Notapilot69 Posted July 18, 2020 Author Report Share Posted July 18, 2020 I have both coils working again and tach works. Still facing the cutout problem and it idles like crap. Reinstalling the air cleaner now to see if plugging up all vacuum leaks has any effect. 1 Quote Link to comment
Notapilot69 Posted July 18, 2020 Author Report Share Posted July 18, 2020 Vacuum diagram is a pain in the butt. I have nipples on the carb that don't appear to go to anything 1 Quote Link to comment
Notapilot69 Posted July 19, 2020 Author Report Share Posted July 19, 2020 My friends, I have made some real progress. Fixed a bunch of vacuum lines and replaced some broken ones, set timing, and now I have a truck that runs to redline?! Not sure what was going on with the coils still but I'm not out of the woods yet. I now have a very wonky idle. Runs fine at 1000 for a min, then drops to 300 or so and back oscillating, then up to 2000 for a few seconds. I know we don't have an IACV, what else could it be? 1 Quote Link to comment
Notapilot69 Posted July 19, 2020 Author Report Share Posted July 19, 2020 Every vacuum line is in its home, with the exception of one of the hardlines previously mentioned. The third one, closest to the fenderwell, has no home. I can't find anywhere in the FSM or online that points to where it belongs. Definitely vacuum advance on the trucks equipped with it. Other than that just need to figure out this surging idle issue. I'm just glad I can rev the thing up finally 1 Quote Link to comment
bottomwatcher Posted July 20, 2020 Report Share Posted July 20, 2020 Listen for a leak. You might feel silly but a hose in the ear and move it around the engine bay. Vacuum to the distributor came off one of the hard lines mounted to the front of the engine. 1 Quote Link to comment
Notapilot69 Posted July 22, 2020 Author Report Share Posted July 22, 2020 I don't have vacuum advance sir being the TBI, so I'm not sure where the heck this line is supposed to go. I'll keep digging online and under to hood to see if I can figure it out. I think you're right, it has to be a silly leak somewhere 1 Quote Link to comment
Notapilot69 Posted July 24, 2020 Author Report Share Posted July 24, 2020 Alright I have it all figured out for the most part. Timing was way off and idle cranked way up to compensate i suppose. Timing is correct and no vacuum leaks. Truck doesn't want to idle until warm where it idles perfect. Is it the wax type fast idle solenoid? Digging through the FSM now to find into. 1 Quote Link to comment
datzenmike Posted July 24, 2020 Report Share Posted July 24, 2020 Idle is probably 5 degrees like the carb Z24. 1 Quote Link to comment
TommyBsolid Posted July 29, 2020 Report Share Posted July 29, 2020 Be sure that its 5 degrees before tdc, so the mark on the crank pulley should be to the left of the 0 on the degree plate. 1 Quote Link to comment
Notapilot69 Posted July 29, 2020 Author Report Share Posted July 29, 2020 Yes sir I have timing set at 5° at idle. My problem of spark cutting out when I go full throttle has returned. No idea what it could be at this point. Both coils lose spark when I hit the gas fully, then itll backfire after it sits for a bit so I know there's fuel. Maybe the modules for the coils are acting up 1 Quote Link to comment
Notapilot69 Posted July 29, 2020 Author Report Share Posted July 29, 2020 I've also figured out my truck is supposed to have an SUV box and valve that had been removed. That's where my extra vacuum line would go 1 Quote Link to comment
TommyBsolid Posted July 29, 2020 Report Share Posted July 29, 2020 How do you know the sparks stop when you stomp on the throttle? 1 Quote Link to comment
Notapilot69 Posted July 29, 2020 Author Report Share Posted July 29, 2020 Just now, TommyBsolid said: How do you know the sparks stop when you stomp on the throttle? Timing light on wires from either coil. Both do the same thing. 1 Quote Link to comment
Crashtd420 Posted July 29, 2020 Report Share Posted July 29, 2020 Just reading what your saying makes me wonder if you have a switch on the throttle causing a short when you go full throttle? I dont have a 720 so I could be talking out of my ass right now.... I know earlier datsuns had some extra switches to deactivate a second set of of points under certain conditions.... I know you dont have points but a switch on the throttle is possible.... pretty sure my 93 pathfinder had something.... I thought it was a kickdown switch for the automatic but I'm not really sure.... 2 Quote Link to comment
Notapilot69 Posted July 29, 2020 Author Report Share Posted July 29, 2020 Could be related to the speed at which the throttle position sensor is moving. I have a replacement I'm going to throw in and see if it makes a difference. Definitely something going weird in there. 2 Quote Link to comment
datzenmike Posted July 30, 2020 Report Share Posted July 30, 2020 Keep going..... Quote Link to comment
Notapilot69 Posted July 30, 2020 Author Report Share Posted July 30, 2020 Will report back tomorrow with results. Finding the right spot for the TPS is a pain in the a**! Where the idle switch is in the right spot.. 1 Quote Link to comment
Notapilot69 Posted August 7, 2020 Author Report Share Posted August 7, 2020 Sorry for the delay fellas. Replaced TPS and checked vacuum lines again. No dice. Same problem. 1 Quote Link to comment
Notapilot69 Posted August 11, 2020 Author Report Share Posted August 11, 2020 Today I replaced both coils and fixed some wiring on the little control modules going to them. Same problem. Roll on the throttle and it goes to 5k, floor it and it cuts spark like a rev limiter 1 Quote Link to comment
datzenmike Posted August 11, 2020 Report Share Posted August 11, 2020 Run a jumper wire from a 12v source directly to the + side of the coils. Now, at least, power cannot be interrupted. 1 Quote Link to comment
Notapilot69 Posted August 12, 2020 Author Report Share Posted August 12, 2020 21 hours ago, datzenmike said: Run a jumper wire from a 12v source directly to the + side of the coils. Now, at least, power cannot be interrupted. Good idea Mike. Any idea on a good switched power source I can pull from? Also, only code I have now is 21, ignition signal 1 Quote Link to comment
Notapilot69 Posted August 12, 2020 Author Report Share Posted August 12, 2020 Fixed power to the coils. Spark still cuts out under full throttle according to my timing light. Not sure how to link a video but I took one of the timing light 1 Quote Link to comment
Notapilot69 Posted August 12, 2020 Author Report Share Posted August 12, 2020 1 Quote Link to comment
datzenmike Posted August 12, 2020 Report Share Posted August 12, 2020 Then the loss of spark is on the negative side. Is there an ignition module in the crank angle sensor??? or is it controlled by the ECU box??? 1 Quote Link to comment
Charlie69 Posted August 12, 2020 Report Share Posted August 12, 2020 Move to AZ put a Weber on it and enjoy driving your truck! Quote Link to comment
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