pwgibbs
Recruit
- Joined
- Jul 3, 2010
- Messages
- 3
'Morning All! Done LOTS of research on my issues here on this board and the posts I've read led me to the troubleshooting steps I've taken and the results I've gotten. ONE question remains, but first, a little background:
Engine: 1998 volvo Penta 5.0GL PBYC - 3868854
Alternator: VP 65 amp 3856600
Symptoms: Engine starts, runs 2-3 minutes, dies. Repeat.
Fuel filters cleaned/replaced, replaced anti-siphon valve.
Have NOT done a fuel pressure test (yet) but, through troubleshooting, am ALMOST ready to rule out fuel pump and Carb issue (Carb cleaned/inspected last summer).
Troubleshooting revealed the following:
With engine OFF and key in the RUN position, I'm reading 12v at the LIGHT terminal on the alternator (green lead to fuel pump). With the engine RUNNING at IDLE, the voltage drops to < 10v. As engine RPM INCREASES, output voltage DECREASES.
With the green lead disconnected from the alternator and connected to alternate 12v supply, fuel pump runs fine, eliminating the in-line diode as the culprit (I think!) If I'm not mistaken, the fuel pump is a 12v, constant-speed (~4000rpm) pump.
Observations and questions:
Something tells me that this is NOT normal...for two reasons:
First, seems to me that I should NOT be getting ANY voltage across the "Light" terminal unless the engine is physically RUNNING, and
Second, seems to me that the voltage should be a constant 12v regardless of the engine RPM (thanks to a voltage regulator?). The alternator is charging my batteries just fine, it just appears that it is not supplying the correct voltage to the fuel pump with the key in the RUN position.
My question, obviously, is: Is my alternator jacked? I suspect YES, but there are lots of folks here that are smarter than me that may give more insight!
Remaining at PD.
-Paul
Engine: 1998 volvo Penta 5.0GL PBYC - 3868854
Alternator: VP 65 amp 3856600
Symptoms: Engine starts, runs 2-3 minutes, dies. Repeat.
Fuel filters cleaned/replaced, replaced anti-siphon valve.
Have NOT done a fuel pressure test (yet) but, through troubleshooting, am ALMOST ready to rule out fuel pump and Carb issue (Carb cleaned/inspected last summer).
Troubleshooting revealed the following:
With engine OFF and key in the RUN position, I'm reading 12v at the LIGHT terminal on the alternator (green lead to fuel pump). With the engine RUNNING at IDLE, the voltage drops to < 10v. As engine RPM INCREASES, output voltage DECREASES.
With the green lead disconnected from the alternator and connected to alternate 12v supply, fuel pump runs fine, eliminating the in-line diode as the culprit (I think!) If I'm not mistaken, the fuel pump is a 12v, constant-speed (~4000rpm) pump.
Observations and questions:
Something tells me that this is NOT normal...for two reasons:
First, seems to me that I should NOT be getting ANY voltage across the "Light" terminal unless the engine is physically RUNNING, and
Second, seems to me that the voltage should be a constant 12v regardless of the engine RPM (thanks to a voltage regulator?). The alternator is charging my batteries just fine, it just appears that it is not supplying the correct voltage to the fuel pump with the key in the RUN position.
My question, obviously, is: Is my alternator jacked? I suspect YES, but there are lots of folks here that are smarter than me that may give more insight!
Remaining at PD.
-Paul
