1990 tach problem
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Joined: Mar 2002
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From: sharpsburg GA
1990 tach problem
Hello, has anyone seen this kind of tach problem?
At start up the tach needle pegs out and then slams back to past zero and stays there. I disconnected the tach lead at the distributor and checked at the distributor with a meter that read rpm it showed about 800 rpm. Next I started the engine with the tach lead from the distributor still disconnected, as i drove the car the tach needle rose slowly all the way to peg out and then slammed back down to zero and stayes there. I also disconnected the plug at the tach filter and took a reading comming out of the filter. As best that i could tell it was reading close to the same as at the distributor but a little bit eratic. Could this probem still be the tach filter? I tried to get one from the dealer and they said they discontinued them, that kind of tells me that they didnot have trouble with them.
THANKS FOR ANY AND ALL INPUT ON THIS ONE.
At start up the tach needle pegs out and then slams back to past zero and stays there. I disconnected the tach lead at the distributor and checked at the distributor with a meter that read rpm it showed about 800 rpm. Next I started the engine with the tach lead from the distributor still disconnected, as i drove the car the tach needle rose slowly all the way to peg out and then slammed back down to zero and stayes there. I also disconnected the plug at the tach filter and took a reading comming out of the filter. As best that i could tell it was reading close to the same as at the distributor but a little bit eratic. Could this probem still be the tach filter? I tried to get one from the dealer and they said they discontinued them, that kind of tells me that they didnot have trouble with them.
THANKS FOR ANY AND ALL INPUT ON THIS ONE.
Burning Brakes
Joined: Apr 2001
Posts: 889
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From: Victoria BC
Re: 1990 tach problem (bdtenore)
I would check the grounds on the back of your block as that is where your cluster gets its ground from. They are on the drivers side on the rear of the head and on the block just below the ones on the head. I believe there is also one on your car on the A-pillar on the passenger side almost at the top of the sill, where it curves up to meet the dash. I know the earlier cars did have this but as yours is a 90 this may have changed because the the relocation of the ECM. There will be one more ground up front on the frame rail basically parallel or just in front of the serp belt on the top of the rail. You will find that a vast majority of electrical problems in C-4's are Ground based. Just my two bits. Good luck and I hope you have very small hands :D
PS a quick run to the dealer to ask for a ground location chart wouldn't hurt, as yours may have more than I described and tell you approx location of which.
[Modified by Ron D, 8:44 PM 3/13/2002]
PS a quick run to the dealer to ask for a ground location chart wouldn't hurt, as yours may have more than I described and tell you approx location of which.
[Modified by Ron D, 8:44 PM 3/13/2002]
