Won't accelerate past 3500 RPM?

[FredK]

I have a friend who has an OBD-I M52 swapped E30.

It ran fine before he parked it for the winter.

After the winter, he took it out and the car would accelerate normally, but then refuse to accelerate past 3500 RPM. It feels like there is a physical rev limit preventing the car from doing anything past 3500.

The car does rev past 3500 only in neutral.

I'm thinking it might be a fuel pump that went bad. The main engine ground is fine. It's not the cluster with, for example, a corrupted VSS. We swapped clusters and the car performed the same.

[ForcedFirebird]

Do a fuel volume test before and after the fuel filter. Jump the fuel pump relay with the loose hose in a container, it should flow at least 1pt in 15sec. If it's less after the filter, change filter, if it's less before, look into the pump. A lot of times a pump will pass a pressure test, but not a volume test. If the car hasn't been started since stored, fuel may have coagulated.

[FredK]

Seems reasonable to me, thanks for the feedback!

[kronus]

isn't that the rev limit of limp mode?

[FredK]

I am not sure. It is an OBD-I swapped M52--I've amended my initial post.

I don't think a 413 even has a limp mode?

[kronus]

oh if it's OBD1 it doesn't have that IIRC

[e304lyfe]

Try a new crankshaft sensor.