Bleeding the fuel system

[Motorradmark]

Coming back to finish the project.
300tdi.
Backstory: Replaced o ring in FIP as it was leaking. Done.
Installed a new sedimentor and 12v fuel pump, per recommendation of the distinguished mr davis. Done.

Pump comes on with ignition and is pumping. Not started, just ignition on. Bled air at filter- fuel fountain.

Bled at inlet on FIP. Fuel comes out.

Am not getting fuel at injector pipes. Am getting fuel at leak down and return line.

What am I missing, short of turning the key? Battery is presently on charger.
Is there another bleed point on the FIP?

Thanks
Mark

 

[chris snell]

I don't see how you would expect to get fuel at the injector pipes unless you turn the motor over with the starter or a roll-start. Maybe I'm missing something here.

 

[jymmiejamz]

Sounds like you just need to crank it. It should fire right up I would think.

 

[Motorradmark]

that was what I thought, but can't until my battery comes up enough. was just checking. I am sure the FIP must, ah, pump to get the fuel all the way to the injectors and beyond. thanks for confirming. key is turning tomorrow.


cheers
Mark

 

[Motorradmark]

Ok. Everything is buttoned up, no leaking fuel spotted. Starts hard, runs normal then starts to sputter. If I hit the throttle, it is rough and dies.

I keep loosenjng connections while running, fuel comes out and re-tighten.

Any suggestions ?

 

[chris snell]

You're probably getting air ingress. It won't necessarily leak or even weep but it can still suck in air. I had this problem around my 12V fuel pump and fixed it with a coat of Permatex High Tack gasket sealant around all hose-to-barb connections.

 

[RDavisinVA]

How long did you let it run?

We keep a spare 12V fuel pump and back feed the feed line from the lift pump to the tank.
Then any air leak becomes a fuel leak.
High Tack on the threads is a good idea.

 

[Motorradmark]

It ran for good 15-20 minutes. Would purr normally, then start to vibrate and sputter. If I hit the throttle, it would rev then start sputtering and vibrating. Usually recovers but doesn't like the throttle.

Let me review my layout.

Tank-sedimentor-elec pump- lift pump-filter-FIP- engine.

Could using both pumps at same time be an issue?
Need to get extra pump as backup, anyway, I suppose.

I didn't use the barbs, I cut the nylon and used 3/8 id line pushed over the nylon with fuel injection clamps. I did find one break in the nylon and was able to cut it out and use longer 3/8 fuel line to join.
Thx

 

[RDavisinVA]

It ran for good 15-20 minutes. Would purr normally, then start to vibrate and sputter. If I hit the throttle, it would rev then start sputtering and vibrating. Usually recovers but doesn't like the throttle.

Let me review my layout.

Tank-sedimentor-elec pump- lift pump-filter-FIP- engine.

Could using both pumps at same time be an issue?
Need to get extra pump as backup, anyway, I suppose.

I didn't use the barbs, I cut the nylon and used 3/8 id line pushed over the nylon with fuel injection clamps. I did find one break in the nylon and was able to cut it out and use longer 3/8 fuel line to join.
Thx

So now it comes out that you used the nylon line...
That stuff is an air leak waiting to happen get rid of it.
I bet if you pressurized the system the nylon connections will look like a sprinkler system and would also bet the fuel system is bleeding air and draining back which could account for delayed starting while the 12V pump purges out some of the air.

 

[Motorradmark]

Well, I didn't use nylon, I just didn't take it all out. Sounds like I would be better off with about 20 ft of 3/8 fuel line and replace the whole lot.
Based on my obvious expert description of the running, would you lean toward air leaking?

 

[Uncle Douglas]

you used the nylon line...
That stuff is an air leak waiting to happen get rid of it.
I bet if you pressurized the system the nylon connections will look like a sprinkler system

broken record you are

 

[chris snell]

By nylon, do you guys mean the black hard plastic line?

 

[RDavisinVA]

By nylon, do you guys mean the black hard plastic line?

Yes

Well, I didn't use nylon, I just didn't take it all out. Sounds like I would be better off with about 20 ft of 3/8 fuel line and replace the whole lot.
Based on my obvious expert description of the running, would you lean toward air leaking?

Likely culprit is air in the fuel.

broken record you are

They keep ringing the bell !!!

 

[chris snell]

Yes

Ha, I did exactly what Motorradmark did and clamped hose around the nylon line. I did use hard tack on the connection. It's worked well for 15k miles so far but I trust your advice and will add it to the to-do list.

What's the best way to tie the fuel hose to the lift pump? I'm not in front of the truck but I recall that the nylon line is melted onto the end of a little fitting on the lift pump housing. Do I need to replace that with a barbed fitting or can I just slide the hose onto it?

 

[RDavisinVA]

The TDI lift pumps have an olive and a female fitting.
2 options:
Crack the olive off and remove the female fitting then slide the fuel line over and clamp.
Clip the end of the nylon line and use a wire wheel, razor blade, whatever to remove the nylon line from the fitting then clamp the rubber fuel line onto the old fitting then tighten it into the female fitting on the lift pump.