Hello Everyone,

These are two fuel system questions.

The car in question is my 1990 745T automatic 197,000 mi. original turbo and transmission. I am the second owner and have put on the last 120,000 mi. IPD sway bars fore and aft, somewhat modified exhaust to lower back pressure. Mostly Premium gas. Draw-Tite trailer hitch, model specific, with the shank, sticking out through a carefully cut square hole in the aft air skirt, the only part of the hitch that is visible from behind the car. Two 2-in. inlets for the air filter box, the standard inlet leads from the bottom of the air filter box into the right front fender hollow, and I run the second of the two inlets forward and underneath with 2-in. flexible metal ducting into that empty room between the air filter box and the windshield washer reservoir.

I went to check the fuel pressure regulator by way of measuring fuel line output downstream of the regulator with the engine idling. I got three-quarters of a gallon of fuel pumped through the regulator after one minute. This and other indications tell me that the FPR is working.

Here's the question: my car's fuel system routing sends the gas forward from the fuel pumps into the rail and then to the fuel pressure regulator, from where the gas returns to the field tank. That is, fuel is pumped to the fuel rail before the fuel gets to the fuel pressure regulator. I had expected the reverse. Is my system hooked up backwards? I have looked all over the Brickboard website and related websites for the answer to this, and have also asked a knowledgeable local mechanic, and haven't found anything on this issue. The dealers would know, but they are down in Milwaukee and Madison.

Here is the second question: Can I clean the fuel injectors by hooking up a gravity drip to the fuel rail, opening the other end of the fuel rail , letting GM Top Engine Cleaner dribble down into the fuel rail while I am opening and closing the fuel injectors? I would of course depower the main fuel pump and disable the ignition for this. I figure turning the ignition key to start in this scenario would still open and close the injectors, and that gravity would dribble the Top Engine Cleaner down through the injectors and solubilize any crud in there. After doing that for a while - mindful of overheating the starter -, I would hook everything back up and run the engine. Does this sound like a fair idea?

I recently ran Top Engine Cleaner through the vacuum line leading through the Idle Control Valve at idle and, at engine speed above that, through the main air intake to get the TEC into the intake manifold. I measured the results somewhat with a big piece of clean cardboard beneath and behind the exhaust tailpipe. Some soot and small smeary black particles were blown down onto the cardboard. But this procedure did not reach the fuel injectors.

I will carefully read any posts that any of you write and send up. Thank you all very much.

Paul Scesniak
"Jenny II"