# CAV DPS injection pump problem MF30D



## Larry Welch (May 20, 2020)

Greetings,
I am new to the site and have as issue with the fuel injection pump.
The backhoe has a Perkins 3-152 three cylinder diesel, fresh rebuild due to two cylinders with low compression. 
I took the pump and injectors to a local shop who quoted over $1700 to replace nozzles and rebuild the pump. I retrieved the components, all separated in a box, inspected the pieces and determined I needed an advance housing and a rebuild kit. The pump is a CAV 5233F671.
I used information from the internet and cleaned and assembled the pump. I bench tested the pump and had fuel to all injectors. 
The problem is, I crank the engine and it will not start but, when I stop cranking I hear bubbles in the fuel tank, the injector pump is pressurized with air and the fuel filter bleeds off air. There is fuel delivering to the cylinders (white smoke and burning eyes) but it is not sufficient to make it run.
I assume I have overlooked or incorrectly installed some component(s) that is allowing pressure in the wrong direction.
Any suggestions would be greatly appreciated.


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## XLENDI (Jul 22, 2019)

Larry, strong possibility your injector break out pressure is to low and compression is going back through the injectors. i think break out?????? on these injectors is around 1600 to 1800 psi.
How did you adjust the injectors , keep in mind they can take your eye out or zap your blood vessels. There is a way to test on engine but must be CAREFUL. Burning eyes , stinging throat , unburnt fuel. When the injector breaks out you want atomized fuel , not any sign of solid fuel, and when it breaks out you will hear a distinct noise. If not all you are doing is over fueling and cylinder is to wet to generate compression , this will cause a whole mess of problems. Cheers. Alex.


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## thepumpguysc (Jan 25, 2015)

Larry, theres a 100 & 1 things u could have done incorrectly while rebuilding that pump.. Let me name a few to see if it jogs your memory..
Did I take off the top portion of the rotor, the 2 5/16 screws.??
Did u put the cam ring in correctly for your application.?? It'll go clockwise or anti-clockwise..
That transfer pump liner has a cut on it.. did u orientate the cut correctly.?
Did u put the piston in the advance hsg. correctly.??
Are u sure u engaged the throttle lever w/ the thr. shaft.??
Did u engage the shut off bar w. the sh-off shaft.??
Does the transfer pump piston slide freely in the regulating sleeve.?
Did u assemble the sleeve w/ piston & springs correctly.??
BTW.. if your in the STATES, I coulda done the job for less than 1/2 the price quoted..


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## Larry Welch (May 20, 2020)

XLENDI said:


> Larry, strong possibility your injector break out pressure is to low and compression is going back through the injectors. i think break out?????? on these injectors is around 1600 to 1800 psi.
> How did you adjust the injectors , keep in mind they can take your eye out or zap your blood vessels. There is a way to test on engine but must be CAREFUL. Burning eyes , stinging throat , unburnt fuel. When the injector breaks out you want atomized fuel , not any sign of solid fuel, and when it breaks out you will hear a distinct noise. If not all you are doing is over fueling and cylinder is to wet to generate compression , this will cause a whole mess of problems. Cheers. Alex.


Xlendi,
I did not have a way to adjust the injectors, I ordered new nozzles and trusted the shop I picked them up from did not change anything on the top side of the injector. I will get them tested and advise the results.
Thanks for the prompt response,
LW


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## thepumpguysc (Jan 25, 2015)

I don’t understand..
U had a shop just get the nozzles and putm in & not check the pressure??
BTW.. did u engage the dowel pin & the master tooth on the pump drive when u put the pump on.?


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## Larry Welch (May 20, 2020)

thepumpguysc said:


> Larry, theres a 100 & 1 things u could have done incorrectly while rebuilding that pump.. Let me name a few to see if it jogs your memory..
> Did I take off the top portion of the rotor, the 2 5/16 screws.??
> Did u put the cam ring in correctly for your application.?? It'll go clockwise or anti-clockwise..
> That transfer pump liner has a cut on it.. did u orientate the cut correctly.?
> ...


The Pump Guy,
I am sure about the rotor, cam ring, pump liner, advance piston, thr. shaft and the cutoff bar, the transfer pump vanes are close fitting but free (I have ordered new vanes and a sleeve just in case) I am not clear on the "sleeve w/piston & springs", I made sure I had the governor spring and hole locations correct. 
I may be taking you up on the job if I cannot clear this up. My plan is to remove the pump and go back through it step by step when I replace the liner and vanes. I need to find a local source to test the injectors to be sure they are functioning properly. 
Thank you for your input!
Regards,
LW


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## thepumpguysc (Jan 25, 2015)

I’ll do the injectors too


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## Larry Welch (May 20, 2020)

thepumpguysc said:


> I don’t understand..
> U had a shop just get the nozzles and putm in & not check the pressure??
> BTW.. did u engage the dowel pin & the master tooth on the pump drive when u put the pump on.?


I identified the nozzles, the shop said they were bad, and ordered new nozzles.
I currently have no way to check injector pressure at home. Since I asked them only to test them I hoped they would be close. 
Lesson learned.
I have a friend about an hour away that has a tester I will borrow.
The pump aligned with the case mark properly and the gear is located and torqued per the book.


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## Larry Welch (May 20, 2020)

Ok, I obtained the test pump, pulled the injectors and proceeded to clean the nozzles and discovered my local fuel injection guy had torn down every injector and assembled the nozzle push rod on top of the spring prior to making sure the adjustment caps were tight. After they were cleaned, assembled correctly and set the engine is running great. 
My thanks to thepumpguy and XLENDI for your input!


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