v8bobber Posted January 23, 2009 Share Posted January 23, 2009 I've finally managed to squeeze the 3.9 and HP22 auto in the 80" frame and now that the heaviest oily bits are in place i'm starting to look at what to do and in what order. Amogst the massive list of things I need, I have selected a fuel tank of just over 2 gallons with breather/feed/return, but am now on the look out for a fuel pump for the injection engine. It's something that I know very little about, being used to working on petrol vehicle with carbs, or diesels. I was wondering whether anyone could recommend a fuel pump for my application, and do I need a pressure regulator Cheers, Dave Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 23, 2009 Share Posted January 23, 2009 The pressure reg should be on the fuel rail behind the plenum. There are a few external EFI pumps that will suck from a tank but the vast majority will melt if they have to draw fuel & pump it, especially with the angles yours will see. If you can get an internal pump into the tank, that's neater and abandoned Subaru & Mitsubishi ones are peanuts on eBlag (all the tuning boys upgrade to bigger pumps, innit). The alternative is a carb-style lift pump feeding an inline EFI pump. Quote Link to comment Share on other sites More sharing options...
v8bobber Posted January 23, 2009 Author Share Posted January 23, 2009 Cheers Fridge, I had a horrible feeling that it may not be as simple as I first thought. All in-tank pumps I've come across in the past have been recessed into the top of the tank, held in with a few screws, almost like the old senders in series land rovers? I think that the problem I may have there is that a car pump is fairly deep but my alloy tank will probably be 250-300mm deep, and I obviously want the pump to pick up from fairly near the bottom of the tank? Help me out here if i'm going off tangent? Dave Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted January 23, 2009 Share Posted January 23, 2009 The standard 3.9 EFI pump from the steel tank is held in with six small allen bolts which go into blind threaded tubes pressed into the top of the tank. Sort of like long blind nutserts if you know what I mean? I think that the pump probably reaches about 250mm to 300mm deep and I would have thought would be about perfect for your application? There is also a more recent plastic tank, but I don't know how the pump fastens in that. If you new (fabricated?) tank is not stainless then how about cutting the whole section - including the pump and it's mounting - out of the top of an old steel tank and welding it into the top of the new one? Rog Quote Link to comment Share on other sites More sharing options...
mickeyw Posted January 23, 2009 Share Posted January 23, 2009 I think that the problem I may have there is that a car pump is fairly deep but my alloy tank will probably be 250-300mm deep, and I obviously want the pump to pick up from fairly near the bottom of the tank? Help me out here if i'm going off tangent?Dave You can either lengthen or shorten the original efi pump pickup pipe. I had to do this when I put RRC pump into the tank on my 90. The screw holes were the same number and position. Quote Link to comment Share on other sites More sharing options...
Rizla 1 Posted January 23, 2009 Share Posted January 23, 2009 If its for trials ? then i would say like fridge said fit a facet pump but put it through a swirl pot and then to a high pressure pump to the engine - works any angle then - Quote Link to comment Share on other sites More sharing options...
steve_d Posted January 23, 2009 Share Posted January 23, 2009 Shoot me down if I'm on the wrong track as I don't know exactly what a 'trialler' does. Is it going to see extreme angles front to back or side to side? Is it going to see sustained side G forces? If either, then the risk exists where the fuel surge or tilt angle of the tank will leave the pickup drawing air. This will quickly kill an efi pump and the lean running engine will not be happy either. If at an angle for any length of time the engine will get no fuel and stall. IMHO you should fit a surge tank which could be about a foot long and 4" diameter vertically to a bulkhead. Fit a low pressure pump from the tank to supply a surge tank and a return from the surge to the tank. The efi pump then takes fuel from the bottom of the surge and the return from the fuel rail also goes to the top of the surge. The result is that no matter what angle you are sitting at or what G is being applied there will be about 2 litres of fuel to use even if no more is coming from the main tank. Steve ETA Damn, took too long typing. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted January 23, 2009 Share Posted January 23, 2009 I've been through a similar thought process with a v8 series conversion. I ended up modifying the RR fuel pump to fit my tank - piccies here Not sure if it would be any good for your application, but might give you a few ideas. Quote Link to comment Share on other sites More sharing options...
Rizla 1 Posted January 23, 2009 Share Posted January 23, 2009 [quote name='steve_d' date='Jan 23 2009, 09:30 IMHO you should fit a surge tank which could be about a foot long and 4" diameter vertically to a bulkhead. Fit a low pressure pump from the tank to supply a surge tank and a return from the surge to the tank. The efi pump then takes fuel from the bottom of the surge and the return from the fuel rail also goes to the top of the surge. The result is that no matter what angle you are sitting at or what G is being applied there will be about 2 litres of fuel to use even if no more is coming from the main tank. Steve ETA Damn, took too long typing. Just what i said above ?? i call it a swirl pot - you called it a surge tank ? Quote Link to comment Share on other sites More sharing options...
Rizla 1 Posted January 23, 2009 Share Posted January 23, 2009 [quote name='steve_d' date='Jan 23 2009, 09:30 IMHO you should fit a surge tank which could be about a foot long and 4" diameter vertically to a bulkhead. Fit a low pressure pump from the tank to supply a surge tank and a return from the surge to the tank. The efi pump then takes fuel from the bottom of the surge and the return from the fuel rail also goes to the top of the surge. The result is that no matter what angle you are sitting at or what G is being applied there will be about 2 litres of fuel to use even if no more is coming from the main tank. Steve ETA Damn, took too long typing. ------------------------------------------------------------------------------------------------------------ Just what i said above ?? i call it a swirl pot - you called it a surge tank ? Quote Link to comment Share on other sites More sharing options...
jules Posted January 23, 2009 Share Posted January 23, 2009 A lot of the early EFI conversion used the 2.0 moteago efi pumps my first Range Rover had one. My racer has a swirl tanks under the fuel cell in the back and I don't suffer form fuel problems in that. (it had a external pump) Quote Link to comment Share on other sites More sharing options...
tel Posted January 23, 2009 Share Posted January 23, 2009 my bobtail runs a vauxhall calibra pump and is good as gold and also cheap as chips its an external one like the bosch type ones Quote Link to comment Share on other sites More sharing options...
steve_d Posted January 23, 2009 Share Posted January 23, 2009 Just what i said above ?? i call it a swirl pot - you called it a surge tank ? Have been challenged in the past about using the swirl pot description as most on the market are not correctly designed and do not 'swirl'. If the the pipes from the tank and from the fuel rail enter the pot at a tangent it will make the fuel in the pot rotate (swirl) this gives time for bubbles to go to the top and be returned to the tank rather than going to the fuel rail. Swirl is important for a dry sump oil system but petrol is so thin a simple tank will work fine and could even be square/rectangular. Steve Quote Link to comment Share on other sites More sharing options...
v8bobber Posted January 23, 2009 Author Share Posted January 23, 2009 Thanks guys, I think I know what direction i'm going in now. I think what i'll do is buy ones of the alloy tanks from ebay and then cut a hole in the top and sink the standard pump into it. I like keeping bits like that standard as I know they'll work with the engine. I'll do what I did last time, and try and get a tallish tank so the pickup is always covered with fuel. I need to fund a tank now, anyone want to buy a secondhand Mallory and a Facet carb fuel pump? Thanks again Dave Quote Link to comment Share on other sites More sharing options...
steve_d Posted January 23, 2009 Share Posted January 23, 2009 A facet or other make external pump will be a better job than an OEM in-tank one and will be easier all round. as you already have a tank and low pressure you only need a high pressure pump, a surge pot and some pipe. Steve Quote Link to comment Share on other sites More sharing options...
v8bobber Posted January 24, 2009 Author Share Posted January 24, 2009 A facet or other make external pump will be a better job than an OEM in-tank one and will be easier all round. as you already have a tank and low pressure you only need a high pressure pump, a surge pot and some pipe.Steve Is a surge/swirl pot an absolute must then? I will be going for a 3.5 gallon tank and guess it will only use a gallon or two over a morning and usually refill at lunch time anyway. I've been looking on ebay for standard land rover in-tank pumps and it seems that there is a problem in that the 3.9efi pump has a plastic top, is quite large and would be a bugger to fit to a relatively small tank. The older 3.5 efi pump would be alot easier to fit although i'm not sure whether it would be up to the job of supplying fuel for the bigger capacity engine. The other option I seem to be left with is the external aftermarket job like a Sytec, getting on for a hundred quid but will seem to do the job. I am not sure which way to go at the moment as I would prefer not to spend the extra money as new internal pumps can be had for under forty quid More thinking methinks Dave Quote Link to comment Share on other sites More sharing options...
steve_d Posted January 24, 2009 Share Posted January 24, 2009 Is a surge/swirl pot an absolute must then? I will be going for a 3.5 gallon tank and guess it will only use a gallon or two over a morning and usually refill at lunch time anyway. I've been looking on ebay for standard land rover in-tank pumps and it seems that there is a problem in that the 3.9efi pump has a plastic top, is quite large and would be a bugger to fit to a relatively small tank. The older 3.5 efi pump would be alot easier to fit although i'm not sure whether it would be up to the job of supplying fuel for the bigger capacity engine.The other option I seem to be left with is the external aftermarket job like a Sytec, getting on for a hundred quid but will seem to do the job. I am not sure which way to go at the moment as I would prefer not to spend the extra money as new internal pumps can be had for under forty quid More thinking methinks Dave If you are confident that no driving situation will leave the tank outlet drawing air or the same for an internal pump then no you don't need a pot. I see no reason why a 3.5 pump will not cope. Others further back have mentioned a number of external pumps you could pick up from the breakers. You could do your install and have two spares for the price of a new pump. An external would be easier to carry as a spare than an internal which is a bit bulky and fragile. An external will be a far simpler first install and much quicker to swap out when required. Steve Quote Link to comment Share on other sites More sharing options...
Hamish Grundy Posted January 24, 2009 Share Posted January 24, 2009 i have an 88 trialer 3.5 efi, i kept all the fuel system standard, ie pump in tank. when i had the tank made (allisport) they pump a piece of 6mm ali in the top for the pump securing bolts to screw into, i also have baffles either side of the pump, i have never had problems with cutting out or spluttering due to lack of fuel. i say keep it standard, easy to get parts and its worked fine upto now!! i have however fitted a fuel pressure boost valve, suplied by rpi, which in my opinion made alot of differnce, well worth the money!! Quote Link to comment Share on other sites More sharing options...
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