1999 Mercury 225 EFI Start and Die Problem...

[javiert99]

Hi all, hope it's ok to post about a non high performance set up here, but this seems to be the best place for tech info.

I've got a 1999 Merc 225 EFI, that ran like a top last year, and has always run very well. Unfortunately I had to take the boat down for about a year due to a floor issue and partial rebuild.

For about 6 months out of that year the engine sat without starting.

The fuel tank was removed, drained, cleaned, and reinstalled. About 4 months ago it got 30 gallons of fresh gas. At that point, and since then, I've started the boat back up every once in a while, during the rest of putting it back together. It's always started and run for a few seconds with no issues. When I first got it back 4 months ago I ran it for a few minutes on the hose just fine.

Today was her first day to go off the trailer and down the ramp, she fired up, ran for about 15-30 seconds, bogged down, and died out. Ever since then I can get it to crank / fire for about a second or two then it dies out.

Things I've noticed:

Fuel pump ball does stay hard, I'm getting fuel to the engine.
The fuel pump primes for about 10-15 seconds when the key is "on"...
Once primed, if I hit the shraeder valve I have no pressure, fuel just kinda drips out of the valve
DURING priming i'll get some spray pressure out of the valve, but that's it.

I wanted to test actual fuel pressure but my gauge won't thread on, mean for automotive purposes I guess.

I've read a bunch about the VST filter, and am about to go that route, but what do you guys think about it priming, having a little pressure, then having none?

My plans:

Replace Racor separator
Replace spin on filter on the starboard side of the engine
Replace lines going from Racor to engine (fuel tank to racor is new)
Open up VST and see what it looks like in there

Thanks in advance...

[Go Time]

Did you check to ensure you have ignition on all six cylinders? Your list is a good start. When cleaning the VST, check the pressure regulator inlet. You should be able to get a schrader valve fitting/adapter pretty easy so you can connect a gage and check fuel rail pressure. Does the primer bulb pump up and get "solid" indicating the VST is full and the needle and seat are functioning?

[javiert99]

I haven't checked spark yet, I have to find my spark tester, and it was kinda late. But I will, just in case.

I'm looking for adapters to go from a car rail to a small bike pump type schraeder valve, having some trouble finding them. Maybe I'm not searching for the right thing. Worst case I can get a "T" style fuel pressure tester and pop a temporary line in there to check.

Primer bulb pumps up and goes 100% solid, can't pump any further.

Any thoughts on how the pressure builds up while the pump is running but seems to bleed off completely once it finishes it's prime cycle?

[Go Time]

It will bleed off eventually, but it is usually pretty slow. Do you smell gas from an external leak or maybe some internal leakage via the pump, press reg or even an injector ??? just guessing.

[javiert99]

Funny you mention that, I was "sniffing around" yesterday but couldn't find/smell/see any external leaks. An internal leak would be a bit trickier I imagine since it's inside the VST that I'd be looking?

I know on other fuel injected vehicles I've tested (cars), you're right.. the pump would prime and pressure would stick around for a while, but eventually bleed off slowly. This one has zero pressure once it finishes it's prime cycle.

[Go Time]

Your really need a gage on it to see what you have. Not much fuel needs to escape to bleed pressure down significantly, like most fluids systems. You got plenty of things to check.

[javiert99]

Fair enough :) I'll look into getting the proper adapters to get the gauge going. Thanks for the help so far!

[Capt.Insane-o]

Inlet valve on the VST is prolly stuck and/or full of crap.

[javiert99]

I'm hoping for that to be the case! The VST O-ring that everyone talks about is the $40ish ring that seals off the entire VST assembly right?

[Capt.Insane-o]

If you careful it can be re used.

[javiert99]

Cool, maybe i'll disassemble it and take a peak to see what kinda shape it's all in before I buy.

[Black Outlaw]

Sometimes that o-ring swells when you remove it. If that is the case put it in the freezer while your working on you VST and it should shrink back to normal size. We have had a pump run but not make pressure so don't rule it out just because its running. We have 2 1999 250's on our personal boat, Pretty simple fuel system

[javiert99]

Thanks, I'm prepared at the possibility that the pump may have died from sitting. There's a source here in Florida that sells the high pressure pump with new filter at a more respectable $350.

It does look pretty basic, i'm crossing my fingers that it's just clogged, but we'll see!

I can't find the right adapter to use with a standard automotive fuel pressure tester. What are you guys normally using to check pressure at the schraeder valve with?

[Black Outlaw]

I believe napa has a cheap gauge with an adapter for the small valve included. It's a real crappy gauge but it will do the job. But you may have to use a valve core tool to remove the core then screw it on if I end up at napa today I will look

[Enticer1]

I had the same issue with my 1998 Pro Max and it was the pump. The inside of the VST was absolutely spotless. The dealer told me that the pump was no longer avaliable so I went the Bosh route

[Go Time]

You can still get those pumps. There are several after market sources. The last one I got was off Ebay (new) for less that 300$ w/ the filter. Make sure to get one that includes the inlet filter if the filter is suspect. The filter alone is crazy expensive.

[Capt.Insane-o]

The last filter I bought was from Yammi, as it's the same and was $100 less than what Maocury wanted. The filters clean up well with Dawn and hot water unless it's borked totally.

[javiert99]

Finally got around to this.

Thinking that replacing the pump wouldn't be a bad idea anyways, I went ahead and ordered one. Went the ebay route, came with a new filter and all o-rings. Purchased the new VST tank o-ring as well.

Got everything taken apart, cleaned up, including disassembling the float / needle assembly and cleaning all passages. Put everything back together.

Try again and... nothing.

So.. still, no fuel pressure gauge to work with this setup, going to rig something tomorrow. But since I'm done working for the night...

Once the system primes, there is nothing but a dribble coming out of the schaeder valve when pressed. That can't be right.

I'm thinking I might have a leaking injector, but my friend keeps mentioning the fuel pressure regulator. Could it possible be that?

Of course I haven't ruled out ignition but this really feels / sounds like fuel.

[CharlieB53]

If it worked when you parked it but not now, the vanes in the fuel pump may be stuck.

Once the VST is apart put just enough wally world super tech carb cleaner or comparable light solvent in the VST to cover the pump p/u, trigger the pump to prime a couple times, it should desolve and free the pump vanes.

[javiert99]

Hi Charlie,

I actually replaced the pump, mentioned it in the post just above yours.

On a good note, yesterday I decided to tinker some more. I did some testing on the fuel pressure regulator, found that to be OK (pulled it and verified it would not leak when key off), pulled the whole fuel manifold assembly, checked for leaking injectors, all clear, cranked with no plugs to see that the injectors would pulse, all looked good.

So, dejected that I didn't find anything I put it all back together and cranked it two or three more times. To my surprised she fired and held.

Ran her on the hose for a little while and sounded healthy enough to drop in the water.

Ended up taking the boat on a 2 hours joy ride with the mrs... ha! Has a little off idle roughness that I'd like to clean up. Thinking a decarbon and some fresh plugs should do the trick. Other than that, idle is smooth and top end looks good and has all the RPM.

Thanks for all the help everyone.