Diesel fuel pumps

[vic008]

Hi, need to buy one but see on ebay, that while they often say petrol or diesel, when you read a little further it often will say for carburettors and odd one said not suitable for injection type. Is there really a difference between carbs /injector. Anything I should look out for? (little 2 cyl diesel-it has no pump at all, except whatever is inside the injector pump) Thank you

 

[William_H]

A carburettor has a float valve so the pump has to cope with a blocked exit while maintaining pressure. The old diaphram electric SU fuel pumps used to rattle away till pressure rose then slowed and stopped.
Fuel injection on cars uses a lot bigger pump of high volume usually centrifugal because precise pressure is maintained by bleading off excess fuel back to the tank.
I guess your diesel engine requires something betweeen the two. Some volume of flow because some fuel is returned to the tank )if indeed it does from the injection pump) but often mostly a low flow rate with some pressure. I don't imagine the actual fuel type matters both being hydrocarbons petrol more agressive and volitile I imagine.
So ultimately i don't know the answer to what pump you need if you need a pump at all. gravity feed might do in which case you could use a header tank and transfer pump. Perhaps witha float valve. If direct feed than I would guess at needing a diaphram type. good luck olewill

 

[lynall]

As a rough guide carb pump will be 3 to 5psi, petrol injection pump will be 50 to 60 psi, most common rail diesels are fed 60psi to the high pressure pump, not sure on std old diesel inj pump supply pressure, not to high would be my guess.
Quick google on my old land rover engine comes up with 11psi.


Lynall

 

[ianj99]

I use one on my 4108 sold by Thornycroft on ebay, but also available from ASAP. Note that many of the car types have to be gravity fed, ie they are only designed to 'blow' not 'suck' and are designed for mounting under the vehicle near the tank outlet.
(It makes bleeding the air out a quick one-man job)
Ian

 

[gordmac]

Why do you need a pump? If it is just to move fuel to the injection pump one for carbs is what you want, a basic cheap solid state one should be ok although if the engine needs one to go you may wish to get a spare or a quality one.

 

[oldbilbo]

Why do you need a pump?

Surely some degree of 'pull/push' is needed to overcome the resistance of the filters?

 

[The Dogs Pollacks Brother]

Just fitted one this weekend.......easy enough job and all done through a switch panel and fuses. The pump is mounted prior to the main filters and at about mid-tank level. There was a small in-line filter with the pump that said "this filter "MUST" be fittet on the inlet side of the pump".The engine idles just fine, but now, when under way, the engine revs die a little then pick back up all the time. It did'nt actualy stop the engine, but its just not right and a little worrying. My initial thoughts are that the in-line filter that attaches to the inlet side of the pump is too fine and not letting the diesel flow through enough. I think I will try mounting the pump AFTER my primary filters without its in-line filter and try it that way. The revs dropping issue was with the pump "on" and "off" by the way...