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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10979
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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Motor will start but won't stay running. Checked the relay

Customer Question

motor will start but won't stay running. Checked the relay and thought the diagnosis was the relay and not the fuel pump. Bought a new relay and had the same problems. I can prime the carb by throttling the throttle a couple times and it'll start, but when I look into the carb I don't see any fuel going in. What's the next step. I can jump the relay and get the pump to run.
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.
Hello. My name is Tan. Connect a volt meter to the fuel pump. Now crank the engine does the pump get voltage? Once engine starts does the voltage go away? Could I get the engine model number please?
Customer: replied 2 years ago.
5.0 Volvo Penta GL-B S/N:(###) ###-####
I checked the voltage earlier across the relay, had voltage while cranking but I didn't let it start.
Expert:  Tan replied 2 years ago.
Will the engine start and run then die? If yes we need to verify the fuel pump is getting voltage. The relay is turned on when cranking then once the engine is running the alternator turns the relay on.
Customer: replied 2 years ago.
Still has voltage when the engine starts.
Expert:  Tan replied 2 years ago.
Ok the next step is to check fuel pressure at the carburetor. Check and see that you aren't loosing voltage at the ignition coil.
Customer: replied 2 years ago.
ok how do we test for voltage? I don't have a pressure gage
Expert:  Tan replied 2 years ago.
Test for voltage with a volt meter at the ignition coil positive side. How did you check for voltage to the fuel pump? Loosen the fuel fitting on the carburetor crank the engine do you have fuel squirting from the fitting. Wrap a rag around the fitting to catch the fuel. Be very careful raw fuel is a fire hazard.
Customer: replied 2 years ago.
Disconnected the harness from the fuel pump and tested the harness. I'll check for pressure.
Expert:  Tan replied 2 years ago.
Did you test for voltage while engine was running?
Customer: replied 2 years ago.
Yes I did. Had 13V while running. Just checked for the fuel pressure, had good pressure to the carburetor. I'm assuming now that I've probably got a stuck float.
Expert:  Tan replied 2 years ago.
Yep the carburetor is dirty. Stuck float or debris in the carb. If your going to have the carb apart you might as well disassemble completely, clean and install a carb kit. Post back if you need further assistance.

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