help please

I have begun to work on my 928, just got a battery to see what it does. I noticed that when i turn the motor over. That the speedo jumps around a good bit. The man that sold me the car says that it needs the fuel injection computer. Can anyone help me diagnose this so that i can enjoy the drive.thank you.

Skipper,
We need more info. Model year and ROW/US would be helpful. Also, some history on the car would be great. Has it been sitting up? What maintenance has been done?

Does the speedo jump around but the RPMs do not or both etc.....

The car has been sitting for a little more than a year. It's an 1981 with a 4.5, i have no real maintenance records. The fluids look good,it has 77,000 on the clock. I don't know what relays or what fuses do what i don't see where that a labeled.

The car has been sitting about a year.i don't know much about the maintenance history. Its an 1981 us spec. It turns over and sounds like it has compression. Their is fire

Skipper, you need to go to 928gt.com and print off the fuse/relay chart for your car to keep as a reference. Better yet, you should contact Roger at 928sRus and order the Jim Morehouse CD collection. That will be the best $70 you ever spend on your 928. Virtually all of the tech information concerning the 928 is on that CD set.

Open your gas gap. Can you smell varnished fuel? If yes, then you have a lot of work to do to prepare the car to run again. If you're unsure, spray a mist of starting fluid into the intake and start the car. If it responds to the starting fluid, then you have a definite fuel issue. If not, then you must confirm spark and compression.

See if the car responds to starting fluid and report back.