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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 11077
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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My 1995 pro boss GT-40 EFI turns over like normal but won't

Customer Question

My 1995 pro boss GT-40 EFI turns over like normal but won't fire. In my 12 years of ownership, never had an issue. My local dealer gave me a quick diagnosis of bad fuel pump and would not help any further. How can I verify that fuel pump is my issue?
JA: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else important you think the Marine Mechanic should know?
Customer: I have heard that the fuel pumps for this model are no longer available in their original form and an after market one is. I want to make sure it is not something else to consider. Thanks, Dana
Submitted: 2 months ago.
Category: Boat
Expert:  Tan replied 2 months ago.

Hello, I'm Tan. Welcome to JustAnswer. I'm reviewing your question and will reply momentarily.

Expert:  Tan replied 2 months ago.

The easiest way to check fuel pump is check for voltage on the terminals of the fuel pump. If you have voltage do you hear the fuel pump running?

Customer: replied 2 months ago.
Will I hear it with just the ignition on, or will it have to be turning over?
Expert:  Tan replied 2 months ago.

It should run momentarily with key turned to on position.

If you can't here it loosen a fuel line on the pressure side of pump and crank engine do you have fuel.

Customer: replied 2 months ago.
Thanks, ***** ***** check and see. The boat is in my storage building remote from me.
Expert:  Tan replied 2 months ago.

Ok post back with findings. We can find the issue.

Customer: replied 2 months ago.
Turned key on, heard two click type sounds, cranked over and it started. Ever heard of such a thing?
Expert:  Tan replied 2 months ago.

The clicks could be the relays that tun on the fuel pumps. If the relays had a bad connection or low voltage they won't come on and the fuel pumps will not run. What made the mechanic think fuel pumps were bad? Did he do any troubleshooting?

Customer: replied 2 months ago.
That is a good question. I am going to launch and test soon and see if operates properly. Thanks
Expert:  Tan replied 2 months ago.

Ok keep me posted. Thank you..........Tan

Customer: replied 2 months ago.
Just to let you know, put boat in the water and it fired for a second and that was it. It cranked good but no fire. I loosened the fuel line and could not detect any gas being pumped.
Expert:  Tan replied 2 months ago.

Have you done any voltage tests to the pump? You could have an electrical issue with no voltage to the pumps or failing fuel pumps. We have to check for voltage to the fuel pumps. If you have voltage we have to see if the pumps are running. This requires a fuel pressure test.

Customer: replied 2 months ago.
Thanks, ***** ***** test.
Expert:  Tan replied 2 months ago.

If fuel pump doesn't have voltage replace fuel pump relay. If fuel pump still doesn't have voltage post back and we can troubleshoot further.

Customer: replied 2 months ago.
Do you have the part number of the fuel pump relay for this motor? I did not detect any voltage.
Customer: replied 2 months ago.
Also, how do you check the 12.5 fuse to make sure it is ok?
Expert:  Tan replied 2 months ago.

Fuel pump relay R130011. Here is a link to the part. https://www.nautiqueparts.com/product/relay-pcm-for-gt40-fuel-pump-and-ecm-r130011/

To test the fuse you can check for voltage on both wires going to the fuse or test fuse with ohm meter you should have continuity.

Customer: replied 2 months ago.
Installed relay and tested fuse. Still did not detect any power to the fuel pump.
Expert:  Tan replied 2 months ago.

We need to check for voltage on # 21 green/yellow and #17 blue/black going to the relay when cranking engine. Connect volt meter to these 2 wires. It doesn't matter which is which we just want to see voltage.

These turn relay on to turn fuel pump on. Be sure we have 12 volts on the red/purple.

Expert:  Tan replied 2 months ago.

Sorry # 21 is a blue/orange the green/yellow is power to fuel pumps.

So test for voltage on the blue/orange and purple/black. Do you have voltage when cranking engine?

Expert:  Tan replied 2 months ago.

Blue/orange is ground from ECA # 11 and purple black is voltage from EEC system relay # 13.