Heater fuel starvation

Graham_Wright said:
Please explain. The thought has occurred to me but couldn't see the connection. The supplied line is soft plastic and, as it commences its run in the engine room, I don't think it is appropriate safety wise.
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When I installed my (Eberspacher) heater, several years ago and before cheaper models were available, I used 2mm copper tube. I don't know the full technical reasons why the makers say 2mm, but they do, and presumably have a reason. My guess would be that if you use a bigger size, there is more chance of fuel running back and emptying the tube, making starting more difficult. Sometimes, if all else fails, follow the instructions. ?
 
owen-cox said:
Ok that’s good. What you are probably seeing is a problem with the tollerances of the pumps. The pumps are not really designed to lift fuel from the tank and its particularly the case with chinese pumps where the tollerances can be somewhat slack. I had no end of trouble with chinese pumps when i fitted them for a while. They do not suck anything like as well as genuine branded pumps. They will push fuel once primed but it can run back when the heater is stopped. Increasing the bore of the pipe will make it harder to clear all the air out of the lines and make it have to run longer potentially dry when priming.
This is obviously not good. Ideally you need to run them from a tank higher than the pump. What you can do to test the pumps is dab 12V onto the pump terminals briefly repeatedly. If you remove the fuel line from the heater or pump outlet end and Pump fuel into a pot it should be 22ml per 100 clicks if its the standard chinese pump. Dont hold the 12V too long on the pump or you may burn it out.
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#7 "I have also ordered a pulse generator to drive the pump on the bench. I can then establish any connection between fuel line length, diameter and the ratios of suction and pressure sections."

I'll report back.
 
NormanS said:
When I installed my (Eberspacher) heater, several years ago and before cheaper models were available, I used 2mm copper tube. I don't know the full technical reasons why the makers say 2mm, but they do, and presumably have a reason. My guess would be that if you use a bigger size, there is more chance of fuel running back and emptying the tube, making starting more difficult. Sometimes, if all else fails, follow the instructions. ?
Click to expand...
Ebers, AFAIK, will only pump so many strokes before sulking if there's no flame.
So a large bore hose is more strokes to prime and more chance of a lockout.
Also these pumps don't suck air very well. When they are dry, they may be poor at priming any size line.
A bigger bore, more chance of a big bubble forming, big enough for a 'no fire lockout'. A small bore pipe will give a series of smaller bubbles, which the heater will splutter on but not actually stop.
If the pump and its feed pipe is primed, with no significant air bubbles it will likely keep working.
I put the filter horizontal, higher than the pump.
I had a reason for using bigger tubing, I wanted an accessible shutoff valve.
Aside from the safety aspect, the shutoff makes it easy to properly prime the line using a syringe.

These days I would not use copper pipe for diesel.

If you suspect fuel is running back, then being able to see fuel in the filter is a big plus.

That's my limited experience of ebers. May or may not help with other makes,
HTH.
 
Graham_Wright said:
#7 "I have also ordered a pulse generator to drive the pump on the bench. I can then establish any connection between fuel line length, diameter and the ratios of suction and pressure sections."

I'll report back.
Click to expand...
What display unit do you have? If its the digital version you can run the pump independently of the heater so no need to mess around with pulse generators or live wires. Instructions are in the manual.

If the tank is in bilge you should also stick with the specified diameter (and length ideally - again see the manual for an explanation) of the supplied fuel pipe.

Try sucking through a hose as opposed to a straw if you want to test the theory :-)

lw395 said:
Ebers, AFAIK, will only pump so many strokes before sulking if there's no flame.
So a large bore hose is more strokes to prime and more chance of a lockout.
Also these pumps don't suck air very well. When they are dry, they may be poor at priming any size line.
A bigger bore, more chance of a big bubble forming, big enough for a 'no fire lockout'. A small bore pipe will give a series of smaller bubbles, which the heater will splutter on but not actually stop.
If the pump and its feed pipe is primed, with no significant air bubbles it will likely keep working.
I put the filter horizontal, higher than the pump.
I had a reason for using bigger tubing, I wanted an accessible shutoff valve.
Aside from the safety aspect, the shutoff makes it easy to properly prime the line using a syringe.

These days I would not use copper pipe for diesel.

If you suspect fuel is running back, then being able to see fuel in the filter is a big plus.

That's my limited experience of ebers. May or may not help with other makes,
HTH.
Click to expand...
 
lw395 said:
Ebers, AFAIK, will only pump so many strokes before sulking if there's no flame.
So a large bore hose is more strokes to prime and more chance of a lockout.
Also these pumps don't suck air very well. When they are dry, they may be poor at priming any size line.
A bigger bore, more chance of a big bubble forming, big enough for a 'no fire lockout'. A small bore pipe will give a series of smaller bubbles, which the heater will splutter on but not actually stop.
If the pump and its feed pipe is primed, with no significant air bubbles it will likely keep working.
I put the filter horizontal, higher than the pump.
I had a reason for using bigger tubing, I wanted an accessible shutoff valve.
Aside from the safety aspect, the shutoff makes it easy to properly prime the line using a syringe.

These days I would not use copper pipe for diesel.

If you suspect fuel is running back, then being able to see fuel in the filter is a big plus.

That's my limited experience of ebers. May or may not help with other makes,
HTH.
Click to expand...

That's all very fair. I actually installed a dedicated 20 litre tank for my Eber, which I feed with kerosene, so copper shouldn't be a problem. The tank is probably a couple of metres away, and substantially lower, than the pump (which is installed close to the heater). At first install, what I did to fill the copper tube was to slacken the joint at the pump, and with a dinghy pump, gently pressurise the tank until fuel appeared at the slackened joint, ensuring that the tube was full. Incidentally, I installed a two-way cock so that I can feed the brute either from the kero tank or from one of the main fuel tanks. Each tank has its own shutoff cock. I have had no problems. (Dangerous thing to say).
 
My chinese heater pump is close to the heater and below it.
It draws fuel from the diesel tank some 4-5 ft lower than the pump and 10ft away using the supplied tubing.
Never had a problem.
You can change the pump feed speed , running temp, fan speed and heat output for a given setting and can switch to pump only to help prime on a new installation
 
Chaktoura said:
What display unit do you have? If its the digital version you can run the pump independently of the heater so no need to mess around with pulse generators or live wires. Instructions are in the manual.
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The same applies to the simple basic controller (although you have to solve the Chinglish to find it!).

I would prefer to do a test in the workshop as it is easier to modify the conditions. I still don't understand the rationale behind using small bore tube. I naîvely thought the bigger the hose the less friction.

Owen-cox's contribution of 22ml per 100 clicks is invaluable. I can vary the feed line length to see what effect it has.
 
Graham_Wright said:
The same applies to the simple basic controller (although you have to solve the Chinglish to find it!).

I would prefer to do a test in the workshop as it is easier to modify the conditions. I still don't understand the rationale behind using small bore tube. I naîvely thought the bigger the hose the less friction.

Owen-cox's contribution of 22ml per 100 clicks is invaluable. I can vary the feed line length to see what effect it has.
Click to expand...
 
Graham_Wright said:
!
The run is substantially horizontal. The actual lift is around 400mm.
(I am/was a physicist!).
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In that case, like most scientists i assume you havent read the manual! :-)
Joking aside, ive used 8mm fuel line from the tank to the pump so this may not be your problem, although as my pump is below the level of tank gravity is on my side. Have you used the prescribed length of 2mm pipe from the pump to the heater as if its too short this can cause problems. The correct length helps smooth thefuel delivery
 
Chaktoura said:
In that case, like most scientists i assume you havent read the manual! :)
Click to expand...
………………and you haven't read #1! (It is in Chinglish although better than most).

I suspect the problem lies in the lift from the tank to the filters. Although the line drops back to tank level, the loop could cause problems.
First stage is to shift from suckin to blowin.
When the pulser arrives, I can do a bit of scientific (ahem!) investigation without being squashed in narrow spaces.

I might end up installing a header tank in the engine bay. The existing fuel pump (not really necessary for engine running but handy for air bleeding and fuel transfer between tanks) could fill it. The tank would generate positive pressure in the line to the heater.
 
Graham_Wright said:
I might end up installing a header tank in the engine bay. The existing fuel pump (not really necessary for engine running but handy for air bleeding and fuel transfer between tanks) could fill it. The tank would generate positive pressure in the line to the heater.
Click to expand...

That's something I'd want to avoid! Heaters should just work, without needing to mess about filling a header tank every few hours. The Eberspacher on my old HR was mounted above the engine and happily sucked its fuel from the tank in the keel under the engine.
 
My Planar, won't pull fuel through a normal diesel filter.

My Genuine Planar. Pump mounted on a level with the base of the tank.

Just to make it clear.

Mike
 
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When posting on here about "Planar" heaters, it might be useful to remember, if it's a cheap Chinese Ebay Planar, it isn't a Planar. Those posting "My Planar does so and so" might be kind enough to mention if theirs is a genuine Planar or not. There is a big difference.
 
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