'72 3020 Gas - Hard Starting Warm

sfsouter

Member
Hi, I know there are a few threads on this issue, but I wanted to check into where best to start a potential resolution to starting problems on these old gasers. In general when cold, and plugged in if applicable, mine starts fine. When shutdown warm, attempts to restart are often painful. I appreciate your insight.
Scott
 
I have a '71 3020 gas with the dreaded MS carburetor. Never plug it in and starts easily on the coldest day. Have to start at just off idle on the throttle, rpm when running will be less than 800 and usually closer to 500 rpm. Then gradually bump it up.

When warm or hot I have to do about the same, throttle just off idle (not much) and have to choke it just a bit. If I flood it, put throttle 2/3 and starts well.

I only use premium 91 or 93 octane, alcohol free gas. Otherwise it will want to run on after shutdown. I also let it idle for awhile before shutting down.
 
If the hydraulic pump has a manual destroker try destroking the pump and note if it cranks faster/starts better.

If no destroker try rotating the steering wheel back and forth a bit while cranking (which relieves hydraulic pressure) and note if that helps.

Bottom line is that when the starter is working hard it draws down battery voltage and makes for a weaker spark.

Check that the ''starting bypass'' circuit is working, as well.

If you REALLY want it to crank fast and start install a starter for the LP gas version.

It's several Delco model series larger and makes an unbelievable difference.

Others will probably chime in with a favorite gear reduction starter.
 
Couple of other thoughts to aid in starting.

Have the clutch pedal depressed when starting, 3 point lever fully forward so it is not trying to raise, but if no implement on the 3 point, lower the arms and once down bring the lever to rear to raise as you are starting. It only helps for a few seconds, about like turning the steering wheel but doesn't last long.

My hydraulics leak off if sitting for a few days so I don't have to have a destroke valve, but this of course is with the engine cold, not your situation.

Have you done a tune up? Checked the timing?
 

Hi, I thought I'd reach out and ask if other have found that the fuel shutoff solenoid on these Zeniths can be more problematic when hot. I leaning towards removing it and would be keen to learn others experience in that regard and how they've blocked it off. The previous owner of my tractor had the same issue as me starting hot some time back and the fix was a new solenoid.
 
(quoted from post at 12:14:22 11/26/22)
Hi, I thought I'd reach out and ask if other have found that the fuel shutoff solenoid on these Zeniths can be more problematic when hot. I leaning towards removing it and would be keen to learn others experience in that regard and how they've blocked it off. The previous owner of my tractor had the same issue as me starting hot some time back and the fix was a new solenoid.

If the load mixture adjustment is made by a screw in the end of that solenoid you will need to find and install a manual adjustment needle set up. I don't think the solenoid can just be removed, and the hole blocked off.
 
Someone noted that pre 1968 the Zenith's didn't have the solenoid and that the needle and spring from the older can be used to replace the one with the hole in it to accept the fuel shutoff needle. The carb pics on JD site look completely different however.



01E18 old Zenith - https://partscatalog.deere.com/jdrc/sidebyside/equipment/80960/referrer/navigation/pgId/150513



01E19 newer Zenith - https://partscatalog.deere.com/jdrc/sidebyside/equipment/80960/referrer/navigation/pgId/150681



Can the jet on the newer one, part number R13031 on 01E19 carb be replaced with the older needle H20954 from the older Zenith 01E18?



Perhaps it's wiser to just cut the tip off the solenoid needle and leave in place? Makes for any later owners scratching their heads however.
 

The parts might work as it looks like some of the solenoids sub to one JD part number now. I would suggest calling a place like MacDonald Carb and Ignition and talking to someone. Have your carb info in hand when you do. They may have the right parts to convert from the electric solenoid needle to a manual adjusted needle for your carb. They helped me when I had a bad solenoid on a 2020. They also have some solenoids at a lower price the JD. A web search using the JD part number for the solenoid you need, may give more options. I haven't used them, but NORFAR shows a number of solenoids.
 

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