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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through July 28, 2009 » EFI experts please help « Previous Next »
By gp (goinboardn) on Tuesday, July 21, 2009 - 10:01 pm:    Edit Post Delete Post
1998 Mercruiser 350 MAG MPI EFI

Trying to be absolutely sure before I spend the $350 to replace Fuel pump and cooler (can only purchase the complete unit now)

Out surfing and the boat bogged down and just died. will turn over but not start.

- Spark yes
- Fuel pump makes normal start up noise when ignition is turned to the on position
- Fuel/water separator and filter full of 3/4 H2O and grime - replaced and filled with clean fuel.
- fuses related to EFI good
- Kill switch good
- Main breaker good

If i take a primer bulb in a fresh can of fuel and hook it straight into the fuel/water separator housing I can prime and start the boat and keep it running (albeit rough)... my last hope is that there may be a relay or something??

Anyone have any last ditch ideas for me?

 
By Ian Scarlet (imscarlet) on Tuesday, July 21, 2009 - 10:13 pm:    Edit Post Delete Post
Did you replace the filter or clean it? Replace it before going further! Also may pay to run injector cleaner through it as you may have dirt in the injectors if filter was bad. Also does it now run from the tank or have you not tried? Finally check fuel pressure at the rail to see if its high or low as your problem could be caused by the pressure regulator.
 
By gp (goinboardn) on Tuesday, July 21, 2009 - 10:54 pm:    Edit Post Delete Post
Did you replace the filter or clean it? Replaced

Also may pay to run injector cleaner through it as you may have dirt in the injectors if filter was bad. good idea

Also does it now run from the tank or have you not tried? Tried after i pressurize with the bulb, disconnect and reconnect main line. runs for about 15 seconds then dies.

Finally check fuel pressure at the rail to see if its high or low as your problem could be caused by the pressure regulator. Going to pick up a gauge tomorrow. where is the regulator?

 
By Ian Scarlet (imscarlet) on Wednesday, July 22, 2009 - 1:20 am:    Edit Post Delete Post
Usually at the other end of the rail from where the fuel pipe from the pump goes to, the regulator controls the fuel pressure going into the injectors by controlling the amount of fuel that leaves the rail. The regulator will usually have a vacuum line attached to it.
 
By Brock Landers (formfunction) on Wednesday, July 22, 2009 - 6:05 am:    Edit Post Delete Post
There should be a cap at the end of your fuel rail,if you remove it there should be what looks like a valve stem on a tire.This is where you check the final pressure.
 
By gp (goinboardn) on Wednesday, July 22, 2009 - 12:37 pm:    Edit Post Delete Post
Zero pressure at the rail... guess its time for a fuel pump. Thanks for the input.
 
By Johnathan Boggs (sharkbit) on Wednesday, July 22, 2009 - 12:53 pm:    Edit Post Delete Post
Let it cool off and see if you have fuel pressure. Could be a vapor lock issue. Had the same problems with my boat. Turned out to be bad seawater pump impeller was not getting enough cooling water through fuel cooler and the fuel was boiling to vapor.

If you get fuel pressure after it cools check your impeller.

 
By gp (goinboardn) on Wednesday, July 22, 2009 - 1:19 pm:    Edit Post Delete Post
It has been dead in the water since Sunday
 
By gp (goinboardn) on Wednesday, July 22, 2009 - 10:14 pm:    Edit Post Delete Post
Well, it was the fuel pump... still stumped at why Mercruiser no longer sells the pump as an individual item and you have to now pay twice as much to get a fuel cooler that you don't even need! $433 later i am up and running.
 

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