SlammedhappySteveO Posted January 2, 2013 Report Share Posted January 2, 2013 Soo picked up another 85 nissan 720.... Been sitting for a minute, threw a battery in it and some gas an had it running in 20 min. Running beautiful.... All oem untouched or modified.... Sooo been driving it for a few days now n then las night it shut down on me completely with no warning... Few pumps of the pedal and cranks of the ignition and she fired up, but seemed to stumble a lil bit when driving home... Next day I get up fire it up and had it warm up for 10 - 15 min, I go to pull out and she dies... So I start to run throught it fuel-good, battery good, terminals-good . Ive got 12 volts goin into each coil... Nothin comin out, of either.... No spark! What are the chances of both coils takin a dirt nap at the same time? Am I missing anything? Also, I checked the ignition relay on the passenger side fender well and its good ... Any ideas? Im also looking for a new windshield seal... Anyone know where to find one for an 85 720 king cab? Lastly, dunmo ifn I jus tarded or what buuut I cant seem to be able to post any pics on ratsun, I know I have before, did something change or can I just not do it for mobile? Thanks in advance! Happy New Year to all! Quote Link to comment
ggzilla Posted January 2, 2013 Report Share Posted January 2, 2013 Yes, something changed. Ratsun broke the photo stuff on Dec 14. It will still work if you do it a certain way. See http://community.ratsun.net/topic/691-how-to-post-pictures-and-keep-online-photo-albums/?do=findComment&comment=817027 > No spark! What are the chances of both coils takin a dirt nap at the same time? Almost zero. You are missing something. How are you testing for spark? 1 Quote Link to comment
datzenmike Posted January 2, 2013 Report Share Posted January 2, 2013 Pull the coil wire off the cap and stick an old plug in it and lay on a grounded surface. Have someone crank the motor and watch for spark. Now try the other. There is no ignition relay on the 720. Power goes to the ignition switch and from there directly to the intake side coil when in the ON position. The exhaust coil is powered through a fuse powered from the ignition switch in the ON position. I'm doubtful it's electric. More likely a fuel delivery problem. Quote Link to comment
ggzilla Posted January 2, 2013 Report Share Posted January 2, 2013 > stick an old plug in it and lay on a grounded surface Good idea. Some guys try to check for spark at the coil center terminal, and that is not a good test. Quote Link to comment
datzenmike Posted January 2, 2013 Report Share Posted January 2, 2013 I don't have the correct year FSM, I have an '84. It shows a small black terminal box, usually mounted to the top of the rad in front of the dizzy area. Three wires go in and the wires going out go to the distributor. Brown, Red and White/Blue stripe.Two wires go to the negative terminals of the two coils. The BROWN one should read 12 volts when the ignition switch is turned to ON. This is the power to the ignition module. The '85 may be the same. Quote Link to comment
SlammedhappySteveO Posted January 2, 2013 Author Report Share Posted January 2, 2013 @ ggzilla, pulled plug wires one by one n did the screwdriver test for spark jump n has nada sooo I pulled each coil wire n did the same thing n got nadA... Most my tools are at work so ima follow up on it when I get off and ill try the test with a spark plug and see if that makes a difference... I dont think its a fuel delivery problem, im getting fuel, and it ran flawlessly for the last 120 miles since I got it runnin... All the fuses have been pulled, checked cleaned and repaced... @ Datzenmike , I thought that was the case too reguarding the ignition relay but some guy from another forum said thats what the blue relay by the battery is for, he replaced his n it worked for him! So I checked it none the less And ya shoot, I did run it outa gas the other day... Damn sending unit shows half tank all the time :-( Sooo I recon I better snag a fuel filter and replace that... Quote Link to comment
datzenmike Posted January 2, 2013 Report Share Posted January 2, 2013 Not remembering a blue or any other color relay near the battery. Relay look like this one... Quote Link to comment
SlammedhappySteveO Posted January 2, 2013 Author Report Share Posted January 2, 2013 Yuuuup! Its dark out now buut yes sir... 2 on the fenderwell just above the battery, both my 84 and my 85 have em... Course I dont have my manuals so I dunno what they truly go to... I do believe itll b something stupid, and comon as it usually proves itself to b! Quote Link to comment
ggzilla Posted January 2, 2013 Report Share Posted January 2, 2013 Fuel pump relay. Quote Link to comment
datzenmike Posted January 2, 2013 Report Share Posted January 2, 2013 That should be under dash between glove box and kick pad. Quote Link to comment
SlammedhappySteveO Posted January 2, 2013 Author Report Share Posted January 2, 2013 Soo the blue relay by the battery is the fuel pump relay? Ima have to grab my book! N whada u guys think of the inline spark testor? Ive got one of those, or should I just rock a plug n grounding surface... I get off in an hour n hope to be home before its dark so I can see whats good! Or bad! Appreciate both your guys input! now back to work! Quote Link to comment
ggzilla Posted January 2, 2013 Report Share Posted January 2, 2013 I have used a spark plug set on bare metal for 30+ years. Works for me. Quote Link to comment
datsunaholic Posted January 2, 2013 Report Share Posted January 2, 2013 Truck have a tach? Quick way to know if the ignition module went bad is that when you crank it, the tach won't move at all. Though sometimes it's cranking too slow (plus the heavy battery load) it won't show either, but on mine the tach needle moves when cranking IF the ignition module is working. Quote Link to comment
datzenmike Posted January 2, 2013 Report Share Posted January 2, 2013 Soo the blue relay by the battery is the fuel pump relay? Fuel pump relay? That should be under dash between glove box and kick pad. The relays by the battery are, ( from front to back.... ) Fuel cut relay (manual trans non California trucks) ECC relay (California models only) two prong plug for the tach dropping resistor (if applicable) ASCD inhibit relay (only if you have cruise control) ASCD relay (for cuuise control and auto trans) The fuel pump relay as mentioned is under the dash just above the side kick pad. Looks like this... Quote Link to comment
SlammedhappySteveO Posted January 3, 2013 Author Report Share Posted January 3, 2013 Ok sooo grabbed what col daylight was left... Still no spark from either coil... N not a factory tach truck soo insure of ignition module... This truck is definately set up different than my 84... The wires from the coils go into a 2 piece factory harness, unlike the 84 where they go into that distribution block that seperates the wires. With my trusty fluke and with the key on I have 12 volts at each positive terminal of each coil.... I did pop the cap n check the wiring to the ignition module and does not appear frayed broken or derelict... So im assuming at this point its down to brass tacks n basics.... Complete tune-up this weekend and fresh fuel and uninterupted project time! :-) that b what im after... Always amazes me how perfect it could run one day and not run at all the next.... :-( I have faith! I shall overcome n make er road worthy! Quote Link to comment
ssnapz Posted January 3, 2013 Report Share Posted January 3, 2013 probably not the case, but did you check to see if the rotor turns while cranking. not common but possible. you can test the coils by tapping aground wire to the neg side with the key on. it will spark if good. Quote Link to comment
thestrange Posted January 5, 2013 Report Share Posted January 5, 2013 i went through the same damn thing with my z22 720. it came down to rust! i pulled the cap and rotor, and the rest of all the bits off the dizzy. then sanded the rust off the shaft, no problems since. i thought for sure the icm went bad, but it was tested 3 times. Quote Link to comment
SlammedhappySteveO Posted January 6, 2013 Author Report Share Posted January 6, 2013 Ooookay.... So, yep yep the dizzy spins.... And both coils check out, fuel filters clean n replaced... I bumped it ok nce this a.m. and it started ran for a minute n died... Pulled the plugs, all look good, wires good fuel to carb good.... Sooo I guess now im down to the dizzy? @ thestrange, what am I looking for exactly? Or should it be self evident? I know rust and ground problems were abundant with these.... I will say I did find the dizzy ground to be nonexistant, jus floatin in the air unattached.... Any suggestions on how to test the ognition module in the dizzy? And should I worry bout the ecm under the drivers seat for anything? Trying to cover all my bases :-) .... Thanks to each and everyone of you guys for your input n help! Very much appreciated... Quote Link to comment
datzenmike Posted January 6, 2013 Report Share Posted January 6, 2013 The grounding of the dizzy is paramount. There is a power wire TO it but ground return is assumed through the mounting bolts and dizzy shaft. Make sure it is bolted down securely. Run your own dedicated ground wire to it from a valve cover bolt or something. Quote Link to comment
SlammedhappySteveO Posted January 6, 2013 Author Report Share Posted January 6, 2013 Have no idea how long the ground was disconnected, but that wouldnt stop it from starting would it? Anyone think theres any chance I fried my ignition module? Quote Link to comment
ggzilla Posted January 6, 2013 Report Share Posted January 6, 2013 Very unlikely to fry the module. It almost never happens. Yes, a ground problem can stop it from starting. It only takes 5 minutes to bolt the distributor housing bare metal to bare metal of the engine block or timing cover. Do it. Quote Link to comment
SlammedhappySteveO Posted January 6, 2013 Author Report Share Posted January 6, 2013 Ditributor housing clean and has full surface contact... Ground has been repaired, replaced, re established.... Guess its time to pull the dizzy n dis assemble and look for rust or corrosion Quote Link to comment
ggzilla Posted January 6, 2013 Report Share Posted January 6, 2013 Don't bother with that. Just pull the rotor off and if it is coated with rust, clean it up. Also inspect the wire connections inside the distributor. Quote Link to comment
SlammedhappySteveO Posted January 6, 2013 Author Report Share Posted January 6, 2013 I doo see soe surface rust on the shaft but cant seem to pull that 4 point star off above the ign. Module so I can remove it and clean it..... Is there a set screw or something im missing to remove it? Quote Link to comment
ggzilla Posted January 6, 2013 Report Share Posted January 6, 2013 I would not disassemble the distributor! Yes, there is a set screw. Don't remove the module, just pull each wire off one at a time and see if the terminals are clean. Quote Link to comment
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