New tach jumping
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Klind
- New Member
- Posts: 1
- Joined: Sat Oct 01, 2022 9:07 pm
New tach jumping
Hey all. I am new to this forum. I have a 69' F250 with a 360. I installed an Autogage tach tonight and when I started her up the tach was jumping. I've checked my wiring and the dip switch in the gauge to ensure it is all correct. The jump will go from 0 rpm to whatever the truck is running at so at idle in park it's jumping from 0 to a little under 1k. If I rev it it will jump from that point down to 0 and back up. This is constant not intermittent. Any help would really be appreciated
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1972hiboy
- 100% FORDified!
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- Joined: Thu Sep 09, 2010 5:44 pm
- Location: California, Santa Cruz
Re: New tach jumping
Defective gauge?
Rich
1973 f350 super c/s 460/c6 22k orig miles
1972 f350 srw crewcab special 390
1972 f250 4x4 sport custom 390fe Red
1972 f250 4x4 custom 360 FE " Ranger Ric"
1972 f250 4x4 custom 84k og miles 390
1971 f250 4x4 sport custom 56k og miles. 360
1970 f250 4x4 428 fe hp60 205 d60
Dont eat yellow snow.....
1973 f350 super c/s 460/c6 22k orig miles
1972 f350 srw crewcab special 390
1972 f250 4x4 sport custom 390fe Red
1972 f250 4x4 custom 360 FE " Ranger Ric"
1972 f250 4x4 custom 84k og miles 390
1971 f250 4x4 sport custom 56k og miles. 360
1970 f250 4x4 428 fe hp60 205 d60
Dont eat yellow snow.....
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zgerbic
- New Member
- Posts: 78
- Joined: Sat Jun 27, 2020 12:37 am
Re: New tach jumping
highboy is probably right that it is a defective tach, however a little more analysis should be done to be sure.
Common problems are:
--- Bad grounds (most common problem).
Make sure the engine is grounded really well to the body through the large ground strap from the intake manifold to the firewall. Make sure there is no corrosion at either end of the strap.
Make sure the tach is well grounded to the firewall.
--- Wrong power point.
Make sure the tach power is to the switched side of the ignition. Make sure you don't connect the tach power to the instrument panel voltage regulator output (to the gauges). This power connection switches on and off at a regular interval. Connect either to the fuse panel (ignition switch controlled power) or to the ignition switch wire going to the fuse box.
--- Tach signal.
Make sure the tach is compatible with the type of ignition circuit being used. These would be a standard points ignition or an electronic ignition like a Pertronix or MSD.
Common problems are:
--- Bad grounds (most common problem).
Make sure the engine is grounded really well to the body through the large ground strap from the intake manifold to the firewall. Make sure there is no corrosion at either end of the strap.
Make sure the tach is well grounded to the firewall.
--- Wrong power point.
Make sure the tach power is to the switched side of the ignition. Make sure you don't connect the tach power to the instrument panel voltage regulator output (to the gauges). This power connection switches on and off at a regular interval. Connect either to the fuse panel (ignition switch controlled power) or to the ignition switch wire going to the fuse box.
--- Tach signal.
Make sure the tach is compatible with the type of ignition circuit being used. These would be a standard points ignition or an electronic ignition like a Pertronix or MSD.