4.3 LX Starting Problems

[bobuk]

hi bug up, i'm very new to mercruisers myself, but i think i read somewhere that the electric fuel pump operates when there is oil pressures, i'm not 100% sure as i have a mechanical pump! A sure way could be to check when the fuel pump actually operates with a voltmeter across it. As well as this you could try checking for fuel delivery to the carb by disconnecting the inlet pipe, but i cannot emphasise enough that you must find a method of doing this safely, grounding the h't lead to make sure theres not gonna be any sparks , and collecting pumped fuel into a connected pipe away from the engine. As for when it starts, could it be the angle the boat sits in the water? Good luck bob

I am having a hard time starting my 4.3LX. It will start fine in the driveway or when I first launch at the boat launch, however my problems have been after it has been in the lake over night. I know this sounds wierd but every morning or after it has sat for 5 hours or in the water the following happens: I pump it once and it starts and runs for about 20 - 30 seconds and then dies. I then removed the flame arrestor and asked my buddy to pump the throttle and I can't see any fuel being shot in. After this the only way I can get it to start is by putting a little gas or ether down the carb and then it will fire. After it starts I then have to hold the revs at 1500 until I get some temp and then I can bring it back to idle.

Some questions I have are :

1. Any idea of what is happening because it is getting a little embarassing at the camp site?

2. When I turn the key on should I be able to hear the electric fuel pump? I hear nothing and I am curious if this is why I can't get fuel when I try to prime it.

Please help. Thanks

 

[bugup]

Re: 4.3 LX Starting Problems

Bob:

That just dawned on me as well. The angle that the boat sits in the water I believe is the reason it won't start. I think that the carb must drain at that angle where as in the drive way on the trailer it does not, therefore it has no fuel to run on. Could this be actually whats happening and if so, what may be the problem as why it would drain?

 

[bugup]

Re: 4.3 LX Starting Problems

I'm bugup as well, however, I was having trouble logging on so I had to sign up with a new name.

 

[bamadave]

Re: 4.3 LX Starting Problems

1-if you can't see fuel shooting down the throat of the carb when you apply throttle- rebuild the carb
2-Fuel pump is controlled by a oil pressure switch, carb should have enough gas to start engine, when oil pressure comes up, fuel pump will come on.
If you aren't familiar with the carb, take it to a qualified shop.

 

[bugup]

Re: 4.3 LX Starting Problems

I was thinking last night that when I do start it after a night in the lake it wil run for about 30 sec or so however it then dies and I can't get fuel to the carb. Is it possible that the fuel is draining back into the tank during long sits and as a result the engine will run on whats left in the carb but then has no more fuel because the oil pressure hasn't had time to come up yet? Is there a one way valve out of the tank to prevent this and as a result may not be closing properly at the angle it sits in the water and the fuel drains out of the line slowly during long sits? Then when I put some fuel down the carb it is enough to get it started and get the oil press up so the pump will kick in and keep it running.

 

[1994almeida]

Re: 4.3 LX Starting Problems

I have a similar problem.

Check the connection switch of the electric fuel pump.

The pump has internal pins, that are difficult to connect with the switch.

.

 

[bugup]

Re: 4.3 LX Starting Problems

1994almeida

Can you expand some more on this. What exactly am I looking for?

 

[1994almeida]

Re: 4.3 LX Starting Problems

My 1998 4.3 LX with electric fuel pump, starts and runs for about 20 - 30 seconds and then dies.
The cause of this problem was a bad electric connection of the electric fuel pump.

The fuel pump has an electrical connector which pins could retract with the engine vibration and than interrupt the electrical supply to pump.

During the start, after the engine raise enough oil pressure, the electric fuel pump begins to work, obviously if it has electric supply.

Best regards Almeida

 

[bugup]

Re: 4.3 LX Starting Problems

I don't believe this is the problem because it works no problem on the trailer. It only does this after sitting in the water for 7+ hours. I think maybe the float in the carb is not set right so ( in the water at that angle) after you shut it down the bowl thinks it is full and won't allow anymore fuel in. Any comments?