Fuel line pickup problem

Fuel line pickup problem
I have a 2019 sdx 270 with a verado 300 OB. I recently had the boat detailed. It ran for about 10 mins then bogged down and stopped after that. The guy who sold it to me had warned me to avoid washing the fuel vent outlet. I don't know if this happened. I pulled the vent off and the screen is clean. The engine runs perfectly from an external fuel tank. There is no inline fuel-water separator. There is a squeeze bulb that is dry in the original line. I replaced it. Still won't prime. I siphoned fuel up to the bulb but it won't stay primed. I checked the hose clamps for air leaks and checked the lines for cracks. Is there some vent line filter that could have been clogged by water, etc? I checked the fuel I siphoned and it is clean. Basically, the neither the engine nor a bulb will pull fuel from the tank. I tried leaving the fill cap open but that didn't help either. Thank you

Does your tank have an anti-siphon valve on it? Looks like a brass fitting the fuel line connects to. They do go bad and are cheap to replace.

Some fuel pickups in the tank have a metallic or plastic "sock" filter on it. Sometimes that sock will get all crapped up.

I have pulled some pretty nasty ones out of fuel tanks. Sometimes they can be cleaned, others, not so much and need to be replaced.

Thank you for the insights. I don’t know if there’s an anti siphon valve. It’s tough to see much about the fuel system as there’s just a 6” access plate in the deck. I will look further.

I just picked an order from my preferred local marina for a new tank pickup, shutoff etc. 28 year old boat so figure it can't hurt as I just replaced all the fuel lines, clamps, filter housings, etc. When I pulled the old unit, it had quite the curve set in it and would have been far from where I'd expect it at 1/2 to 1" from tank bottom. Filter screen was clear after all this time, but you never know... Hidden filters/screens are not something that tend to get checked.

I do not believe you would have a vent line filter, but there should be a loop in the line. The previous owners warning was probably because water from pressure water entering the vent could enter the line and settle at the bottom of that loop. It would not enter the vent house and then drain water straight into the fuel tank. I occasionally blow into my fuel fill and confirm it doesn't build pressure when I do so. Helps me confirm that there is no blockage in the vent line, especially the loop in the line.

I have an anti-syphon valve under my cowl, just prior to the fuel pump. As stated, these can go bad, for me, its part of the fuel pump rebuild kit. Not just a fuel tank/systems maint item.

You mentioned the primer valve isn't pulling fuel to bulb unless you siphon it, and not holding prime. Those bulbs also can go bad. You did say that your external tank worked as expected. Does the external tank have its own line and bulb? Or did you hook the boat line/bulb to the tank? Can you switch out the bulb to eliminate that from your list of suspects? I'm assuming that you replaced the fuel water separating filter at start of season, have you confirmed it is seated and sealed properly? Besides hose clamps, that filter/housing could potentially be another air source.

That fuel pickup tube should pull out of the tank

I replaced the fuel line bulb and don’t have a fuel water separator in the line. Sounds like taking the pickup tube out of the tank and inspecting it is the next step.

the previous owner said he had mistakenly pressure washed the vent outlet and then his engine wouldn’t run. He said he had to have some filter replaced in the vent line to fix the problem. Could a vent line filter cause this? I would think the fuel line would pickup fine even if the vent line was clogged, as long as the fill cap was open to let air in. My fuel pickup won’t work even with the full cap open.

Probably a charcoal filter for emissions. I'd take it off and leave it off, I'm sure it's saturated. I would go that route first before the pickup tube

You could confirm the vent issue by cruising with the gas cap off.

It won’t pick up fuel with the gas cap on or off. Does that mean it’s more likely something in the pickup, or can the vent line filter still cause a problem even if the gas cap is off?

If the fuel tank isn't so overfull that fuel is into the fill line there will be an air at top of tank that goes out fill hose to relieve vacuum. That removed cap will act the same as the vent line does.

I personally would remove the dip tube and inspect. Make sure you clean well around the fitting before you start. You don't want to have debris fall into tank. Also have tools handy to clean out the old sealant from threads, and thread sealant for re-installation when done.

Someone in SW Florida with a relatively new 270 SDX recently had the same problem. Marine Max took care of it. I do not remember the member’s name or the topic. He may chime in or someone else may be able to find the post.

I pulled the charcoal filter off- it was not wet and air flowed freely. I pulled the pickup tube and the screen was clear. The little ball valve near the female connector that goes to the pickup tube had a ball type spring switch in it and that was fine too. I put it all back together and still couldn’t get flow from the fuel line in the aft cabin with a suction bulb or siphon. It’s like air is getting in the line somewhere. Could the seal at the neck of the pickup tube be bad? The plastic tube just sits on the aluminum neck and is not clamped or sealed in any way.
Even though it’s out of warranty I would take it to our marine max here and have them fix it, but it would be weeks- they are slammed with work.

someone mentioned putting a regular outboard engine fuel plug connector in place of the dipstick to test it- I can’t find the specs on the threaded right angle (stainless or aluminum) dipstick head to try to connect it either through the Tank wall or at the head itself.
I’d welcome any other ideas. Thank you!

I ordered the one on the right in this picture from a local. Sounds like you have the press in on the left hand side? Does it look similar?

the replace pickup I ordered did not have a filter, I purchased a hose barbed filter instead. Added that to the pickup and treaded into tank after setting length.

try using the same method you would find a tire leak. Soapy water at all hose connections, add air pressure and see where bubbles froth.

My suggestion was, since the test fuel tank had no bulb or running issues it’s something in the section that the test tank eliminates. Edit: at what point did you tie in the external fuel tank?

If you have the spare fuel line length, you can trim off where the current hose clamps are and reconnect on fresh rubber with 360 degree clamps. They don’t tear up the hose like the other gear style.

I connected the external tank in the aft locker just before it turns up and back to the outboard.
My pickup looks similar to the picture you provided- not sure of the diameter, I’ll have to check.
Here is a pic of the anti siphon fitting. Is it safe to remove that and should I?

thanks for the advice!

It would be fine to remove, to test / eliminate as the problem. My concern would be that the fitting in the pic looks nasty and I would be concerned removing it may cause some damage to the threads, or what ever. Soak in plenty of PB Blaster before removing.

Is that a crack in the lower left corner?

They are fairly cheap to replace, if needed.

They are there as a safety for in the event the boat capsizes, the vent won't siphon fuel from tank. Boat will run fine with out it.

Find the problem?

The final answer to the problem: it was the junction between the fuel pickup tube and the connector. It was a tight space- it would work for a while with a new tube and then maybe rattle loose again. A mechanic checked it out for me and replaced it with a very tight 3/8” pickup tube. Works fine now. The part number for the new tube is below in case anyone else runs into this.
17-0948 ¾ x24"