D1105 air in fuel lines (Youtube video). Help Please

[awitty]

Hi

I previously posted a thread about an odd problem I have with air bubbles in the fuel line which either prevents my engine from starting, or makes it quit a few seconds after running. I've now got round making a video which demonstrates the problem.

The machine has been sat in the garage for some time and I've tinkered with a fair bit to get it to this stage. I am now at a bit of loss to figure out where this air is coming from.

Any advice appreciated.

see the video here

 

[GreensvilleJay]

Generally speaking air gets into the fuel from either 'loose' fittings, improperly tightened hose clamps, or porus fuel line, all on the 'input' or 'suction' side of the fuel pump.
Depending on the age of the unit, you may want to replace all of the 'rubber' fuel lines. when you do be sure there are NO tight corners in the lines. Over time vibration can stretch and micro crack the rubber,enough to allow air in but not diesel out. If the tank is plastic, the connection to the 'spigot' might be just a little loose. If the hose is fairly new, cut 1-2" off and reattach,hose clamps should be 'snug' not Superman tight..maybe replace the primary fuel filter between tanks and pump. A microfracture in the plastic spigots could be where the air gets in. Be sure fuel lines are supported and not allowed to bounce.
Maybe others that have your machine will reply, if they've had similar issue.

 

[awitty]

Generally speaking air gets into the fuel from either 'loose' fittings, improperly tightened hose clamps, or porus fuel line, all on the 'input' or 'suction' side of the fuel pump.
Depending on the age of the unit, you may want to replace all of the 'rubber' fuel lines. when you do be sure there are NO tight corners in the lines. Over time vibration can stretch and micro crack the rubber,enough to allow air in but not diesel out. If the tank is plastic, the connection to the 'spigot' might be just a little loose. If the hose is fairly new, cut 1-2" off and reattach,hose clamps should be 'snug' not Superman tight..maybe replace the primary fuel filter between tanks and pump. A microfracture in the plastic spigots could be where the air gets in. Be sure fuel lines are supported and not allowed to bounce.
Maybe others that have your machine will reply, if they've had similar issue.

Thanks for taking time to reply. I've checked most of what you have suggested already, hence I recorded the video to see if anybody has any further ideas. Did you view the video?

 

[GreensvilleJay]

OK ,saw it a bit now...
If that's plain old vinyl clear tubing THAT is your problem. I've never ,ever seen 'clear' diesel fuel rated tubing. For sure the clear stuff is NOT rated for gasoline, just r+r a snowblower with that on.

 

[awitty]

OK ,saw it a bit now...
If that's plain old vinyl clear tubing THAT is your problem. I've never ,ever seen 'clear' diesel fuel rated tubing. For sure the clear stuff is NOT rated for gasoline, just r+r a snowblower with that on.

It's only on there so I can see what's going on.

 

[GreensvilleJay]

so when you replace it with the proper diesel fuel rated tubing, what happens ?

 

[PoTreeBoy]

I'm no expert, but based on the diagram below, I'd say something has gone wonky in your injection pump. There doesn't seem to be air in the fuel supply, but there's air coming out of the injector pump drain line. The source of the air seems to be the injector pump, maybe a seal? I don't know is that's user serviceable.

 

[GreensvilleJay]

air could be sucked in at the hose connection AT the injector pump or the piece with the two copper rings on it(??),or as PTB says leak in the pump,or the hose going to the injectors ( it's clear plastic..)

 

[PoTreeBoy]

air could be sucked in at the hose connection AT the injector pump or the piece with the two copper rings on it(??),or as PTB says leak in the pump,or the hose going to the injectors ( it's clear plastic..)

I think he has a supply pump ahead of the injector pump, so if the supply connection is leaking there should be a drip.
And the air seems to be moving from the pump to the injector.

 

[GreensvilleJay]

I've seen first hand where air can get sucked into a line yet no gas will drip out. The tubing wall isn't a 'two way street'

 

[awitty]

I'm no expert, but based on the diagram below, I'd say something has gone wonky in your injection pump. There doesn't seem to be air in the fuel supply, but there's air coming out of the injector pump drain line. The source of the air seems to be the injector pump, maybe a seal? I don't know is that's user serviceable.

View attachment 73287

Thanks, I'm also thinking it might be the injection pump. I do have another d1105 on a working machine so I might swap them and see if the problem persists.

Could air be coming down the injection line from a bad injector perhaps?

 

[PoTreeBoy]

Could air be coming down the injection line from a bad injector perhaps?

In your video, it looks like it's moving from the pump to the injector. Could you pull the line off at the injector, cap the injector nipple, and dunk the line from the pump in a small container of fuel? Again, I'm no expert.

You do have a lift/boost pump, right? Have you verified that it is supplying pressure?

 

[awitty]

In your video, it looks like it's moving from the pump to the injector. Could you pull the line off at the injector, cap the injector nipple, and dunk the line from the pump in a small container of fuel? Again, I'm no expert.

You do have a lift/boost pump, right? Have you verified that it is supplying pressure?

I might give that a go as it sounds straightforward enough. Although I'm not sure if it will prove anything as I expect to see air coming from the pump and hence a mix of air and fuel still getting sent to the injectors.

I may even go back to the mechanical lift pump to rule out a pressure problem from the electric unit.

Nothing to loose other than a bit of time !

 

[PoTreeBoy]

I might give that a go as it sounds straightforward enough. Although I'm not sure if it will prove anything as I expect to see air coming from the pump and hence a mix of air and fuel still getting sent to the injectors.

I may even go back to the mechanical lift pump to rule out a pressure problem from the electric unit.

Nothing to loose other than a bit of time !

Would just confirm that the air originates at the pump and not an injector.

 

[whitetiger]

Thanks, I'm also thinking it might be the injection pump. I do have another d1105 on a working machine so I might swap them and see if the problem persists.

Could air be coming down the injection line from a bad injector perhaps?

Before you R&R the injection pump, pull the injectors and have them tested. I think you will find your problem there.

 

[awitty]

Well i fixed it!

It was caused by a faulty injector delivery valve.

Full details here

 

[GSD-Keegan]

Good job! where is this delivery valve? Guessing at the injector? So air was theoretically being pulled backwards back to the injector pump?

 

[awitty]

Good job! where is this delivery valve? Guessing at the injector? So air was theoretically being pulled backwards back to the injector pump?

Yes that's right. Part 12 in the attached diagram. So easy to fix but an absolute bugger to diagnose!

 

[PoTreeBoy]

Thanks for posting the resolution.