97 4.3L performance

[garyrayjackson]

Engine acts like it is running out of fuel at hyway speeds. Have replaced fuel pump and filter, MAF sensor(as per "0101" code). throttle position sensor checks out good, but hard acceleration causes engine to knock and then stall. It always starts back up and limps home, then runs marginally better untill the next hard acceleraction.

[planedude]

check your fuel pressure when accelerating it could be your pressure regulator.

[[email protected]]

Check the IAT. It could make your MAF read off.

You either have a calculation problem or a delivery problem. It is hard to tell from your post if the problem occurs at steady cruise or cruise speed under hard acceleration. Fuel calculation is based on the O2 sensors (closed loop) at cruise when warmed up. Fuel calculation is based on the MAF (open loop) when cold and wide open throttle. Secondary sensors to the MAF during open loop include the TPS, ECT, and IAT.

So if the problem is at steady cruise and WOT, it is probably not a calculation problem because two entirely unrelated methods are used. If it is only at WOT, it could be the MAF or IAT.

If not a calculation problem, it is a delivery problem which would probably be the fuel pump or the fuel filter. When the regulator fails, it usually does not reduce the pressure with increasing vacuum, resulting in a rich idle. It is possible to fail with less pressure but unlikely. If it were injector problems, they would likely also give problems at idle and steady cruise.

Let us know.