In tank fuel pump retrofit. The worrying bit!
Discussion
High Graham. Was just reading your posts on le mans thread and reminiscing about our trip. Hope to go next year if car is together again.
separate hp pump in each tank with built in surge control. Also using speed control to combat the overheating fuel problem that I have been plagued with ever since converting to EFI.
Because of the size of the pump flange I have had to put it in the sloping side of the tank which makes in situ drilling a little tricky but so far so good!
separate hp pump in each tank with built in surge control. Also using speed control to combat the overheating fuel problem that I have been plagued with ever since converting to EFI.
Because of the size of the pump flange I have had to put it in the sloping side of the tank which makes in situ drilling a little tricky but so far so good!
Interesting to see the progress on this, not many people would the balls to play with a 'used' fuel tank in-situ.
That foam is available from Merlin, easier to cut when out of the tank, I guess the challenge is getting the well in the right place so that it always has fuel in it.
I'm thinking of going next year to the Classic, maybe organise something early next year.
That foam is available from Merlin, easier to cut when out of the tank, I guess the challenge is getting the well in the right place so that it always has fuel in it.
I'm thinking of going next year to the Classic, maybe organise something early next year.
Pics self explanatory I guess. Tank was emptied and then filled to brim with water to prevent hazards! Water drained and dried out. Fitting at an angle not particularly easy but doable. decent right angle drill required. Note rubber bucket which sits on bottom of tank with 4 small holes to reduce drain out under heavy g loads. Pump positioned as far back as poss and in centre of tank so g forces of acceleration and cornering will have min effect. Decel is off throttle. Tanks now completely separate with 2 pevekoil 3 port valves to control flow and return.
Pump/gauge changeover in cockpit swaps tanks as before. Supply from speed/pressure controller to pumps is swapped with 4 pole relay also with same cockpit switch. Simples
Racingroj said:
Hi Mark
I've been following this with interest as I need to change my fuel system next winter. Following my post last September about fuel cavitation its happened again whilst on the way to Cholmondelely. Please keep posting.
Thanks
Roj
Roj - me too, fuel cavitation. What set up do you have?I've been following this with interest as I need to change my fuel system next winter. Following my post last September about fuel cavitation its happened again whilst on the way to Cholmondelely. Please keep posting.
Thanks
Roj
I am running factory standard fuel swirl pot system with Bosch 044 pump fed by a -6 line.
Mark
Bog
Not very scientifically. The foam was soaked with it but overnight it all dropped into bottom of tank. Hole is quite big (3.25 inches) and quite a bit more foam cut out so I was able to soak it up with kitchen towel. remember that there is always small amounts of water in fuel. I intend to fill with petrol and then pump out and allow any thing left to separate out before refilling.
Filling with water is the recommended way to do any work on a tank that has had fuel in it before.
Not very scientifically. The foam was soaked with it but overnight it all dropped into bottom of tank. Hole is quite big (3.25 inches) and quite a bit more foam cut out so I was able to soak it up with kitchen towel. remember that there is always small amounts of water in fuel. I intend to fill with petrol and then pump out and allow any thing left to separate out before refilling.
Filling with water is the recommended way to do any work on a tank that has had fuel in it before.
Mark
As far as I know its standard factory but I will only really know when I take the engine and gearbox out in the winter and look at it all. At the moment I'm thinking about the AB option which means removing the tanks by cutting the GRP inside the wheel arch. If there is a way that is as good but DIY and much cheaper then I will look at that. As I am learning all the time on these changes the AB option appeals as it has all been tried and tested.
Roj
As far as I know its standard factory but I will only really know when I take the engine and gearbox out in the winter and look at it all. At the moment I'm thinking about the AB option which means removing the tanks by cutting the GRP inside the wheel arch. If there is a way that is as good but DIY and much cheaper then I will look at that. As I am learning all the time on these changes the AB option appeals as it has all been tried and tested.
Roj
Have to say that if I were to revamp my fuel system I would want to weld a swirl pot into the rear of the passenger side fuel tank, same as Mark but with the rear of the tank squared off and sink that HP pump and well etc in there. My tanks are linked by -12 fittings so fuel could be returned to either tank and no need for pumping fuel from one tank to another.
I am no expert but the comments here do seem to be a bit OTT.
Removing the tanks is not necessary and retro fitting HP pumps in the tank with all the associated costs seems excessive IMO.
I had issues with fuel vapourisation (60+ degrees on my fuel temp sensor) in 33deg C temps and stop start driving for an hour at Le Mans last year queuing to get into the St Saturnin car show last year. With some simple changes I have never seen fuel temperatures (yes, I do measure fuel temperature)above 32 degrees since my changes. These have been documented on here before.
My cost was for a low pressure pump and a few hose fittings. Less than £300.
We are dealing with a fuel system that is not ideal for EFI, but it is not necessary to spend vast amounts to solve the issues.
All my opinion, of course.
Paul
Removing the tanks is not necessary and retro fitting HP pumps in the tank with all the associated costs seems excessive IMO.
I had issues with fuel vapourisation (60+ degrees on my fuel temp sensor) in 33deg C temps and stop start driving for an hour at Le Mans last year queuing to get into the St Saturnin car show last year. With some simple changes I have never seen fuel temperatures (yes, I do measure fuel temperature)above 32 degrees since my changes. These have been documented on here before.
My cost was for a low pressure pump and a few hose fittings. Less than £300.
We are dealing with a fuel system that is not ideal for EFI, but it is not necessary to spend vast amounts to solve the issues.
All my opinion, of course.
Paul
Agreed Paul. Removing tanks is an unnecessary hassle and expense. It was your system that got me started on doing the conversion but I was not keen to loose the 2 tank system and so came up with my solution. Fitting the in tank pump took under 2 hours and can be done by any half decent DIYer. Not only does it solve the cavitation problems that some are experiencing but it also removes a whole load of pipe work from the very cramped engine bay particularly in an LS powered car. This has positive implications for safety and aesthetics as well as removing the very real potential for engine damage due to the extremely weak fuel mixtures encountered when cavitation occurs.(often weak enough to cause the engine to stop altogether)
It is a blessing for those who experience this that the nature of the problem experienced in our cars is that it usually occurs at low throttle opening after prolonged periods sat in traffic etc.
It is probably completely unnecessary to add the pump speed/pressure controller with this system but I do not see the point of having a fuel pump (or 2) which pumps 300 litres/hr continually pumping at that rate when 95% of the time we are probably consuming in the region of 10 litres/hr.
A bit of research into how all high performance production cars overcome these problems turns up that they all now use in tank pumps with speed control all of which is built into the engine ECU. In fact GM ecu's of later design have this facility built in with a solid state fuel pump relay which produces a PWM current to the fuel pump. Aftermarket ECU's are now being produced with this facility as well following the surge in EFI conversions which are happening especially in the US hot rod market.
It is a blessing for those who experience this that the nature of the problem experienced in our cars is that it usually occurs at low throttle opening after prolonged periods sat in traffic etc.
It is probably completely unnecessary to add the pump speed/pressure controller with this system but I do not see the point of having a fuel pump (or 2) which pumps 300 litres/hr continually pumping at that rate when 95% of the time we are probably consuming in the region of 10 litres/hr.
A bit of research into how all high performance production cars overcome these problems turns up that they all now use in tank pumps with speed control all of which is built into the engine ECU. In fact GM ecu's of later design have this facility built in with a solid state fuel pump relay which produces a PWM current to the fuel pump. Aftermarket ECU's are now being produced with this facility as well following the surge in EFI conversions which are happening especially in the US hot rod market.
Pump kit @ £400 available in UK.
Lack of space especially in LS cars combined with the amount of fuel hoses running all over the place does seem to contribute to the problem so one has to conclude that heat absorption is part of the problem. However curing that problem with confidence could/would cost at least as much. Do not overlook the amount of work done by the HP pump to pump this amount of fuel around and around the system. It does cause an increase in fuel temp. The main issue I believe is the restriction in the supply pipe to the HP pump. This causes very low pressure at the point of suction. Enough to cause cavitation in some cases. Fuel pump manufacturers recommend bigger pipe and as shorter length as possible for the feed to the HP pump. The possibility of cavitation increases as temperature rises and pressure drops. The design of this pipe is critical to the correct running of external pump systems.
The internal pumps have no supply pipe obviously and a large intake port.
Lack of space especially in LS cars combined with the amount of fuel hoses running all over the place does seem to contribute to the problem so one has to conclude that heat absorption is part of the problem. However curing that problem with confidence could/would cost at least as much. Do not overlook the amount of work done by the HP pump to pump this amount of fuel around and around the system. It does cause an increase in fuel temp. The main issue I believe is the restriction in the supply pipe to the HP pump. This causes very low pressure at the point of suction. Enough to cause cavitation in some cases. Fuel pump manufacturers recommend bigger pipe and as shorter length as possible for the feed to the HP pump. The possibility of cavitation increases as temperature rises and pressure drops. The design of this pipe is critical to the correct running of external pump systems.
The internal pumps have no supply pipe obviously and a large intake port.
Following the recent threads and posts on the subject of overheating fuel and the negative side effects and potential dangers, I always thought that the in tank pump solution could/would solve most of the problems. Eliminating unnecessary fuel pipes around the engine bay reduces heat sink in a very hot environment.
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