Stanadyne DB2 4531 pump problems

cdhearn70 · Aug 20, 2016

Ive got a diesel powered air compressor that has been setting a few years and now cant get any fuel out of the pump. The prepump is working fine and delivering fuel to the pump. I pulled the electric cutoff off and it was stuck but got it freed up and working but still no fuel coming out of the pump to injectors. Do I need to just get it rebuilt? How much would it cost?

jacksun65 · Aug 20, 2016

If your lucky you can have it rebuilt if not the pump was also corroded and broke.
Those parts are starting to be made of unobtanium. Had mine rebuilt and wasn't broke
cost $400.

Billy Shafer · Aug 20, 2016

I would get it rebuilt. Cost would be what parts are replaced and labor. Last pump I had done was a little over 560.00 dollars.

Al Baker(pumpman) · Aug 20, 2016

You plungers and or metering valve are stuck. VERY common problem with the new fuel we have available nowadays. Pump needs to be torn down and resealed. When you send it in dont let them hose you. You should be able to get the job done for $450.00 or less. If no one in your area wants to treat you right I would be glad to help you out. I have done a dozen or so stuck pumps this summer alone. Turn around time is a few days to a week topss. Al 231/757/0064

JDEM · Aug 21, 2016

The electric shut-off has no direct mechanical connection to the fuel metering-valve. It is the metering-valve that turns the injection-pump "on" or "off." So, even if
solenoid and swing-arm is working, the metering-valve may be stuck. Just reach and move it by hand and if stuck - break it loose. It is on top of the pump and one of the
first things to dry out.

More rare, but the main pump-plungers may be stuck. If so - sometimes you can just free them up with compressed air. Just hook an air-line to one of the injector-line
ports, and rotate the pump. When the port in the rotor lines up with the port the air-line is hooked to, that 100-150 PSI will push on those plungers and sometimes free
them. Note that cannot be stuck "out" because the cam-ring would push them back in when the pump rotates. So if stuck, they will be stuck "in" and compressed-air and
sometimes push them out.

cdhearn70 · Aug 21, 2016

Thanks for the replys everybody. I did pull the electric shutoff and pop loose the shutoff in the pump and got it that working. Still no outgoing fuel. Jdem I'm going to try the air to the outgoing ports. I was thinking it was probably something like that but didn't want to chance messing something up.

cdhearn70 · Aug 26, 2016

Still no luck. I hooked air up to all 3 injection ports coming out of the pump. I even hooked it up to the fuel line in and turned it over. The pump doesn't have but 27 hours on it so I know its not wore out. Just been setting a long time. When I hooked air up to each injector port I did get a little blow out on the other 2 ports and the fuel line in. Acts like I'm not getting fuel to the injector ports. I know I'm getting fuel to the pump though.

Stanadyne DB2 4531 pump problems

cdhearn70

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jacksun65

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Billy Shafer

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Al Baker(pumpman)

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JDEM

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cdhearn70

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cdhearn70

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