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Location:
Townsville, Queensland
Registered:
September 2002
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Toymods Club Treasurer
Location:
Sydney
Registered:
May 2002
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Re: electronic fuel pump conversion on carby engine? (help)
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Mon, 26 January 2004 02:53
 
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Where does the current return pipe from the mechanical fuel pump go?
You need a return line from the engine to the tank.
To do an electronic pump conversion you need a carby fuel pump, not an EFI one (I don't know if that's what you meant by facet pump)
You need a filter between the tank & the pump. Same as what you're currently running.
Carby fuel pumps are self priming so it doesn't matter where you mount it, although near the tank is a good idea.
You can still push start a car, as there will be fuel still in the line, & once it's started, the electrics will run off the alternator.
If the tank is that bad, take it out & give it a clean.
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Location:
Townsville, Queensland
Registered:
September 2002
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Re: electronic fuel pump conversion on carby engine? (help)
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Mon, 26 January 2004 06:52
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The return from the mechanical goes back into the tank (as it should). The current mechanical has three hoses going to it at the moment. In, out and return. I was going to put a Y piece in place of the mechanical pump (plate the hole in the head) and make the return section of the Y piece smaller (like it should be, as the return hose/piping is smaller).
The facet pump is one of those "tick, tick, tick" pumps pretty sure they are designed for carby usage, was in a 2L carby Rodeo (aftermarket pump).
The tank is not too bad, fuel in Townsville can be the problem, I would be pulling the tank out pretty often.
Might remove some of the under fueling issues (carby has had the float done properly etc) and maybe a little bit more revy and remove some noise from the head.
Where could I get a Y piece from. Get it fabricated to the right hose size or see Rice Barn (auto barn) or super cheap. Will probably hunt around the performance shops and auto shops in Townsville (about 6 places maybe).
thanks
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: electronic fuel pump conversion on carby engine? (help)
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Mon, 26 January 2004 07:00
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i have a 34DMS weber on my rolla..
the later corollas had the return to furl pump line, but mine, being a KE15, never did.
i used a "fuel miser" pump for "4 cyl" which puts out enough fuel and is internally regulated to 3psi.
the return line from the weber is blocked off.
originally, the weber would have had a pressure regulator after it, to keep the pressure at the float needle to around 3-4psi, but since the elec pump is self regulated, the return line is not needed.
hope this helps.
Cya, Stewart
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Location:
Townsville, Queensland
Registered:
September 2002
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Re: electronic fuel pump conversion on carby engine? (help)
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Mon, 26 January 2004 07:06
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is that Webber like the one they used to put on XF Falcons (stock)? If so I sort of know the setup you ae talking about.
I guy told me to run the return etc just with the electronic fuel pump but near the Y piece to start with put a clear cheapo filter. If the filter is always full with the return setup then it is getting plenty enough presure. But if it is always empty might not be pushing enough or return might be too large.
Think I might talk to a shop about it.
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Toymods Club Treasurer
Location:
Sydney
Registered:
May 2002
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Re: electronic fuel pump conversion on carby engine? (help)
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Mon, 26 January 2004 22:11
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How many fuel lines are attached to the carby?
If there are 2, then one is the fuel feed, & the other the return line.
Attach the fuel feed to the mechanical pump to the fuel feed to the carby, & the return line from the carby to the return line to the tank.
You shouldn't need a Y piece anywhere.
What lines were you going to attach the Y piece to? It kind of doesn't make sense the way you're describing it (plus I've never had a car with mechanical pump, except my current diesel, which is completely different again)
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: electronic fuel pump conversion on carby engine? (help)
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Tue, 27 January 2004 01:56
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the weber is from a 1974 Fiat 124 sports 
but it's vaguely like a DGV type carb.
the factory setup for a weber carb has fuel going into the carb (into the little bowl where the filter is, but before the float needle) which comes from the fuel pump.
it also has a smaller line leaving the carb (from this same small bowl before the float needle) and this is the return line that goes to a pressure regulator, to keep the pressure at about 3-4psi.
you have a few choices.
run an unregulated pump (carby not efi) to the inlet of carb, then have the outlet running to a pressure regulator, and then back to the tank.
you run an unregulated pump near the fuel tank, and have a pressre regulator immediately after it, then have the retun going to tank, and then either run the reg outlet to the carb inlet AND outlet, or block the outlet and only run it to the inlet.
OR
use an internally regulated fuel pump, and run the pumps outlet to both the inlet and outlet of the carb, or block off the carb outlet and only run the fuel line to the inlet.
i have blocked my outlet and have an internally regulated pump running to the carbs inlet. i never have problems with vapour lock as the pump is right next to the tank, and if fuel evaporates from the carb float bowl, it takes maybe 5-10 seconds to fill it before starting the car.
Cya, Stewart
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Location:
Townsville, Queensland
Registered:
September 2002
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Re: electronic fuel pump conversion on carby engine? (help)
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Tue, 27 January 2004 06:41
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the carby I currenly have only has a line in and no return. The return is built into the mechanical fuel pump. So at the moment I have.
- Two lines running from the fuel tank to the mechanical fuel pump, one is larger than the other this is the sender the other one is smaller and is the return
-one line then leaves the mechanical pump and goes into the carby
That is about it at them moment. I think there may be provisioning for the removal of a plug in the carby to make it a return type. But the less hoses I have to run near the exhaust manifold the better (already have braided line for the current sender hose)
I might just take it to a shop and see what they say. might take some pics of the setup if I get around to it.
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Location:
Townsville, Queensland
Registered:
September 2002
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Re: electronic fuel pump conversion on carby engine? (help)
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Thu, 29 January 2004 13:20
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here are some pics of the current setup, this setup is stock bar the replacement carby.
So both the stock carby and aftermarket carby do/did not have a return built into them.
I want your guys ideas, but I was thinking of putting either a T piece or a Y piece in where the current mechanical pump is and mounting an electronic pump in near the tank. The restriction in the smaller return I thought would hold pressure enough to the carby as the mechanical one did.
See what you think from the pics.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: electronic fuel pump conversion on carby engine? (help)
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Thu, 29 January 2004 15:40
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i think exactly the same as before.
remove fuel pump.
remove or block return line.
get fuel pump that is internally regulated to 3psi (or whatever you think the weber needs)
run fuel line from pump to carby inlet..
thats it..
there should be no confusion here.. all you need to do is get fuel to the carb at the right pressure...
if you really want to use the retun line, remove the fuel pump and replace with a pressure regulator, whose return uses the original fuel pump return line..
if this is over your head, get a mechanic to instal it 
wtf do you need a T piece in there???? all you need is one fuel line 
Cya, Stewart
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Registered:
May 2002
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Re: electronic fuel pump conversion on carby engine? (help)
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Fri, 30 January 2004 00:06
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I hate to stir someone else's porridge, but when i converted to an electronic carbie pump (facet one) i originally didn't utilise the return line, but then the car wouldn't idle the best and used lots of fuel (excess pooring staight into the motor).
I spoke to someone who deals lots with carbies and they gave me a T-piece unit which has the same diametre opening straight throught the top of the T and a smaller (needle like) opening on other side. The reason for this is when the pressure builds up in the carbies, instead of overflowing into the motor (as there is nowhere else to travel), the excess pressure flows through the needle and back into the tank.
It is a simple design made for simple carbie setups where low pressure systems are in use. It works the same way as a fuel pressure regulator, but doesn't require a return line off the carbie as it's connected onto the feed line just before the fuel entres the carbie.
This is just my 2c worth as the above setup was used on my car and worked. "tercelboy" you seem to have all tha parts, so just try it out.
Good luck!
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: electronic fuel pump conversion on carby engine? (help)
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Fri, 30 January 2004 11:34
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well, no porridge intended..
the reason this happened was because your facet fuel pump was internally or externally regulated to the correct pressur for the carbs. i think facets are around 6-9psi?? whereas most carbs want 3-4psi..
the t-piece with a small hole is a poor mans regulator..
there is actually a holley carb pressure regulator on ebay atm for $25. well worth getting for you Tercelboy. just plug it in, with it's retun going back to tank and you are golden...
you need
REGULATED FUEL PRESSURE
either by REGULATED PUMP
or EXTERNAL REGULATOR
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