86.5 Z motor. won't start

[Drafteddesign]

My buddy bought a 86.5 Hardbody with the Z engine in it after its sat in his friends backyard for roughly 3 years. We went over today to work on it to try it get it going and it wouldn't do anything. When I turned the key,the fuel pump primed itself and the relays on the fuse panel clicked, but that was it. The starter wouldn't do anything, headlights won't turn on, the interior light won't come on, no dash lights, but the wipers will work. Someone had tried swapping the computers under the seat before, but the comps had different numbers on top of them. The stock computer was numbered 40, but the one the previous guy had swapped into it was numbered 14.Are these numbers important or are they all the same? The 14 computer wouldn't even let the fuel pump prime itself and the leds inside it wouldn't light up. After removing it and hooking up the original 40 computer, the led's lit up and the fuel pump started working. On the passenger side fender well, there is a bank of relays with two called fuel pump relay and the other called main relay. We swapped those two relays to see if the main relay was the issue, but nothing changed. The fuel pump still primed itself, but the starter didn't engage , the solenoid didn't click, lights wouldn't work, etc etc etc. We checked all of the fuses in the fuse panel and they were all good.

Does this sound like something that any of you have run into? Any help you guys can give on this would be greatly appreciated

[Rev_D21]

Are all the fuses good? While you are in there check to make sure the fusible links haven't melted. There could be so much green on the main cable that the truck isn't getting enough power to do anything. Why was the computer changed the first time? 40 and 14 will be different. You might be chasing an electrical gremlin at this point. Don't change too much stuff without testing and condemning it first. I don't have an 86.5 manual in my collection yet to help guide you.

[Drafteddesign]

The truck was originally parked in the yard bc they said it seem as though the injector in the throttle body was constantly spraying, rather than pulsing with the cycles of the piston and timing. They changed the throttle body, which did nothing. Then they changed the injector(all of this is hear-say from the previous owner, none of this is first person knowledge). Neither of these things worked, so they assumed the ecu was bad. Someone went to a junkyard and picked up the different ecu. This still didn't fix the issue so they just shut the hood and walked away from it. 3 yrs later, my buddy is looking for a project truck and voila! he has this thing on his hands.

I looked at the wiring coming away from the positive side terminal and never could find anything that looked like a fusible link. That was my first hunch, too. How far down that length of wiring is the fusible link? If it is the fusible link,can he pick one of these up at a parts store or is a dealer type part?

Thanks for the help, Rev.

[Saudade]

Given how long it sat, you could have some major corrosion inside a wire bundle, or rodents gnawing through wires to gather nesting material. Have you had a good look under the dash to see if there's any carnage in any of the wiring?

[Drafteddesign]

underneath the dash, the truck looks like it has never left the showroom. There was no dust on the wires, etc. I was shocked at how clean and mint the interior is. The problem most likely lies in the engine bay of the truck. He is going to have it towed to his house this week hopefully, so we can look at it more thoroughly and test the electrical system.

[Drafteddesign]

This black plug here in these two pics looks as though it should plug into something under his dash, however, nothing is there to match this. The only thing that even comes to mind that this MIGHT be is an OBDI connector, but I don't know if that was even around in '86. Could this be an issue? He hit it with a test light, but couldn't find any power on any of these wires, but then again, we don't know whether it SHOULD have power to begin with. Does anyone recognize this plug? It wasn't attached to anything, it just hung under the dash. (The fuse panel is hanging bc we unbolted it so we could check the back of it for loose or disconnected wires.)

[longtooth]

That plug in your hand looks like the diagnostic connector. This era was pre odb 1 The baud rate is super slow so if you find a scan tool it will take it awhile to pull a code.

My old shop had the snap on modis and it acutally had a connector for my 89 D21. It seemed forever to pull codes by todays standards.

[Drafteddesign]

I found one problem on this. Sorry, i forgot to update... just behind the battery, there are two small plastic connectors on the wiring harness. I wiggled one of them and the engine turned over when my buddy hit the key. We found what we assume to be dielectric grease packed inside of it. cleaned all of that crap out, and now the engine turns over fine. It still won't run, tho. It's as though the injectors aren't being told to spray. It has fuel to the TB and it has fire, so thats the only thing we can think of.

Nothing else in the truck still works, though. He checked all circuits at the fuse box with a test light and each of them has current coming to them, so I'm guessing there's a major ground that's out of place somewhere. Again, when i say nothing, I mean NOTHING but the fuel pump, the wipers, and the starter. No headlights, no dome light, no horn, no tailllights... Does this make sense?

[DAN 1]

Howdy "Nissaners". I have a 1986 Nissan pickup with the 4 cylinder engine that has two spark plugs per cylinder and fuel injection. I thought this looked like a good appropriate string of higher mechanical intelligence than mine, so I enter it to see if someone can help me with my problem.

I really like my little Nissan pickup, but it has been doing something aggravating for the last couple of years, (during cool weather only). It has been cutting out when I press the throttle more than halfway down. This causes my rig to "bog or choke out"...until I lift my foot to above the half throttle mark. When entering the freeway from a side street or feeder, this can get to be kind of scary, because of the lessened ability to quickly accelerate to safe freeway speed. I can get to this desired speed, but it takes longer than it should at about half throttle.

Have any of you encountered this malfunction before? What does it take to fix it?

By the way. That is a good lookin Teal Nissan in the pictures.

[Drafteddesign]

I don't know honestly. I've got the Ka24e engine in mine. I've never worked on another truck with the Z engine other than the one that this thread is about and obviously, its not running so its of no use to me either. If I had to venture a guess, I'd say check your plugs for fouling and also if you have access to a timing light, check your engine timing. Your Throttle Position Sensor could cause this as well, but again, TAKE THESE WITH A GRAIN OF SALT, I'M NOT POSITIVE.

Not trying to be rude, so please don't take it that way, but if you have any questions you'd like to ask, on the forum page(the page you were on when you clicked into this one) there's a button towards the top of the page on the left hand side just above all of the threads that says "NEW TOPIC". You can start your own thread which would make it easier for you to keep track of the information coming and going on your topic. I'm not mad at the thread jacking, just keep it mind for your next question. Good luck with your truck and I hope you get it fixed!

[DAN 1]

Thanks "Drafteddesign". Your tips, especially about the "Throttle Position Sensor" looks hopeful.

I'll follow your advice and open up my own string about this. Have a great day.

[Drafteddesign]

You're welcome. I have got alot of help from guys on forums like this one and I return the favor whenever possible.

[liljax10]

draft design have you had any luck yet at getting this truck to start? if this post was older i would have thought i got the truck next as im dealing with the same exact thing even went as far to put a new timming set in mine also. just curious if it was running since im hitting my head on the wall with mine at this time and open to fresh ideas