When cold start engine sputters and tachometer needle jumps up and down

Hi and thanks for using 2CarPros.com.

I realize the carburetor had been rebuilt. However, has the metering needle been adjusted? It sounds like it is dumping fuel. What I would suggest, and it has been awhile since I did one, is to remove the plastic cap at top and locate the orifice adjusting screw down inside the carburetor. Next, turning the screw clockwise will lessen the amount of fuel to the engine (make it a leaner mixture). Turning it counter clockwise will increase the amount of fuel. Based on your video, it sounds like this is where the problem lies. When you make the adjustment, I would recommend no more than half a turn at a time on the orifice adjusting screw. Once you get it to run properly, then there is nothing more than a throttle stop screw to adjust.

Try this and let me know what you find. If you have other questions, let me know. One last thing, make sure there are no vacuum leaks to the engine. Here is a link which shows how to locate them:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, this could also be related to the electronic ignition. Let me know if the adjustment works.

Joe

Hi Joe, thanks for the tip. I tried it but the problem is still the same. When the engine is cold she sputters and stays at 300 rpm intil the engine is hot. You can smell the gasoline.

Have you rechecked the needle and seat as well as the float level? Has anyone changed the fuel pump type? It is dumping fuel as you already know. Either the needle valve is not closing off the inlet of fuel, the float is set too low, or for some reason there is too much fuel pressure (in the event the pump type was changed).

Let me know.

Joe

I did what you recommended and yes she starts now. It is fine tuning the carburetor and hopefully she will start normal when the engine is cold. I will let you now. But tomorrow I leave on Holiday for one week.

So I just tried to start because the engine was cold and it the same problem over again. So after my Holiday trip I will be looking back to the problem. I will let you know!

Okay, I am back from holiday. I tried to start it worked. Did a drive came back home let the engine cool and after a hour or two tried to start again and same problem over again, let it warm a little bit and took the car back for a spin. Now what happened after a while is it started to sputter and the needle of the rpm jumped up and down.

See the video and check rpm needle. Need help cannot find the problem.

Have you replaced and set the points, condenser, cap, rotor and plug wires? Also, can you pull the new plugs out to see what they look like. Do all cylinders and take a video of them please.

Cheers, Ken

It is electronic ignition and the color of the spark plugs are very good.

It is good the spark plugs are new. I need to see the electrode color to see if the engine is lean or rich? Also, do you have nex plug wires? Do you install EI? Because that car came with points and condenser.

Hi Ken, I will take a picture for you tomorrow and yes I installed the electronic ignition myself and it always worked fine, the plug wires came with the electronic ignition I measured the ohms and they are all okay. A other mechanic on the forum told me to look to the settings of the Stromberg but I am waiting for the special tool to change the settings.

Okay, if we can see the plugs I can tell you which way I would go. By the way, I have had nothing but problems with some aftermarket systems. What is the brand name?

Hi, here is a picture of the spark plug cylinder four.

I am a little carburetor oriented.

My thoughts on the super videos you sent are either:

A vacuum leak or a fuel issue. I am leaning towards a fuel issue.

This quick test might verify both possibilities.

Get you a sacrificial squirt bottle capable of stream or mist.

Load it with a few ounces of fuel.

I really suggest doing this outside away from other precious things with a first line of defense (big wet towel) and a second line of defense (fire extinguisher).

Remove the air cleaner and crank it up.

Start by misting fuel into the carburetor throat.

Does running improve?

If yes, we may still have a carburetor issue or a vacuum leak.

Before tearing into the carburetor for a problem.

I would rule out the vacuum leak possibility.

Check those hoses for cracks/ being unhooked/ swelled on the ends letting air by.

Here is how to really check it out:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Who built the carburetor?

Who adjusted the carburetor (on vehicle) Or was it just put on as is?

Keep us posted on results!

Maybe some closer pictures of the carburetor?

The Medic

Okay, thanks. I will do the suggestions you made and let you know ASAP, Jan