paulshockey Posted February 17, 2017 Report Share Posted February 17, 2017 Hi all! I just joined last week and have owned my 720 (with a Z24 engine) for over a month. Last weekend I put in a new battery and starter and Shazaam! - it fired right up! This morning on the way to work, I noticed that my high beams came on, then off, then on and then the truck died. I was able to get it to the shoulder (I20 rush hour traffic in Columbia SC is no joke!). I popped the hood to check my connections - positive on the battery was fine and when I went to check the negative, it sparked and was hot as all get out, burning my thumb! The junction of the negative wire to the terminal (I replaced the terminals last week) was burnt clear through. I noticed that the negative was grounded on the manifold and whew I reattached it, sparks flew and the connection at the manifold started to glow. I have been wrenching for a while (I'm 58) but am not great with electrical items! What are some of the common electrical problems of the truck that are within a gear heads grasp? Appreciate any and all suggestions. BTW, I love the truck, quite snappy with the Z24 in it! I'll post some pictures when I get my truck delivered to me. Thanks all! Quote Link to comment
datzenmike Posted February 17, 2017 Report Share Posted February 17, 2017 Takes a lot of current to make that connection glow.The strange thing is there are fuses and fusible links that are there to protect from just that thing. Check the length of the positive battery cable to the starter. If it's worn through the insulation and touching the engine or frame this would give those results. Quote Link to comment
paulshockey Posted February 17, 2017 Author Report Share Posted February 17, 2017 I will definitely check for that! Thank you. Quote Link to comment
paulshockey Posted February 17, 2017 Author Report Share Posted February 17, 2017 BTW, the prior owner removed the fusible link. One of the things on my list to replace/redo, sooner than later.... Quote Link to comment
datzenmike Posted February 17, 2017 Report Share Posted February 17, 2017 There should be 3 fusible links connected to the positive battery terminal I believe and the purpose is to protect the power wires going to the headlamps, fuse box and the ignition switch. If the ignition is off and the wire gets hot then the battery will be discharged in a short time. This needs to be fixed before the wires involved melt the insulation and touch internally. Quote Link to comment
paulshockey Posted February 17, 2017 Author Report Share Posted February 17, 2017 Thank you for the update. I have the manual at home and will put them back on. I don't know why they would have removed them, unless they were too cheap to replace them if they had blown... 1 Quote Link to comment
datzenmike Posted February 18, 2017 Report Share Posted February 18, 2017 Does this do this with the ignition OFF? There should be ZERO draw on the battery with everything off. (well maybe the clock) Otherwise every thing should be off or the battery will drain in a few hours or over night. Quote Link to comment
paulshockey Posted February 22, 2017 Author Report Share Posted February 22, 2017 So, a great ending to this story. It appears that the positive cable from the battery was shorting out. That has been fixed along with adding fusible links back into the wiring. Thank you very much for the help! Quote Link to comment
DIY 1985 Posted February 22, 2017 Report Share Posted February 22, 2017 I just discovered a bad wire on my 85. It is/was green, running from the positive terminal. It was ignition affective. Insulation was bad. I wrapped it without knowing that the copper was toast. No connectivity, I broken it. Okay, so I spliced 16 guage crimps, plus a stripped section of 16 guage (to fill space to get a tight crimp) on the prepared damaged wire that was deoxidized with scour pad. A 4" jumper was installed and the whole thing was sealed with vulcanizing electrical tape. Is the fusible link in the plastic rectangular piece along these wires, or the wire itself (like the ones sold next to the inline fuses at the automotive store)? Quote Link to comment
Lockleaf Posted February 23, 2017 Report Share Posted February 23, 2017 The wire itself is the fusible link. It is that stuff by the fuses your referred to Quote Link to comment
DIY 1985 Posted February 23, 2017 Report Share Posted February 23, 2017 Thanks. I'm in an '85 gas model. Any idea of the amperage that I should replace it with? I just read a thread, somewhere, explaining a skillful installation; not an OEM fusible link to connect. I just did plugs and wires, but I think that the fusible link was age related. I noticed a possible spark when I reconnected the battery? It ran fine for groceries, but now I'm going to undo the negative cable. Quote Link to comment
DIY 1985 Posted February 23, 2017 Report Share Posted February 23, 2017 Umm, a previous owner had wired the fuel pump by tapping into the ignition fuse on the fuse box. Where is power supplied via under the passenger seat to the fuel pump and what clues to look for to restore that circuit? The original carburetor is not fully wired or vacuum hosed in several places. Can an OEM '85 computer carburetor be plugged, or is that the job for a Weber? Quote Link to comment
datzenmike Posted February 23, 2017 Report Share Posted February 23, 2017 Replace with the special fusible link wire, NOT ordinary wire. Fusible link wires are different in that the use Hypalon (a plastic) coating that resists catching fire. You've got the right idea, just the wrong wire. Yes, you could put in fuses like most cars today but a fusible link will resist blowing for 5-10 seconds if the short condition is not too long in duration. Fuses are ok but blow almost instantly. Keep spares in glove box. Umm, a previous owner had wired the fuel pump by tapping into the ignition fuse on the fuse box. Where is power supplied via under the passenger seat to the fuel pump and what clues to look for to restore that circuit? The original carburetor is not fully wired or vacuum hosed in several places. Can an OEM '85 computer carburetor be plugged, or is that the job for a Weber? Power to the fuel pump is from the fuel pump relay above the pass side kick panel beside the glove box and just forward of the upper door hinge. It requires a charging alternator and oil pressure to keep powering the fuel pump. This is so the fuel pump will automatically shut off in case on an accident. Engine stalls....fuel pump stops pumping. Good idea if there was ever a fire. I see no problem powering it directly from the ignition.... just so you know why it's there. Here... https://axleaddict.com/auto-repair/The-Datsun-and-Nissan-Pickup-Fuel-Pump-Relay-What-the-Haynes-Automotive-Repair-Manual-Wont-Tell-You The ECC electrically controlled carburetor is problematic for sure. Probably replacing the vacuum lines to stock may fix any problems. Previous owners are idiots and remove things rather than fixing them and cause more problems. However you can get a replacement Weber 32/36 for your 720. Be sure that you identity properly what carb you have. If you have an O2 sensor in the exhaust then you have the ECC (carb) It has a slightly different mount that the other carbs used. Quote Link to comment
DIY 1985 Posted February 23, 2017 Report Share Posted February 23, 2017 Thanks for the lantern in the cave. I now have my work cut out for me. Quote Link to comment
datzenmike Posted February 23, 2017 Report Share Posted February 23, 2017 Try e-Bay for a FSM (factory service manual) for your year. It will have all the diagrams and descriptions of the carb and emissions functions and hose routing $30-$50. These are the bible of manuals and way way better that a Haynes or Chilton's. If going Weber get the Redline direct replacement one just under $300 ad has everything. Quote Link to comment
MikeRL411 Posted February 24, 2017 Report Share Posted February 24, 2017 BTW, the prior owner removed the fusible link. One of the things on my list to replace/redo, sooner than later.... BINGO on the glow! Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.