Bad fuel ecomomy - fuel pressure is the key - Volvo-Penta bulletin P-23-7
JohnnyCake
Member Posts: 29 ✭✭
We have 2006 Rinker FV250 with Volvo-Penta 5.0 GXI-E 270hp (400hours).
We have been suffering from poor fuel economy for a past two summers. Our fuel economy sank over 25%, from average of 2 liters/ Nautical Mile to 2,6 liters / Nautical Mile. This means about 100-120 gallons extra fuel per summer for us.
I have checked almost everything and couldn't solve the problem. I even changed the distributor, since it was quite rotten inside and could lead to weak spark. It helped some, but didn't solved the problem. ( http://rinkerboats.vanillaforums.com/discussion/2151/fv250-volvo-penta-270hp-fuel-economy-issue-solved)
Couple of days ago I decided to change spark plugs. The were very black and dirty (see the picture below) which means that the engine is running very rich.
At the same time I changed the fuel filter. When I started the engine, I could hear a quite loud whining noise from the fuel pump.
Since the engine is injection engine and the fuel pump was whining, this was the key to find a problem. If the pressure in the fuel system is too high, the engine will get too much fuel. Engine adjusts the fuel mixture by adjusting fuel pressure. I googled and the fuel pressure should be around 45psi. I borrowed a fuel pressure gauge and when a started the engine, pressure went to 90psi and didn't stay steady, it was jumping between 75-100. This caused cavitation inside the high pressure fuel pump and made the whining noise.
Some more googling, and I found this VP bulletin about fuel pressure regulator (it allows fuel to route back to filter if the pressure is too high in the fuel pipes on the engine). This bulletin is also attatched to this post.
https://www.dropbox.com/s/i3y1kznhp9btg7g/156 PB P-23-7 N03 V01 Fuel Pressure Regulator.pdf?dl=0
You really should read this thru. This is important. This bulletin indicates the problem with all engines older than 2010.
I opened the regulator and it was cloaked. I changed this screen with the pin mentioned in the bulletin and started the engine. The fuel pressure was 46psi!
So the problem was a faulty fuel screen, worth $2, and it took 10minutes to change with a since screw driver. Sometimes a small problem causes big struggles..
I guess the problem has started 2-3 years ago and got worse all the time until it was so bad the fuel pump didn't work anymore. This was the key finding. I hope this solves somebody else fuel economy problem without two years hunting.
Pics:
Bad spark blug vs new
Fuel screen inside the regulator:
Finally, a correct fuel pressure:
We have been suffering from poor fuel economy for a past two summers. Our fuel economy sank over 25%, from average of 2 liters/ Nautical Mile to 2,6 liters / Nautical Mile. This means about 100-120 gallons extra fuel per summer for us.
I have checked almost everything and couldn't solve the problem. I even changed the distributor, since it was quite rotten inside and could lead to weak spark. It helped some, but didn't solved the problem. ( http://rinkerboats.vanillaforums.com/discussion/2151/fv250-volvo-penta-270hp-fuel-economy-issue-solved)
Couple of days ago I decided to change spark plugs. The were very black and dirty (see the picture below) which means that the engine is running very rich.
At the same time I changed the fuel filter. When I started the engine, I could hear a quite loud whining noise from the fuel pump.
Since the engine is injection engine and the fuel pump was whining, this was the key to find a problem. If the pressure in the fuel system is too high, the engine will get too much fuel. Engine adjusts the fuel mixture by adjusting fuel pressure. I googled and the fuel pressure should be around 45psi. I borrowed a fuel pressure gauge and when a started the engine, pressure went to 90psi and didn't stay steady, it was jumping between 75-100. This caused cavitation inside the high pressure fuel pump and made the whining noise.
Some more googling, and I found this VP bulletin about fuel pressure regulator (it allows fuel to route back to filter if the pressure is too high in the fuel pipes on the engine). This bulletin is also attatched to this post.
https://www.dropbox.com/s/i3y1kznhp9btg7g/156 PB P-23-7 N03 V01 Fuel Pressure Regulator.pdf?dl=0
You really should read this thru. This is important. This bulletin indicates the problem with all engines older than 2010.
I opened the regulator and it was cloaked. I changed this screen with the pin mentioned in the bulletin and started the engine. The fuel pressure was 46psi!
So the problem was a faulty fuel screen, worth $2, and it took 10minutes to change with a since screw driver. Sometimes a small problem causes big struggles..
I guess the problem has started 2-3 years ago and got worse all the time until it was so bad the fuel pump didn't work anymore. This was the key finding. I hope this solves somebody else fuel economy problem without two years hunting.
Pics:
Bad spark blug vs new
Fuel screen inside the regulator:
Finally, a correct fuel pressure:
Comments
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Andy
Andy
rinkerboats.vanillaforums.com/discussion/1899/volvo-engines-check-your-oil-hose-connectors
Andy
Removing the regulator was easy, pull the retaining pin, and after a wiggle or two it came out. The fuel inside was milky, not sure why.
Thanks to our Finnish friend JohnnyCake for bringing this to our attention. The bulletin from VP made the install straightforward. Anyone with pre 2010 5.0 VP power should do this fix before the high pressure problem happens.
I love this forum!
Andy
Andy
2007 300 EC, 350 Mags, B3's, Table Rock Lake, MO
Just a thought ?
whats going to stop the crap getting into the ejectors if you take the screen out
..does nothing to keep debris from.injectors