No Start -'73 Vega GT V8

[ol55]

Been having intermittent no start issue. Returned battery (4/15 date), they charged and said no problem found. Voltage can be over 12v and will not start. Will start when jumped or with charger connected. Voltage drop on cable to starter less than .01. Volage drop through switch, less than .5.

Today was typical. With switch on gauge reads over 12v. When starter button is pushed, no start and voltage on meter drops to about 8.5. Ideas??







Thanks,
Larry

[Smiley]

do you have another battery you can hook up for testing ?
Usually if it drops below 9 volts from 12 when cranking I would replace the battery.
Some places that sell batteries over the counter are not good at properly testing for bad ones and don't like giving out replacements.
when did this problem start ? After you replaced the clutch ?

[EVL VEGA]

do you have another battery you can hook up for testing ?
Usually if it drops below 9 volts from 12 when cranking I would replace the battery.
Some places that sell batteries over the counter are not good at properly testing for bad ones and don't like giving out replacements.
when did this problem start ? After you replaced the clutch ?

This is true. I've had batteries that show full charge but it's only surface charge. When you apply a load they drop.
Usually good places (like Sears services centers) will put it on a heavy test cycle that will check it under various loads...sometimes takes an hour+
I've had batteries that a place like Pep Boys says are good but a real shop shows they have a bad cell.

[spencerforhire]

If that drop in voltage while trying to crank is measured at the battery with a meter, you may indeed have a bad battery. It looks like you're reading it on the gauge in the dash, so it may indicate that there's not enough current getting through the ignition switch. These cars have fusible links in the main 12 volt feed wires that connect to the battery at the large stud on the starter. Turn the ignition on inside the car and then jump the solenoid on the starter to see what happens. I guess that could be rather difficult depending upon what headers/manifolds are on the car.
edit: just re-read the whole thread; if it starts every time with a boost or charge, the battery is either bad or you have one heck of a big drain on it.

[ol55]

Update:
Added shut off switch and replaced battery. Still no go
Today I replaced the starter switch. The other one tested fine. Well it started on the first try , and the second . Not on the third try . On the third try the volt meter would not go to 12 volts like it usually does. Only 10v wih NEW battery.

Any ideas??

Thanks,
Larry

[spencerforhire]

Two starts shouldn't kill a good battery. Unless the starter is toasted as well.I suspect there might be a loose connection somewhere.

[gt350fme]

Some rambling thoughts.
How are the grounds, negative battery to frame and to engine must be good?
Starter and solinoid problem?
Loose or corroded wires somewhere?
Neutral safety switch?

[Smiley]

Old battery cables can corrode internally causing slow cranking like a bad starter.

[ol55]

Thanks for all the suggestions!

May have found the problem. This wire was attached to the "Tach" terminal of the HEI for test purposes. I think it was hitting the throttle linkage and grounding out. Has not failed to start since I removed it. Make sense?



Larry

[spencerforhire]

The tach wire is attached to the (-) side of the coil. What triggers the coil to fire is when the pulse from the module goes from (-) to open. Back in the days of breaker points, the recommended way to install a "ignition kill switch" was to install a toggle switch from the (-) side of the coil to ground. When it's connected, the coil can't build any voltage to fire.