Z left me stranded, any help appreciated

[geezer]

Ron what r u smoking? How in the world could a broken/bad mount cause a sudden rise in RPMs? unless the whole motor or tranny spun around several times at high velocity. I think you'd notice this.

Smoking? - 10W30:smoke:

I thought I'd bring up a possibility that wasn't mentioned yet. It doesn't take a lot of torque to twist and bind up linkage when you have a motor mount break loose. It sure would be on my list of things to check, considering the circumstances described. Even if it's on the bottom of my list, looking is free.

[beezee]

Jason, If this happened just after hitting the dip in the road check the exhaust to make sure it,s not flattened.Uncork the header to and recheck power. Rick

[janaka]

-to the original poster-

Have you had your clutch/tranny looked at recently? The only way the engine could suddenly 'leap' to 5k Rpm without changing gears or changing speeds is for the clutch to slip (assuming it's in gear, which you said it was). I've never heard of this randomly happening on a bump before, but I suppose anything is possible... from my point of view that's the most likely explanation for the RPM jump.

Did the bottom of the car 'scrape' on this 'crease?' ... maybe the suspension bottomed out and some part of tranny or clutch slave cylinder knicked the ground?

I haven't had the tranny looked at since I bought the car in Decemeber.

The car definately did not bottom out on the highway, the crease was like the end of new pavement to where they had ripped off the old topcoat, so like a 2" drop suddenly.

It is remotely possible that your POR15 detached and is blocking your pickup tube in the gas tank during movement. (Kind of like a floating garbage bag) Another fuel pincher is a possible grain of sand/etc in your return line from your SU's. There is a restrictive opening in the return end of the fuel rail. (about the size of a pin)

I wouldn't even want to imagine a safe way to test fuel flow under operating conditions. A pressure guage could be rigged to where you could read it perhaps. (Drive with hood open to read guage possibly.)

is the return line on the carb was clogged as mentioned would the car still run on its own with no load on the motor?

After re-reading the origninal post...

I'm not sure I understand the bit about the RPM jump. The car was in gear with no actual acceleration and decided to rev freely right? Might have a broken/bent shift fork in the tranny??? (Gear might be engaging and disengaging) Any noises/vibes from the tranny during this loss of power. Could it rev freely with the clutch depressed?

If you isolate the tranny from the engine which is causing things to bog down?

the car was in 5th gear at about 2500-3000rpm maintaining speed. I hit the bump and then, with no change in throttle position the rpm would spike/plumet which is when i lost power. If I tried accelerating through it I got vibrations through the peddle and no acceleration. No noises from the tranny that I isolated at the time. With the clutch depressed I could rev the motor to my (and my wife's) recollection.

IMO this seems tranny is causing the issues becuase with no load on the motor, IE. in neutral, there are no issues, as soon as it goes into gear (1st, or 2nd even) and I start to load the motor by accelerating even at 10% throttle it'll bog down on me. Its not like it's bogging at 50-100% throttle only. I can get it into first gear if I nurse off the clutch slowly with no throttle and the car rolling (ie down hill a little). but again as soon as i try to accelerate it wants to bog till i clutch in.

That said almost 9/10 people I talk to about this say fuel issue. One person is blaming the Holley Red pump as its more of a race pump I'm told than a daily driver pump and that the fuel pressure at idle is ok but once under load the volume is not where it needs to be. Makes sense except I don't get how it can rev to 5k with no fueling issues then at 10mph it bogs at 2000rpm

Other people say fuel filters, clogged lines etc etc but again how would they flow to support 5k rev and again nothing at 10mph? That's what confuses me the most.

The 1/10 that think tranny say maybe a spring pop'd off the clutch and it will grab under little/no load, ie coasting but as soon as load is applied its slipping/disengaging. And the bent fork option as said above.

Sorry for the long winded response. I certainly appreciate all the help and patience with the Z newb (carb newb too).

When I find out what this is I will certainly post for all to know.

Jason

[JimmyZ]

In neutral the mainshaft and halfshaft are turning. If there are any crunchies swimming in the tranny or a bearing gone bad it will be difficult to turn. The only way to isolate the engine from the tranny is to use the clutch. (Assuming it releases properly) The more I think about it it is probably something in the tranny. Drain the tranny fluid and see what's up.

Jim

[JimmyZ]

It's got to be the tranny or rear end. I'd almost bet my left nut on it. ALMOST!!

Jim

[Mat M]

I still think Fuel.

I have been having mucho problems evicting the gremlins from my car, thinking I had them licked, only to find that they are back with a vengance.

I ran for 140 problem free miles, then all the sudden, loss of power, lurching power, tach bouncing all over the place, stumble, solid power for a bit, then boging to a slow death. If I let her sit for a while, she would start right back up, and without load, would rev freely to 5K. BUT, when I would put 'er in gear and try to get home, the thing would NOT rev past 2K. Frustrating and embarrassing. I even had a guy honk at me as he was passing, like I had a choice where I was broken down, and stalled it right where he was driving on purpose!

My solution (after my wife came to the rescue) was to install a 73-74 elect. fuel pump using the supplied wiring, jumping the unused "T" connector behind the radio. The pump is loud until I get the car started, then you can't hear it. So far, no more problems, but I have only driven about 15 miles since.

BTW, you have pretty much the same set-up for which I am saving my duckets, janaka. I hope this issue gets solved soon! Please let us know what it ends up being!

[janaka]

well its running again it seems.

WOO HOO

i feel like an idiot the size of ontario but I can deal with that since I have a running/driving Z again.

I should have done the KISS method. I looked at my fluids, all of them that i could find and one little carb damper bowl was dry. :? so I went into my chiltons, found the lubircant/oil needed SAE20 and went to buy some. Took me about half a dozen stores but I found it. Silly thing is they only had a 4L jug of it and i needed about 1.5oz of it..

needless to say last night I filled both to the fill lines and today (just now) fired it up and rolled it to the street... waited about 30seconds then gave her hell. Drives like a champ again.

Now my brakes are squeaking so i'll get that looked at but nevertheless I'm happy as a proverbial pig in $^!# !

Thanks guys for all the help and advice and postiveness!

Jason

[JimmyZ]

Huh?? I've had mine run dry before but never encountered the problems you described.

I thought you had it rev several thousand rpm higher while in gear at speed followed by a loss of power.

Glad to hear you're back at least!

[janaka]

hey now don't jinx me...... i'm taking the car out for cruise night tonight so we will see how it goes...

[JimmyZ]

hey now don't jinx me...... i'm taking the car out for cruise night tonight so we will see how it goes...

I wouldn't want to do that but I'd really hate to see you get towed home again too. My Z has only been towed twice in 18 years. Did you ever get to checking the tranny fluid?

Good luck:classic:

Jim

[janaka]

^^^ seemed ok. i will be doing full tranny fluid change this weekend though

oh and i got there and back in one piece, under Z power!

[janaka]

just a further update. i've put 200miles on the car no issues. yesterday I did check the fluid in the differential and at the front and everything was still brand new looking not burnt, not even brown still yellow oil coloud.