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IH 504 Diesel cranks, runs then slowly dies?

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Borrowed time means, get the work you need done now, finished until you can be down. Some people tend to think they have fixed the pump by opening up the return fitting. The dying and sputtering if fixed, but the root of the problem is still there, pump needs serviced. I would do the return in top of pump and gut the factory one making sure the hole is at least 1/8" diameter. DB pumps don't like return restrictions.

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While I am not any smarter than anyone else, it's the tools and training that opening a book cannot provide. There is a reason there are specialty shops like mine to do the rebuilds of these pumps. Wh

Fuel return line is plugging. Plastic ring in pump is probably breaking up.

Something plugged that return fitting. Find out what it is by taking timing window off side of injection pump. Fuel will run out along with coffee grounds if it is as everyone expects , flex ring fail

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On 4/11/2021 at 6:32 PM, IHRedDrive said:

I had mine rebuilt at a professional shop for just over $500. Some will say that's too much, others it's a bargain. All I know is the fellow who did the work has many years of experience and the ability to bench test the pump. The tractor runs as it should.

I'd be happy with $500 anymore.  Most are charging 1k pretty much flat rate no matter what anymore. 

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22 hours ago, Cdfarabaugh said:

I'd be happy with $500 anymore.  Most are charging 1k pretty much flat rate no matter what anymore. 

Fellow we work with does all of them. We have a Ford 8000, big Simms Minimec pump on it. That was more, close to 2k.

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You can run this for a long time with the flex ring gone.

It will start to eat away at the aluminum case over time but not enough to scrap the case.

Most times the pins are fine as they are hardened.

The worst case is you would need a new governor weight retainer.

Then you buy the one that does not use the flex ring and it is fixed forever.

The Elastacast ring (flex ring) was originally put in to stop governor surge issues.

But running one with the solid retainer never caused any governor issues.

Here is one for $85.00 so you know what you are looking at.


So I would suggest, like the others, remove the under tank check fitting and replace it with the one on top of the pump. Looks like this.


Then get your work done and have the pump serviced when you have the time and don't need the tractor.

Be sure to run Stanadyne fuel conditioner in this tractor. It is that important.


1 bottle will probably run you a long time as it treats 60 gallons.



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I appreciate all the feedback especially with the links to the parts needed. I will only use it this season which may only be a total of 30-40 hours. Then at the end of fall I will take her in to get rebuilt. 

Like you and others have mentioned I will use the in line check valve that goes in the top of the pump but it drives me crazy that I can’t find an OEM or equivalent under tank check valve! Seems they don’t exist. LOL

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On the earlier tractors that return the fuel into the bottom of the tank I have been making a new line and returning the fuel into the top of the fuel tank . You can use soft copper line or steel brake line , drill a hole in the top front of the tank and tap it with 1/8” tap then use compression style fitting to clamp to the new line . 
‘the reason for this is back in the day when it was returned to the bottom of the tank the forgot about the weight of the fuel pushing back on the injection pump so it’s harder to return the fuel when the tank is full . 
like the other guys are telling you if the flex ring is broke up and gone you do want to fix it , the pins on the cage will slam back and forth causing metal floating around in the pump and that’s a big no no , it ends up in the injectors , damages the head of the pump, oh and when it cuts those pins off on the governor cage it will run wild 😳

‘Pull it and fix it is my advise .


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