Never seen this before while starting my car
 

I went to start up my 88 today to keep the fluids circulated since I don't drive it (it's new to me and the brakes are 100% gone). Usually the tach starts registering it's turning over and after a few seconds it'll start and run. Today, the tach wasn't moving but the speedometer was. Also, the whole time it was cranking, my trip meter was spinning, a few 1/10ths or so of a mile every second. Throughout the whole time I was trying to start it, my car gained about 2 miles on the odometer. I've never seen something like that happen, any clue what might be causing it? It never did that before since I've had it.

Poor connections/shorts in the flexible instrument binnacle circuit board.

Fairly common, actually.

Low voltage or lack of grounding will do it. If the battery is strong then the best place to start is with the cluster connections/circuit board, as Greg says. Problems here are very common with the XJS. Lots of archived info

Cheers
DD

If all else fails. There was a service bulletin about this i believe. It involved fitting a supresser on the yellow feed wire at the rear of the trip computer. It worked for me.

So you think its refusal to actually fire and run like usual is just coincidental? If it's just a loose or dirty wire behind the cluster im not too concerned about it right now, as i probably wont work towards making it drivable until spring anyways. Just didn't know if it was something serious causing that issue. Thanks for the help guys.

I did not understand from your original post that the car was starting unusually slowly. What exactly happened as far as the starting was concerned, please?

Probably a coincidence.

But.....

The ECU likes to see lots of voltage just like the speedometer does.

Check voltage at the two firewall junctions posts. These distribute supply voltage to the car. The voltage should be the same, or virtually the same, as the reading taken at the battery itself. Now repeat the checks while a helper cranks the starter. How much does the voltage drop? Below 11? Below 10? Less drop the better, of course.

Cheers
​​​​​​​DD

One comment to make is that occassionally starting a car that doesn't get driven is actually detrimental to to it. You end up with condensation inside the engine, which leads to the oil emulsifying in the same way as if you had a coolent leak into the oil. Even if the temperature gauge gets up to running temp, it's not the same as actually driving the car and getting it properly up to temperature.

It's hard to do that when the car has no brakes because of worn out old seals or lines leaked every drop of fluid out.

My point was that you're better off just not running it.