10 meter mid cabin fuel starve

[mrrudely]

My port engine was fuel starved at 3000rpm
I removed and cleaned a dirty anti syphon valve with no improvement
I removed the anti syphon valve a second time, it was clean, so I took it out of the loop and problem solved
I would like to replace the anti syphon valve with a new one but I'm thinking that won't help
I am wondering if the problem is in the fuel pick up tube
There is a bushing on top of the tank that seems impossible to loosen
I am afraid to force it
Another mystery is that I ran a wire down the tube to see if I could learn something and it came up dry
There is definitely fuel in the tank, can't figure that one out
any ideas?

[zedtwentyate]

If you have the original Rochester quadrajets, check the filter in the carb. Sediment can build up in there. How about the in-line fuel filters too?

[mrrudely]

Thanks for that but when I open the crossover there is no problem so I don’t think it has anything to do with the filters

[prowlersfish]

Is the cross-over before or after the filters?

[zedtwentyate]

Cross-over should be after the anti-siphon and before the canister filter and carb filter.

Check with Bob to see if he has the original size anti-siphons. I had to use a different. Size that I found at a local shop.

Even if they look clean, just a little bit of ethanol crap will mess it up…

[prowlersfish]

Cross-over should be after the anti-siphon and before the canister filter and carb filter.

Check with Bob to see if he has the original size anti-siphons. I had to use a different. Size that I found at a local shop.

Even if they look clean, just a little bit of ethanol crap will mess it up…

On a diagram, I just dug up it shows the cross-over valve after the canaster fuel filters (not the carb ones of course) . This diagram is for early( F36/32 ? ) Trojans so the 10 meters may or may not be the same.

So check the canister filters it's the same. As could be bypassing one with the cross-over open.

[mrrudely]

I’m reasonably certain I can rule out filters
Unless there is a filter at the end of the pick up tube which I guess could be at the heart of the issue
Does anyone know?
If so do I fear trying to remove the pick up tube?

[BobCT]

Hi, just rec’d your IM as well. There isn’t a filter at the end of the pick up screen but it’s worth checking the tube though.

But, I’m willing to bet it’s the anti-siphon valve which is the issue. That is the fitting that the line connects to on the tank. It doesn’t look like anything from the outside but has a ball/spring which gets clogged. I had the exact same issue on mine when I first bought the boat.

They can be cleaned or replaced, I carry a spare now.


(Forget all of that, just scrolled back up and read your post). Let me think on that but unfortunately no screen that I recall on that pick up tube).

Bob

[mrrudely]

thanks for the prompt reply

I can now rule out filter at the bottom of the pick up tube since there isn't one
everything is pointing to the anti syphon valve
I cleaned the old one and still had the problem
Perhaps even clean they can malfunction
I will replace with a new one and report back

Separately I put a wire down the pick up tube and it seemingly turned up dry
No question that there is fuel in the tank
I wonder if the tube has a hole in it or is decomposed and the wire never got to the bottom or even near
is the tube plastic or metal?

thanks again
rr

[WayWeGo]

Any chance that tank is baffled and the connection between the section with the pickup tube and the rest of the tank is clogged, leaving fuel in the tank but that section dry?

[mrrudely]

I would think the tank would be baffled, that would explain the dry wire, but I don't think that's it
As I said before with the crossover off and the anti siphon valve removed there is no problem
I just ordered a new valve
Will report back after it is installed

[BobCT]

I bet it’s the valve… I think these get overlooked a lot because it just looks like a fitting. Once you get your fuel system clean, you shouldn’t have to touch it again.

If that doesn’t work, I would run that engine off a gas can as a next step.


Bob

[mikeandanne]

Any chance you have a generator fuel feed line tapped into that engines fuel line ?

[kallen]

No one has mentioned what is used for a fuel pump. Do a pressure and volume test on the pump at the carb. Generator has a separate pick up from the tank on my 81 F-32. When I removed the fuel pickup from the main tank there was 6" of copper pipe then a 20" fuel line hose to the bottom of the tank ( not the very bottom ). Maybe the hose has collapsed inside. Also check the flexible fuel hose from the filter to the pump.

[Big D]

+1
Another good test is checking fuel system vacuum. A good diagnostic tool to use in this situation is a digital vacuum meter on the suction side. Maximum vacuum should be 2 inches of mercury at idle otherwise you risk reduced volume, vapor lock, collapsing weak hoses, etc. Any restriction in the suction side will increase vacuum. This could be too many fittings, a kink in the hose, collapsed hoses, clogged or stuck anti-siphon valves, clogged intakes, etc. Compare the reading with and without the anti-siphon valve and that will tell you if the issue is the valve or something else or a combination of both.

BTW, under the right conditions, simply inserting a wire down the pick up tube may not reveal anything as fuel can evaporate by the time you get the wire out and check for signs of it being wet. Inserting something that reacts with fuel and changes once in contact with it is a sure way of telling whether your test probe touches fuel or not.