Non Removable Pickup Tube

[Rmccormi]

I have a 30 year old Yanmar 3GM30 engine and have been experiencing some fuel problems. The engine was running great and suddenly died. After replacing the primary and secondary filters, I bled the low pressure side of the engine. Yanmar started but shortly there after died. Next I bled the high pressure side and the engine ran fine but started to run rough after 30 minutes. I have installed a diesel fuel pump ball inline before the primary filter for bleeding purposes and when lightly pumped the engine runs smooth.

I have a vacuum gauge and it indicates the filters are fine. I checked the tank vent and it is clear. I wanted to check the pick up tube but it appears to be integral to the tank and is not removable.

Any ideas how to install a new pick up tube? The tank is .090 aluminum and only has a hole for the fuel sending unit and a bung for the pickup tube. The tank is in a C&C landfall 38.

Could this also be a fuel pump issue?

Any advice would be much appreciated.

[Jammer]

Originally Posted by Rmccormi

Any ideas how to install a new pick up tube? The tank is .090 aluminum and only has a hole for the fuel sending unit and a bung for the pickup tube. The tank is in a C&C landfall 38.

You would cut an access hole in the top of the tank and install an inspection port fitting when done.

Could this also be a fuel pump issue?

Any advice would be much appreciated.

It is unlikely to have anything to do with the pickup tube. If the pickup tube were blocked, the vacuum gauge on your fuel filter would show a vacuum, and the pump ball would be squished and therefore not do anything when you squished it further.

There are various ways of ruling out problems with the pickup tube. You could connect some compressed air and observe a satisfying degree of bubbling. You could connect it to, say, a turkey baster, and observe that you are able to withdraw bubble-free fuel at a reasonable rate.

I think you are likely to find that you have a leak in your fuel line that is allowing air to enter. Or, perhaps the fuel pump is shot.

There are many ways to diagnose these problems. You could connect a portable fuel source directly to the fuel pump and see whether the problem resolves. You could place a piece of transparent fuel line, temporarily, between the fuel pump and the filter, and observe the presence or absence of bubbles. You could connect a T to this line and run a line from the T to a vacuum gauge to confirm the presence or absence of blockage.

[donradcliffe]

disconnect the fuel line at the tank side of the first filter, and use the squeeze bulb pump to put fuel into a container. If the pump puts out fuel and the squeeze bulb is not slow to refill, you do not have a blocked pickup.

[jimbunyard]

Don't be so sure that there isn't a block or partial block in the pickup tube. The surest way to tell is to run the engine out of a clean fuel container; stick the end of the hose connected to your squeeze bulb in a half gallon of diesel in a milk jug and see what happens.

For some crazy reason tank manufacturers often put a screen in the bottom of the pickup tube, and debris washing around in the bottom of the tank can get sucked up onto it, restricting flow, and then when you shut down, it falls away and then the process begins anew when you restart.

I usually cut the end of the tube off, but it you can't remove it, that option's out. If there's a removable fitting on top of the tube maybe you could stick a thin metal rod down the tube and drive it out, otherwise you'll have to go with a new pickup.

There are many ways to add a tube. A good starting point would be to see a picture of the existing tube where it exits the tank...

[Badsanta]

I would bleed at the injectors again, make sure you get a good flow. It takes more than you think.

[Rmccormi]

All, thank you for your ideas. I will be back down to the boat on Wednesday to continue investigating the issue. Like the idea running the engine with an auxiliary container to isolate the tank. Will put into action many of the suggestions and update the forum accordingly. Will also include some pics as suggested.

[foufou]

There was a similar post recently and no mention of the small filter on the engine. It might help to rule out this filter as the cause of the problem

[Techtool]

Disconnect the fuel line to the tank. Hook a temporary line to your filter inlet. Drop the temporary line in a clean can of diesel. Bleed the system and run it for a couple of hours. If the problem goes away it’s the tank. If it doesn’t go away it’s from the filter to the engine. Splitting the tank out of the equation removes the guessing.

[Lepke]

I doubt it's the pickup tube. Plugged tube would give very high vacuum readings and pumping the bulb proved enough fuel can be pumped to run the engine.
It's most likely air being drawn into the fuel lines. Rough running is a common sign of air entering the fuel lines. As soon as air makes it to the injector pump to injector tubes, the air in the tube compresses and causes the injector to misfire. Either the injector fails to open or provides a weak stream of fuel.
A bad lift pump is the 2nd most likely problem.

[Symphony]

Subscribed!

[theway]

I’ve had this happen many times with my ‘97 3gm30.

(In no particular order)

1: There is a third (secret) bleed nut on the engine. I had to use once and it got things working. It’s located on the end with the belts, opposite of the transmission side. Towards the top I think... I’ll try to find an image for reference.

2: If you’re using Racor filters Check that the bowls and filters are screwed on tight and gasket is making a good seal. Also check the drain plugs to make sure they are right and not leaking air.

3: Check hoses and valves for air leaks. My boat has a T-valve to bleed air before it gets to the engine, once that valve was closed all the way and let air in.

4: Check your air element to make sure it isn’t completely blocked. Could be a lack of air not fuel.

5: I had this happen two days ago and by pumping the ball could keep it going. The problem was I needed to bleed it again and more thoroughly. How long are you turning the engine when you bleed the injectors? (Don’t forget to shut off the water intake if doing it for long periods)

austin