Dual lift pumps
Discussion
Hi,
in the past I've had the fuel pump on my car fail at inconvenient moments, the worst being on the M4 near Basingstoke. Fortunately that time I realised the problem and was able to leave at the next exit before the engine stopped. I might not be so lucky next time.
There is no pattern to the pump failure and the present one is around four years and 30000 miles old but I've had them fail after just 5000 miles so no discernible pattern to pump life.
As a result of this I carry a spare pump thought about plumbing it in so that in the event of failure the other pump can be used (by operating a switch). This makes more sense to me than having the spare packed with tools in the boot and needing to spend a messy half an hour swapping them over.
The installation would need non-return valves to prevent the fuel being pumped in the wrong direction and a single-pole change-over switch to select either pump, the idea being to use alternate pumps on each trip to ensure both get some use.
Any flaws in this plan?
The fuel pump is a Facet solid-state fast road pump with the pre-filter fitted, the fuel tank is stainless steel and when last inspected free from dirt and debris.
in the past I've had the fuel pump on my car fail at inconvenient moments, the worst being on the M4 near Basingstoke. Fortunately that time I realised the problem and was able to leave at the next exit before the engine stopped. I might not be so lucky next time.
There is no pattern to the pump failure and the present one is around four years and 30000 miles old but I've had them fail after just 5000 miles so no discernible pattern to pump life.
As a result of this I carry a spare pump thought about plumbing it in so that in the event of failure the other pump can be used (by operating a switch). This makes more sense to me than having the spare packed with tools in the boot and needing to spend a messy half an hour swapping them over.
The installation would need non-return valves to prevent the fuel being pumped in the wrong direction and a single-pole change-over switch to select either pump, the idea being to use alternate pumps on each trip to ensure both get some use.
Any flaws in this plan?
The fuel pump is a Facet solid-state fast road pump with the pre-filter fitted, the fuel tank is stainless steel and when last inspected free from dirt and debris.
tapkaJohnD said:
A fuel pump is not a valve, and petrol can flow backwards through it. In fact they are designed to back-leak slightly to allow down stream pressure to dissipate when switched off. I've recently been involved with two competition cars, one a classic rally mini, the other a racing TR4A, that had Facet gold top pumps in parallel.
One was fitted with non-return valves after each pump, before the lines joined, and worked well, but after many years the hoses were porous, the fuel smell was sickening and we revised the set up to pumps-in-series, to minimise the number of connections. Worked well.
The other had no one-way valves, and there was a misfire at high revs. Diagnosed as fuel starvation, we did a similar revision which cured it.
Dual pumps are a well known competition addition for reliability - one fails, switch to the other - and they work in series or parallel, IF one way valves are added to the parallel layout. I don't know if a solid-state Facet will obstruct reverse flow or back-leak, but Glencoe Ltd, the UK supplier of Facets (http://www.glencoeltd.co.uk/ ) can no doubt inform you.
John
Thank you John,One was fitted with non-return valves after each pump, before the lines joined, and worked well, but after many years the hoses were porous, the fuel smell was sickening and we revised the set up to pumps-in-series, to minimise the number of connections. Worked well.
The other had no one-way valves, and there was a misfire at high revs. Diagnosed as fuel starvation, we did a similar revision which cured it.
Dual pumps are a well known competition addition for reliability - one fails, switch to the other - and they work in series or parallel, IF one way valves are added to the parallel layout. I don't know if a solid-state Facet will obstruct reverse flow or back-leak, but Glencoe Ltd, the UK supplier of Facets (http://www.glencoeltd.co.uk/ ) can no doubt inform you.
John
Edited by tapkaJohnD on Saturday 25th March 10:14
I think that dual pumps is a better solution than adding another (reliability unknown) device to manage a single pump. I'll contact Glencoe for advice.
The pump is located below the bottom of the fuel tank in a cool area so is gravity fed.
100SRV
GreenV8S said:
What state is the inside of the tank in?
Now able to get work done on various projects during weekday evenings so this job has cropped up again.The tank is stainless steel and was pristine when I refitted it.
Fuel tank filler neck has a fine gauze ( Land-Rover Series filler neck) and the pump has the pre-filter fitted.
Looking on PH for similar threads resulted in:
https://www.pistonheads.com/gassing/topic.asp?t=15...
Edited by 100SRV on Tuesday 16th January 18:16
Max_Torque said:
You definitely need to post mortem then last failed pump! Even establishing if it was a mechanical, electrical or hydraulic failure is going to help a lot to eradicate it occurring again!
I agree, unfortunately the last time I replaced the pump was in 2014/5 and I no longer have the failed part. I'd left it on my bench to post-mortem and a colleague kindly cleared up.:-(
Thread resurrection time!
I'm considering eliminating the lift pump / swirl pot system.
The new arrangement will move the EFi pump to a position near to and below the bottom of the fuel tank (where lift pump used to be). Fuel pickup would be a Holley hydramat.
Before I spend money who has tried the HydraMat and did it work?
Reason for the HydraMat is the fuel tank is long and shallow and this is the simplest means I can think of to prevent fuel slosh starving the pump.
I'm considering eliminating the lift pump / swirl pot system.
The new arrangement will move the EFi pump to a position near to and below the bottom of the fuel tank (where lift pump used to be). Fuel pickup would be a Holley hydramat.
Before I spend money who has tried the HydraMat and did it work?
Reason for the HydraMat is the fuel tank is long and shallow and this is the simplest means I can think of to prevent fuel slosh starving the pump.
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