Gunner Dog; Sep 6, 2013 at 02:04 PM. Reason: Added more info
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My external mallory pump got a lot more quiet when I switched to a lower pressure drop pre filter. It use to get more noisier as the fuel level got lower.
Any sort of restriction on the inlet will increase the pump noise level.
Hot fuel can flash to a vapor in the pump causing it to cavitate. A different noise, but that does make the pump work harder.
While you have it out I would consider back flushing the pump and looking for debris.
Any sort of restriction on the inlet will increase the pump noise level.
Hot fuel can flash to a vapor in the pump causing it to cavitate. A different noise, but that does make the pump work harder.
While you have it out I would consider back flushing the pump and looking for debris.
I've had several cars with walbro pumps and they have all whined a little. All my walbros have had check valves built in and didn't require any additional priming. Is this an external pump or in tank? I had a bosch 044 external and it whined super loud and the pitch changed constantly. It also had no check valve and I would have to prime it multiple times.
My external mallory pump got a lot more quiet when I switched to a lower pressure drop pre filter. It use to get more noisier as the fuel level got lower.
Any sort of restriction on the inlet will increase the pump noise level.
Hot fuel can flash to a vapor in the pump causing it to cavitate. A different noise, but that does make the pump work harder.
While you have it out I would consider back flushing the pump and looking for debris.
Any sort of restriction on the inlet will increase the pump noise level.
Hot fuel can flash to a vapor in the pump causing it to cavitate. A different noise, but that does make the pump work harder.
While you have it out I would consider back flushing the pump and looking for debris.
I've got a 100 mike inline RobbMc pre-filter with a large 10 mike BG canister post-filter, is that too restrictive?
Having said all that mine is still pretty noisy. A good part of that is due to the way I have it mounted and the total lack of sound deadener in the car. But I also think 140 gph is way more pump than I need. It would probably be a lot more quiet with something about 100 gph.
But to the OP, pumps don't like to suck as much as push, so any restriction in the intake path will make the pump work harder increasing noise. That could also be affecting your ability to build pressure. I could see where a line leak or loose fitting on the inlet side would do the same.
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Update I wanted to post to close the loop on this thread. First I checked the fuel pressure, which was 62 psi. Next I pulled my in-tank pump to check the overall length of the pick-up tube. Decided to trim 1/4" off the the tube to allow some additional room at the pick-up filter. That fixed it and no more whine!
I went ahead and installed a Russell check valve in the fuel supply line as well. I have immediate starting now too.
Thanks for the suggestions.
I went ahead and installed a Russell check valve in the fuel supply line as well. I have immediate starting now too.
Thanks for the suggestions.
LOL
"I also used a PCV valve (one way valve) mounted above the tank to relieve the gas pressure build-up in the tank...I would not think this is contributing the pump pressure issue at start-up?"
U can't use a 1 way valve that vents, but shuts off when the tank pressure drops.
Fuel heats up, pushes the air out of the tank..OK
Fuel cools down, and the valve closes.. No deal. The pump inlet is now operating under a vacuum. That will kill it, as it will cause cavitation.
U can't use a 1 way valve that vents, but shuts off when the tank pressure drops.
Fuel heats up, pushes the air out of the tank..OK
Fuel cools down, and the valve closes.. No deal. The pump inlet is now operating under a vacuum. That will kill it, as it will cause cavitation.
Thread Starter
Teching In
Joined: Jun 2013
Posts: 15
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"I also used a PCV valve (one way valve) mounted above the tank to relieve the gas pressure build-up in the tank...I would not think this is contributing the pump pressure issue at start-up?"
U can't use a 1 way valve that vents, but shuts off when the tank pressure drops.
Fuel heats up, pushes the air out of the tank..OK
Fuel cools down, and the valve closes.. No deal. The pump inlet is now operating under a vacuum. That will kill it, as it will cause cavitation.
U can't use a 1 way valve that vents, but shuts off when the tank pressure drops.
Fuel heats up, pushes the air out of the tank..OK
Fuel cools down, and the valve closes.. No deal. The pump inlet is now operating under a vacuum. That will kill it, as it will cause cavitation.
