# Hot no start problem on 86.5



## yellowrosefarm (Dec 11, 2011)

Hello, first time poster here, though I have been reading and searching this forum for a year. I've made my living as a mechanic on power equipment and tractors for 25 years so I know the basics and maybe a little more but I'm not too old to learn something new or benefit from someone elses experience. I'm really stumped on this truck, though, I have to admit. It is an 86.5 D21 Z24 4x4. It starts fine when dead cold and most of the rest of the time. Some times, say if I'm driving to work and stop for a biscuit, it will not crank back up when I come out of the store unless I wait about 10 minutes. If I was to drive it the same distance and turn it off and immediately try to restart, it will crank every time. So, it seems to be related to a hot soak condition. It has done this for the whole year I have owned it. So far I have replaced the distributor (new), along with the cap and wires, put a new wire harness for the distributor, replaced both temp sensors, replaced all vacuum lines, replaced the MAF sensor (used), and replaced the O2 sensor. When it takes a notion to not start, it whirls over fine and so far, if I wait long enough it has started back up and ran fine. It has plenty of power and is getting decent fuel mileage (around 18 in town). Once, before I replaced the distributor, it goofed up and I had some carb cleaner with me which I sprayed down the intake. It didn't start so I figured no spark and put the new distributor in. That was about 5 months ago and it never missed a beat until this morning when I ran down to the store about 6 miles away and it wouldn't re crank for 15 minutes. 
One last thing and maybe I should have put this first. It is not the original engine. The 86 should have a vacuum valve in the intake manifold and this motor has the bracket for the electric operated vacuum valve and the intake had no hole. It does now with the correct valve in it, but that took a while to figure out also. The wire harness is the 86 because it does not have the plug for the electric vacuum valve. I don't see any other differences. I have an 89 parts truck to compare with.


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## zanegrey (Dec 5, 2005)

IF YOU DID NE THING TO THAT TRUCK AND DID NOT CHECK THE CODES U JUST WASTED YOUR TIME AND MONEY..

SO NOW READ THE CODES .. IT'S A NISSAN TRUCK NOT A TRACTOR...


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## yellowrosefarm (Dec 11, 2011)

Gee, that was helpful. It isn't throwing codes. I have the Nissan service manual for the truck that I bought from a guy here so I know all about the "codes".


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## zanegrey (Dec 5, 2005)

it would have been helpful if you just told us that there were no codes..

i do not think u know all about the codes .. if you did you would have not put all those parts on there .. if the ecm does not say those parts were bad then they were not bad.. to boot you put all those parts on there and the problem still exists..

consider cleaning out the gas tank and then repace all filters including the charcaol filter at the end of the vacumn lines..

also since it is a carb reroute the choke vacumn to a manifold source...


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## smj999smj (Jan 1, 2006)

If it's an 86.5 HB, it should have throttle body fuel injection, not a carb. By the symptoms, it sounds like a bad ignition module. Classic symptoms of a bad ignition module include running fine until it heats up and then no or intermittent spark as it gets "hot." Bottom line is we need to determine if it is fuel or spark related. In order to do that, one must get the vehicle to fail before diagnosing it. There are a number of ways to test for spark; I like to use a timing light, personally. Spraying carb cleaner into the engine is a good test as long as the plugs aren't fouled at the time. Once we are sure it is a spark or fuel issue, then we can start using methods to isolate the problem. As far as codes, the systems used in these trucks were pretty crude by today's standards and have a bad part will not always cause a code to set.


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## yellowrosefarm (Dec 11, 2011)

smj999smj said:


> If it's an 86.5 HB, it should have throttle body fuel injection, not a carb. By the symptoms, it sounds like a bad ignition module. Classic symptoms of a bad ignition module include running fine until it heats up and then no or intermittent spark as it gets "hot." Bottom line is we need to determine if it is fuel or spark related. In order to do that, one must get the vehicle to fail before diagnosing it. There are a number of ways to test for spark; I like to use a timing light, personally. Spraying carb cleaner into the engine is a good test as long as the plugs aren't fouled at the time. Once we are sure it is a spark or fuel issue, then we can start using methods to isolate the problem. As far as codes, the systems used in these trucks were pretty crude by today's standards and have a bad part will not always cause a code to set.


Thank you for that excellent suggestion of using the timing light. As much as I've used one for checking timing, I didn't think of using it to check for spark. That, I can throw behind the seat for the next time it fails and be able to hook it up and see it while cranking the engine. The engine runs great and usually fires up on the 2 or 3rd revolution. If it whirls over more than that, I know I'm in "fail" mode. The fuel pump, btw, is working. I can hear it run when I turn the key on until it times out. I did put a new one in last year when I bought the truck as I've been stranded by an old electric pump in the past. Do you happen to know if the computer from the 89 will work in this 86.5 in case I get to that point?


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## yellowrosefarm (Dec 11, 2011)

So, it died at my usual convienience store today and I put the timing light on it and...... no spark..........on either coil. Cranked occasionally for about 5 minutes, no spark at all, then cranked one more time, I saw the light flash and it started up. Is there anything between the coils and the computer? Does anyone know if I can use the computer off my 89 on the 86.5?


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## zanegrey (Dec 5, 2005)

CHECK ALL FUSIBLE LINKS ..

ALSO CHECK AND CLEAN MAIN ENGINE RELAY BLOCK IN ENGINE BAY RELAY BOX..

( IF BOTH ECM'S ARE THE SAME COLOR OR COLORS AND THE PLUG INS ARE IN THE SAME CONFIGURATION.. THEN MOST LIKELY IT WILL WORK.)

BUT THIS SOUNDS LIKE A BAD FUSIBLE LINK ...


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## smj999smj (Jan 1, 2006)

The ECM's aren't swappable. The 89 has a KA24E with multiport fuel injection and a single ignition system while the 86.5 has a Z24i with throttle body injection and a dual-ignition system.


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## zanegrey (Dec 5, 2005)

THE 90'S TRUCKS HAVE THE KA24E...


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## yellowrosefarm (Dec 11, 2011)

smj999smj said:


> The ECM's aren't swappable. The 89 has a KA24E with multiport fuel injection and a single ignition system while the 86.5 has a Z24i with throttle body injection and a dual-ignition system.


Definitely a Z24 in the 89, that's the whole reason I bought it. Eventually I want to build that motor to put in the 86.5, ZG, I'm with you on the main relay. I see in the service manual wiring diagram that it is the one thing common to both coils. I'll check that out this weekend. Thanks everyone.


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## yellowrosefarm (Dec 11, 2011)

I put a new relay in and so far so good. I've been a couple of places where it would not start before and it started fine. Time will tell on this one.


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## yellowrosefarm (Dec 11, 2011)

Well, I guess it wasn't the main relay after all. I drove down to the store this morning and when I came out, it started and then cut off and would not restart. I ate my breakfast sandwich and then got out the timing light. Once the light was hooked up, it started on the first crank and ran fine the rest of the day. So, I don't know for sure that it was lack of spark this time.


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## smj999smj (Jan 1, 2006)

Still sounds like a bad ignition module...


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## zanegrey (Dec 5, 2005)

EXCEPT FOR HE HAS ALREADY REPLACED THE DIZZY AT LEAST ONCE..

CHECK , CLEAN AND OR REPLACE THE FUSIBLE LINKS...


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## smj999smj (Jan 1, 2006)

zanegrey said:


> EXCEPT FOR HE HAS ALREADY REPLACED THE DIZZY AT LEAST ONCE..
> 
> CHECK , CLEAN AND OR REPLACE THE FUSIBLE LINKS...


That's true, but he also says :"I figured no spark and put the new distributor in. That was about 5 months ago and it never missed a beat until this morning when I ran down to the store about 6 miles away and it wouldn't re crank for 15 minutes." If it's an aftermarket reman. unit, I would find it very possible that the ignition module went bad. If it was a genuine Nissan reman., I would find it less likely, but still possible. The fact that it ran for 5 months without a problem with the distributor replacement and the fact that it is failing under "hot soak" conditions and working after it cools down are all familiar symptoms for a failing ignition module. If he can confirm that there is no spark when it fails to start, that would be the first thing I'd look at.


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## yellowrosefarm (Dec 11, 2011)

smj999smj said:


> That's true, but he also says :"I figured no spark and put the new distributor in. That was about 5 months ago and it never missed a beat until this morning when I ran down to the store about 6 miles away and it wouldn't re crank for 15 minutes." If it's an aftermarket reman. unit, I would find it very possible that the ignition module went bad. If it was a genuine Nissan reman., I would find it less likely, but still possible. The fact that it ran for 5 months without a problem with the distributor replacement and the fact that it is failing under "hot soak" conditions and working after it cools down are all familiar symptoms for a failing ignition module. If he can confirm that there is no spark when it fails to start, that would be the first thing I'd look at.


It was a Beck/Arnley reman. It is possible that it has a bad module but it seems unlikely that it would exhibit exactly the same symptoms as the old one. It is the intermittancy that makes me think it is still something I haven't touched on yet. I've been to this same store 4 or 5 times since I replaced the relay and it started there, as well as, everywhere else. I don't have enough confidence in it to drive it every day so the fact I didn't have a problem for 5 months may have more to do with that than the new dist fixing the problem. I have not messed with the fusible links yet, only because I thought if they weren't passing current I would see some other function also not working. Radio, lights, heater fan, etc. However, since it did start this time when I hooked the timing light positive clip up to the connection where the battery and fusible link meet, I do think that area deserves some attention. It could have been just coincidence too since I decided to eat my biscuit hot rather than working on the truck. My bad. I can always swap the distributor from the 89 in and see what happens.


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## zanegrey (Dec 5, 2005)

the definition of crazy is doing something over and over despite its meaning or contribution..

the fusiable links heat up and stop working and you would not necessarily see it on other systems..

they are a cheap fix as well..


do not make me call you a biscuit eater...


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## yellowrosefarm (Dec 11, 2011)

zanegrey said:


> the definition of crazy is doing something over and over despite its meaning or contribution..
> 
> the fusiable links heat up and stop working and you would not necessarily see it on other systems..
> 
> ...


I hear ya, but believe me, if these biscuits weren't so dang good, I'd quit going there. :crazy:
Links are next on the list.


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## zanegrey (Dec 5, 2005)

UPDATE .......


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## yellowrosefarm (Dec 11, 2011)

I just got it back in the garage last night after I finished the other project that was in there. Way too wet to work in mother natures garage.


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## yellowrosefarm (Dec 11, 2011)

I pulled the computer out of the 89, brought it down the the garage and pulled the seat on the 86.5. Before I pulled the old computer, I flipped the switch to check for codes and surprise, I got 2, 23 and 24. Hard idle switch and clutch interlock. I didn't have time to dig into those but did throw the 89 computer in just for grins. Either it's bad or an 89 computer won't run an 86.5 truck. It turned over but would not fire up. I put the old one back in and it did start. Tonight I'll start chasing down the codes.


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## yellowrosefarm (Dec 11, 2011)

Geeze, I'm a moron. I did the whole test procedure for the idle switch only to find out it all worked as it's supposed to. Then I backed up in the manual to be reminded that those two codes are normal on startup. 24 did not go away and turn into 44, however, so I tested the neutral switch at the trans and it's bad. So, it wasn't all wasted effort. Still no insight on the hot no start problem. ZG, I'm not sure on the fusible link. There is a wire from the + bat terminal that looks like it could be a F-L but there is nothing to check. Where exactly are you talking about?


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## yellowrosefarm (Dec 11, 2011)

I got the neutral switch swapped out and got code 44 so I'm good to go there. I also got the brush guard and trailer hitch on so it was productive shop time. Tomorrow's Saturday and time for a biscuit, we'll see what happens.


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## zanegrey (Dec 5, 2005)

fusable links are on the pos bat post they are red green and black short wires with terminal ends .. they are a special wire tha burn out before they hurt more essential systems..


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## yellowrosefarm (Dec 11, 2011)

No fusible links as you describe. There are two spade connectors with a ring terminal attached that bolt onto the pos batt terminal. The other side of the spade is attached to a fat wire that looks like fusible link stock although it is not labeled as such. I cleaned and tightened all those connections and made a sucessful biscuit run this morning. Only time will tell on this one. Mileage seems a bit better at 19.5 on this mornings fill up. So, getting the coils straight may have impacted that. Next on the list is new front axles and ball joints. I'm waiting for the threat of snow to be gone before I start that.


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## zanegrey (Dec 5, 2005)

post a pic of ur bat...


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## yellowrosefarm (Dec 11, 2011)

I don't think I have enough membership to post pictures. I drove it again today with 2 more sucessful starts in places where it did not start before.


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## SPEEDO (Jun 9, 2003)

you should have 2 f-l, one has blk & grn wires(1 of ea), the other has 3 brn wires... plug in connectors at both ends, maybe 5-6" long (total legnth)
you did change the blue relay.. right (I keep a spare along with f-l in my glove box, had to use the relay once)


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## yellowrosefarm (Dec 11, 2011)

SPEEDO said:


> you should have 2 f-l, one has blk & grn wires(1 of ea), the other has 3 brn wires... plug in connectors at both ends, maybe 5-6" long (total legnth)
> you did change the blue relay.. right (I keep a spare along with f-l in my glove box, had to use the relay once)


Yes, that describes what is at the + bat terminal. I did change out the relay but it acted stupid just like before so I saved the old one for a spare. So far so good after cleaning the connections at the F_L's. I may get a chance to try out the 4x4 Sunday if we get the snow they are talking about. I bought this truck after the back winter we had in 2010 and it hasn't snowed enough to use it since. Best insurance plan I ever bought.


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## CMax03 (Jan 17, 2009)

That IMO is fuel related.....fuel pump or pressure regulator on it's way out! Check your timing to make sure it's where it should be as well....


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## yellowrosefarm (Dec 11, 2011)

So far so good. I've been everywhere it had died before and no problems. I can't get my head around why the connection at the batt post would have caused a hot no start but it hasn't done it since I cleaned that area really well. I'm giving credit to ZG for pushing me to look there. Thanks!


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## zanegrey (Dec 5, 2005)

it is the nature of the fusible links to give out if there is too much resistance (heat)..

plus i am a badd ass old man who knows alot about these trucks..

with a singular wit...


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