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catmastertech, Technician
Category: Heavy Equipment
Satisfied Customers: 2321
Experience:  19 years Cat, 3 years Case
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Caterpillar C7 starts hard/ wont start

Customer Question

Caterpillar C7 starts hard/ won't start
Submitted: 8 years ago.
Category: Heavy Equipment
Expert:  Don replied 8 years ago.
hi there my name is don
can you please explain a little more please what happens when you try to start
what have to done so far

what model

Customer: replied 8 years ago.
Replaced HEUI oil pump and ICP sensor. Does not build enough pressure in the HEUI oil system to start, but will run mint, good power, smooth, when started on starting fluid. Also starts INSTANTLY on starting fluid . Engine is a Cat C7 , 2005.
Expert:  Don replied 8 years ago.
hi there

although i am familure and have worked on the heui system they require high pressure for the solinoids to actuate 800 pounds cracking pressure
i have used the cat sis system to diagnose
i am going to opt out and let someone who woeks on these system regularly to help you thanks
Expert:  Diesel Pro replied 8 years ago.



From what i understand, the engine will start and stay running when starting fluid is used, wright? But will not start on it own, wright?

Seems like you have changed everything on the system except the IPR (injection pressure regulator) which will cause no start or hard starting.It is located on the high pressure pump screwed on the side. Need to change out.


If you are satisfied with my answer, please press the accept button to process payment. If not, let me know how i can help.Thanks.

Customer: replied 8 years ago.
New HEUI pump came with new IPR. New style C7 HEUI pump has the IPR inside. Oil system only builds to 500 psi when cranking. Did a pressure test at the pump "deadheaded" and the pump builds to 5000.
Expert:  Diesel Pro replied 8 years ago.

Do you have a check engine light that comes on?

Have you had a computer diagnosis done on the engine?If yes, what are the codes?

Expert:  catmastertech replied 8 years ago.
Remove the valve cover and look at injectors while cranking, it is possible to have one loosing too much oil, preventing enough pressure to start. You may need to start engine to see this. Injector seal will leak around cup hole and bad injector will spray lots of oil out the side ports. Seal and injectors have been trouble spots for C7's. Check your fuel tank as well, a seal leak could dump oil into your tank.

Did you have proper pressure when engine is running?
catmastertech, Technician
Category: Heavy Equipment
Satisfied Customers: 2321
Experience: 19 years Cat, 3 years Case
catmastertech and 3 other Heavy Equipment Specialists are ready to help you
Customer: replied 8 years ago.
Yes Donnie, Injector #3 was squirting like a gyser when cranking, upper O-ring broken. Thanks