HELP! Terrible Fuel Mileage

[backyard2]

First the history:

1995 Bonneville SSEi Supercharged
155K miles. Engine rebuilt 80K ago (not by me).

Barely made the 1500 mi. trip to new home in Florida. It had VERY little power to climb even a slight grade. It would rev high and slow to a crawl.

Local mechanic (pretty good guy but limited experience and no supercharger experience) checked it out and found multiple and various problems that I thought were reasonable. He replaced the throttle position sensor and O2 sensor the water pump and the catalyst which was making lots of noise.

When I took it out to test it was quieter (exhaust noise) and idled better but didn't have the power of a 3.8 SC. I drove it 60 miles on the highway and it used about a third of a tank of gas! You could almost see the gage dropping. When I sat at idle for any length of time the temp. rose pretty high but not to the red.

Today:

GTP Dad had some good recommendations when I posted in June but the transmission checked out good and now I need to make the car reliable for a trip back north to be gifted to my son.

I don't mind the temp rise but the power isn't what it should be and the mileage is still terrible. I'm afraid it's and indication that there is definitely something wrong that should be corrected.

I don't want to throw money at a dealer if I can help it.

Any suggestions would be appreciated.

Thanks.

[GTP Dad]

I thought about this problem overnight but the real answer still eludes me. Based on what you are saying it sounds like a transmission problem but you ruled that out. There are a couple of items that I would look at. First, check to see if the fuel pressure is holding properly. Low fuel pressure will cause a lack of power since there is not enough fuel going to the cylinders to give you the power you want. Since the fuel mileage is low indicating high usage the regulator may be fine but the plugs could be fouled and not firing properly. I would replace both plugs and wires if you have not done so in the recent past just due to the cat issue. Finally, have the vehicle speed sensor on the transmission changed. Call me crazy but these sensors can cause the PCM to do wierd things and therefore the car may not run correctly. I really have no other suggestions.

[backyard2]

Thanks very much for the thought and reply.

I'll let you know what I find.

Ray.

[backyard2]

Well, a mechanic discovered the camshaft sensor to be bad. For some reason the analyzer didn't show the problem but somehow he found the crank and cam were our of sync. He replaced the magnet as well and the engine runs like a top.

I still have the transmission under watchful eye.

Thanks for your help.

Ray.