Tach working eratic and stalling when trying to accelerate

[PEISPIDERMAN]

1980 Spider FI
Tach is jumping like crazy and stalls when trying to accelerate, all hose connections seems good (re previous forum on air intake hose loose not sure what hose exactly but everything seems tight on mine). Any suggestions please send along, first sign of good weather here and car not working, ugh!!! Started a couple of weeks ago would show signs of problem then it would be ok, now it is not coming out of problem and stalls out constantly. Will run if idling it along but that is just painful.

[So Cal Mark]

if the tach jumps at idle, it could be a faulty tach. try unplugging it at the coil and see if the running problem goes away. The problem with the intake boot on the FI model is splits or cracks in between the folds of the hose.
You could also have an ign pickup in the dist that has cracked wires. As the advance works, the pickup unit moves and makes the wires flex causing erratic ign if the wires are brittle

[baggins987]

I'm having similar issues although the car isn't stalling. Very similar to KensSpider's "Crazy Tach" post.

Just got the car back Friday from my mechanic who checked the coil, dizzy, set the points and timing (single points setup), replaced the condenser. Noticed over the weekend the crazy tach symptoms - accelerating or changing gears made the tach swing +/- 1K before settling down while cruising at a constant speed.

New symptom this AM: car wouldn't start - no starter turning, no lights. Opened the trunk and found the battery was leaking. Removed the battery and cleaned up as best I could. Jumped the car with my other ride and it started fine; kept running after I disconnected the jumper cables (a friend said if the car didn't keep running it could mean a bad voltage regltr). But I did notice that at "regular sounding" idle speed the tach was pegged out; tapping the gas made the tach come DOWN before pegging out again when I let the car return to idle.

Any ideas on what to check next?

[So Cal Mark]

I'd swap another tach in. Disconnecting the battery is a touchy way to test the alternator; the electrical surge when reconnecting can damage the alternator. Definitely don't try it on a computerized car!

[HOLLYWOODSPIDER]

Also, the wire to the tach may be stripped at some point and grounding out or shorting to another circuit in your electrical system. If it's only for a split second, it could cause a sputter and a jump or a drop in the tach reading.

I recently traced a no start/ starting and dying problem to a tach wire that was grounding out. New wire, problems are all gone.

And, if your battery was leaking, it must've heated up pretty good. Figure out what's causing that, as well. That could be scary, and may also indicate a crossed/shorted circuit.

I know you've already cleaned up the trunk, but it wouldn't hurt to make a solution of baking soda and water and spray the whole area lightly to neutralize any acid residue. Not too liberally unless you can let it dry, open, in the sun for a while... these cars don't need help to start rusting.

[PEISPIDERMAN]

Thanks for all the ideas to run with, the tach works steady at idle, it does not start jumping until the gas is pressed. Will be looking at the tach wire for sure, The tack goes to zero immediately on the stall. Mark, what item is the intake boot? is this the large hard rubber air duct form the air flow meter to the intake plennum?

Thanks for all the input will let you know... I might get a few moments at lunch to look it over.

Kent

[So Cal Mark]

the intake boot is the hose between the AFM and the throttle body, and it should be pliable. When they get hard from heat, they tend to crack since the engine moves when running. Does the engine run okay or does it surge as the tach needle fluctuates? If the engine runs normally, it's probably just a tach issue. If the engine fluctuates too, then you've got another issue

[PEISPIDERMAN]

HI Mark

I removed the tach connection and it is still happening, stalling that is as the tach is not doing anything, I will have to remove the air intake hose to investigate further. I don't think I have any spare ignition parts so I may have to order some in to test. my next item is the pick up unit. I will be checking all connections first and grounds to see if things are good there.

Still stalling.... and its sunny and hot.....perfect day for cruising...

Kent

[So Cal Mark]

you can remove the dist cap to inspect the pickup wires, and I'd also check the AFM flap to make sure it moves freely

[baggins987]

Which wire from the coil is the tach wire?

Also, where is the engine-to-frame ground wire supposed to be?
I looked around the tranny and didn't see one...

[So Cal Mark]

ground strap is on the left side of the bellhousing to the unibody

[PEISPIDERMAN]

Which wire from the coil is the tach wire?

Also, where is the engine-to-frame ground wire supposed to be?
I looked around the tranny and didn't see one...

The tach wire was on the right of the coil on mine. Closest to the front of the car, it has a connector and the tach connector is a piggy back connector to this.

Kent

[baggins987]

I've got one brown wire to the (-) terminal, one blue/black wire to the (+) terminal. Both go into a wrapped wire harness that goes thru the firewall.

?

[baggins987]

ground strap is on the left side of the bellhousing to the unibody

left = driver's side?

[PEISPIDERMAN]

Thanks for all the tips and help I finally got some time to look at the Spider and it was a snap to fix. Took off the distrubuter cap and rotor and one look at the pick up and voila there was my problem. The wires basically disintegrated when I touched them. Ordered a new pick up (should have a spare on hand) so might order another.

Happy motoring (fingers crossed) in a few days....

Thanks Everyone for your posts...


Kent