All tachcometers dead

[whoover]

Hello, all four of my tachs on my 1973 convertible have stopped. I have Cummins 903 naturals with electric tachs. I'm going to start checking connections this weekend beginning at the instruments themselves. Any thoughts or help would be great, I am expecting to have to buy at least two new ones for the fly bridge.

Thanks
Walt Hoover

[bigbill]

both engines? it has to be something in common with both engines, i would start with ground wires/connections

[Tim Powell]

both engines? it has to be something in common with both engines, i would start with ground wires/connections

the row of slow blow fushes that are lockated behind the panel where the power is turned off and own. I may be incorrect but it seems some of
those fushes read tacks. In my 52c under the bridge are circuit brakers that control some juice to the gages. Another thought if you have a glendenning is it working is power to it there are sending units attached that are electral.
I went back and read your post again. You were saying you may have to purchase two new tacks. If they are the big black ones (VDO) Jarret Bay surplus has 4 of them they are 12 volt if they had been 24 i would have purchased them.
.

[scottinsydney]

The tacos should all share a common earth and positive + on each panel. Check power is received at first tach which probably daisy chains to the second tachometer. Then each engine will have one sender wire going to either Port or starboard side dashboards. If you have DC power at rachis then my guess is a bad connection in the sender wires, probably st a common junction or location point. You could also go to Jaycar/ RadioShack and obtain an inexpensive counter to test. If buying new tacos, nowadays there is a petrol/gas and diesel version. Seems odd that both tachos refuse to work. If you have Floscan tacho sensors then the boats tachos may have been connected to them. I experienced this issue and WD40 solved the problem.

[Tim Powell]

The tacos should all share a common earth and positive + on each panel. Check power is received at first tach which probably daisy chains to the second tachometer. Then each engine will have one sender wire going to either Port or starboard side dashboards. If you have DC power at rachis then my guess is a bad connection in the sender wires, probably st a common junction or location point. You could also go to Jaycar/ RadioShack and obtain an inexpensive counter to test. If buying new tacos, nowadays there is a petrol/gas and diesel version. Seems odd that both tachos refuse to work. If you have Floscan tacho sensors then the boats tachos may have been connected to them. I experienced this issue and WD40 solved the problem.

He is saying all 4 tacks are not working. Therefor i thought it would be a feed problem. Fushes blown or glendenning not feeding senders.

[scottinsydney]

Sorry misread original thread on my phone.

Assuming there is power to the tachos, Then its likely to be where all four sender wires are connected/routed. A simple counter from Radioshack would help nail it.

[whoover]

Hello, no Glendenning and no floscans. I will check all of the fuses under the helm console and below. I will also start checking for power to the tachs and grounding.

Thanks
Walt Hoover