Installed new tachometer and put a 70s fuel gauge in 85 cluster and now truck won’t start any ideas?

[justicemclinden]

Doing work for a customer and his old tachometer had a built in fuel gauge that wasn’t working so I took a tachometer that didn’t have a built-in fuel gauge and put that in place and have it all wired correctly. I also took a 70s fuel gauge out of an older C 10 and wired that in all correctly and now the truck won’t start. I need some ideas of what could’ve happened I checked all my fuses and the wiring diagram again

 

[justicemclinden]

I also have a different cluster in there but all other gauges work other then the ones I put into the truck and I think I missed something anything would be greatly appreciated

 

[Ricko1966]

Disconnect the tach see if it starts. The tach is probably killing ignition pulse.

 

[justicemclinden]

Update number 1: I got it running there was a bad wire from previous work done to it, now I just can’t get the rpm gauge to work and the fuel gauge is still INOP

 

[justicemclinden]

Disconnect the tach see if it starts. The tach is probably killing ignition pulse.

I got it running with the new tach in it just no RPMs are showing

 

[Bextreme04]

I got it running with the new tach in it just no RPMs are showing

Tach in a square will have a separate harness with power/ground connections and a single wire that runs from signal on the tach to the tach output on the HEI. If this vehicle had a hacked together setup for the heavy duty combo tach cluster to work, it likely needs to have that harness made or fixed.

 

[justicemclinden]

Tach in a square will have a separate harness with power/ground connections and a single wire that runs from signal on the tach to the tach output on the HEI. If this vehicle had a hacked together setup for the heavy duty combo tach cluster to work, it likely needs to have that harness made or fixed.

Whoever was working on the truck before me definitely redid the wiring harness and there is a bunch of bs that has been done and now the customer is getting pissed with me because I am trying to do it the right way and it’s taking to long I appreciate the 2 cents because I did put the other wiring harness in and i hooked up the HEI wire and the constant 12v and then I ran the ground with a stock clip to the ground post right behind the cluster and it still isn’t working, I appreciate the info