*** SOLVED *** SD40 Carburetor issues after rebuild (1 Viewer)

[Wadesters]

My 1965 FJ45 LPB (from Arizona) engine was completely rebuilt also the SD40 carburetor. Yesterday was fire up day. It started immediately, ran well and idled. When throttling up it would stall or run rough. Looked at all vacuum points and all good. Determined it must be with SD40. Reason being when choke completely closed it will run better. That tells me something is wrong inside carburetor.

Shop that rebuilt engine and SD40 is sending their lead mechanic here Tuesday (3 hours one way from me). He said that he set up SD40 the way he took it apart. He asked me to put a questionnaire out to the "guru's". What comes to mind is: accelerator pump, jets, needle valves.

Any diagnose help extremely appreciated and I will share with him upon arrival Tuesday.

THANK YOU!

 

[CRZR45]

Timing? Try playing with it?

 

[xtremeVA]

@Wadesters - I had the same problem after a rebuild... and spent a bunch of time fiddling with the float level to get it to run better off choke. Of course in my case setting the float level was "builder error" because I was adjusting it the wrong direction at first . I love the "big window" because it shows the float level (edit...fuel level in bowl) , but it is a bit of pain to adjust since you have to pull apart the carb to do so. Good luck...please post what the diagnosis/ cure to your carb issue because I may have the exact same problem.

 

[Wadesters]

@xtremeVA Wouldn't the site glass denote where the fuel level is or is that unrelated?

 

[xtremeVA]

...yes, sorry, you are correct. My wording is not precise. The fuel level in the bowl is what you see in the big window, but it's showing you that the float is at the proper adjustment and closing the fuel inlet at the proper fuel level.

The strange thing with mine is that the fuel level is on the line when start up and idle in the garage. I took it around my neighborhood and when I parked it the fuel level was higher then the line on the glass. I was just happy to get the 1.5 miles around the neighborhood without towing it home. Small victories.

 

[Wadesters]

I hear you! I made it to the end of my street (and back) just determined to drive it after all this time, and of course $$$

 

[Wadesters]

** UPDATE **
First, I appreciate greatly everyones help with this. My issue was none of the suggestions. Lead Mechanic and engine builder drove 3 hours one way here this morning. He went through the normal troubleshooting. Looked and sprayed for manifold leaks, found none. Checked over carburetor and all looked normal. Fired it up and he checked timing and that was good. Next he did something I had not seen. He attached the timing light to each spark plug wire. When he reached plug wire #2 found it was not firing. He used an ohm meter and checked #2 spark plug wire (brand new oem wires). The spark plug wire checked out fine. Then he removed #2 spark plug. These to were brand new. #2 spark plug showed bad even though brand new out of the box (luckily he purchased and installed them before it came back to me). Never heard of a bad spark plug but he said it does happen. Replaced the spark plug and I AM ON THE ROAD DRIVING. Hated for him to come all this way but I would have not thought of that.

Again THANK YOU everyone for the help!!

 

[Lifelong40Fan]

Wow, shocking. But very helpful. We'll now all have that in our arsenal of diagnosing a poor running engine.

 

[red66toy]

** UPDATE **
First, I appreciate greatly everyones help with this. My issue was none of the suggestions. Lead Mechanic and engine builder drove 3 hours one way here this morning. He went through the normal troubleshooting. Looked and sprayed for manifold leaks, found none. Checked over carburetor and all looked normal. Fired it up and he checked timing and that was good. Next he did something I had not seen. He attached the timing light to each spark plug wire. When he reached plug wire #2 found it was not firing. He used an ohm meter and checked #2 spark plug wire (brand new oem wires). The spark plug wire checked out fine. Then he removed #2 spark plug. These to were brand new. #2 spark plug showed bad even though brand new out of the box (luckily he purchased and installed them before it came back to me). Never heard of a bad spark plug but he said it does happen. Replaced the spark plug and I AM ON THE ROAD DRIVING. Hated for him to come all this way but I would have not thought of that.

Again THANK YOU everyone for the help!!

View attachment 3553389

Crazy! Glad it was an easy fix though.

 

[middlecalf]

…when choke completely closed it will run better.

Awesome it’s running better. Still wondering why full choking overcame a dead cylinder though.

 

[Spike Strip]

99% of all Carburetor problems are electrical.

 

[xtremeVA]

Glad you’re “one step closer”. What a great feeling hear the engine purr after so many years.