Hello,

I am about to replace the vaccum lines on my 1989 744GL with a B230f engine in an effort to fix a wandering idle problem (and after 13 years, they should be changed anyways).

However, as a newbie to the world of repairs, I was wondering where all the lines are (does someone have a schematic and/or good description of the procedure). All I know is that there is a vaccum canister that looks like a large juice container by the air filter box that has a few lines going to it.

Any help is appreciated and I thank you in advance.

Tim

Not many vac lines on this engine...

Flame trap to manifold nipple (be sure to rod out the nipple of carbon build up. I use a 1/8" drill bit)

Fuel vapor canister. Two lines. A source of gasoline smell if cracked.

Plastic line with rubber "elbow" on each end runs from Ignition control Module to throttle body.

Check the larger hoses: intake bellows near the throttle position switch to flame trap, and those two which link the bellows to/from the Idle Control Valve. good idea to remove and clean out the arbon from that valve, as well.

Check the throttle body gasket & three bolts. If leaking/loose, this can give erratic idle. Spray carb cleaner around it to see if idle changes.

Same with injector seals

Check hose and fuel line connected to the Fuel Pressure Regulator. If hose is wet, the FPR is leaking. If cracked, pressure not being regulated adequately.

There is also a large hose to the brake servo attatched to a white plastic check valve. Valve sometimes fails, giving stalling symptoms.

The intake bellows itself cracks, causing weird cross-signals from differing inputs to AMM and Throttle Positioning Switch.

Clean and adjust throttle body