Hello All,

I recently learned something that might be very helpful to others who replace their K-Jet engine wiring harness. After helping my son replace his harness with a brand new Volvo harness, the car would not start. It would blow fuse 7 (the main fuel pump fuse) every time. With the help of some Bricksters, and about 20 new 16-amp fuses, we started tracking the problem. The car is a 1981 auxilary-air-valve, non-Turbo, non-California car.

Guess what? It turns out that for some cars the new Volvo harness #9139228 needs to be modified to work. The control pressure regulator plug wires on the new harness need to be reversed for some cars. One must test the resistance of each of the two connecting points on the CPR to ground, and make sure that the black wire of the harness plugs into the pin on the CPR that has 0 or near-zero resistance. In our case we had to reverse the two wires in the CPR plug on the brand new harness. No problem now. Adam is out driving the car as I write this. Below is the post we found in the archives about this, originally posted by Steve Seekins. Thank you Steve and again, thanks to all who helped with this.

Steve Seekins' original post:

"Did you check all your fuses? On some models with the Bosch K-Jet injection system, the connections for the control pressure regulator (under the manifold) are different and requires removing the wire terminals from the connector and moving them. Failure to do so causes a short and blows the main fuel pump fuse fuse. Obviously the car will not start without the main fuel pump running. There was an article on this in the Jul/Aug 98 Rolling Shade Tree Column.

The problem is that there was a change in the control pressure regulators and the connector pins were changed. The connector has two leads - blue and black. Some folks may have a problem and others not depending on the year and whether or not the control pressure regulator has been replaced. You can check the control pressure regulator pins with an ohm meter. One terminal should read 0 ohms to the case, and the other between 10 and 20 ohms to the case. The BLACK lead from the connector should be connected to the pin that reads 0 ohms. If not, peel the harness connector boot back and use a small pick or thin wire to release the terminals from the connector and swap them.

Of course, on many cars where the harnesses have deteriorated, some of the engine sensors may not have been working properly. Often the engine has been tuned to compensate for these. Installation of a new harness may restore the faulty signals and the engine must be re-tuned. I would start with properly setting up the idle control according to the base idle adjust procedure in the manual. Then proceed to check the signals from all the engine sensors - especially the temperature sensors (the single wire one between #2 & 3 runners is gage only)."

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Thanks to everyone for the help, Doug C. 81 242 Brick Off Blocks, stock, M46; 86 240, 135k

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Thanks to everyone for the help, Doug C. 81 242 Brick Off Blocks, stock, M46; 86 240, 133k