88 740 GLE is running way to rich.......hard to start.....runs ruff @45-55 mph.....getting about 100 feet to the gallon.So far we

have new plugs,wires,d-cap,rotor,hall sensor.also new air mass meter.So far everything I've read points to clogged fuel injectors.

Can I clean these on my own?What about IAC?Throttle switch? Do I need professional help.....shrink,mechanic or both?

if you are running rich, how will a clogged injector cause that? a clogged injector will reduce the flow of gas and cause a lean condition. In fact, most problems in the fuel supply system will cause a lean condition (reduction in fuel supply). Why do you think the engine is running rich? do you smell gas from the tail pipe? do you have backfires when you downthrottle? You might want to check for vacuum leaks (a lean condition can give similar symptoms). Also, check the condition of the spark (ie coil, wires and timing). If the timing is off, you get the same type of problems. My next door neighbor had a similar problem that finally turn out to be a bad harmonic balancer (the crankshaft pully had twisted on the rubber bushing so that the timing notch on the pully was no longer at TDC)

the fastest thing to do is take it to a mechanic had have a smog test done on it. this will give you the 4-gas readings at high and low rpm and will just about pin point what is going on. (if you are rich, the HC reading should be extremely high)

Tap on the Fuel Pressure regulator with the handle of a screwdriver or hammer. This is a simple first test, not always conclusive but most of the time it works for me. If the car runs better momentarily after rapping on the pressure regulator, you need to replace the regulator.

Best thing would be to hook up a fuel pressure gauge. In lieu of that you can check the fuel flow coming out the back of the regulator. SAFETY is the keyword here. A plugged regulator will return almost no fuel to the tank.

Whatever you find, be sure to change your oil once you have the right fuel mix. Running this rich it is sure to put a lot of fuel in the crankcase.

Dan,

The fuel presure regulator makes sense.This is a used replacement motor out of a wrecked vehicle(102K)been sitting? Everything

from the throttlebody on up was extremely gummed up. I've had the fuel rail off twice to check fuel injectors & change the

O-rings and in doing so I dump all of the gas out of the rail & regulator.The car will start right up after reassembly & no black

smoke.....well, for a few minutes anyway.When I take off the fuel lines to the rail,there doesn't seem to be any on the return

side.Should there be? I recall having to plug both lines when I pulled the motor because of fuel leaks from these lines.Thanks.

1. Check the fuel pressure. I could watch the fuel gage drop on my '90 745t when the fuel pressure regulator went bad. They usually fail to a rich, ie too much pressure condition. $50 from dealer.

2. Oxygen sensor. You can test with a multimeter, replacements are available for as little as $30.

3. Fuel injection coolant temp sensor. Test with multimeter. $35 from toyota/volvo of keene

3. Cold start injector leaking (may not have one on this year)

Just some simple things to start with..

Brendan

'90 745t m46 171k

have you change to 02 sensor as yet ,it plays a verry inportant role on these cars, good luck.

This is an add on for my own message.....this car has a replacement motor from an 87 740GLE 102K...all the new stuff was

carry over from the other motor which my son had blown up.......Note to parents,advise children not to drive car without

coolant! :-(