Not getting fuel...question

[Lazy Geckos]

Hello all!

Wondering if anyone has experience with my issue.

Specs in order from tank to engine:

Full tank of fuel with a tube for fuel intake
Racor Primary Filter housing
Volvo Penta feeding pump
Engine mounted Secondary filter
1985 Volvo Penta 2003 Diesel


Symptoms:
During normal engine operation the motor started to bog down, eventually stalling. After changing primary and secondary fuel filters and priming, the engine starts and then symptoms will repeat after about 10-15 minutes of normal operation.

When I manually prime the engine, fuel only lasts until the primary filter is empty and then the venting screw runs dry. Fuel is not being transferred from the fuel tank (mounted at a lower altitude from the primary) to the primary at any time, thats the issue. There isn't a sending unit in the tank, only a tube that reaches the bottom. All lines have been removed and verified to be clear of obstruction.

Does anyone know why fuel wouldn't be transferring from the tank to the primary if the lines are clear? Or what actually controls the suction from the tank?

Thanks!

[Suijin]

Sounds like the fuel pump. Creates a vacuum, drawing fuel from the tank. Is your Racor mounted higher than the fuel pump? It might have enough life left to draw primed fuel in the Racor but not enough to lift from the tank.

[Captain Bill]

The fuel transfers because the fuel pump is pulling a vacuum and requires a fuel line full of fuel or a lot of pumping to get the air out. If the fuel pump is pumping then you have an air leak upstream of the fuel pump. The leak is most likely in a joint in the fuel line or in the o-rings om the racor. One other possibility is a crack at the top of the dip tube in the fuel tank. What ever the source air is your problem.

[a64pilot]

Could be fuel pump, but I would pull the dip tube from the tank and be sure its clear first.
My problem turned out to be a blockage in the elbow at the top of the tank, the tube and fuel line were clear, but the "stuff" blocked the elbow.
A simple test is to disconnect the fuel line and see if you can blow back through it, you should hear bubbling in the tank

[Hoofsmit]

Could be an air leak in the line? I had a problem with the o ring on the top of my racor that caused an introduction of air into the fuel line
Also- I had a gauze filter at the fuel tank pickup that 'fizzed' the fuel on another engine causing the racor to have an air pocket every time I ran at anything over low revs
Good luck finding the problem



Sent from my iPad.......i apologise for the auto corrects !!!

[Captain Bill]

Originally Posted by a64pilot

Could be fuel pump, but I would pull the dip tube from the tank and be sure its clear first.
My problem turned out to be a blockage in the elbow at the top of the tank, the tube and fuel line were clear, but the "stuff" blocked the elbow.
A simple test is to disconnect the fuel line and see if you can blow back through it, you should hear bubbling in the tank

I did that with a blockage in my pick up tube once and got a nice steady flow of bubbles. Then the thing would run for a while and stop again. I finally pulled the pickup tube and found a fibrous piece of something stuck in the end of the tube. Of course when I blew it out everything was great but it eventually got sucked back up in the tube. It appeared to be a piece of oil adsorbent rag. The last place I bought fuel handed me the fuel nozzle with the oil absorbent rag wrapped around it and asked that I keep it there while filling. I didn't think much of it at the time, but a piece must have broken off and gone in the tank. While blowing through the hose might indicate a clear line it might not completely eliminate the possibility of a clog. Been there.

[donradcliffe]

My experience is also that your symptoms are caused by a blockage in the fuel pickup tube or in a shutoff valve at the top of the tank.

[Lazy Geckos]

Thank you for the input! Problem is still not solved but here's what I know.

- Pick up tube, clear and free of cracks.
- Line from tank to racor filter, clear and will pick up fuel if I use a hand pump.
- Line from racor to fuel pump, clear and is pumping fuel when I fill the racor.

Engine runs fine when I fill the racor by hand and then prime it, until the racor empties and the engine starves.

I'm leaning towards the racor failing somehow, planning on pulling it tomorrow. I also hooked a hand pump to the end of the fuel system (fuel pump), tried to pump fuel through the system and couldn't get anything. It acted blocked.

[Cheechako]

Check you tank vent that it's not clogged. after running and your engine dies, open the deck fitting... do you hear a vacuum as you open it?

[shakey doug]

Check filter screen inside lift pump, undo centre fastening to access, only if not the sealed type as there are 2 types in the 2000 engine range.

[bustylady]

I had the exact same problem with my Perkins 4.154. It kept running the ray-cores dry. I pulled all the fuel lines and blew thru them and they seemed fine and clear of blockage!!!!???? , I ended up running the engine on an axillary 6 gallon tank for a couple hours with out the raycores. Then engine ran perfect. I ran it for 5 hours on that tank. While knowing there was nothing wrong with the fuel pumps i started replacing all the fuel lines, the line going into the first ray core was calapsed as it slides over the inlet barb, when i pulled it of the calapsed part opened a bit making me think there was nothing wrong with the fuel lines, just enough fuel would come thru to make the engine run for like 5 or 8 mins until the engine statved with fuel. When i would go doen there and pump the lift pump a hundred times , the engine would restart and do it all again. So replacing the fuel lines fixed the problems.

[Diesel Bill]

Originally Posted by Captain Bill

The fuel transfers because the fuel pump is pulling a vacuum and requires a fuel line full of fuel or a lot of pumping to get the air out. If the fuel pump is pumping then you have an air leak upstream of the fuel pump. The leak is most likely in a joint in the fuel line or in the o-rings om the racor. One other possibility is a crack at the top of the dip tube in the fuel tank. What ever the source air is your problem.

Same thing happened to me last year motoring north from Mexico to San Diego.
Port engine would run fine for a while then die. Air bound. Bleed with primer bulb from Racor to lift pump through secondary filter on engine. Then bleed injection pump then lines to injectors. Always at night and when I'm off watch and asleep. Turned out to be loose fitting at lift pump inlet line sucking air. Intermittent loss of prime. It SUCKED

[JSSailem]

I installed a vacuum gage on the engine side of the Racor. It normally runs about 2 in of vacuum. If it drops to zero... air leak from gage thru Racor to Fuel Tank. If it goes up to 10 in... then blockage from gage thru Racor to fuel tank (i.e.clogged filter - change it).