914 tachometer acting funny Options

[recko911]

What would be the cause for the tachometer needle to move irregular. It's starts off normal but as I get to the end of the gear it jumps irradically. Then returns to normal. It also feels as if the engine will shut off but it doesn't. Advice would be appreciated.

[Cap'n Krusty]

The FIRST step in tach diagnosis in a stock 914 is to check the dwell and set it to specs as necessary.

The Cap'n

[Tom]

If it has been a while since the last tune-up, replace the points and set dwell, then check timing. Use only the Bosch points.
Tom

[realred914]

(IMG:style_emoticons/default/smash.gif) tach get signal from tjhe spark coil. low coil voltage (measure it when running, should be close to battery voltage) can cause proeblms as can bad points. if your still running points I suggest you invest ina Pertronix or simular electric ignition so you r dwell and timing issues will be a thing of the past, you will get better spark timing with electronic ignition plus higher energy sparks as the dwell is maximized for the best spark).

so look for defiencies in the ignition system coil voltage and condition of points (best to replace with Pertronix type device) also check for loose wire and such too. if you have low voltage at the coil you will find better sparks if you can get teh voltage back up to near battery voltage. on one non-914 car i added a relay to give the coil a direct path to the power source rather than the long route (and voltage drop) via the key switch.

have fun (IMG:style_emoticons/default/chowtime.gif) (IMG:style_emoticons/default/driving-girl.gif) (IMG:style_emoticons/default/driving.gif)

[recko911]

I have electronic ignition on there now. But it's about 3 years old and I just replaced the coil. I have also noticed that When I arrived to work today I turned my car off and then. Tried to turn it back on and nothing not even an engine crank or the starter as if it were dead . Ignition light on like normal but no engine response. I just went out there and car started fine

[ConeDodger]

The Cap'n is right on. The needle jumps because of something in your points, condenser, or coil is causing a little electrical storm. Time to sort that out.

[realred914]

I have electronic ignition on there now. But it's about 3 years old and I just replaced the coil. I have also noticed that When I arrived to work today I turned my car off and then. Tried to turn it back on and nothing not even an engine crank or the starter as if it were dead . Ignition light on like normal but no engine response. I just went out there and car started fine

intermittant probelm? maybe your key switch is dieing? these switches do die, that can cuase low voltage back at the coil and probelms with not cranking over.

, get a volt reading on the coil, with ignition on, measure from the positive terminal (power from ignition switch) top ground, it should be close to battery voltage then try it with the engine running ansd confirm teh voltage does nto drop to much if the voltage is low, than can point towards teh key switch or the associated connections or even a bad engine ground strap!

also be sure the coil is hooked up right make sure teh positve marked terminal is indded conected to the ignition power and that the wire from the negitive terminal is indeed going to the distribuator. the coil is polarity sensitive (you will get a hotter sprak when hooked up right, poor sprak when hooked up reveresed.

so let us know how your voltage readings are?

good luck (IMG:style_emoticons/default/confused24.gif) (IMG:style_emoticons/default/confused24.gif) (IMG:style_emoticons/default/chowtime.gif) (IMG:style_emoticons/default/flag.gif) (IMG:style_emoticons/default/first.gif) (IMG:style_emoticons/default/santa_smiley.gif) (IMG:style_emoticons/default/cheer.gif) (IMG:style_emoticons/default/aktion035.gif) (IMG:style_emoticons/default/lol-2.gif)

[mburkhart]

I had an issue last year where a corroded fuse (on the panel below the steering wheel) was causing the tach to cut out and then on again. Cleaning the fuse fixed it.

[recko911]

The FIRST step in tach diagnosis in a stock 914 is to check the dwell and set it to specs as necessary.

The Cap'n

How doi check dwell. I'm not too familiar

[recko911]

Hopefully I make it home with this rain.

I also just found that on the distributor only two have a spark at the cap. Does that mean I need a valve adjustment

[Cap'n Krusty]

The FIRST step in tach diagnosis in a stock 914 is to check the dwell and set it to specs as necessary.

The Cap'n

How doi check dwell. I'm not too familiar

You don't check or set the dwell with electronic ignition.

The Cap'n

[realred914]

Hopefully I make it home with this rain.

I also just found that on the distributor only two have a spark at the cap. Does that mean I need a valve adjustment

at teh cap only two of the four throw a spark??? uhm, how are you testing it? if your holding the spark wire just above the cap looking for a spark, you have to be sure the wire you are using is grounded and in good condition.

also never ever ever run a pertronix equiped motor with no spark plug wires attahed, you always MUST have at least one spark plug attached, or have the center terminal on the coil grounded with a jumper. if you crank the motor with no spark plugs attached to the distributor, the spark will have no place to go, the charge will continue to build until it frys the pertronix, do not even crank a motor with out the coil having a path to ground else it is bye bye pertronix.

now that is nto your problem, for if the pertronix failed, you'd get no spark. so double check you test wire you use to see spark jump if you still have no spark on two terbminals I'd suspect bad cap or you wires you use to test are bad.

try this test, take spare spark plug, and ground it to the engine (a jumper wire hosed clamped to the spark plug threads on one end,a dn grounded to the engine case on the other works nice. then crank the motor, and confirm spark or not. do this for each of the four spark plug wires.


the valve adjustment would nto effect the spark, so lets not mess with the valves yet.

you have no dwell adjustment to worry about with electronic points, however you still need to set iming, BUT the timing will not effect te lack of spark you now have.

likely bad spark plug wire, or cap.


you can also ohm out the spark plug3wires, make sure the "good" ones read simular resistance to teh two "bad ones" also check the center coil wire the same way, the longer wires will generally have a hgiher resistance. be sure to wiggle the ends to make sure any breaks in the wires are not intermittant.

good lucky

[iamchappy]

I've had a bad alternator or regulator make the tach1 act funny.

[recko911]

Driving home I continued to have issues. Car almost stalled a couple of times especially when I would reach 3000 rpm the needle would jump and car would stall. I will trouble shoot the issue.

When I check for spark I remove spark plug wire from cap and check for spark. 2 of the wires I remove don't cause spark. So I have a few issues to deal with