| Author |
Message |
    
Jonathan Carn
New member
Username: joncarn
Post Number: 1
Registered: 05-2009
| | Posted on Monday, May 18, 2009 - 06:52 pm: | 
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I have a 1998 Volvo Penta 5.0 GL PBYC and I can start and idle, even poke along at about 1500rpm but will only run for about 10-15 seconds above 2000rpm. I have rebuilt the carb, replaced the fuel filter and fuel, new plugs. Actually runs smooth for the few seconds. I can jump the fuel pump and hear it run and then it will start. Is this a relay issue or something else? |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 223
Registered: 03-2009
| | Posted on Monday, May 18, 2009 - 07:01 pm: |
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This system may have a low oil pressure fuel pump shut down switch. It most likely does if the fuel pump is electric and from what you say regarding "jumping" the pump. 
The starter motor circuit provides a "By-Pass" source of power to the fuel pump during cranking only!!! If the oil pressure switch is not working, it would explain a portion of what you are describing..... possibly!
You'll need to check/test the oil pressure switch.
DO NOT, repeat, DO NOT circumvent this switch..... it is a critical safety feature for any I/B Gasoline Marine engine equippped with an electric fuel pump!!!!!! |
Jonathan Carn
New member
Username: joncarn
Post Number: 2
Registered: 05-2009
| | Posted on Monday, May 18, 2009 - 08:00 pm: |
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10-4 on the by-pass, I understand how important.
My oil level is fine. Is this part of the oil pressure sending unit? If not, where is it located? |
Jonathan Carn
New member
Username: joncarn
Post Number: 3
Registered: 05-2009
| | Posted on Tuesday, May 19, 2009 - 09:30 pm: |
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I found the oil pressure sending unit and it has 1 purple wire connected and it goes back to the guage. I started the engine and checked the yellow wire from the relay to the fuel pump with a test light and it has power during idle. There is a green wire from the alternator to the fuel pump rely and it had power also. The oil guage shows good pressure and the needle moves slightly while running so I think the unit is working. Would it be OK to hot-wire past the fuel rely and try running WO to rule out a carb problem? |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 227
Registered: 03-2009
| | Posted on Tuesday, May 19, 2009 - 09:48 pm: |
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Quote: "Would it be OK to hot-wire past the fuel rely and try running WO to rule out a carb problem?"
I would not/could not recommend that you try this as it would violate USCG regs. Your call. |
Jonathan Carn
Member
Username: joncarn
Post Number: 4
Registered: 05-2009
| | Posted on Wednesday, May 20, 2009 - 09:05 am: |
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How do I find out if I have a low oil pressure shut down switch? |
Steve Nash
New member
Username: scnash
Post Number: 1
Registered: 07-2009
| | Posted on Tuesday, July 14, 2009 - 02:43 pm: |
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I had a similar problem and could not figure it out. It was when I thought the problem could be in the fuel supply line or fuel filter that I found my problem. I disconnected fuel line between fuel filter and carb and used a 5 gallon gas can as a temporary fuel line. Engine cranked and ran fine at idle and at cruise speed. My problem turned out to be the in-line check valve at the gas tank. The plastic housing for the checkvalve ball had cracked inside the valve. When gas was flowing at a low rate it was not a problem, but as more gas was required the plastic pieces were sucked toward the fuel line and shut off flow to the engine. I replaced the check valve and my problem was resolved. This may be a stretch, but you never know. |
