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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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Was running my Yamaha HDPI 200 hp. It just died. Fuel bulb

Customer Question

Was running my Yamaha HDPI 200 hp. It just died. Fuel bulb was soft. Pumped it up it tries to start but the bulb goes soft. Plenty of fuel on board.
Submitted: 2 months ago.
Category: Boat
Expert:  Jeff G. replied 2 months ago.

When the bulb goes soft does it flatten our, collapse?

Customer: replied 2 months ago.
No sir just gets soft
Expert:  Jeff G. replied 2 months ago.

Sorry for the delay I typed out a long explanation only to have the program crash.

A primer bulb takes the place of a fuel pump to fill the engine with fuel. As you squeeze the primer bulb the carburetors or VST in the case of fuel injection has an inlet that lets the fuel in. Once full the inlet closes and the bulb gets firm. Once the engine starts running the inlet opens to allow more fuel to enter and the bulb softens. As long as the bulb doesn't deform or flatten you should be good to go. When running the bulb is just a part of the fuel delivery system. Being the softest part of the system if there is a restriction it flattens first.

You can rule out the fuel delivery by running the engine on a portable tank and different fuel line.

Being that you have a HPDI engine some of the fuel pressures, particularly while running or shortly afterwards, are extremely high. It is an engine I don't recommend someone without the training to work on without the training or proper tools. So a trip to the local shop would be in order.

Now that doesn't mean you can't check some things.

Start the engine. While running slowly have a helper squeeze the primer bulb. Does the engine stay running? If so then the lift pump, a low pressure pump that brings fuel to the engine may be due for an overhaul.

Try this and let me know what you find. We'll go from there.

Finally do you have any fuel injection tools or background?


Customer: replied 2 months ago.
No tools or background. I will try the primer bulb issue and get back with you.
Expert:  Jeff G. replied 2 months ago.

Thanks, we'll go from there.

Customer: replied 2 months ago.
Jeff it appears that by tapping on the fuel filter there is no fuel in it. Haven't taken off yet to confirm. Does this help you narrow down my problem? Could it be electrical in nature?
Expert:  Jeff G. replied 2 months ago.

If you squeeze the primer bulb do you get fuel to flow to the engine?

Customer: replied 2 months ago.
When we do that it seems like it wants to fire? But doesn't seem to be getting fuel to fire. Is there a sending unit from the tank?
Expert:  Jeff G. replied 2 months ago.

The only thing between the engine and tank is the hose, primer bulb and a anti-siphon valve. Get a quart jar. Follow the fuel line to the filter and disconnect it. Put the fuel line in the jar and squeeze the primer bulb, you should get a strong flow of fuel, may take a few squeezes. If not then you have a restriction. Post back then.

Customer: replied 2 months ago.
Found the problem. There was a 3/8 in line barbed connects that is broken, we have a new brass one and will be installing it shortly.
Expert:  Jeff G. replied 2 months ago.

OK let me know how it goes.

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