I am planning to perform an engine compression check on a MY97 850 next weekend. What is the best way to disable fuel pump? Is there a fuse somewhere?

And while I am on this subject -- What is the optimum and minimum psi numbers for engine compression? Since our engine compression ratio of turbo'ed 2.3L is 8.5:1, I'll take a guess that it is in the neighborhood of 150 psi optimum and 130 psi mimimum.

 

fuse should be under the hood on the cowel near windshields wiper

 

I believe the compression is between 135 - 150 psi. At any rate there should not be a reading less than 80% of the highest cylinder. Remember, all plugs have to be pulled prior to starting the readings. Lastly, the engine has to have been run up to operating temperature prior to checking compression

 

I almost forgot about warming the engine up to operating temperature first. Thanks for reminding me.

 

Did you figure out how to disable it yet?

 

I purchased the car on Wednesday. I am waiting for the car to be delivered sometime late next week.

An interesting point is that the car was converted over the AMSOIL synthetic around 45K miles. The car now has 110K miles. The previous owner changed oil and filter every 10K miles.

I have always sworn by using conventional Valvoline straight 30W in the summer and 10W30 in the winter. I have friends that swear by using conventional Castrol GTX 20W50 year round. I have always chanted the "change oil every 2-3K miles" mantra my whole life -- not because the oil is worn out, but because of contaminates (fuel, exhaust blow-by, condensation, etc) that eventually find their way into the oil.

I have started doing a little research. I am curious. My local Volvo dealer wanted $140 to perform an engine compression test. I am planning to purchase a nice engine compression test kit including all of the spark plug threaded adapters from NAPA for around $100 and do it myself.

Run engine until it reaches operating temp. Pull fuse to fuel pump. Run engine until lingering fuel is consumed. Remove all five spark plugs. Screw in proper sized threaded adapter in cylinder one. Hook up engine compression tester. Have friend bump starter while I take readings for dry compression. Remove adapter, squirt in a little oil, install adapter and obtain wet compression readings. Repeat process for cylinders two thru five. I may do a cylinder leak down test, if I can figure out how to do it.

Anyway, AMSOIL says that I can extend oil drain service intervals.

http://www.amsoil.com/storefront/atm.aspx -- 10W30
http://www.amsoil.com/storefront/amo.aspx -- 10W40
In personal cars and light-duty trucks with non-turbocharged gasoline engines, drain oil at 25,000 miles or one-year intervals, whichever comes first. In turbocharged gasoline engines, change oil at three times the engine manufacturer's recommended drain interval or six months, whichever comes first.

I would like to learn more about synthetic oils. My educated guess is that obtaining my car's engine compression readings and comparing against optimum specs would be a good test. Also, I figure that a large difference between dry and wet compression readings would indicate a problem such as worn piston rings.

 

When you are ready to disable the pump let me know and I will tell you how to do it.
On most of them the fuse also disables the injectors as well.Or won't disable it at all.