Datz350 Posted June 29, 2012 Share Posted June 29, 2012 Ok, there are three wires coming from the fan. Ground, power... And ignition??? Ground is mounted on the frame, I know that for sure. I can't tell the difference between the other two. One is wired to a fuse going to...a fuse block?? Not sure what it is, but it also has the third wire connected to it, the third is connected directly to the...fuse block?? Again, I don't know what it is, soory, newbie. I know that through this, "block", the fan gets its power because it has a wire going to my ignition. As soon as I turn the key to accesories the fan kicks on. When I turn the key to "on", the fuel pump kicks on... Now my problem..... The wire on the fan that is hooked, in the same spot as the one that has the fuse, gets really hot. I'm thinking that because of that, the fuel pump doesn't cut on. Why does my electric fan affect my fuel pump. Help please. Btw, car is a 71 240z. Quote Link to comment Share on other sites More sharing options...
78zstyle Posted June 29, 2012 Share Posted June 29, 2012 You said the fuel pump kicks on, then the next sentence you said it doesn't.. which is it? Quote Link to comment Share on other sites More sharing options...
Datz350 Posted June 29, 2012 Author Share Posted June 29, 2012 It doesn't right now. It would before, thats what I was saying first. At first it would kick on with the key on. It isn't doing it now. Which is why I'm asking if the fan wire getting hot is affecting my fuel pump. Sorry about the confusion. Quote Link to comment Share on other sites More sharing options...
78zstyle Posted June 29, 2012 Share Posted June 29, 2012 well those fans generally pull a lot of amps, and the relays get hot, I believe this is normal. Quote Link to comment Share on other sites More sharing options...
rsicard Posted June 29, 2012 Share Posted June 29, 2012 Caution! If relays and wiring is getting hot, the wire is not large enough for the current passing through it. Relays getting hot says they are not rated for the current passing through them. Need higher current rated relays. Quote Link to comment Share on other sites More sharing options...
Datz350 Posted June 29, 2012 Author Share Posted June 29, 2012 Forgot to mention that the fan is wired up to stay on all the time. And, should both ignition and power wires be routed to the same spot? Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 29, 2012 Share Posted June 29, 2012 (edited) There might be an inline fuse in the wire to the pump that has blown. If the wires are getting hot, then the fuses are getting hot and that's how they function, they melt to save the wires. Overall, it sounds like someone did a poor job of wiring in your fan and fuel pump. 71 didn't come with an electric pump, I believe, so yours must be a custom installation. You should probably start from scratch, using the right wire gauge, relays and fuses, before something melts and/or catches on fire. You just got the car? Some details on what you're working with would be interesting. Edited June 29, 2012 by NewZed Quote Link to comment Share on other sites More sharing options...
Datz350 Posted June 29, 2012 Author Share Posted June 29, 2012 Yes, I did just get the car. It's a 71 240z w/ chevy 305 matted to a th350. The fan has a wire hooked up to a 30a fuse which is wired to some sort of distribution block with different wire provisions. I noticed this same block has a red wire in it coming, from what I think is the ignition, which is why the fan turns on with the key. Why does my fan have three wires and why does the third wire, without the fuse getting so hot? What is the third wire for? Quote Link to comment Share on other sites More sharing options...
rsicard Posted June 29, 2012 Share Posted June 29, 2012 Likely the fan has three wires because it is a two speed fan. Remove both of the positive wires and connect only one at a time to see what happens to the fan. Cap and stow the unneeded fan wire. Quote Link to comment Share on other sites More sharing options...
Datz350 Posted June 30, 2012 Author Share Posted June 30, 2012 Well just figured out what the fan is hooked up to is a fan relay, such a newb... That same fan relay has a wire going into the cabin which is then hooked up to a fuse, looks to be air con. 20A, and another wire going to a blue w/yellow stripe, (ignition??), and then back out to a yellow w/black stripe wire, (not sure what that is). After the blue w/yellow, (ignition?), the wire has bits of it sticking out of the insulation. I'm thinking thats bad, right? Quote Link to comment Share on other sites More sharing options...
rsicard Posted July 1, 2012 Share Posted July 1, 2012 If there are strands of conductor wire sticking out of the insulation, that is a BAD thing. Insulate the bare strands of wire with GOOD electrical tape as insulation such that bare conductor strands do not come in direct contact with anything else, especially not the metal chassis of the car. Quote Link to comment Share on other sites More sharing options...
Michael Posted July 1, 2012 Share Posted July 1, 2012 The electric fan should have a heavy-gauge black wire to ground (say, 12 gauge or even 10 gauge), a heavy red wire going to a source of +12V (also probably 12 or 10 gauge), a "control" wire which goes to a switch that engages current-flow, and possibly a fourth wire connected to a water temperature gauge, which also goes to a switch of sorts. It sounds like the electric fan was miswired. Cooling fan companies such as Flex-a-lite (the brand that I happen to have, but others should be similar) should have wiring diagrams for free download. Quote Link to comment Share on other sites More sharing options...
Datz350 Posted July 1, 2012 Author Share Posted July 1, 2012 Just to recap, my problem is that the electric fuel pump isn't turning on. The reason I'm bringing up the fan is because I noticed that one of the power wires on the electric fan had been melted to the plastic wire cover. After separating it the fuel pump cut on, I was surprised. That's why I'm asking if the wiring for the fan has something to do with the fuel pump. Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 1, 2012 Share Posted July 1, 2012 You answered your own question "one of the power wires on the electric fan had been melted to the plastic wire cover. After separating it the fuel pump cut on". So, in your custom-wiring case, the answer is yes, the fan wiring has something to do with the pump. But it doesn't need to. Your wiring has all been installed by someone with their own ideas of what might be right. Melted insulation and hot wires indicate that they were wrong. The best thing to do is to tear it all out and start over, or have someone help you do the same. It's only two simple electrical devices, it's not complicated. You'll be surprised at how easy it is once you dig in to it. There's no simple one-wire solution for you. Quote Link to comment Share on other sites More sharing options...
Datz350 Posted July 1, 2012 Author Share Posted July 1, 2012 What about wiring the fuel pump to a switch? And the fan to a switch. Would that be a bad idea? Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted July 1, 2012 Share Posted July 1, 2012 Fan to a switch is a good idea, for like a track day or if you need the extra cooling power on a hot day. That's how my set up is, although originally I was planning on using the switch temporarily before I hooked up a thermotime switch. Which I never did since it works and I don't mind having to flick a switch after my car warms up. Fuel pump to a switch is a horrible idea because if you get in a worse enough accident, the fuel won't stop and if you're unconscious and it ignites...well you get the idea. Quote Link to comment Share on other sites More sharing options...
Michael Posted July 1, 2012 Share Posted July 1, 2012 Off-topic here, but it sounds like you've stumbled on a conversion-project which essentially does run, but which suffers from myriad problems, because it was done cheaply and without love. This happens often. Presently you have the fuel-pump/fan electrical problem. Once that's solved, other problems will present themselves. And so on, for several months. But on the bright side, you have a more or less functional conversion, which you probably bought for pennies on the dollar. Conceivably a not-too-distant project will be swapping the powertrain to a 350 or 383, with a T5 or similar 5-speed, or a 700R4. You already have the foundation for it, and if enough minor annoyances such as the fan/fuel-pump conspire against you, eventually you might decided to rid yourself of these problems with one concerted effort - namely, a full powertrain swap. Quote Link to comment Share on other sites More sharing options...
Miles Posted July 1, 2012 Share Posted July 1, 2012 (edited) The previous owner (PO) made a mess of the fan and, possibly, the fuel pump wiring. The wiring on my first 240Z V8 project car was so messed up by the PO that I had to completely redo the engine bay and fuel pump wiring. There was no other choice but to gut the getto wiring and start over. Recommendations: 1. Buy the Jags That Run book "Datsun Z V8 Conversion Manual" here: http://www.jagsthatr...tsun_Z_V-8.html The manual explains how to do a 240Z V8 conversion. Among many conversion topics, the JTR manual explains how to safely wire the fuel pump through an oil pressure fuel pump safety switch. Run the output from the oil pressure safety switch to the trigger contact on a Painless Fuel Pump relay kit. The kit comes with correctly sized wires and instructions. Note that the 240Z has an unused fuel pump wire (green) that you can attach the relay output to. Search HybridZ for the green fuel pump wire. Read the JTR manual at least five times. It covers about 90% of what you need to know to own a V8 Z car. Do not run your fuel pump through a switch without using an oil pressure fuel cut-off switch. Without the fuel cut-off switch imagine yourself pinned in the car and the fuel pump is still running and dumping fuel on the ground. 2. Obtain electrical schematics for your Z car such as a Haynes Manual, Factory Service manual on-line download etc. Search HybridZ and/or Google for schematics. 3. If electrical wiring is not your strong point, have someone with automotive electrical experience check out the car's wiring. You want a reliable and safe car when you are done. 4. Be sure that the fan and fuel pump are on separate fused circuits. 5. Electric fans draw high amps. Do you have the best fan and radiator combination for your application? Again, see the JTR manual. I use the JTR radiator and Flex-a Lite FXL-180 fan (built-in thermostat control) Attached is a picture of an oil pressure fuel cut-off switch. Does your car have one? Edited July 1, 2012 by Miles Quote Link to comment Share on other sites More sharing options...
Datz350 Posted July 4, 2012 Author Share Posted July 4, 2012 The beast is up and running again!!! Found out that the wire coming from the ignition to the fuel pump relay was disconnected. Who ever wired it up did it with a, (female/male?), connection which had been separated. Hooked them back up and BAM, fuel pump is running again. A concern persists though. Why does the fuel pump sound like it skips? And ever time I'm on the brakes the voltage meter on the dash drops, then rises when I release the brake. Sounds like the fuel pump loses power then gets it back. I'm bewildered, any help? Quote Link to comment Share on other sites More sharing options...
Scarab73 Posted July 5, 2012 Share Posted July 5, 2012 The beast is up and running again!!! Found out that the wire coming from the ignition to the fuel pump relay was disconnected. Who ever wired it up did it with a, (female/male?), connection which had been separated. Hooked them back up and BAM, fuel pump is running again. A concern persists though. Why does the fuel pump sound like it skips? And ever time I'm on the brakes the voltage meter on the dash drops, then rises when I release the brake. Sounds like the fuel pump loses power then gets it back. I'm bewildered, any help? Hi, Since you mentioned all of this is new to you, my advice is purchase a well defined wiring schematic and Google for how relays work and their value when working with high Amp draw components. The old Zs , "out of the gate" should have headlight relays (both low & high beams), your fan should have one, as well as, the electric fuel pump. You mentioned the fan and the fuel pump, use relays already. Re-check the wiring to each of them. You mentioned one of them is getting hot? Basically, that's what they guard against....something getting hot. The connections are simple once you understand how they work. You mention "voltage meter". Don't you mean "AMP" gauge? They are two different gauges. The early Zs had AMP gauges, which, I personally feel they are dangerous, and more so, as the car ages. I just finished a wiring "re-do" of a 73 Scarab wannabe with a 350. Installed a relay for the fuel pump and a water temp switch and relay for an electric fan. The temp switch switches the fan on at about 185 deg. The T/S opens around 160. Good Luck with your new toy. Quote Link to comment Share on other sites More sharing options...
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