zzzzed Posted November 5, 2011 Posted November 5, 2011 Oh my lord.. are you guys coming on to me think i better be careful next time i come to vic haha Quote
Roberto Posted December 30, 2011 Author Posted December 30, 2011 Well, today i finally got to spend some time on the Z. It has been over 2 months due to other life chores.... Today i mounted a Mallory high volume, low pressure fuel pump near the fuel tank. These are supposed to be really quiet. I had to make a bracket and bolted it up to the existing holes that are there. I will use the existing wires to a relay and run a wire directly to the battery with an inline fuse for stable current since this fuel pump does not need a fuel pressure regulator (according to the manual). It is the 4070LP Comp Pump. Any suggestions on where to actually run the wire from the battery to the fuel pump?? Inside the car or underneath? Quote
benny Posted December 30, 2011 Posted December 30, 2011 Looking good... Definitely run the cables through the cabin you should be able to tuck them down through the overflow hose hole to the pump, the last thing you want is losing fuel when your going hard through some twisties!! Quote
zzzzed Posted December 30, 2011 Posted December 30, 2011 Nice work. I am currently sorting out fuel pumps my self. I must drop your screw driver back soon too. Quote
Moderators Zedman240® Posted December 30, 2011 Moderators Posted December 30, 2011 You can use the big chunky green wire that already runs to the back of the z already. It starts from behind the heater control panel and runs to the back were you have mounted the pump. You should find a 2 pin plug with a rather large (compared to the other wires there) green wire, One will be +12 and you can wire up the relay there. I've used it in my EFI setup as its running the main & lift pump. Quote
Roberto Posted December 30, 2011 Author Posted December 30, 2011 You can use the big chunky green wire that already runs to the back of the z already. It starts from behind the heater control panel and runs to the back were you have mounted the pump. You should find a 2 pin plug with a rather large (compared to the other wires there) green wire, One will be +12 and you can wire up the relay there. I've used it in my EFI setup as its running the main & lift pump. Dimitri, are you suggesting mounting the relay under the dash where the green wire originates and then using the green wire as power for the fuel pump by routing it to the battery? This would eliminate the need to run an additional wire to the tank. You are referring to the green wire in the first pic, right? Quote
RB30X Posted December 30, 2011 Posted December 30, 2011 Any reason why you put the filter on the suction side of the pump, and not the discharge? Quote
Ben Posted December 31, 2011 Posted December 31, 2011 Ideally you'd run a filter on both sides of the pump (just in case the pump loses a bit of itself one day...). I used the original green power feed on my 240Z to power my Bosch 910 (via a relay) with no issues. At one stage it was running a Carter lift pump and HP pump (model unknown). And Roberto, the rust in the front 'wings' adjacent the headlights was a big problem in my car too - much MIGging was required to rebuild the area. What were the figures for the head on the flowbench? She's looking good - keen to cop an eyeful once it's built Quote
RB30X Posted December 31, 2011 Posted December 31, 2011 Its just that a high pressure / low volume fuel pump will be no good a sucking and by introducing a filter on its suction, you create a potential for cavitation (vacuum bubbles forming) whcih destroys pump impellors. You see it quite regularly in magazines where they have a big flash surge tank set up and multiple HP pumps with a filter between the two? I would put it on the pressure side of the pump, not the vacuum. Most factory vehicles are set up this way. Quote
Moderators Zedman240® Posted December 31, 2011 Moderators Posted December 31, 2011 Correct, that first pic with the green wire runs through to behind the heater control panel. From memory, where it ends at that plug with the second green wire, that wire already has +12V (and one thing to note is the 12V to the pumps must have 12+ always even under crank as some +12 wiring shuts off while under crank so the ignition system gets full power) you just need to wire the 85 & 86 terminals of the relay. The 31 and 87 are connected to those to green wires. Quote
Roberto Posted December 31, 2011 Author Posted December 31, 2011 Any reason why you put the filter on the suction side of the pump, and not the discharge? Tim, the manual that comes with the pump suggests running the filter before the pump and also another one just before the carbs. This way debris doesn't go into the pump and cause damage to it. Correct, that first pic with the green wire runs through to behind the heater control panel. From memory, where it ends at that plug with the second green wire, that wire already has +12V (and one thing to note is the 12V to the pumps must have 12+ always even under crank as some +12 wiring shuts off while under crank so the ignition system gets full power) you just need to wire the 85 & 86 terminals of the relay. The 31 and 87 are connected to those to green wires. Thanks Dimitri. I will try and find these wires. And Roberto, the rust in the front 'wings' adjacent the headlights was a big problem in my car too - much MIGging was required to rebuild the area. What were the figures for the head on the flowbench? She's looking good - keen to cop an eyeful once it's built Thanks Ben. Luckily Captain Mick was able to come to the rescue. I have attached a pic of the head flow numbers that SW gave Peter. The numbers don't mean too much to me but I was assured by Pete they are good. Quote
Riceburner Posted December 31, 2011 Posted December 31, 2011 Numbers look good Roberto. I use a filter before the pump and near the carbs too. Does the back pressure from the filter after the pump reduce the chances of it cavitating? Quote
RB30X Posted December 31, 2011 Posted December 31, 2011 From WIKI: Cavitation is the formation and then immediate implosion of cavities in a liquid – i.e. small liquid-free zones ("bubbles") – that are the consequence of forces acting upon the liquid.[1] It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. Cavitation is a significant cause of wear in some engineering contexts. When entering high pressure areas, cavitation bubbles that implode on a metal surface cause cyclic stress. This results in surface fatigue of the metal causing a type of wear also called "cavitation". The most common examples of this kind of wear are pump impellers and bends when a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behaviour: inertial (or transient) cavitation and non-inertial cavitation. Inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Inertial cavitation occurs in nature in the strikes of mantis shrimps and pistol shrimps, as well as in the vascular tissues of plants. In man-made objects, it can occur in control valves, pumps, propellers and impellers. Non inertial cavitation is the process in which a bubble in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic field. Such cavitation is often employed in ultrasonic cleaning baths and can also be observed in pumps, propellers, etc. Since the shock waves formed by cavitation are strong enough to significantly damage moving parts, cavitation is usually an undesirable phenomenon. It is specifically avoided in the design of machines such as turbines or propellers, and eliminating cavitation is a major field in the study of fluid dynamics. I've seen the results of cavitation on large industrial scale and its not pretty. Most commonly it can be seen on boat props. Your 'in-tank' low pressure / high volume lift pump should have a screen/filter to stop debris getting into you HP pump. Quote
Roberto Posted January 5, 2012 Author Posted January 5, 2012 Correct, that first pic with the green wire runs through to behind the heater control panel. From memory, where it ends at that plug with the second green wire, that wire already has +12V (and one thing to note is the 12V to the pumps must have 12+ always even under crank as some +12 wiring shuts off while under crank so the ignition system gets full power) you just need to wire the 85 & 86 terminals of the relay. The 31 and 87 are connected to those to green wires. Dimitri, I looked and looked for the green wire behind the heater panel, but I could not find it. I did find that the green wire runs into the body wiring loom near the rear right light cover. This is where i have put the relay and it tucks in nicely into the dome of the light cover. Quote
Ben Posted January 5, 2012 Posted January 5, 2012 look up near the coloured body/dash connector block adjacent the accelerator pedal - you should find it taped up to the loom with just a little loop of wire visible. **edit** hang on a minute, I'll go & check on my car - but it's not 100% guaranteed that it's the right place, as I've re-loomed the whole thing... Well that wasn't a bad guess - the tail light harness comes up from behind the accelerator pedal and terminates under the dash in a large blue and small white connector. The pump wire is exposed at this point and is significantly larger in OD than the other wires. Quote
260DET Posted January 6, 2012 Posted January 6, 2012 Its just that a high pressure / low volume fuel pump will be no good a sucking and by introducing a filter on its suction, you create a potential for cavitation (vacuum bubbles forming) whcih destroys pump impellors. You see it quite regularly in magazines where they have a big flash surge tank set up and multiple HP pumps with a filter between the two? I would put it on the pressure side of the pump, not the vacuum. Most factory vehicles are set up this way. Agree most definately. Minimumise potential problems and you are well on the way to a successful build. Quote
Roberto Posted January 6, 2012 Author Posted January 6, 2012 I hear you guys, but the installation instructions clearly tell me to use at least a 40 micron filter between tank and pump aswell as one just before the carbs. What do I do !! Quote
peter mc Posted January 6, 2012 Posted January 6, 2012 that's the way to do it mate just a normal fuel filter before will do the job Quote
Moderators Zedman240® Posted January 6, 2012 Moderators Posted January 6, 2012 I'm sure if the filter is below the tank level, gravity will take care of the fuel; always filling the filter without the pump needing to suck the fuel through it.. Also, regarding the green wire, looking at a 240Z dash loom removed from a dash board, I found the green wires with the 2 pin plug taped to the main loom near where the fuse block and fan blower looms plug into it. Tomorrow I'll take a pic of it if you still need it. Quote
260DET Posted January 6, 2012 Posted January 6, 2012 I hear you guys, but the installation instructions clearly tell me to use at least a 40 micron filter between tank and pump aswell as one just before the carbs. What do I do !! OK let's look at this systematically. The pump manufacturer's main concern is minimumising warranty claims and problems so of course he is going to recommend using a filter before his pump, to protect it and so protect him. But your main concern is fuel flow efficiency and minimumising the chance of a lean out which may cause serious engine damage. As RB30X has shown, your pump will operate more efficiently pushing fuel through a filter rather that sucking it through. So if the filter becomes blocked to some degree fuel flow efficiency will drop more if the pump is sucking and so an engine/pump failure is more likely to happen in that situation. There is more but RB30X has pretty well covered that so the above will do. When you have a turbo engine you become very aware of potential fuel failures, I removed the internal filter from the suction side of my pickup pump and located a see through coarse filter between it and the EFI pump with the fine EFI filter after that. All I do is periodically check the see through filter. Quote
peter mc Posted January 6, 2012 Posted January 6, 2012 mmm iv changed about a thousand pumps in cars in the last 25 years and 70% we because there was no filter before the pump or the in tank gauss was riped so make shore there is a filter before mate ,there is more chance of a lean mixture from a pump failure than cav just put the filter and pump lower and let gravity help and there will be no problem Quote
260DET Posted January 7, 2012 Posted January 7, 2012 So you are saying that the pumps were blocked or buggered by junk P? If so wouldn't a pre pump filter have been blocked anyway or the pump have failed due to the reasons RB30X has given? I don't quite follow your chain of causation. Quote
peter mc Posted January 7, 2012 Posted January 7, 2012 well you do have to change the filter as u service the car ,do some maintenance and you wont have problems... Quote
Moderators Zedman240® Posted January 7, 2012 Moderators Posted January 7, 2012 Heres the pic of that wire taped to the loom. One of the wires runs through to the rear for a factory pump. Quote
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