Mercury 40-HP FOURSTROKE Fuel Problems - Moderated Discussion Areas

  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Whaler Repairs/Mods
  Mercury 40-HP FOURSTROKE Fuel Problems

search | FAQ | profile | register | author help

Author Topic:   Mercury 40-HP FOURSTROKE Fuel Problems

mikester08_75 posted 08-08-2009 08:26 PM ET (US)
I have a 2004 Mercury 40-HP FOURSTROKE motor on my 130 Sport. At first, it would idle fine, but when I revved up to get on plane, the motor would sputter and choke. Eventually the overheating alarm would go off. Now the motor won't start at all. It seems like it isn't getting fuel. I have checked all that I know: fuel filter, priming bulb, spark plugs, etc. I was told that when the engine is turned on, I should be able to hear the fuel pump hum. Is this true? I don't hear anything.
Fuel makes it to the fuel filter when I pump the primer bulb, but obviously it doesn't make it all the way to the fuel injectors. Do I need a new fuel pump? Where can I get one? Can I install it myself?
jimh posted 08-09-2009 08:20 AM ET (US)
Are you certain that your 2004 Mercury FOURSTROKE 40-HP has electronic fuel injection? The cowling decals using indicate this clearly with the letters "EFI."
It is typical in most modern motors with electronic fuel injection that there will be an electrically operated fuel pump which provides fuel under pressure to the fuel injectors. The pump may be integrated into an assembly with a fuel-vapor separator and recirculation filters. Typically you can hear the electric motor in the fuel pump run when the ignition key is turned to ON from OFF and the motor has not been running for some time (so that the pressure in the fuel rail has declined). The introduction of gasoline blended with ethanol has been a problem for some components in the fuel system.
weekendwarrior posted 08-09-2009 10:35 AM ET (US)
Are you sure it is a fuel problem? Overheat is not normal for a 4-stroke ever. Might be worth the few minutes it takes to run a compression check. Blown head gasgets are a common side effect to an overheat on a 4-stroke.
mikester08_75 posted 08-09-2009 12:47 PM ET (US)
Jimh: Thanks for your response. The motor is indeed "EFI." I do not hear any "hum" when I turn ignition key to ON. I have been told by knowledgable, but non-expert people that I probably need to replace the fuel pump. I can't seem to find one, however. Any suggestions? Is there any way to verify that this indeed is the problem?
weekend: I don't know for sure that the engine was actually overheating, it's just that the "alarm" was going off. I suppose that could indicate other warnings, as well. Can you tell me how to run a compression check? I admit that I'm new to all this. Thanks for your help.
weekendwarrior posted 08-10-2009 04:02 PM ET (US)
To run a compression check you will need a compression tester, available at your favorite tool store (sears!) for not much money. If you don't think it actually overheated then maybe you do have an actual fuel issue.
jimh posted 08-11-2009 04:01 AM ET (US)
To locate the fuel pump, follow the path of the fuel hose from the tank to the motor. Typically there is a lift pump which is operated from crankcase pulses that pulls fuel from the tank to the motor. The lift pump feeds into the electric fuel pump for the fuel injection. Follow the hoses.

Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.

Author	Topic: Mercury 40-HP FOURSTROKE Fuel Problems
mikester08_75	posted 08-08-2009 08:26 PM ET (US) I have a 2004 Mercury 40-HP FOURSTROKE motor on my 130 Sport. At first, it would idle fine, but when I revved up to get on plane, the motor would sputter and choke. Eventually the overheating alarm would go off. Now the motor won't start at all. It seems like it isn't getting fuel. I have checked all that I know: fuel filter, priming bulb, spark plugs, etc. I was told that when the engine is turned on, I should be able to hear the fuel pump hum. Is this true? I don't hear anything. Fuel makes it to the fuel filter when I pump the primer bulb, but obviously it doesn't make it all the way to the fuel injectors. Do I need a new fuel pump? Where can I get one? Can I install it myself?
jimh	posted 08-09-2009 08:20 AM ET (US) Are you certain that your 2004 Mercury FOURSTROKE 40-HP has electronic fuel injection? The cowling decals using indicate this clearly with the letters "EFI." It is typical in most modern motors with electronic fuel injection that there will be an electrically operated fuel pump which provides fuel under pressure to the fuel injectors. The pump may be integrated into an assembly with a fuel-vapor separator and recirculation filters. Typically you can hear the electric motor in the fuel pump run when the ignition key is turned to ON from OFF and the motor has not been running for some time (so that the pressure in the fuel rail has declined). The introduction of gasoline blended with ethanol has been a problem for some components in the fuel system.
weekendwarrior	posted 08-09-2009 10:35 AM ET (US) Are you sure it is a fuel problem? Overheat is not normal for a 4-stroke ever. Might be worth the few minutes it takes to run a compression check. Blown head gasgets are a common side effect to an overheat on a 4-stroke.
mikester08_75	posted 08-09-2009 12:47 PM ET (US) Jimh: Thanks for your response. The motor is indeed "EFI." I do not hear any "hum" when I turn ignition key to ON. I have been told by knowledgable, but non-expert people that I probably need to replace the fuel pump. I can't seem to find one, however. Any suggestions? Is there any way to verify that this indeed is the problem? weekend: I don't know for sure that the engine was actually overheating, it's just that the "alarm" was going off. I suppose that could indicate other warnings, as well. Can you tell me how to run a compression check? I admit that I'm new to all this. Thanks for your help.
weekendwarrior	posted 08-10-2009 04:02 PM ET (US) To run a compression check you will need a compression tester, available at your favorite tool store (sears!) for not much money. If you don't think it actually overheated then maybe you do have an actual fuel issue.
jimh	posted 08-11-2009 04:01 AM ET (US) To locate the fuel pump, follow the path of the fuel hose from the tank to the motor. Typically there is a lift pump which is operated from crankcase pulses that pulls fuel from the tank to the motor. The lift pump feeds into the electric fuel pump for the fuel injection. Follow the hoses.