Mercruiser only starts with starting fluid

[BrennanB]

I’ve had an annoying problem this summer with my tige 22i it has a Mercruiser 350.

it doesn’t matter if it hasn’t been started or if it’s warmed up it will not even bump over once without starting fluid. Give it a spray of starting fluid and it idles flawless, has a little stutter at lower rpm’s but runs great after 2500rpms.

Fuel pressure goes to 4 after one key cycle then 39 after 2-3 more cycles. I’ve replaced the low pressure pump, fuel/water separator, it’s went through 3 full tanks of gas, the fuel pressure regulator screen was spotless and vent hose is dry, high pressure pump sounds good.

what could it be?

[Vettedrmr]

How does it run between idle and 2500 rpm?

Edit to ask more questions: Have you performed a fuel pressure bleed down check? It should hold pressure fairly well. I had a need to test mine today ('08 22ve), and it bled down from 48 to 45 psi in 10 minutes.

Have you looked at the plugs? You might find one (or more) that are sooty and rich running. If so, you might have an injector that's leaking.

[BrennanB]

Thanks for the reply!

it has a bit of sputter between 1500-2500 roughly.

I did do a bleed check and it lost about 1 psi/minute, ai says it’s not that bad lol.

for the spark plugs, whoever got ahold of them last over tightened them way too much, so trying not to open that can of worms yet.

[Vettedrmr]

Seems to me like a 1 psi/minute leakdown could be pointing to injectors that need servicing or replacing (I'd replace them, they're what, 20 years old?). Option 2 would be a weak ignition coil. I like that option less because I think it wouldn't smooth out at higher rpms. Leaky injectors tend to clean up as you demand more power from the engine, just because the leak is overcome by the fuel demand.

HTH, and have a good one,
Mike

[BrennanB]

Ok. I’ll order some and see what happens, I’ll let you know.

if it’s just a couple injectors, wouldn’t it atleast sound like it’s getting some fuel and trying to turn over?

[BrennanB]

Also, this may change things I totally forgot. It sat for two years. I drained as much of the bad gas as a could. Then filled it up with premium and added octane booster. It started by itself like 1-2 times and after that but never did again.

[Vettedrmr]

Ok. I’ll order some and see what happens, I’ll let you know.

if it’s just a couple injectors, wouldn’t it atleast sound like it’s getting some fuel and trying to turn over?

The opposite. I'm thinking the engine is trying to start flooded; the starter fluid forces a combustion event, which gets air into the engine, and off you go.