Fuel System Convert to Full Pressure
Being playing around with the fuel system on the odd day here and there last few months.
Today I have converted it to a full pressure system with an AeroFlow AF49-1013 in tank pump, not diesel rated but wanted something affordable to test proof of concept. If I am happy I will run it till it breaks then replace with the new 200 Bosch which is the 044 replacement but actually states diesel in its specs.
So atm I have pump in modified housing as a drop in fit back in the tank, but only 2 lines hooked up being of course an outgoing high pressure one to the fuel filter and a return one back to the tank.
Yet to go for a test spin as I was doing other crap in between working out the replumbing of the existing lines as I am always out to use what's there.
One of the things I found after trial and error on previous sessions was to run an internal drain line from the pumps return line spout (which normally just sprays the fuel over the pump internals) right down into the bottom of the fuel pot, this was because I had experimented previously with bypassing the fuel filter completely on the return side and running straight back to tank (with and without the air bleed in line) and was getting the problems of hard starting and needing air purges when tank had low fuel (so usually just between the last 2 white marks on fuel gauge)
I waited till it was low on fuel again and today was as good a day as any, so quite looking forward to going on a run tomorrow with a spare jerry of fuel and see how low the gauge gets !
I will put some pics up at some point later.
14 Attachment(s)
Fuel System Convert to Full Pressure
Attachment 192061 Attachment 192062 Attachment 192063 Attachment 192064 Attachment 192057
A while back my MSA 100000 pot regulator (fuel pressure on my gauge was 4.2Bar with it) had started leaking and I replaced it with a 3.7Bar unit from the local upullit wreckers, also used an EU3 FPR housing with the front of head return line blocked off, this is so I can fit a fuel pressure sensor in at a later stage. The last few months the car hadn't been pulling well at highway speeds so on Saturday I fitted the go faster red aftermarket unit and adjusted it for 4.6 Bar and Sunday I went for a run to Port Pirie and back. Smidgen better by a bees thingy but nothing satisfying.
As I had an aftermarket in tank pump on hand which had been purchased with the regulator a longish time ago for the fuel system conversion I was 'gunna' do but was dragging my feet, I decided to NIKE it and put the POS at the back of the carport Monday morning and got stuck into it.
Attachment 192065 So out with the pump assembly. The carpet had been cut half inch under the plastic trim either side by a thoughtful previous owner or mechanic so no faffing about.
Attachment 192066 Attachment 192067 So pump assembly got pulled apart, no idea how I would be able to simply replace the actual pump itself with just another pump and avoid buying the full unit in a new housing. I have read that it supposedly has been done, but every housing I have pulled apart those convoluted fuel lines are well and truly hardened and have needed to be slit longways on the nipples to get them off.
You can see I have cut away the support housing that held the original pump in place as the replacement is a lot fatter. I used a length of submersible efi line with 2 efi clamps to hook it back up to the top housing but it is now pumping out through what was the Low Pressure return line from the fuel filter.
Attachment 192068 This is the in tank pump model I bought, it doesn't mention anything about diesel compatibility in the specs but it was a shed load cheaper (and on special at the time) than the current 044 (044 is superseded from 2 yrs ago) replacement which is the Bosch 0 580 464 200, also the Bosch needs a pickup filter assembly if used as an in tank pump as it is sold with fuel fittings at both ends to be a drop in replacement for the 044. If or when this setup fails I am going to modify a housing with just a filtered pickup line sitting in a swirl pot and return tubing going into the swirl pot and external full pressure pump.
Attachment 192069 So on re install I did the following, the return Air bleed line (white) is left disconnected. The Green line moves to the left where the white was. The Blue line moves left to where the green was. The other two ports on the housing are blocked off, I had kept the plastic bits that came with new pumps so used them. I have looped the white and black unused lines to keep crud out. Same connector plugs back in as I cut and reconnected the wires to the new pump + - .
Attachment 192056 Next is the fuel filter block, the inner rear connector (next to chassis) stays as is, the outer rear (closer to you) is blocked off and left floating. The inner front is blocked off and initially leave it floating. The outer front is disconnected and push it up out the way, pull the inner front towards you and connect it there instead.
I put the removed connectors on each end of a short hose and clipped the 2 unused lines together to keep crud out.
Attachment 192057 next is the fuel pressure regulator block, I don't have a fuel cooler so easy peasy swap top and bottom connectors over. with fuel cooler in situ you swap the return line on the fuel cooler (that goes to the tank) over with the fuel supply (top line on FPR block ). I can't say what your mileage is there as I removed mine couple years or more back and cut/fitted new quick connector.
Attachment 192058 So after the customary 5 push bleed then hold foot flat to floor to get it coughing it fired up and settled down to this pressure. Now bear in mind this is going through a 3.7Bar regulator (which read 3.8Bar on my fuel pressure gauge whenever I had previously measured it) so when push comes to shove its definitely got flow . I noticed it was whining a bit load like the previous pumps when I was playing around with air bleed valve setups over the last couple months.So after a cuppa or so I thought well the air bleed is a restriction and the return fuel basically goes back to the HP side of the pump. So I pulled the pump assembly out and put a line from the formerly return air bleed (now just a full open flow return line) down into the bottom of the swirl pot, voila ! the pump went nice and quiet !
Attachment 192059 And another jump in line pressure (maybe coz the discharge tube is now exiting against the weight of the diesel in the tank ?) I have always noticed in the RAVE the air bleed line does extend to the bottom of the fuel pump assembly but every time I have pulled a pump at wreckers and also the VDO that was in my vehicle and the aftermarket I have purchased, that return extension is not there. Anyway there is a whole other story on all the experiments I have done that explains the factory fuel plumbing setup in my tiny little mind but suffice to say what I have done at this point works and I am a happy chappy.
Attachment 192060 Here is the mud map. Bit convoluted as far as fuel pressure regulator block explanation goes but I am hoping it's enough for anyone who has been contemplating how to get out of paying stupid prices for a new pump. I don't believe the cheap clone assemblies can hold up the flow/pressure requirements when the going gets tough but ok if it's a daily commuter.
I have learnt a lot out of necessity as both my vdo and then aftermarket pumps started squealing/whining and I couldn't afford to keep throwing big money around (big by my standards is anything more than couple hundred, which has to be saved up first anyway!)
So here are my thoughts anyway.
I believe the fuel system setup from factory is up to the task when maintained with parts that meet or exceed factory specs.
The non return valve which seems to be awol in a lot of vehicles should be put in place if you can get one at a decent price. This helps retain fuel in the line.
The air bleed valve should be changed as part of the fault finding process if your pump starts whining and you get the hard starts at low fuel tank levels or on sloped driveways after parking overnight. And in my opinion changed as a service item every 5-7 years.
When you fit a new pump go to the small effort it takes to fit a return line from the air bleed connection to the swirl pot, there is an opening on the pump assembly already there for you to pass it down, make sure you use enough length to get right to the bottom. This becomes an anti siphoning feature which along with the air bleed valve and non return valve as originally specced keeps the fuel rails in the head primed.
I have gone this route because it was a lot cheaper for me to fiddle a bit and swap fuel lines around (how easy was that, nothing new to make up) and have a decent performance spec pump rather than get another cheapy clone which I believed couldn't keep up under load, I do think my air bleed valve was faulty which I now know from playing around is very important to the proper functioning of the factory setup.
I hope this rough guide helps others as I have seen many threads in various forums going back years but no one saying I did it and this is how.
I am sure it has been done plenty times just not put out there (I mean what fuel setups do those rally and racing Td5 units run, not factory surely)