Surging at idle

[JackFish]

Funny thing just started happening.

Drove a couple of blocks and stopped to let my wife off.
It started to stop, and then speed up again.
Almost dying, and then surging back up to rpm, down, up.

I was hoping it might be something easy like the fuel pump.
The only thing I did today was wash the car. Maybe some water in the gas? Normally I'd expect sputtering with that.

 

[Stormin' Norman]

I'd check the pump first, but I agree - water could be a factor. Some fuel de-icer might get rid of it. Pinched line?

 

[oldgrezmonke]

Did you wash the engine ? Maybe you got water in the distributor .

 

[JackFish]

No, I didn't open the hood.
I thinking that maybe the float got stuck or something, because I went back out to move the car and it seemed to have fixed itself.
Will test some more later today.

 

[chad]

Funny thing just started happening.
Drove a couple of blocks and stopped to let my wife off.
It started to stop, and then speed up again.
Almost dying, and then surging back up to rpm, down, up.
I was hoping it might be something easy like the fuel pump.
The only thing I did today was wash the car. Maybe some water in the gas? Normally I'd expect sputtering with that.

1st I am not a mechanic - worse case? balancer, timing? best case fuel filter? I'm sure others have other more zeroed in ideas.
Good luck, let us know as U proceed, I had to rebuild a YF (form help saved me) w/same problem - gone now.

 

[JackFish]

Might be a vacuum leak.
Took the carb off and replaced it with something I cobbled together from spare parts.
Too dark to finish tuning tonight.

 

[JackFish]

Whoa well I'm not sure if I made it worse!

Now it has a high idle and missing. And when I try to back off the idle speed screw it just dies.
I'll check the float level again tomorrow, and the plugs. I'll cap all the vacuum feeds off and take it from there. :smash:

 

[woodbutcher]

Nobody has mentioned this yet,BUT,have you checked for cracks?Hope that there are none
but check for them.
Good luck.
Leo

 

[JackFish]

As in head cracks or exhaust manifold?
The exhaust manifold is ok. I'm rebuilding another carb at the moment.
Finding all kinds of problems, like the mix idle screw hole being damaged from over-tightening. Float level too low. Stripped threads. Incorrect choke adjustment. Fortunately I have a small stash of parts carbs.

 

[JackFish]

Swapped out the fuel pump, it was toast.
Still having a rough idle though. Hesitation at tip in, bit of a bog.
Almost dying at lights, but not quite.

 

[CobraSix]

idle circuit clogged on the carb?

 

[JackFish]

idle circuit clogged on the carb?

Ya, that or float level. Going to check it today.

 

[MPGmustang]

so your getting random idle rpms? random acceleration feeling? and randomly wants to die...

it sounds like when my throttle shaft gave out, I limped like that for months... pony carbs fixed it for free as it was their carb...

check to see, with helper in car, engine off, watch the throttle move up and down, does it go in the correct direction angle? dose the linkage rub up against anything else? keep your eye on it...

when cold disconnect the pedal linkage and see if you can move the carb throttle linkage easily in any directio that it's not intended for...

I'm throwing it out there as it sounds familiar....

 

[JackFish]

Well one thing leads to another.
After finding and solving a few problems I got it running reasonably smooth.
I could do some more tuning, but I've been hearing a knocking which I have finally identified as the oil pump.
So that gets a new thread... :x