My Brick has an intermittant hesitation which occurs during acceleration. This sometimes becomes a violent bucking. So far, I have replaced the Hall Sensor, checked the wires, plugs, rotor, cleaned throttle body, cleaned IAC motor, checked wiring harness. The harness will be replaced in the Spring, but I have checked all important connections to make sure these are good. The tach does not die when this occurs. The hardest part is that the problem does not happen all the time, just when it wants to.

This morning I was thinking about the alternator which hasn't been touched since 1990. Could it be that the brushes have worn to the point of intermittant contact, and this may may be causing the hesitation? I need your help.

Thanks for the help.

1987 745 Ti,std trans, 297,000 km, Toronto, On.

If tach stays up during the time the engine tries to die then primary ignition is fine. You need not have replaced the Hall. If ignition secondary OK then problem is fuel related. Before thinking about pumps, filter etc resolder the fuel relay. That is probably the most common failure for the problem you describe.

I have resoldered and checked the fuel pump (white in-dash)relay and the radio (black)relay under the hood.

with 297k on the odo it very well could be your primary fuel pump,
before spending the $ on the pump ,try changing your fuel filter
first, also open your fuel tank drain briefly to remove any water from your fuel tank, water in fuel can cause hick ups etc... and will cause a filter
become resrticed. It would also be a good idea to have your fuel system pressure & delivery tested before just replacing the pump. make sure you have no vacuum leaks on the intake side of your mass airflow meter. any leaks in vacuum (or air let in)_ past the MAF will greatly affect perfomance. The ECM will not propperly adjust fuel mix. Dirty fuel injectors can also cause hesation. One of the best pour in, over the counter, injector cleaner solutions available is Techron (made by chevron).
(do not use more than 4 times between oil changes,as stated by manufacturer) not only does it clean your injectors but it also removes carbon deposits from the valves. excessive carbon on the back of intake valves will cause hesation. the carbon acts sort of like a sponge, it will actually absorb fuel to some extent.and if built up enough restrict air flow. Hope this helps

Bentwrench

I had the same problem with my 240. it turned out to be the intank fuel pump was shot, so it wasn't pressurizing the system properly. it's a cheep part to replace and pretty simple to do.