Volvo Penta Fuel Pump

Joined
May 22, 2018
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7
Hello,

After experiencing several of the Penta fuel pump issues outlined on other threads I replaced the entire fuel pump assembly on a 5'7 GXI-H with an Amazon special. When attempting to start, the exhaust was throwing gas and the engine would sputter. I pulled the electric to the LP pump and this would at least allow the engine to run. After further exploration, I discovered that the pump was sending fuel to the manifold. This seems very odd and guessing the pump is garbage. Disconnected the line in the picture and the electric from the LP pump and it's running fine. Looking to understand what each line/vacuum is from the pump. Pictures attached...

The LP pump seems to be loading the air intake and the blue valve is pulling pressure when i put my finger on it. Pulled the hose to the vacuum and pulled the power to the LP pump and the boat's running fine. Does anyone have the purpose of each module on the fuel pump assembly? Saw several posts but don't understand the purpose of each mechanism in the assembly. Also looking to understand if the pump should be pushing gas to the manifold? Any response is appreciated. Thanks!
 

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Scott Danforth

Grumpy Vintage Moderator still playing with boats
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take a look at the fuel section in the manual
 

alldodge

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exhaust was throwing gas and the engine would sputter.
Disconnected the line in the picture and the electric from the LP pump and it's running fine.

The lines in your pic I see as fuel return lines, not vacuum. Disconnecting the LP pump will reduce the amount of fuel that the HP pump has available by restricting the fuel supply.

With to much fuel going into the exhaust, would be caused by one or more injectors which are leaking or stuck open, or the regulator is stuck closed.

The item with the blue valve should be a pressure sensor

Suggest getting a fuel pressure gauge and connect to the fuel rail shrader valve (item 23). The valve will have a cap over it which unscrews.

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7746190-23-21521.aspx
 
Joined
May 22, 2018
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Thank you for your response.

I did in fact check the fuel diagram but it does not state the purpose of each component in the pump assembly and how it works. I also checked the pressure on the rail and it's reading 55-60 PSI which I believe is appropriate.

So looking at the diagram and reading your post. If I understand correctly, hose #17 should not have fuel pumping through it? That's the issue I'm having when the LP pump is plugged in.

The engine runs completely fine with the LP pump and the identified hose disconnected. With them both connected, it completely floods out and gasoline comes out the exhaust. Guessing there is an issue internally with the pump if fuel should not be coming from that hose? The hose in the picture with the yellow arrow. The other two feed the fuel rail.
 
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BRICH1260

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Jul 6, 2011
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I`m no expert, but have rebuilt my fuel pump to head off any pump failure issues. Something is wrong, and I think it is in your hook up. The low pressure pumps role is to pull fuel from the tank and filter and feed the high pressure pump, whose job is to feed the fuel rail at high pressure, with the excess build up being sent back to the fuel float chamber. It shouldn't really run well at all with only one pump energized. Double check your pump hoses against a proper diagram or photo and make sure everything is in its proper place .
 
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alldodge

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If I understand correctly, hose #17 should not have fuel pumping through it?

Correct, that lines has fuel in it only when the pump seal is bad. It keeps fuel from leaking into the bilge and directs it to the intake manifold.

With that line having fuel in it, the pump seal on the Amazon pump is leaking
 

alldodge

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I doubt you can swap the fuel lines because they should be different sizes, but do check this
 
Joined
May 22, 2018
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Thanks again! Yes, the fuel lines are different sizes so it'd be difficult to mess that up. But the plugs for the pumps are the same. Guessing it does not matter if these get reversed?
 
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