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California98Civic · 03-14-2015, 05:16 PM

The second new fuel pressure regulator seems to work fine. Problems have disappeared again. But because of my recent fueling issues and persistent fuel-fouled (or oil-fouled) spark plugs that also show lean-burn flaky white/gray residue, I decided to test fuel pressure and compression carefully. Here are the results.

Fuel Pressure: PASSING

Priming pump without running engine: 42 psi (38-46 psi is normal range in Honda FSM), but the fuel pressure quickly drops to 38psi and then slowly drops slightly lower than 38.

Running the engine with vacuum tube connected = 31psi steady, jumps to 34 for a second when I hit throttle hard.

Disconnect vacuum tube, pinch it, and run engine = 42 psi steady and then back down to 31 when I reconnect vacuum hose to FPR. Disconnect again and back to 42psi. (Again, Honda FSM says I should see 38-46psi with the vacuum hose disconnected.)

No more idle or fuel trim trouble (so far), even when warmed until fan runs, even when driven 25-30 miles straight.

Compression test: PASSING

Honda FSM says compression should be 184psi (nominal), 135psi (minimum), and no variation greater than 28 psi between cylinders.

Cyl #1: (179) (170, 165, 167)
Cyl #2: (169) (165, 167, 165)
Cyl #3: (174) (171, 170, 171)
Cyl #4: (170) (173, 173, 172)

The parentheses group separate connections of the tester and commas separate multiple tests during one connection of the tester. I connected the test twice to each cyl and tested each cyl a total of 4 times.

If I am burning or leaking any oil, it must be quite little.

QUESTION: Even though these numbers are fairly good, should I do a "wet" compression test just to see what happens? Would it yield valuable information as to whether the compression drop is rings or valves?

03-14-2015, 05:16 PM	#244 (permalink)
California98Civic Cyborg ECU Join Date: Mar 2011 Location: Coastal Southern California Posts: 6,299 Black and Green - '98 Honda Civic DX Coupe Team Honda 90 day: 66.42 mpg (US) Black and Red - '00 Nashbar Custom built eBike 90 day: 3671.43 mpg (US) Thanks: 2,373 Thanked 2,172 Times in 1,469 Posts	Fuel pressure and cylinder compression test results The second new fuel pressure regulator seems to work fine. Problems have disappeared again. But because of my recent fueling issues and persistent fuel-fouled (or oil-fouled) spark plugs that also show lean-burn flaky white/gray residue, I decided to test fuel pressure and compression carefully. Here are the results. Fuel Pressure: PASSING Priming pump without running engine: 42 psi (38-46 psi is normal range in Honda FSM), but the fuel pressure quickly drops to 38psi and then slowly drops slightly lower than 38. Running the engine with vacuum tube connected = 31psi steady, jumps to 34 for a second when I hit throttle hard. Disconnect vacuum tube, pinch it, and run engine = 42 psi steady and then back down to 31 when I reconnect vacuum hose to FPR. Disconnect again and back to 42psi. (Again, Honda FSM says I should see 38-46psi with the vacuum hose disconnected.) No more idle or fuel trim trouble (so far), even when warmed until fan runs, even when driven 25-30 miles straight. Compression test: PASSING Honda FSM says compression should be 184psi (nominal), 135psi (minimum), and no variation greater than 28 psi between cylinders. Cyl #1: (179) (170, 165, 167) Cyl #2: (169) (165, 167, 165) Cyl #3: (174) (171, 170, 171) Cyl #4: (170) (173, 173, 172) The parentheses group separate connections of the tester and commas separate multiple tests during one connection of the tester. I connected the test twice to each cyl and tested each cyl a total of 4 times. If I am burning or leaking any oil, it must be quite little. QUESTION: Even though these numbers are fairly good, should I do a "wet" compression test just to see what happens? Would it yield valuable information as to whether the compression drop is rings or valves? __________________ See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.