Cranks but won't start?

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7

73 408 Duster

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Location
San Marcos, CA
Alright folks I have had it with my 73 Duster and it's lack of ability to start, I hope you all can help me. I have searched the forum and read through every single post concerning a no start and I have triple checked the entire system with no luck, please help.

Little history: I have been building this car for about a year and half, the car was originally a slant six car and now has a bone stock 360/727. Motor is timed properly and is getting plenty of fuel. The main problem I am having is weak and intermittent spark from the coil only about 11V or so and obviouly no spark at the plugs.

New components:

Plug wires
Cap
Rotor
Plugs
ECU (5 pin)
Battery Cables
Coil
Fuel pump

Please help I want to get her running...

Brandon
 
check the wiring that plugs into the ecu to make sure it's not a four pin,and if it is a five pin as with your new module try an old module,if not that check the air gap in the distributor,check to make sure there is a ground from the engine to the body,then try the old coil.if none of that works check the fridge for more beer and check everything else =)
 
where are you measuring the 11v?
(at coil + during crank?)

hows the dual resistor condition,
and connections.

also original ign switch? do you have access to a load testing
device (vat 40 or similar) to ck volt drop during cranking?
 
My 73 has a extra little ground wire between the negative battery terminal and the radiater support. I had replaced that cable end ( terminal clamp ) with one of those poke the wires under a strap POS.
It was a poor patch job and would arch from time to time. After a long period of start, no start, flooded trying to start, I went to Advance auto and got a new ECU. Still no start. Walked away. Went back and properly repaired the negitive battery cable. Talked Advance into replacing a defetive ECU. Made sure to chassis ground it well before plugging in its connecter. No problem since. It's my theory that changes in technolgy over the years has caused many revisions inside those ECUs other than the 5th wire nolonger needed. Insufficient or intermittent ground will kill them. Good luck
 
i ve seen ballast resistor do this. i've got an extra single in the dart and a double in the duster.m2cw. air gap too. also bought new that was junk.never know. good luck man, let us know.
 
Bypass the ballast resistor. Run a wire from the battery positive terminal to the coil side of the ballast terminal. I suggest a 14 ga wire with alligator cilps at both ends. I made this and it's part of my tool box. If the car fires and runs then it's the ballast. Be aware that the motor will NOT shut off if you do this unless you disconnect the wire. And dont run it more than 1/2 hr. The ecu will get too hot and you will burn it up.

I actually have battery positive to a switch and then to coil + just in case the ballast pops on my M body. I run the FBO ign and MSD ballast and the FBO tends to run the ballast very hot. To help with poping ballasts I also spaced the ballast out from the fire wall about an inch by putting a nut on the back side of the ballast mounting bolt. This gives it a little better air circulation.

I also ran a ground wire directly from the neg battery terminal to the FBO ecu body..

I have also seen intermitant spart due to a cracked coil which had lost it's oil. Goddam accel garbage..

And yes,where are you measuring that voltage?
 
Alright guys thanks for your help thus far, I have done everything listed so far with no improvement. What I have found:

-Ecu/module and harness is a 5 pin
-Have a ground from neg. batt. to rad support
-Have a ground from firewall to intake manifold (near coil)
-I have tried both the old and new coil with the same results, 10.25 V during crank and 12.25 V with key on (measured from pos. side of coil to neg. side of batt.
-Dual ballast resistor and wiring are original but look good
-Original ign. switch
-Reluctor and pickup original

Side notes: No grounds were hooked up initially from the engine or the battery during the first attempted start, could this of screwed something up?

The neutral safety switch is currently jumpered, could this be a problem?

How do I check the ballast resistor and air gap on the distributor?

:angry7:Thanks for the help please keep chiming in with your expertise, I am freaking frusterated with this thing!!!
 
Did the car ever run when you had the 6 in it? Are you sure the engine is timed correctly for inital start up on TDC on compression stroke? Any spark at all? It sounds like it may be wiring related. Make sure the wiring to the distributor is in good shape. It could also be a pick up problem but I would definatly put a new ballest resistor on it to be sure.
 
same problem here no start with a battery under 12 volts. i got the biggest battery i could 800 cca. and still only gets spark when battery is over 12. if its high comp. motor you may need a high torque starter.
 
Check to make sure you have power going in and coming out of block on the firewall.(for ignition)I just had this problem,old wiring!
 
:cheers:Got her to start today, she sounds good. Thank you to everyone for your help. It ended up being three things a bad "new" coil, a bad ballast resistor, and a bad ignition wire.

Thanks again!
 
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