Hard starting??

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landy-lee

landy-lee

Well-Known Member
Posts
706
Location
derby
Good evening all

When rebuilding my defender i replaced the fuel lines and fitted a a sedimenter. I also rooted them a different way because i have fitter a auxiliary fuel tank with a change over valve.

Fuel is draining back in the fuel lines so i was thinking about fitting a none return valve or maybe even a 12v pump and bypassing the lift pump?

Whats your thoughts one this and have you had a similar problem and fitted a none return valve?

Cheers Landy Lee
 
landy-lee said:
Good evening all

When rebuilding my defender i replaced the fuel lines and fitted a a sedimenter. I also rooted them a different way because i have fitter a auxiliary fuel tank with a change over valve.

Fuel is draining back in the fuel lines so i was thinking about fitting a none return valve or maybe even a 12v pump and bypassing the lift pump?

Whats your thoughts one this and have you had a similar problem and fitted a none return valve?

Cheers Landy Lee
Click to expand...
What sort of engine have you got? Where is the standard fuel tank? And where is the auxiliary tank?
 
I'd stick with the lift pump otherwise you'd need to find some way of blanking that off as well as rigging it up to make sure that the 12v pump is set correctly. The lift pumps are simple, reliable and cheap so if you think its that that's causing the problem then just replace
 
landy-lee said:
Good evening all

When rebuilding my defender i replaced the fuel lines and fitted a a sedimenter. I also rooted them a different way because i have fitter a auxiliary fuel tank with a change over valve.

Fuel is draining back in the fuel lines so i was thinking about fitting a none return valve or maybe even a 12v pump and bypassing the lift pump?

Whats your thoughts one this and have you had a similar problem and fitted a none return valve?

Cheers Landy Lee
Click to expand...

Surely the fuel is draining back to the tank because air is getting into the system? If you go fitting NRV to the fuel lines, it’s only masking a problem, not fixing it.
 
mick 1986 said:
Surely the fuel is draining back to the tank because air is getting into the system? If you go fitting NRV to the fuel lines, it’s only masking a problem, not fixing it.
Click to expand...
Wondered about that myself. The fuel system should be sealed, with both the pick up and return pipes below the level of the diesel in the tank.
So if no air is getting in, the fuel shouldn't be able to run back.
 
mick 1986 said:
Surely the fuel is draining back to the tank because air is getting into the system? If you go fitting NRV to the fuel lines, it’s only masking a problem, not fixing it.
Click to expand...
its not air getting in and i should of added its hard to start cold after 2 days.

the lift pump diaphragm is in good condition to.

So my issue is fuel slowly draining back over a few days.
 
Turboman said:
Wondered about that myself. The fuel system should be sealed, with both the pick up and return pipes below the level of the diesel in the tank.
So if no air is getting in, the fuel shouldn't be able to run back.
Click to expand...

Im 99% sure it runs back into the sedimenter. sedimenter is in the stock location as it would be on a 300Tdi ROW
 
landy-lee said:
its not air getting in and i should of added its hard to start cold after 2 days.

the lift pump diaphragm is in good condition to.

So my issue is fuel slowly draining back over a few days.
Click to expand...

How do you know, no air is getting in? What is making the fuel return to the tank if air isn’t getting in?
 
Just a thought but bypass the sedimenter with some pipe connecting the fuel lines and see if your problem persists. Wouldn't hurt to rule that out. It does sound like air is getting in somewhere. Have you checked the pickup and return pipes on the tank? I've found before that they can rust and get tiny holes that are hard to spot but will draw air in
 
Last edited:
landy-lee said:
All fittings are tight and i have no leaks.

Whats the best way to check for air getting in?

Cheers for the help
Click to expand...
If the leak is in the negative pressure side of the sytem, air may come in, but no fuel will come out.

Visual inspection, or in stubborn cases, put a section of transparent pipe into the intake line just before the filter, you may be able to see bubbles.
 
landy-lee said:
All fittings are tight and i have no leaks.

Whats the best way to check for air getting in?

Cheers for the help
Click to expand...

Don’t assume that because it’s tight and has no leaks that no air is getting in. The fuel system is being “sucked” to the lift pump, so I under negative pressure, if won’t leak from there.

I have a piece of 10mm clear hose in my fuel line permanently, it’s located between the fuel filter and FIP. I can see if any air is in the feed line, up to the FIP. In your case, I would use that location as a starting point. If you see air in that pipe, remove it and move it back. When the air disappears, you on found the area of the fuel system that is letting air in.
 
mick 1986 said:
Don’t assume that because it’s tight and has no leaks that no air is getting in. The fuel system is being “sucked” to the lift pump, so I under negative pressure, if won’t leak from there.

I have a piece of 10mm clear hose in my fuel line permanently, it’s located between the fuel filter and FIP. I can see if any air is in the feed line, up to the FIP. In your case, I would use that location as a starting point. If you see air in that pipe, remove it and move it back. When the air disappears, you on found the area of the fuel system that is letting air in.
Click to expand...
I would say @the_wolf 's suggestion is a good one. Those intake pipes often rust through. In which case, a simple first check would be to remove the sender unit with the pipe, and put a finger over one end of the pipe, and suck on the other. It should be obvious if air is getting in.
 
mick 1986 said:
Don’t assume that because it’s tight and has no leaks that no air is getting in. The fuel system is being “sucked” to the lift pump, so I under negative pressure, if won’t leak from there.

I have a piece of 10mm clear hose in my fuel line permanently, it’s located between the fuel filter and FIP. I can see if any air is in the feed line, up to the FIP. In your case, I would use that location as a starting point. If you see air in that pipe, remove it and move it back. When the air disappears, you on found the area of the fuel system that is letting air in.
Click to expand...
I have been thinking of putting a clear bit of hose like you suggested. Do i need a certain type of rubber so it is ok with the Diesel?

Cheers
 
Turboman said:
I would say @the_wolf 's suggestion is a good one. Those intake pipes often rust through. In which case, a simple first check would be to remove the sender unit with the pipe, and put a finger over one end of the pipe, and suck on the other. It should be obvious if air is getting in.
Click to expand...
For sure

Im going to order some bits n boobs and and check one thing at a time
 
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