4020 injection pump

Gary in WTN · Jul 9, 2016

I recently had the metering valve stick in the injection pump on my 1971 4020. I pulled the pump and had it rebuilt. While it was being rebuilt I asked if them to install the Stanadyne 29111 weight retainer to eliminate the flex ring that routinely fails.
I reinstalled the pump about a month ago but didn?t use the tractor until today. While using the tractor I noticed that throttle doesn?t seem to respond as quickly as it normally does on a 4020. When the throttle is pushed to the slow idle position the engine will idle down and nearly die, and sometimes will die just as I have seen this tractor do when the flex ring is failing.
My question is, should there be a significant difference in the governor operation with the 29111 weight retainer?
My knowledge of pumps is near nothing so I'm not sure my terminology is correct.

David G · Jul 9, 2016

It sounds like you might need to adjust the throttle linkage.

Dieseltech · Jul 9, 2016

Weight retainer has nothing to do with your problem, there may still be some flex ring bits that need cleaned from the return line, but what you describe the metering valve is sticking. If the tractor is the later 4020 with the key electric shutoff you can try to free it up. With the engine at about 1500 RPM turn the key off, then back on again at about 800 RPM. If it uses the throttle shutoff try it the same way. Pumps with the separate stop seem to work to free the valve faster as you have more direct control over the valve movement. If there's ever been water in the fuel it makes the valve stick worse, a lube additive should help too.

David G · Jul 9, 2016

I only know the simple stuff

Gary in WTN · Jul 9, 2016

Dieseltech,

Thanks for the reply.
The flex ring was still in good condition when the pump was removed from the tractor. The pump was pulled because there was no fuel going to the injectors which kept the engine from starting. The problem was thought to be stuck metering valve. There was very faint click from the solenoid in the pump when the key was turned, not the normal easy to hear click.
Do you think that the problem I have now is a valve still sticking causing RPM to not be controlled correctly and if so what lube additive do you recommend?

Gary

Dieseltech · Jul 10, 2016

Anytime an engine with the CAV DPA or Stanadyne-Roosa Master rotary style pump is sluggish on acceleration, and under runs-dies when returning to low idle speed it's the metering valve sticking. It MUST move freely for good governor action. Any fuel lube additive is worth a try, if you have some two cycle oil around try that too. If not really bad I've seen the problem go away with normal tractor use. The worst pumps that did it are the Roosa DM model pump, on AC, JD and White. They used a larger valve than the DB, DC, JDB, and JDC had, and was much more likely to have sticking issues. Neighbor's 2-155 has done it mildly for years, but he lives with it. Very late DMs did go back to the smaller valve to help correct it.

Gary in WTN · Jul 10, 2016

Dieseltech,

Again thanks for the reply.

I tried shutting off the key at 1500 and on at 800 several times early this morning. Didn't seem to help.
I have some two cycle oil handy and will try that tomorrow.

Gary

ET · Jul 10, 2016

I agree!

4020 injection pump

Gary in WTN

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David G

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Dieseltech

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David G

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Gary in WTN

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Dieseltech

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Gary in WTN

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ET

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