Ok, guys, I know I'm wining a bit after my 1.6L engine swap, please bear with me.
When I attempted the swap, I purchased the adapter plate and low pressure fuel pump from Low Range Offroad. Ever since the engine swap, the fuel pump has been making this ticking noise. I had it hooked up to the starter switch, so I went and hooked it up to a relay and gave it power directly from the battery, but the ticking did not go away.
Today I was driving the Zuk to the dunes, and my fuel pump just stopped working. Aparently I had a defected fuel pump, but I do have some questions:
1. Does the fuel pump require a pressure regulator?
2. If the fuel pump is hooked directly to the carb, where will the excess fuel go? I didn't do the installation myself, so I'm not sure if it is going directly to the carb or through some regulator.
If you do a quick search on the forums for it I'm sure you'll turn up a couple topics. Seems like we were discussing it at length a couple months ago and there's a bunch of usefull information in that thread.
Now the pump really did die. I checked all electric lines, and they are all fine. I removed the pump. I made a search on the forum and most threads talk about the high pressure pump, none give details on low-pressure ones. I'm getting a new fuel pump, so I still need to know two things before I get it:
1. The pump was connected without any filters, before or after the pump. Could that have caused the pump to die after just several usages and less than 50 miles?
2. Do I need a fuel regulator? If so, do I need a one with a return line or without a return line?
samurai needs a low pressure high volume pump. The stock pump puts out about 6psi. You need between 4 and 8, don't go over 8 and don't go under 4. If your pressure is unregulated and too high the pump will unseat the needle valve in the carb.
You need a return line before the regulator. That way any fuel held back by the regulator can be diverted to the tank rather than loading up the fuel pump.
You need a fuel filter before the pump to avoid particulates going through the pump and damaging it. Particulates won't kill a pump but it will reduce it's efficiency.
What kills a pump is excess loading on the electric pump motor, either with excess backpressure, or excess draw pressure.
If you didn't have a return line that could have been causing a lot of backpressure which would dammage the valves on your carburetor and would burn out the pump motor.
Things that cause excess draw pressure are clogged in-line filters, clogged or restricted supply lines, or a malfunctioning tank vent.
What needs to be determined here is what sort of pump is being used, and what the manufacturer of that pump recommends.
I've been using electric fuel pumps for over two decades, and that includes installing them on cars that originally had mechanical fuel pumps, and not all of them require return lines.
Some of them (notably SU pumps as fitted to the classic Minis) also tick during normal operation, others don't, it depends on the design.
Also, whether or not you need a fuel pressure regulator will also depend on how much pressure your particular pump can deliver and how much the carburettor needs - if a return is required with your particular pump, where it connects will depend on the regulator.
Just as an example, one of my Suzukis is carburetted, has a low pressure, high volume, "in tank" pump, has no fuel pressure regulator and has a return line - tee'd in to the delivery line just before the connection to the carb - and this, by the way, is the factory setup - the only things that have been changed are the fuel filter (located outside the tank, after the pump by the way) and several small diameter rubber hoses.
The fuel pump I got from Low Range Offroad and it is a universal one. It clearly said in the manual that the fuel pressure regulator is optional.
Ok, all that brings up one more question: How to hook up a return fuel line back to the fuel tank in the Samurai, which is not designed for a return fuel line? Anyone has done it?
Second question: How does the return line junction? Is it only a T-junction before the carb like fordem described, or must it be through a pressure regulator that has a return line in it? How difficult or easy is it?
I have a feeling my pump really didn't need a pressure regulator, but was overwhelmed with the backpressure. Just a feeling. So probably if there is a way to have a return line without buying a pressure regulator, it might solve the problem.
Last edited by alternator; 07-31-2010 at 12:21 PM.
Never seen a carbureted samurai mechanical pump that didn't have a return line off the pump. (Of course I've never seen an in-tank electric pump on a stock carbureted samurai either)
If the vehicle used to have a mechanical pump at one time or another, then you should have a line from the tank that's been blocked off. Should be 3 hard lines coming into the engine compartment: supply, return, and vent.
If the vehicle used to be Throttle body injected and had an in-tank pump then you could just run a return line.
As far as the regulator goes, if its a low pressure pump rated at under 8 psi then there isn't a need for a regulator. With no regulator in-line, you just put a "T" fitting in the fuel line between the carburetor and the fuel pump.
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