1972 240z 3rd gear+ violent loss of power

[Cutlass372]

Hey everyone, over the past few weeks my car has been running progressively worse. I just replaced the spark plugs with new NGK BP6ES plugs and it took away the problems I was having in 1st and 2nd gear (at 5k rpms it would hit almost like a rev limiter, but keep revving sporadically). It was doing this before, but it seems like in 3rd gear or higher it get this violent loss of power and the tach jumps all around. It kind of surges, as if you let off the gas and stomped on it again over and over until you shift or slow down. I think the timing is set around 15 degrees and I am running the pertronix unit and their coil. This isn't something that has been happening for a long time and I don't recall changing anything or making any adjustments prior to this happening. What are your suggestions, Where should I look. Thanks in advance for any help. Any information you can provide would be greatly appreciated.

Thanks, Elliot

[mlc240z]

Might want to check here:

http://www.classiczcars.com/forums/showthread.php?threadid=37452

What ohm coil?

Did you bypass the ballast resistor?

[d240zx2]

Something's loose. Cars just don't behave that way.

Check your locking screws on the distributor to start with. Check your centrifugal weights for freedom of movement. Just two places to start.....

[Cutlass372]

What locking screws are you talking about? And yes its a 3 ohm coil with no resistor. I'll try the washer thing and see if that helps any. Keep the suggestions coming guys.

[olzed]

I have a stock 240z with standard motor and stock ignition. Never had a problem in 15 years. Plugs and points adjustment 10 years ago! On a road car I can't see the point changing to electronic ignition.:

[d240zx2]

The screws that keep the dizzy from turning.....

[Walter Moore]

That is the way that my car acted when the fuel pump was going bad. It would run fine at nearly any speed until you hit about 60MPH, then it was like the car had a governor.

(Which basically it did. When the fuel flow reached it's limit the car literally ran out of gas.)

It sounded like a driveline vibration, but it turned out to be the engine shaking from the fuel failure.

[IdahoKidd]

I'm with Walter and wouldn't rule out a fuel delivery problem, such as a plugged filter, or plugged pickup in the tank in addition to a failing pump. It could still be ignition and could be as simple as a loose wire at the coil. My 52 Chrysler did something to this effect with a bad condensor. My bet is that it is fuel though......

[Cutlass372]

I changed the plugs and tightened a few screws on the dizzy and the problem went away for maybe 30 minutes of driving and then it came back. The timing is staying consistent and not jumping around when revved. I am starting to think the fuel pump maybe the culprit. The fuel filter only fills up maybe 1/2" at most while the car is running. I blew air in the lines and it didn't clear much up. Also, when I pulled the plugs they were sort of dusty white/tan/redish in color. The car even sputters a little now in the lower RPMs. What are your thoughts?

Thanks, Elliot

[Cutlass372]

Anyone have anymore suggestions? I still haven't figured this out.

[Unkle]

Crap plugging the fuel lines intermittently at gas tank ?

Crap fuel flow / pump shot ?

Crap in carbs ?

Crap old gas destabilized ?

Crap in general ?

Crap / rusted fuel lines ?

Edited May 28, 2010 by Unkle
Forgot some crap.

[d240zx2]

Oh, Crap. Why didn't I think of that??? ;-)