Fuel Problem with 98 Mariner 3.0L 225 EFI

[roozter2550]

Sorry for the long post.

I've got a 98 Mariner 3.0L, 225 EFI.

The boat hasn't been used in 1-1/2 years. I used Startron enzyme treatment and Sta-bil stabilizer when it was parked, (didn't think it would be sitting for so long). It's got about 60 gals. in the tank.

I'm getting ready to get back to boating so it's time to go thru everything.

Charged the batteries, (I'll put new batteries in before I take it out on the water but for working on it at home I'll keep charging them). Installed new plugs. Sprayed a little light oil into each cylinder thru the plug hole.
Installed a new Racor water separator, and changed the filter under the cowl.
New primer bulb, and new fuel lines from the Racor all the way to the "pulse" fuel pump, (yes, thru the rigging tube was a pain in the ***)

Prime the system with the bulb.
Motor lights right up first turn of the key, runs for 10-15 secs and dies.
Turn the key again, lights off and instantly dies.
Won't restart at all after that, just cranks and cranks.

To restart, I have to reprime with the bulb.
Starts and runs 10-15 secs and dies.
Same crap again.

First I thought old fuel so I brought out a 5 gal. gas can with fresh fuel, (1 week old) and tried again.
Same crap again.

I tried to start and prime the bulb before it dies out but I can't press the bulb enough times before it sputters and dies.


I don't think it's the high pressure pump in the VST. I checked fuel psi at the schrader valve with a hand held gauge. Turn the key and put the gauge on, got 36psi.

Start the motor, put the gauge on, 36psi at first then slowly dropping until it gets to about 15psi then drops quick to 5 and the motor dies out.

I can hear the high pressure pump running in the VST and it sounds like it's cavitating, (empty or low level in the VST).



I'm thinking the pulse pump maybe shot due to sitting for so long.
Maybe a ruptured diaphram?

I pulled the plugs a couple of times after it wouldn't restart and found them wet with fuel.
I'm thinking that maybe the VST isn't getting enough fuel from the pulse pump, and possibly high engine vacuum may be pulling fuel into the crankcase thru the diaphram.

Am I thinking on the right track before I go throwing a bunch of parts and money at it?

Thanx for any help.

 

[roozter2550]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

Nobody?

crickets...

 

[RLT III]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

Look at the fuel pump that's what it sounds like listening to you. when those diaphragms set like that I think they get weak and then maybe the first crank or a week later they begin to crack and split on the intake side and that is probably what you'll find

let us know

 

[roozter2550]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

Rebuilt the pulse fuel pump today. New gaskets, diaphrams and check valves.

Problem still exists. Runs for approx. 15 secs, then sputters and dies.



I disconnected the line feeding the VST / high pressure pump, annd cranked the motor with no ignition to verify the pulse pump is supplying fuel.

I'm now looking to the high pressure pump.

I removed the VST, and opened it up on the bench.
I removed the pump and ran it off a battery.
It runs stong for a few seconds then starts sounding weaker/slower and "skips / stumbles" a little, (for lack of a better term).
I didn't want to run it dry for too long.

The high pressure pump is pretty damn expensive.
Mercury Parts Express lists the price @ $769.07 !!!

Does anybody else have a source for these?

 

[roozter2550]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

Just an FYI for you guys...

pulled the trigger and bought a high pressure pump on ebay from Speed & Custom Marine in Quincy, FL.

http://cgi.ebay.com/ebaymotors/ws/e...0301318779&viewitem=&sspagename=STRK:MEWNX:IT

$350 plus taxes and shipping.
Pump just came in today. Hopefully, I'll install it this weekend and update on this issue.

Just wanted to let you guys know that there are pumps out there for alot less than merc is charging for them.
I found them going from $350 to $520

By the way, same pump in the yami ox66 motor vst tank

 

[japayton6]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

Did you check the needle and seat in the vapor seperator. They like to stick after sitting .

 

[roozter2550]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

checked and cleaned the needle and seat when I cleaned out the vst.

working smooth and I can blow in when the float is down and can't blow air when the float held up

the one thing I'm unsure of is the amount of volume which the pulse pump should put out.
I rebuilt it with new Merc parts but the only way I could think of to test it was with the ignition disconnected and cranking the motor while having it freeflow into a container.

 

[sschefer]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

checked and cleaned the needle and seat when I cleaned out the vst.

working smooth and I can blow in when the float is down and can't blow air when the float held up

the one thing I'm unsure of is the amount of volume which the pulse pump should put out.
I rebuilt it with new Merc parts but the only way I could think of to test it was with the ignition disconnected and cranking the motor while having it freeflow into a container.

The best way I've found is to T in a vaccum gauge on the pull side. Look for 2.5 normal and about 4 with the line pinched closed. You can put a pressure gauge on the output side also, 3-5 is good. Volume is dependent on the fuel line size if the vaccum is good. Some were 3/8 and others are 5/16. Stick with whatever the stock fittings call for.

 

[roozter2550]

Re: Fuel Problem with 98 Mariner 3.0L 225 EFI

just finished replacing the high pressure pump...

reconnected the batteries, filled the vst with 50:1 premix thru the fitting which comes from the filter/pulse pump.

check over all connections and fired up.

fingers crossed as I watched the pressure gauge....




...fuel pressure stayed steady at 36psi


kept on running and running.






now on to other problems