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Topic: My 620 broke down...again...questions?
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pac. coast 521
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 bullet Topic: My 620 broke down...again...questions?
    Posted: 17 October 2006 at 3:52am
OK i was driving to work today & got a few miles away & all of a sudden the truck started jerking back & forth violently like it was running out of gas [had a 1/4 tank full] & then she died & rolled to a stop. I popped the hood & noticed the fuel filter was empty & looked dirty inside. I ran into a similar problem last week & i replaced the fuel filter & it solved the problem so i suppose ill have to drop the gas tank again & clean it out. What has me concerned it that i noticed the ignition swith has been getting really warm the lasy few times i drove it & today it got so hot that the wires on the back of the switch were almost melting. When i tried to restart the truck the battery was dead too & it's a newer battery also i saw a small spark on the back of the ignition switch. Could this be a bad ignition switch or possibly a short somewhere in the harness?? If it's a bad ig. switch can i hook up one of those replacement switches? This is the 4th time it's left me stranded & it's getting old fast! Im hoping you guys can shoot some ideas my way on how to fix it...again. Thanks guys.
My 1965 L 320 {all original}

69 L 521 w/KA swap
94 Hardbody [custom]
74 620 project
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layinga521
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 bullet Posted: 17 October 2006 at 6:04am
Mark, I hooked up a universal ign switch I got from carquest. Mine shorted out on me, but it melted the plug to the switch. I'd say you're gonna need to drop the tank... again, & clean out all the sediment that Im sure is inside it. Mine did the exact same thing when I decided to just rebuild the whole engine & while it was out I ditched the stock tank & ran new lines to an electric pump & fuel cell. Good luck man, L8R.
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Ol Yeller
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 bullet Posted: 17 October 2006 at 8:25am
Mark..looks like you are gonna have to drop the tank and give it a real cleaning out...You can usually take compressed air and after disconnecting the gas lines you can blow them out..I did this when I put Ol Yeller together a couple years ago and the sediment and crud I got out of the lines was incredible..,.it'll work, I promise...as for the ignition switch..hmm never had that problem so my response would be best guess at best...I s'pose I would try replacing the switch with an aftermarketr deal...don't know much else...
2nd charter member of the United States Datsun L Motor Cult....In lightweight valve trains we trust..

Ron Kelley & "Ol Yeller" ("73 620...mildly resto'd w/many newer upgrades and 3:70s out back)
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Hainz
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 bullet Posted: 17 October 2006 at 9:48am
Hope the idle jets arnt plugg also in the carb.
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pac. coast 521
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 bullet Posted: 17 October 2006 at 9:57am
Ive already ran all new fuel line so I'll blast some air through that just to make sure thats clean. I have one of the replacement ignition switches hooked up on my 320 & it was easy because theres only 3 wires that go to that switch, the 620 has 5 wires going to it...i need to know if I can run one of those. If the carb idle jets are clogged i suppose ill have to tear it down & clean them as well.
My 1965 L 320 {all original}

69 L 521 w/KA swap
94 Hardbody [custom]
74 620 project
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icehouse
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 bullet Posted: 17 October 2006 at 10:17am
A hot ignition switch means to much amperage, is everything stock as far as electrical?
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 bullet Posted: 17 October 2006 at 10:28am
maybe run a return line that way under most driving conditions you are recirculating fuel. You'll get the whole tank of gas filtered over and over again. Although you may be replacing the fuel filter often at first it will eventually get rid of the majority of the gunk in the tank.
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BEEBANI
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 bullet Posted: 17 October 2006 at 11:18am

Do you have good grounds on everything Mark?  When I got my truck, all there was for grounds was a wire from the batt. to the motor.  Bad or loose grounds in the system can cause heat and all sorts of problems.

'76 620
'97 D21 4X4 on 33's
'05 Xterra
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pac. coast 521
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 bullet Posted: 17 October 2006 at 11:38am
Icehouse- yeah all stock & i dont even have a stereo hooked up. The only electrical part i replaced was the fuse block when the old one went bad.
Bleach- I still have a return line running along the frame that I can use but where on the carb [or where] would i run it from in the engine bay?
Beebani- I have the ground strap coming off the block & grounding to the firewall. The only wires not hooked up are the ones that go to the heater & they're tucked safely under the dash.
My 1965 L 320 {all original}

69 L 521 w/KA swap
94 Hardbody [custom]
74 620 project
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icehouse
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 bullet Posted: 17 October 2006 at 12:44pm
Maybe you could pull fuses until the switch no longer heats up, that will at least give you an idea.... If you only lived closer, I love electrical challenges. The battery being dead makes me wonder about the altornater, I don't trust the old ones. Its hard to say though.... I'm not a 620 pro yet Isn't your truck a 73?
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pac. coast 521
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 bullet Posted: 17 October 2006 at 1:43pm
Thats a good idea Jeff. The alternator was bought new less than 1 year ago & mine is a 74.
My 1965 L 320 {all original}

69 L 521 w/KA swap
94 Hardbody [custom]
74 620 project
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datsunaholic
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 bullet Posted: 17 October 2006 at 2:23pm
I've had numerous electrical issues in '73-74 620s, which have near identical systems. Typically it's some relay that got corroded and shorted, though loss of grounds has done it too.

As for the fuel issue, my '76 had that problem. It would plug up the fuel LINE with debris, and I had to blow the line out with compressed air every couple weeks. Once I hooked up the stock return lines, not only did I stop having carb overflow issues but the system flushed itself fairly quickly. Unfortunately a '74 didn't have a return line system.
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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pac. coast 521
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 bullet Posted: 21 October 2006 at 3:29am
Well with ALOT of help from M klotz via several PM's I think I have the problem figured out. Seems that when i replaced the fuse block I had 2 wires connected wrong causing the headlights to only work when the key was in the ON position which in turn was causing the ignition switch to get really hot. Today i put the gas tank back in & ran some air through the line & slapped in a new fuel filter. Ill se if it starts up tomorrow....
My 1965 L 320 {all original}

69 L 521 w/KA swap
94 Hardbody [custom]
74 620 project
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icehouse
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 bullet Posted: 22 October 2006 at 3:12pm
That's good to hear.
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steroid
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 bullet Posted: 23 October 2006 at 8:39pm
Man, Mark!!!!!!!!!!!!!!!!!! What You have gone through!!! It almost makes Me feel guilty!!!! Someday, though, You will have a show winner!!! Sorry!!! Mike
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pac. coast 521
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 bullet Posted: 26 October 2006 at 8:08pm
Ok shes back on the road & so far no more hot ignition swith issues. I did drop the tank again & slosh some gas around then dump it out..installed a new fuel filter & had to hand pump the fuel pump till it sucked the gas from the tank...& replaced 2 of the 5 connectors on the switch. It got so hot it melted the metal connectors. I also switched the Black & Black/White wires around on the fuse block. Now the lights work as they should & hell i even hooked my wipers up & they work...now ill be ready when it rains [3 days per year] Mike no worries, i still thank you for the truck to this day i get a kick out of driving it.
My 1965 L 320 {all original}

69 L 521 w/KA swap
94 Hardbody [custom]
74 620 project
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Bleach
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 bullet Posted: 27 October 2006 at 10:33am

just get a Z!

 

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pac. coast 521
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 bullet Posted: 29 October 2006 at 12:44pm
OK guess i was wrong...seems now i may have a short somewhere. I came out from work the other day & the battery needed a jump start. Ran fine going home [28 miles]...came out 4 hours after getting home & she fired up no problem...next morning dead battery...threw it on a trickle charger for 5 hours...tried to start after that & "click click" This is the 2nd battery it's gone through & im not sure whats up now. I disconnected the wiper switch, heater isnt hooked up, no radio...basically no accessories to drain the batttery. Ill check the stop light switch to see if it broke off & go over the fuse block again[its an aftermarket one]. Help!!
My 1965 L 320 {all original}

69 L 521 w/KA swap
94 Hardbody [custom]
74 620 project
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]2eDeYe
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 bullet Posted: 29 October 2006 at 2:51pm

Take off your negative cable with the ignition off and all your accessories off.
Run a test light between your negative cable and the negative post.
If it lights up you have a short.
If not it could be an intermittant voltage reg (get's my vote), bad alternator or maybe your voltage regulator connector is not connected all the way.

Did you get a new regulator when you bought the new alternator?
I was able to limp around on a bad (intermittant) regulator for a while til I converted to the Saturn alternator.
I couldn't justify the price of the 60 amp stock regulator compared to the $30 it cost at pull-a-part to convert to a 90amp internally regulated alternator and my lights never shined so bright.
Thanks Ratwagon

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BEEBANI
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 bullet Posted: 30 October 2006 at 11:08am
I agree Mark, I had a similiar problem until I put the GM alt on.  I can help you do that if that's the problem.
'76 620
'97 D21 4X4 on 33's
'05 Xterra
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