ran fine yesterday, but not today

[clindayag1]

i drove my car around yesterday and it ran perfectly fine with no problems. i tried driving it today and for some reason it had very little power. whenever i would try to floor the pedal for more power, it would do the opposite and decrease in power, it almost feels like its going to stall. when i floor it in neutral its smooth, but doesnt go past 3000 and starts to struggle. i dont know what it could be, maybe fuel related? its weird because it ran so good yesterday:disappoin

[Mat M]

It happens.

Have you made any mods? is you car stock? What is your car, for that matter? carbs or injection?

Sounds like fuel to me, but I have nowhere to go without the above info.

[EScanlon]

My guess: Vacuum Advance Bearing Plate.

Since you mention that it won't rev past 3k, that in neutral it seems to be ok but not past 3k, and it didn't do it yesterday...presuming you did NOT do anything to the car, the small ball bearings in that plastic plate may have worked their way loose.

The situation becomes one that as long as the vacuum is strong the plate will allow the distributor to advance via the vacuum pull (centrifugal is largely unaffected) but won't return to it's prior setting easily.

To define it as the problem, remove the distributor cap, disconnect the vacuum hose from the vacuum pot, and with another hose connected to the vacuum pot ... suck on the hose and watch the rotor/point plate rotate. Release the vacuum you generated with your mouth and watch the rotor/points. It should return (spring) back into the original position (before you applied vacuum) rather promptly...meaning it doesn't take more than a split second. It's not a "snap", as much as a released spring.

If it does NOT do that, either rotate or spring back, it's a good indication that the vacuum advance plate is shot.

This happened to me, with the same symptoms you report. However, other causes may be the reason. This is just my WAG to check.

FWIW

E

[hls30.com]

Is this the 240Z or the 280ZX?

Will

[beandip]

With your temp in the area 104* or so was the engine overheating when this was happening? This could be a factor. Gazza

[clindayag1]

thanks everybody for your replies. well my car is a '72 240z. the only mods i've done to it is a k&n filter and removed the smog stuff. oh and replaced the plugs, cap, rotor, spark plug wires.

it could have something to do with the distributor because when i changed the cap and rotor, the rest of it looked pretty worn out. i will post a pic of it when i get the chance and maybe you guys can decide if i need a new dizzy.

[bigoak]

Check your fuel filter. Sounds like fuel starvation. If your filter has been clogged up, it will do this.

Start here as a fuel filter is cheap and quick.

Do a search, this is discussed ad nauseum on the board.

[EScanlon]

With all the suggestions, keep one thing in mind.... Don't do them all at the same time.

Do the least invasive first. The fuel filter should be a simple swap and not affect timing, etc. The Vac Adv that I suggested only involves opening up and inspecting. After you've inspected then return everything to how it was before.

The changes we were asking about weren't what you've done to the car since you bought it, but from one evening to the next morning. (i.e. it ran fine (day before) yesterday, and the next day it ran badly) During THAT time frame, did you do anything?

If you did NOT do anything, then the change has to be due to something that wore out or broke, or as Gary pointed out, due to the change in climate.

If on the other hand, you got in there and modified the timing, changed spark plugs, put in a new distributor..... well it gets even more complicated than a simple check will reveal.

Determining a requirement for a new dizzy from a picture, unless the old one has obviously been through a chipper, would be hard to do. I've seen distributors that after a good cleaning and re-assembly looked NEW, yet had worn bearings, etc. and needed a complete re-build.

The key is to do ONE thing, and then return the car to it's previous condition until you find the cause. Otherwise, as we've said before on this site, in a couple of years you'll be selling the car with this notice "I parked the car a couple of years ago after it ran poorly and I've not been able to get it to run again....." and someone will pick iit up cheap.

I've bought two that way.

FWIW

E

[clindayag1]

all those changes i have done, including changing the fuel filter, was done last month. i started up the car today but didnt drive it around. after letting it run for a bit i noticed a whistling sound coming from the engine. i think its coming from around the carb area.

[d240zx2]

You just spelled "vacuum leak," I think.

Frank