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Fuel pump not running - 2004 mercruiser 5.0 throttle body

M

Mcgiver

New member
Just serviced the fuel filter/water separator and now the fuel pump won’t run.
usually when I turn the ignition on, it will beep and the pump runs a few seconds to pressure up. Changed the filter cartridge and now the fuel pump never activates. Ran fine before I messed with changing the fuel filter.
Any advice or help is appreciated.
 
A little more.. when you changed the the fuel/water separator (filter) canister did you fill the fuel/water separator canister with gas (3/4 full) before you reinstalled the canister? You should fill fuel/water separator (filter) canister with gas before reinstallation so the fuel pump does have fill the canster first with gas before starting. I'm interested in your solution.

Note: this procedure also applies to (Automotive/Marine/whatever) oil filters. Always fill the oil filter with oil before reinstallation.
 
Did not put in enough gas and the motor started but for about 30 seconds and ran out of gas. In a further look, it appears that the filter may be on the suction line from the fuel tank? One line from the tank to the filter housing on the front side and two lines on the back side of the housing
Anyway, now the fuel pump does not initialize when the key is turned on.
Why?
 
maybe the pump has failed ... or the relay feeding it current has failed...

the relay can be jumped, for testing purposes...
 
This is the second time I’ve heard of having the fuel pump come on when the key is turn on. Is this something they changed in newer designs? How is this CG approved.?

My 1990 mercruiser 4.3 has a oil pressure switch with one power leg running to the starter solenoid and the other through the oil pressure switch. So it only powers the fuel pump when it’s being turned over. Then After the motor fires up and oil pressure is present, the switch engages and keeps the fuel pump running. When the engine dies or is shut off, the fuel pump shuts down.

Kirk
 
Not really, on the early injected motors, the ECU typically controls the fuel pump via a relay...instead of using an oil pressure switch (on the carb versions), it uses the pulses from the distributor to indicate the engine is running..
 
makomark said:
Not really, on the early injected motors, the ECU typically controls the fuel pump via a relay...instead of using an oil pressure switch (on the carb versions), it uses the pulses from the distributor to indicate the engine is running..
Click to expand...
So the fuel pump doesn’t run when the motor isn’t running… that sounds logical. So when you turn over the engine the pulses from the distributor activates the fuel pump to prime it and keep it running once it fires. But what about these guys saying their fuel pump kicks on when they turn on the key? That doesn’t sound right to me…. Kirk
 
on the ECU equipped engines, when the key is turned to RUN, and the ECU 'wakes up', it will activate the fuel pump relay for a couple seconds to prime the fuel rail.

this won't happen on a non-ECU engine when it is wired properly and has no malfunction...

once somebody has started changing parts and wiring, anything can happen....
 
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