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What should the compression be on a Yamaha 250 HPDI. Hard to…

What should the compression...

What should the compression be on a Yamaha 250 HPDI

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Hard to start and idles rough after warming up very hard to start

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Just need to verify compression I have 90 psi on all but 1 cylinder the other has 100 psi what should the compression be

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Answered in 2 minutes by:
1/22/2018
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 18,217
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
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Good morning, my name is ***** ***** am I speaking with? I read what you wrote. Did you just need to know what the specifications where on this engine or are you looking for help in trying to solve a problem?

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Customer reply replied 6 months ago
I just had my power head replaced in September. It ran great at first but then after a few trips it got to where it was hard to start especially later in the day. I’m told by 1 tech that the compression is low (90 psi) I’m told by another tech that 90 is good and the problem is most likely the high pressure pump I’m just trying to verify the info so I can make an informed decision

When the engine was new compression would have been 120 to 130 PSI ballpark. As the engine wears and tears that number will go down. The printed specification in the service manual (What Yamaha puts into print) is 81 psi. 81 PSI is the lower limit. Anything below that and there are going to be no guarantees of if the engine will run, or how well it does run. I do want to make sure you are happy with my service before you go. If you had a further or more specific question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

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Jason

Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 18,217
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
Verified
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