VP 8.1 trouble solved
08-22-2012, 08:37 AM
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VP 8.1 trouble solved
Some time back I posted a plea for help with a "drivability" issue. I want to thank all those who responded and report back on the solution. My original post is below. Turns out the VP tech rep stopped by the shop and performed a cylinder "puff" test, basically a single stroke compression test, and narrowed the problem to one cylinder. Pulled the motor and had a broken piston ring. Time for a complete rebuild... runs great! Thanks!
Steve
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Newbie here, need help!
I bought a used 2002 boat with Volvo Penta 8.1 GI-B engine. Serial number upon request.
Engine ran fine, then second season began occasional “skipping/shuddering” which eventually became constant.
WOT operating range is published as 4200-4600 rpm depending on prop. My boat normally operated at ~4250, now at 3900.
Had fuel injectors professionally cleaned, tested and spray pattern checked and all are within spec.
Fuel rail cleaned.
New fuel pump assembly installed 7/2009.
Fuel filters changed, opened and found clean. New filter sealed with aircraft gasket sealer.
Checked exhaust temp sensors and oil pressure sender. No fault codes set. Engine not in “de-rate mode”.
Spark plugs and spark plug wires replaced.
Grounds to block and ECU checked.
New series 31 battery.
PCV valve checked.
Fuel pressure normal, no drops at WOT.
Cylinder drop test with Volvo computer shows cylinder number 8 is the culprit. No/very little change in rpms when dropping fuel to number 8.
Compression test normal. Leakdown slightly low on #8, but within spec.
Swapped injectors with another cylinder, but # 8 still affected.
Swapped spark plugs and wires with another cylinder, still #8.
Swapped coil pack with another cylinder, still #8.
“Noid light” tested fuel injector wiring harness on #8 and appear to be triggering normally.
Pulled head, replaced valves and seals. No visual defects found.
Checked push rods, found to be straight.
Checked common ground in wiring harness, no intermittent grounding issues found.
Fresh 91 octane no-ethanol fuel.
Ignition timing registering normal.
Could this be the ECU? Any leads on an aftermarket testing/programmer?
Steve
------------------------------------------
Newbie here, need help!
I bought a used 2002 boat with Volvo Penta 8.1 GI-B engine. Serial number upon request.
Engine ran fine, then second season began occasional “skipping/shuddering” which eventually became constant.
WOT operating range is published as 4200-4600 rpm depending on prop. My boat normally operated at ~4250, now at 3900.
Had fuel injectors professionally cleaned, tested and spray pattern checked and all are within spec.
Fuel rail cleaned.
New fuel pump assembly installed 7/2009.
Fuel filters changed, opened and found clean. New filter sealed with aircraft gasket sealer.
Checked exhaust temp sensors and oil pressure sender. No fault codes set. Engine not in “de-rate mode”.
Spark plugs and spark plug wires replaced.
Grounds to block and ECU checked.
New series 31 battery.
PCV valve checked.
Fuel pressure normal, no drops at WOT.
Cylinder drop test with Volvo computer shows cylinder number 8 is the culprit. No/very little change in rpms when dropping fuel to number 8.
Compression test normal. Leakdown slightly low on #8, but within spec.
Swapped injectors with another cylinder, but # 8 still affected.
Swapped spark plugs and wires with another cylinder, still #8.
Swapped coil pack with another cylinder, still #8.
“Noid light” tested fuel injector wiring harness on #8 and appear to be triggering normally.
Pulled head, replaced valves and seals. No visual defects found.
Checked push rods, found to be straight.
Checked common ground in wiring harness, no intermittent grounding issues found.
Fresh 91 octane no-ethanol fuel.
Ignition timing registering normal.
Could this be the ECU? Any leads on an aftermarket testing/programmer?
