I love my 1992 745.Rex/Regina system. Runs like a champ, great fuel economy, comfortable and carries all my gear. But-last year, after driving through a ferocious downpour, the engine stalled. Took five minutes to restart. Then five days later, in warm, dry weather, it stalled out again and would not restart. Ever since, I have had stalling problems when accelerating from idle. Plus cold weather start issues. Plus non starting in rain issues.
The cold weather start issue was solved by unplugging the cold start valve and flashing the ECU.
The wet start issue was solved first by spraying with WD-40 and waiting 10 minutes, then by installing new weather stripping gasket across the underside of the hood AND along the sides. Not factory spec, but wet start issues disappeared.
I also ran auxiliary grounds from battery negative to all metal chassis components, including the intake manifold and grounding lugs on the inner fenders as well as the auxiliary relay ground in front of the battery. That got rid of many strange electrical flukes, such as the spedo registering 30 MPH as soon as they key was turned, but BEFORE starting the engine.
OK - I am still left with stumbling and stalling problem when accelerating. It usually kicks in after the engine has been running and warmed up for 12 minutes. If I ease off the accelerator, I can keep driving. If I try to maintain speed it knocks and dies.
Here’s what has been done:
New ignition wires. New high voltage coil pack. New distributor cap. New fuel filter. Fuel pump was changed long before the problem occurred. New RPM sensor, new oxygen sensor, new air temp sensor, new manifold air pressure sensor. Engine temperature sensor changed.
Throttle body cleaned. New O rings on some fuel injectors.
The problem seems to occur when the gas tank gets low and I refuel. There is a miracle cure, but I need to know why. When I add two bottles of Gunk Total System Fuel Cleaner the problem disappears, sometimes for weeks. After driving long distances the problem disappears for several weeks.
The problem seems worse when parking facing uphill. The Gunk also helps with cold weather starts, which sometimes take four or five tries. Sounds like the engine is starved for fuel. With the Gunk in the tank, it kicks over on the first try.
I could keep buying the Gunk (which is the only stuff that works) but it is expensive on a regular basis and does not answer the basic question: Why?