Df115

[Rct2791]

Have twin df115's on my glacier bay. Starboard engine started shutting off at idle runs fine at high speed. Researched at found that iac valve was possibly the problem. Took boat out yesterday and now port engine is doing the same thing any thoughts waiting on new iac valve will be here Friday before I order another one.

[Moonlighter]

Stalling at idle speeds could be as simple as a bad anti-syphon valve/s on your fuel tank/s. Which could be due to picking up a load of dirty fuel.

That would be the first thing I would do - remove those anti/syphon valves and replace them with a simple elbow fitting. Itsalso the cheapest thing, cost is virtually nil if you spend the small amount of time to do the job yourself.

What is the fuel tank arrangement on your boat? Do both engines share 1 fuel tank, or, separate tanks for each engine?

[Rct2791]

Df115's

They have separate tanks and filters

[catacom225]

Hi, Sounds like you might have some bad fuel to have two go out, as Moonlighter has suggested follow the fuel trail first. Also let us know how it is running, rough or normal

[Rct2791]

Df115

Poured fuel out of fuel filter into glass jar. No water no sediment clean as a whistle. Idles rough up to 1500 rpm then smoothies out like nothing's wrong. Changed spark plugs no difference. Changed iac valve no difference. Still scratching my head on this. Looking for all the advice I can get.

[artdf175]

Fuel question
How old is the fuel and do you use a fuel stabilizer ?
Just to rile out the fuel as the source of your problem- hook up a small fuel tank and run it a while
Other thing did you check the filter screen on the high pressure fuel pump?
Art

[Moonlighter]

Anti-syphon valves on your fuel tanks....... a quite common problem.

At higher revs the motor can suck fuel thru, but at idle insufficient fuel pressure and flow to keep them open..... thus the engine stalls. Fixed the same problem on my mate's Seaswirl Striper, exact same symptoms you described, that got progressively worse. The valves can simply fail due to age.

As I said earlier, its the simplest, easiest and least expensive thing to remove them, as long as you can access the fuel tank fittings where the fuel hose connects.

Either replace them with new ones, or better still, punch the little ball, spring and seat out from inside and reinstall them so they are now just a clear elbow fitting. Exactly what I did on my mate's boat, problem immediately solved.

Nothing to lose by doing this. No downside if this doesnt solve the problem, either, they are not a requirement on outboard powered boats - in fact IMO its just preventing an almost certain future problem.

It would have been the first thing i would have tried......

I would have put money on it not being an IAC valve issue, if they play up the symptoms are usually erratic high revving when engine is started.

[catacom225]

Im thinking bad fuel from the fuel bowser,not uncommon , but you need to tick off all the things the guys are telling you, and sooner or later they will get to the bottom of things. Oh one other thing, try draining the VST and see if any junk comes out. As Moonlighter says "You have nothing to lose"