Author Topic: adding a fuel lift pump  (Read 580 times)

dieselspanner

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Re: adding a fuel lift pump
« Reply #15 on: September 30, 2018, 08:33:32 AM »
Yes, but the pressure may well be higher than the IP would like / tolerate, hence the the idea of putting a tee in the line to recirculate the fuel constantly and to allow the IP to 'back pressure the inlet without restriction.

Cheers
Stef
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

glort

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Re: adding a fuel lift pump
« Reply #16 on: September 30, 2018, 01:47:25 PM »

I can't say mate. The electric pump would be fine. They are meant to work with carbs that have a float and shut the fuel off when there is enough. Obviously the pump has to run at great excess without problem at idle compared to the fuel needed at full power. The design allows for that and any other regulation or shut off in the system.


Garry seems to think the pressure would stress the IP. I don't know enough about the inner workings of these IP's to say either way. I have run my little China Diesel with a similar pump and had not problems with it but, I have never had occasion to disassemble a liter pump to understand the similaraties or variances nor have looked into how they regulate fuel flow.
I can well imagine that there may be tolerances within the pump that pressure would creep past  in a unit designed for gravity feed but if that would have an adverse effect, I have neither the knowledge or experience to say so would have to go with what those that do advise. I also don't know if any of the setups these engines came with did in fact have a pumped supply they would have had to deal with and therefore would be OK.

We both agree that T'ing the output near the inlet to the IP so there was flow but no pressure as would be found in a gravity system,  would be fine.
If you had the pump near the engine which would seem convenient as that's where the power will be also be, then you just make a loop from near the IP inlet back to the inlet side of the pump.  Pressure will be minimal but flow will be all the engine needs and more and there would be absolutely no pressure problems with the IP.

38ac

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Re: adding a fuel lift pump
« Reply #17 on: October 02, 2018, 02:03:59 PM »

 I never said that inlet pressure provided by an external pump as pictured would stress or harm the IP.  I said it would cause what ever internal leaks it has to be magnified,  which is true.  I did say that  the excess fuel pumped  back the inlet line by the injection pump must have a place to go, this is nothing but common sense, no manual needed. Given ridged plumbing between the IP and  supply pump and  the one way discharge valve present in every  clicker type pump there would be no guessing that high pressures will be created and additional stress on the pump and drive components would be created. You may also notice that I also gave room for you and the rest of the "WTF I did it?" crowd by stating it would not cause the pump to self destruct on cycle#1.  The china diesel fuel injection system is operationally identical to a Listeroid.  Did you connect your pumps with a rubber hose? if so I also allowed  that a hose  would created the expansion area needed between the two pumps.


Please be accurate when you  quote me as to point out error in my advise  be it factual, perceived, implied, guessed at or otherwise .

Do as you please if it works good enough to cause you to smile then have at it  ;)
« Last Edit: October 02, 2018, 02:06:12 PM by 38ac »
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glort

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Re: adding a fuel lift pump
« Reply #18 on: October 02, 2018, 02:23:48 PM »

Please be accurate when you  quote me as to point out error in my advise  be it factual, perceived, implied, guessed at or otherwise .

I can see that you seem to be taking issue with what I say a lot lately. Sorry for misquoting but I figured that was the gist of it and I was certainly not trying to challenge or undermine what you said, Completely the opposite.
I know who has the greater and superior knowledge in this area and it's not me so I was trying to point out that your opinion and experience was a lot more creditable than mine and should be heeded and weighed into consideration as such.
I never considered or even had passing thought anything you said was in error, again, completely the opposite.

Sorry for any aggravation caused, it was certainly not intended.