1977 F30 318 cuts off under load

[Martino]

So my starboard engine cuts off trying to get up on plane when I apply the throttle.
Any advise and thoughts would be greatly appreciated !

[Lance F28]

Check your fuel filter. You may have enough flow to idle, or run at low RPMs but it may be starving for fuel under power. When I first purchased my 79 F28 with twin 318's my port side motor picked up some trash from the tank and it would barely run 2500-3000 RPM. I replaced the fuel filter and installed a second cheap inline filter between the water separator and the fuel pump so I could intercept any more debris from that tank. I had to change that filter twice and since then I haven't had any problems.

[captainmaniac]

Agree re the filters, or possibly float or choke issue.

I also once had an issue with distributor not advancing but symptoms are different - couldn't climb above a certain RPM, but engine didn't quit.

[oldboat1]

Water separating filter? May need to empty the canister.

Might do a compression check.

[Paul]

Might want to check the anti-syphon valve at the suction tube on top of the tank. Since it's before the filter, debris tends to get caught up in it and can reduce fuel flow. I experienced this exact problem and the symptoms were that I could run all day under 1800 rpm however as soon as I got on plane at 3200 the fuel bowl would go dry and the boat would go dead in the water. A little cranking and she'd fire back up and let me run up to 1800 rpm again.

Hope this helps.

[AlphaJustin]

Mine does that when the fuel filter isn't sealed and let's air in the line. Runs perfect unless you run 3/4 to full throttle then it just shuts off I've gotten used to popping the hatch and adjusting the filter then a couple cranks later and fires right back up good to go.

[Martino]

I replaced the fuel filters and still the same problem.
Is the anti siphon valve in the hard fuel line going from the fuel tank to the fuel crossover valve ?

[prowlersfish]

Its normally right at the tank fitting

[Martino]

So the suspected Anti Siphon Valve was glogged !

[Paul]

Ok, glad that you found the problem. Now for the root cause; What was it clogged with? Does the tank need to be flushed?

[Martino]

It looked like brown crud and spiders

[Martino]

So the engine still intermittently cuts off and when I raise the rpm level it wants to intermittently lower and raise itself. Also when the starboard engine is running and I go to start the port engine the starboard engine cuts off. I'm stumped now.
Any more advise and help?

[Big D]

The wondering rpm sounds like you still have a fueling issue. An running engine quitting when you start the other engine is an electrical issue; poor/ corroded/loose connections or weak batteries. If there's an internal issue or problem with the starting on the engine you're starting last, it could be drawing way more power at start up than normal. Does this happen no matter which engine is started first?

[Martino]

The wondering rpm sounds like you still have a fueling issue. An running engine quitting when you start the other engine is an electrical issue; poor/ corroded/loose connections or weak batteries. If there's an internal issue or problem with the starting on the engine you're starting last, it could be drawing way more power at start up than normal. Does this happen no matter which engine is started first?

The starboard engine only cuts off when I start the port engine. But if the RPM's are up on the starboard engine it doesn't cut off.
Im going to investigate all connections with the batteries and drain the water separator canisters to get a look at the fuel.

[Martino]

Checked all the battery cables and found nothing out of the ordinary. However, I have to start the starboard engine first and keep it's RPM's above 1000 in order to start the port engine without the starboard engine stalling.
If the port engine is running first and I try to start the starboard engine it just cranks but won't kick over. If the port engine isn't running the starboard engine does start.
Ok this is really a pain in the Butt