Stewart

Hey guys, thanks for sticking with me! I think I am slightly closer to solving this puzzle. 1. I traced that relay near the front passenger side fender and it connects to both the neutral switch on the transmission and the clutch pedal switch. Both switches can be heard activating the relay. The relay is the same blue on as my heater relay by the fuses so I switched them to check and it seems to be fine. My Chilton manual in the wiring diagram for z24 1981-84 shows both switches going to an "inhibitor relay" on both MT and AT. It clearly labels an "inhibitor switch" as AT only and the clutch and neutral switches as MT only but the relay is shown for both. I don't have an idle cut solenoid (deleted with weber install by PO and running fine for several years). 2. I found this: https://www.justanswer.com/nissan/13dpw-not-spark-exhaust-coil-z24-dual-co.html https://www.justanswer.com/nissan/13dpw-not-spark-exhaust-coil-z24-dual-co.html Which seems to show the clutch and the neutral switch being involved in switching from 8 to 4 plug mode. 3. I am only getting spark on the exhaust side plugs. 4. Thus I think the problem is my intake plugs are not firing. The exhaust side plugs are being switched off, by design, to go in to 4 plug mode but since the intake plugs aren't firing this kills the engine! Does that make sense to anyone else? I know that doesn't seem to sync with your FSM and stuff but it seems to fit this other info and symptoms (truck is 1/84 and there were some mid 84 changes I believe). So now I just need to figure out why I quit getting spark on the ignition side a week ago.

I should have mentioned earlier, this has a Weber carb on it, electric choke but I don’t think it has an idle cut solenoid. The clutch pedal switch isn’t just cutting the idle fuel, it kills the engine even with throttle applied. So I must have an electrical fault in there somewhere since it just started doing that. Any pointers for diagnosing the distributor? I’ve never dealt with that before. I have power to both coils but still no spark at the plugs on the ignition side. Switching the coils wires on the distributor makes the ignition side fire but not exhaust. And no, it’s always been a manual 5 speed. I think manufactured 1/84 as a dlx cab and chassis 2wd.

Thanks Mike, I think I’m making progress but really haven’t dealt with ignition stuff much. The fuse is good, but I swapped it with the horn fuse anyways. I switch coil wires on the distributor and got spark on the ignition side and not exhaust. I checked both could for continuity to ground and they are both getting 13+ volts when the engine is running. Both coils are also sending voltage to the distributor (measured voltage at the end of the cable on the ignition side coil and the engine was running off the exhaust side). So now I’m confused why I got spark on the ignition side when I swapped coil wires but both coils seems to be functioning? Distributor problem? And I still haven’t figured out why my pedal switch is triggering the fuel relay. Thanks for your continued help!

Thank Mike, it looks like I only have spark on the plugs on the exhaust side. But doesn’t the intake side only fire at certain rpms or throttle levels? Not sure the best way to check that? Or would it have spark when cranking? I do have a relay of some sort that is connected to the clutch pedal switch, I can hear it clicking when that switch is operated with the key turned to start and when the engine is running and it clicks the engine dies. It’s blue in a clear plastic cover next to the battery. It’s not the fuel pump, I can hear that separately. https://photos.app.goo.gl/TAafADstjRxnqE8BA https://photos.app.goo.gl/ohcRc4W2Uk9eG8Uj6

Thanks for the suggestions, I have narrowed it down a little. The switch leads to the inhibitor relay mounted on the front right fender near the battery. I can hear it click when the pedal switch is pressed. I don’t see any damaged wiring anywhere down there but can anyone tell me how this circuit is supposed to work? My wiring diagram isn’t great on this. I thought that it would cut the ground to the starter when the pedal was up and in gear but the starter still cranks when the switch is pressed so I think it ties in to the coil? What I’m not sure is how it normally works so it stops the engine from starting but doesn’t kill a running engine? Any thoughts to help me trace this. I know I can bypass but I’d rather figure out what happened and do it right. Also not sure if this is related to a poor cold idle that started at the same time.

With the transmission in neutral if the switch is pressed it kills the engine. If the transmission is in gear when the switch is pressed it tries to kill the engine but momentum tries to keep it going resulting in a bucking ride. I know that’s not how it’s supposed to work. I tied giving it gas (in neutral) when I hit the switch (now hanging next to the clutch pedal) and it cuts out immediately still. Could it be the fuel cut off circuit somehow?

So I tried to clean up after an oil filter leak and probably either got oil or water somewhere I shouldn’t have. I was going down the highway after ~20 miles or so and suddenly engine dies. I figured out it would start and run fine but die when I took my foot off the clutch. It’s the neutral safety switch. I pulled it out of the bracket so the clutch pedal wouldn’t press it when the pedal is released and no more issue. But isn’t this tied to the starter relay ground? Why would pressing it cause the running engine to die? And that will probably tell me what I need to pull an clean better. Thanks!

Time to replace my 10 yr old tires on my 84 720 Sunrader Camper. Right now I have some Yokohama Y356s 195/75R14s on it front and rear. Can I fit 205/75R14 on it without danger of the duallys rubbing in the rear (Hankook RA18)? Everything else is pretty stock clearance wise (added leaves on the springs to account for sag a few years ago but no lift). Speedometer currently reads a little fast and I wouldn’t mind the extra ~0.7” clearance if I can get it with minimal other handling effects. Thanks!

Cool, thanks for that, you guys are awesome! I'll see what I can find locally now that I can broaden the search.

What has the problem been? It seems difficult to find a used one that isn’t cracked or warped nowadays.

Thanks! It looks like ATP and Dorman both have different part numbers listed for 85-89. The one for 81-89 or 81-85 is discontinued hence my question. It doesn’t seem like it should be different.

I’m trying to replace mine due to a crack and a huge leak where the pipe attaches. I can’t seem to find one anywhere for an 1/1884 720 but there do seem to be some aftermarket for the 85-89 pickup 2WD. The pics looks the same but it’s the internet and all. Or should i just get an eBay header and call it good (the rest of my exhaust was replaced a year and a half ago so won’t get any power benefit and would prefer to not make things any louder)?

I started a new topic in case anyone is still interested. ?

I moved this to a new thread in case it’s useful to someone. Here is the old one for background. Thanks to everyone who has been helping my meager mind grasp the mechanics involved! I ended up taking it back to my mechanic to look at again. He played with the valve lash as well and it didn’t change much so he did a compression test and got 125 psi on #4 and 175 on 1-3. This is after a new head gasket and all the other associated gaskets. He reminded me he had observed a small sliver of material missing from the top of #4 piston (missing from the edge on the exhaust side). He thinks that is what is causing the noise (probably made noticeable after the cylinder hone on the head, which probably wasn’t really neccesary), there is just enough clearance for it to rattle a bit now. That and the lower compression there is what is causing the spark plug to be a bit dirtier than the others. So barring an engine rebuild that I don’t really have the funds/skills for, how long can I run it? It drives just fine other than the clicking noise. It’s a camper though and we like to get off the main road and don’t want to break down unexpectedly. I don’t think it’d throw a rod or something though, it’d probably get worse slowly over time right? Probably just start fouling that plug?

I decided to pull a couple plugs just to look and the plug (new NGKs about 300 miles ago when the head gasket was done) for the exhaust side of #4 (where it seems noisier) was noticeably sootier and smelled like gas while the plug from Exhaust #1 looked just right. So that means I have incomplete combustion in that cylinder? https://photos.app.goo.gl/4hV2ggVNsQrdBCrQA https://photos.app.goo.gl/4hV2ggVNsQrdBCrQA