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Discussion Starter · #1 ·
Today after class, I'll be spending some time trying to find out why my car is misfiring. The car is an 85 900 base with a 16V n/a from an 87 swapped in.

The problem occurs mostly at greater than 50% throttle input. The limited test driving I've done, sometimes I still get the misfire at WOT and sometimes I do not.

I've already checked the plugs, they seem fine. I'll be at least looking at the cap and rotor and searching for obvious vac. leaks, but I'm by no means a mechanic. Any advice would be appreciated here, since I'm at school with this car, and taking it home to have my dad help me doesn't seem like an option.
 

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Discussion Starter · #2 ·
bump, I'm going to be checking things today, any hints would be greatly appreciated.

I'll be making a 230 mile trip in the car tomorrow against my will. Too bad my AAA towing coverage is only 100 miles.
 

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1985's were the year that they installed the self-degrading environmentally friendly wiring harness that just falls apart over time. Sure as hell hope you don't have one line wire in that gaggle of harness slowly weakening under load.
 

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Replace the plug and coil wires. They were known to go bad especialy the coil wites on them. They would arc through to the rad hose they rested on. this would cause a miss fire under load.
 

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Discussion Starter · #6 ·
Thanks for the help, everyone. As it would turn out, the problem was my own fault, I've been too poor to put any fuel in it. I finally was able to refuel it today. On the way to the gas station it exhibited the problem described above, but once I filled it up the problem went away.

Low fuel, ftl.
 

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Probably the pre pump is bad. There is a small almost like a transfer pump mounted on the side of the pump assy. When they go bad and the tank is low it can't fill the can fast enough that the main pump sits in.
 

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Discussion Starter · #8 ·
Thats good to know, Marty. Is it possible to swap the pre pump from a different assembly?
 

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Yes, they should be the same for all year C900's.
 

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Discussion Starter · #10 ·
Thanks, I'll have a look around in the garage when once I make it home later today and see if I have any more of those pumps floating around, I've swapped them once in this car already.
 
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