EFI Conversion - Fuel Delivery Systems

Some useful articles on doing it yourself
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Mr_B
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Tue Feb 26, 2008 2:55 pm

Hi Guys,

I started this thread so we can discuss the fuel delivery options for the EFI conversion seperately, the other EFI thread is pretty long... On the surge tank option I found a useful article on fabricating such tank, the PDF is attached. Before I race off to get quotes, the following needs to be decided:

Connections:
1. At bottom: Output to HP fuel pump (10mm ID)
2. Close to top: Input for LP fuel pump (6mm ID)
3. Close to top, above LP fuel input: return to main tank (6mm ID)
4. On top: Input for fuel returned from fuel rail pressure regulator (?mm ID, I don't know)

Do you still need to connect the LP fuel pumps 'return to tank'? If so does it return to main or to the surge tank?

Fuel Capacity:

How much fuel should the tank hold? Can the calculation boffins help here? First I read that anything from 500ml to 1 litre will suffice, but later I read that 3 litres is good, but that's probably for racing applications.

Please give us your input and views, maybe there are other EFI fuel delivery solutions we haven't considered!!

Bretton
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Fuel_Surge_Tank_Fabrication.pdf
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Tue Feb 26, 2008 3:38 pm

Bretton, as i said on the other thread i'm looking at having one made up. it will have 4 connections.

top: overflow to the main tank
2 in bout 3/4 way up: return from regulator and inlet from LP pump
bottom: outlet to HP pump.

i was working on 3" piping, bout 120mm long. but on looking at places to fit i could prob go to a bigger diameter tube. the 3" diameter tube section should give me a capacity of bout 0.46 liters. perhaps this is a bit small? although surely it need only contain enough for the steep stuff. which usually isnt very long.

the guys at the performance dyno place i spoke to reckons that the surge tank will never run dry as it will be constantly fed from the pressure regulator and the LP pump. thus if you use a HP pump with a massive flow rate there will be loads of fuel running back into the surge tank. he went on to say that a HP pump with a flow rate of 150L should be more than enough for the 2.2...

Perhaps it'd be better to put the inlet from the LP pump at the top, not 3/4 of the way up. otherwise when the surge tank wont it put 'back pressure' on the LP pump? this should then drain back to the main tank via the LP overflow. is this going to damage the LP pump?

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Tue Feb 26, 2008 4:42 pm

Hey, Bretton, I'm no calculation expert, but this is what common sense tells me:

If you get on average 5 km/l and you have a 1 liter surge tank, then you wll be able to travel 5km on just the fuel in the surge tank ( that is with no feed whatsoever from your LP pump from your main tank).
I have no idea what kind of fuel consumption you get when climbing a steep hill, etc. , but let's presume it's 1 km/l ( which I don't even think a supercharged 350 should give! :shock: ). Anyway, therefore, you should be ble to climb for at least 1 km before running dry - again presuming that there is absolutely no fuel being supplied by the LP pump.

Of course the LP pump should still provide fuel, albeit not enough to keep the motor running without the surge tank. I don't think it's easy to calculate exactly what kind of km's you will get, but I think it's safe to assume you re not easily going to find a 45 degree hill in excess of 1km long. :mrgreen: I think a liter should be more than enough! M2cw
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Tue Feb 26, 2008 6:19 pm

Scorpion, this seems to make good sense. In Bulldog's case, we mounted the HP pump low-down and fairly close to the Main Fuel Tank, but it would add to the reliability factor if we fitted a small surge tank even closer to the HP pump.

I'm converting this thread to a Sticky so that it doesn't get swallowed, let's keep it close to the other EFI thread. Bretton, are you going to transfer your diagram here as well?


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Tue Feb 26, 2008 10:18 pm

Hi F_D,

As requested the updated version:
fuel_delivery_02.gif
fuel_delivery_02.gif (8.68 KiB) Viewed 7049 times
I add the LP pump drain, that used to return excess fuel to the main tank, I think it too can be routed to the surge tank.
This is what would be required for the LP mechnical pump, I'm not sure if this is the same for a elec. LP fuel pump.

Bretton

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Tue Feb 26, 2008 10:25 pm

Oh, thanks Scorpion! Your info makes perfect sense.

I am going to work on 750ml, smaller should be easier to find a good mounting spot for. My dad may be able to assist with the fabrication. Else there's a place in Brackenfell that manufactures custom fuel tanks, so this would be really simple for them. :D

Bretton

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Wed Feb 27, 2008 8:25 am

Bretton If you look at my reply in the other thread I suggested that you rather put the surge tank at the bottom of the vehicle close to the fuel tank. That way you need less connections and it would be more reliable too.

As I was reading this post that Jonathan made, I remembered my old 1988 Golf GTI. It had the plastic surge tank with the fuel pump fitted inside and it worked well. It too was installed underneath the car next to the main tank. Maybe a good idea is to go and see if you can not get a complete pump with surge tank at a scrapyard. Such a unit would most probably fit underneath the load bin tucked away safely and might be a good option to consider. If the surge tank is fed via gravity only the you do not even need a return to the tank.

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Wed Feb 27, 2008 9:31 am

hmm the quote i got for the Golf surge&pump combo is about R1200. interestingly the guy says there is LP lift pump which feeds this surge tank on the golfs....

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Wed Feb 27, 2008 9:38 pm

Hi Bennie,

I took a look under the Lux this evening, I am not persuaded that there's enough space to do a gravity feed surge tank, cause the main tank is already pretty low. I tried to upload a pic, but the upload just hangs. Will try to upload from work.
I guess the ultimate solution is an 'in main tank - surge tank' and HP pump. But I'm not fond of having to cut into the tank and the pump is then really inaccessible. You have a valid point on the mech pump failing, but an elec LP pump could suffer the same fate. A gravity feed system could potentially suffer the same fate, if a fuel line/filter gets blocked.

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Bretton

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Wed Feb 27, 2008 10:13 pm

Hi Bennie,

Taking into account your input on the mech pump failing, what do you think about an installation like this, minimising the HP fuel line length, so the car engine will cut out quickly if there is no fuel.

Image

There is adequate space, the filters and HP pump are really easy to get to. Please forgive me for the Powerpoint diagram, but I like to visualise the solution.

Bretton

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Thu Feb 28, 2008 5:49 am

Bretton

It looks good and I am sure it would work well, it is just that I personally do not have any trust in mechanical fuel pumps, as I have had problems with them before, but I guess a LP electical pump may also do the trick.

My only concern is having so many connections in the fuel line right inside the engine bay. An petrol fire starts very quickly I saw the other day how a guy who had problems with a defective HP pump scratch around with it and within seconds his car was on fire.( nogal a scary experience)

Then also how would heat effect the HP pump as they are normally not designed to be installed under bonnet?

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Fri Feb 29, 2008 1:39 pm

Good point! I have decided to go with the surge tank on the undercarriage. My dad will have a stainless surge tank made to my spec. One question, will a elec LP fuel pump not suffer the same overheating/failure issues as a HP pump, cause it will happen that the LP pump will suck air from time to time - steep incline/decline, empty tank...

Take a look at the pic below of the fuel rail, the wires on the plugs connecting to the injectors have been cut rather short, which could make soldering them up a bit tricky and messy... Can I buy/get these plugs somewhere?

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Bretton

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Fri Feb 29, 2008 1:57 pm

I bought a set of them for R 100 bucks from Dictator (actually supposed to Bosch injector plugs but the fit perfectly) :wink:

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Fri Feb 29, 2008 2:02 pm

O ja a low pressure pump works with a diaphragm so it does not need the fuel as lubrication where as the HP pump works with needle bearings

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Fri Mar 07, 2008 9:48 am

Hi Guys,

Just an update on what's happening on my EFI story, nothing... :cry: I don't have time to do it right now, so much so that I have had the carb repaired for know. I am still considering getting someone, like Wessel, to do the installation for me, but he is a GoTech man through and through. He will install a Dicktator if I really want it, but at extra cost. I had a long discussion with him on the 'fuel only' option, he said the biggest performance and fuel economy gains are via the ECU controlling the timing, so 'fuel only' is not really the best way, just the easiest way...

Bennie, on your issues with the Toy internal coil, I have been told that the coil's resistance is the problem, it's much higher than most external coils, so most of the EFI installers do away with the Toy dizzi and coil, and use a modified Golf one + external coil.

Bretton

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Fri Mar 07, 2008 7:47 pm

Interesting information, Bretton. We opted to to the timing thing, but it has resulted in delays through trial and experimentation, and also in obtaining the required spares. At the end of the day however, it will be worth it. :P


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Fri Mar 07, 2008 9:57 pm

Nahh I do not believe the coil is a problem. My current Igniter fires the coil perfectly, the Dicktator has a setting in which you can adjust the charge time if necessary but I did not have to it works fine. My problem is that initially the Magnetic adapter picked up noice when it was installed inside the dizzy. WHen I moved it outside it worked fine except for one thing. If the battery voltage drops to 12.5v it does not pulse the ECU adequately to start eventhough the starter still swinged the engine decently, so that is why we are doing the optic picup thing now.

The coil issue might be a go tech related problem. Same goes for the Fuel only I have not seen an improvement after we changed the fuel only to an integrated timing setup on the Dicktator. Most of the problems gus do experience with aftermarket ECU's is normally timing related. That is why Eric and I dcided that if this optic pickup solution does not satisfy us 100% we will revert back to the fuel only setup.

BTW I think the reason why the guys in Cape Town like the Gotech is not because the Gotech is a better system but rather because the Gotech's main office is close by and they know the people there. From the few times I saw a Gotech installed I would not spend my money on it even if it was cheaper then Dicktator.

Rather install the system yourself, then it would be easier to do fault fining / optimising afterwards yourself as you get to know the system and its working.

Most guys doing these installations for you have to make a profit so they normally do a "cheap and nasty" in which they only install the minimum required to get the system running. They will normally will not install the electronic idling controllers, AIT sensor etc. For them time is money.

What I have against the golf dizzy on top of the Toyota Dizzy base and external coil is that I suspect a set up like that it might leave you stranded in deep water.

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Mon Mar 10, 2008 10:10 am

BenHurBul wrote:What I have against the golf dizzy on top of the Toyota Dizzy base and external coil is that I suspect a set up like that it might leave you stranded in deep water.
This is what happened to my mate Carlo Voetsek a while ago, and now nobody knows how to fix the problem. The only guy who knows the setup is not in the business any longer and is not overly keen to assist. His bakkie is still stranded :roll: :evil: :evil:
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Mon May 12, 2008 5:16 pm

snipes wrote:Hi Bennie,

Taking into account your input on the mech pump failing, what do you think about an installation like this, minimising the HP fuel line length, so the car engine will cut out quickly if there is no fuel.

Image

There is adequate space, the filters and HP pump are really easy to get to. Please forgive me for the Powerpoint diagram, but I like to visualise the solution.

Bretton

I have a question; do you think it's feasible to put the surge tank on the right hand side as we look at it? on one hand it may be hotter on that side due to the exhaust manifold (how much difference there is between sides of the engine compartment i'm not sure), but on the other hand it will be out of the way of all the electrics.

anyone have any thoughts?

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Tue May 13, 2008 6:17 am

I was also thinking of installing a surge tank in the engine compartment but.... what happens in the event of an accident when you get a hard knock on the side of the tank? The fuel tank might burst and the fuel will be ignited by the extremely hot manifold and exhaust. :shock: :shock: :shock:

So my opinion is I think a surge tank is an excellent idea but not in the engine compartment. :cry:
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Tue May 13, 2008 8:32 am

Good point. I would imagine that due to the fender panel creating a 'second' wall between the engine compartment you'd have to get hit pretty hard.

That and if the tank was made from stainless it should be hard enough to take the knock.

Then again rather safe than sorry...

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Tue May 13, 2008 10:06 am

Also if the mounting is not strong enough for the stainless steels weight combined with the fuel weight, it could come loose when you're pulling G's in an accident or even off-road which could then cause the pipes to disconnect and spray fuel on the manifold :shock: :shock: :shock:
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Tue May 13, 2008 10:18 am

okay so no surge tank for me then.... :roll:

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Tue May 13, 2008 11:33 am

You can mount the surge tank some where else on the vehicle :)

The only problem is you'll have a lot of piping. Do you know why you need a surge tank?
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Tue May 13, 2008 12:39 pm

i understand the theory behind it. whether or not its actually necessary i'm not sure about.

i hate the idea of giving it horns up one of Atlantis's finest and running out of juice....

looks like i'l go with the conventional setup and if that doesnt work i'll move the pump into the tank or look into another surge tank design. i think i might be over thinking this!

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Tue May 13, 2008 1:45 pm

The idea is that the fuel pump can reach the fuel weather you're driving level or at angle. So if you can modify the pick-up on the tank to where there would always be fuel.. you should be fine (the other option is to make sure your tank is at least 3/4 full)
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Tue May 13, 2008 1:50 pm

with the price of fuel its getting harder and harder to keep it 3/4 full!

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Tue May 13, 2008 2:04 pm

Take the plunge and fill it once and then keep it full... :)

That is what I do :)
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Wed May 14, 2008 4:37 pm

Even if the HP pump is inside your regular tank it will not fix the problem. of the pick up sucking air when the vehicle is at strange angles. For that reason cars that came with EFI has special designed tanks with chambers or compartments or similar methods for trapping fuel close to the pick up so that it would stay immersed for longer ( not indefinitely though). Driving off road with a tank that is over 1/2 (3/4??) is still the best option.

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Mon Nov 03, 2008 1:03 pm

I've the 5MGE(2.8i) and do not have a surge tank. From the main tank, thru a cheap LP filter into yhe bonnet, where it goes to a electric LP pump, directly onto the HP pump to the HP filter to the injectors.
It gets hot under that bonnet and never (+5 years) have it gave any problems. Return pipes are same old ones.

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Mon Nov 03, 2008 4:49 pm

Ladies - I didn't have any Fuel Delivery Problems at Boegoeberg this weekend and the ascents/descents were as steep as you can get :shock:

I took 26ltrs of Fuel with me (1 ltr ended up on my load lining futon :oops: ), I just kept her topped up lekker nê :wink:

The "Economy" for the Long Route was: 15kms on 22ltrs of ULP :shock: :shock:

That was over 7 hours hey :wink:

I think our Standard Bennie System works lekker fine hey :D:

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