Merc 4.3 Gen 2 No start & no fuel

[Grant Brown]

1993 Merc 4.3 Alpha 1 Gen 2 - 2bbl. Took boat to ramp and it wouldn't start.
Realized quickly that it wasn't getting fuel. Will run fine when primed and then stall out as soon as the fuel is used.
Got power to fuel pump when cranking.
Can blow through water separator and filter no problem (not blocked at all).
Bench test pump w battery and seems to work (can hear it).
Reinstall pump in boat with line to tank (filter and separator too). Leave top line disconnected. Run jumper power to pump and can hear it running but no fuel comes out. Ran it for a good solid 10 seconds and nothing.

Is the pump shot or am I missing something?

Grant

 

[Eric 3.7LX Alpha 1]

Re: Merc 4.3 Gen 2 No start & no fuel

Sounds like it to me. Possibly try to bench test the pump again but with a portable source connected to the inlet to check for flow.

 

[ENSIGN]

Re: Merc 4.3 Gen 2 No start & no fuel

There's a oil pressure switch on the port side of the engine above the oil filter. disconnect the two wires and temporarly jump them together and see if it will start and stay running

 

[Grant Brown]

Re: Merc 4.3 Gen 2 No start & no fuel

I can hot wire it to get it running independent of the rest of the electrical system. It still isn't pulling any fuel from the tank. The lines and filters are clear.

There is power to the connector when the engine cranks but still no fuel being pumped.

It seems to me that if there is power at the pump connector when the engine is being cranked then the oil pressure sensor/switch should be working fine. Not trying to be difficult if there is an reason why I'm wrong please elaborate. I don't want to spend $340 on a fuel pump for no reason...

Thanks,
Grant

 

[fishinpa]

Re: Merc 4.3 Gen 2 No start & no fuel

If you checked the pump by using a remote fuel source and wired it direct -to run , and you get no flow it seems fairly obvious that your pump is bad !

whether or not you get power to it when cranking is another story ..


fish

 

[Blk-n-Blu]

Re: Merc 4.3 Gen 2 No start & no fuel

Possibly the anti-siphon valve at the tank

 

[Grant Brown]

Re: Merc 4.3 Gen 2 No start & no fuel

I convinced my buddy who was helping to try and suck fuel up out of the tank through the filters...
It worked, better him than me...



So in that case I think it's getting through just no pumping going on.

 

[Bondo]

Re: Merc 4.3 Gen 2 No start & no fuel

So in that case I think it's getting through just no pumping going on.

Ayuh,... Sounds like ya need a New 1...

 

[Bt Doctur]

Re: Merc 4.3 Gen 2 No start & no fuel

there is a safety pressure switch just above and foward of the oil filter. You get power during cranking thru the starter solenoid. Cranking does not always mean you have enough oil pressure to turn it on. bypass the pressure switch for testing,

 

[nofuss]

Re: Merc 4.3 Gen 2 No start & no fuel

If your buddy was able to suck fuel through the system right to the pump intake and the pump is not able to pull fuel after reconnecting (after the suction check) it means you need a new pump. note if u did not try it after you had the fuel sucked through u need to try it again. if i change a filter and i dont full it right back my pumps wont pull the fuel to prime the system. but if i full it or use a primer bulb to suck fuel through the system they work well after wards.
one of my pumps seemed to not pump when i first got my boat to trinidad. 4.3EFI high pressure pump. u could hear it spinning but it would not pump. on cutting it open we realized that the vanes were stuck into the hub so it could not pump. it was actually left sitting with a mixture of fuel and water for about a month, so thats what caused it in my case.

 

[Grant Brown]

Re: Merc 4.3 Gen 2 No start & no fuel

It was the pump. replaced it and the carp, rotor, wires and plugs.
Started on about 1/2 a click of the key! This thing was always hard starting and a slug when cold.
Now it PURRS!
Can't wait to get up early and take it for a run...
Yahoo!
Thanks for all the advise and help, as usual this forum is awesome. What a great use of internet.