not going past 4100 rmps while driving

[Nick_Agosta18]

I just got my Datsun back on the road for spring and I notice while in 3rd and 4th around 4100rmp it feels like there is a rev limiter on the car and is doesn't wanna go past 4100-4200 rmps. it doesn't happen in 1st or 2nd and if I ease into it, it sometimes doesn't happen in 3rd. the car is running strong though so I don't really think its anything mechanical. if anyone has any input I'd greatly appreciate it. thanks!!

[siteunseen]

Read post #4, http://www.classiczcars.com/forums/misc-s30/51848-1972-240z-gas-tank.html, maybe something you're experiencing? I just saw you have FI. Maybe a new fuel filter up front. Check the air filter for acorns or rodent nests. Did you spray the engine bay when you got it back out? Could be moisture somewhere like the TPS or the AFM, you can take the black covers off to see if the vanes are sticking.

[Mark Maras]

Most likely is lack of fuel. Do you have carbs or F.I. Regardless,I'm guessing the engine will rev. to redline with no load (clutch in). Check your fuel filters first then fuel pressure & volume. This not an uncommon problem. It usually is the fuel filter restricting volume. The engine, under a load, only has enough fuel to go that fast but will rev. fine with no load.

Mark in Portland

[FastWoman]

Failing ignition? The fact that you can ease into a higher RPM might be simply that you have a weak enough spark that it fails to jump the gap when the engine is under load.

[Nick_Agosta18]

Thanks for all the info guys! I'll let you know how I make out!!

[Nick_Agosta18]

So I replace he fuel filter and spark plugs was cruising around getting on it a little and it started acting up again, once the rain stops I'm on clean the TPS and spray it down with some wd 40. Maybe it's the fuel pump, or possible injector?

[240260280z]

Pull the TPS connector and try with it disconnected.... so you have a 280z right?

Check timing too.

[Nick_Agosta18]

Pull the TPS connector and try with it disconnected.... so you have a 280z right?

Check timing too.

Yes I do

[Nick_Agosta18]

Whatta mean if I disconnect it and it stops or keeps doing it?

[EuroDat]

I had a failing coil that was doing similar too what you're experiencing, but it would start at lower revs. Actually anywhere above 2500 revs under load. It was the coil and I found it by taping my timing light onto the windscreen so I could see it from the drivers seat and took it for a test drive. The timing light was missing pulses exactly when the "rev limiter" cut in.

Edit: The timing light I was using was not the type that clips over the lead. It actually goes in series (Non-inductive). Its my fathers really old kit he had. The kit had the timing light, a vacuum gauge, dwell meter and a push in compression tester. It came from K-mart which was the biggy of the department stores in the 70's.

I don't think you will see anything with a normal light because he might still register voltage even if its not enough for a spark.

Chas

Edited April 12, 2014 by EuroDat

[240260280z]

Disconnect the TPS and drive it to see if rev limit goes away.

[Nick_Agosta18]

I just tried unplugging the TPS still did it, cleaned the TPS out with some wd-40 let it dry hooked it all back up. It seemed to idle a little lower but this felt a wall/ lack of power around 4500 RPMS.