Why are you installing a lift pump for a vehicle that doesn't normally have one? I was doing it on a couple of conversions and only after having complaints that the cars had less power i read on VWdiesel parts forum that Hager and now a couple of engineers have confirmed that using a feed pump will retard the timing which is the opposite of what i would think you would want and in particular for VO applications] by screwing with the internal pressure of the IP. Now i don't want to start any arguements, but 3 indepentant sources and my own experience seem to show that it may just make things worse. I do know there are ways to inprove the systems that Bosch and VW have developed, however i believe that they have had them installed at the factory if they really needed them. I also think that in installations with looped returns , the pump helps to mask problems that wouldn't be there if the overflow is just returned to the tank like every other diesel system in the world.
Yah after some arguing with a couple of people, all VW PD's have a lift pump. And yes on any PD conversion i will be installing a pump.As for older VW"s i've now done about 18 , mostly older , but about 1/3 TDI's. None have had a premature failure, and a couple have covered over 100,000 kms. One Eurovan i have done has done close to 150,000, kms and just last week his IP kicked the bucket. However the truck has 388,000 kms and even though the pump was rebuilt once, it was at least 6 years ago, and before the conversion was done.As for the timing i should have made it clear that i was talking about non TDi IP's . The full mechanical IP's should not use a lift pump. It screws with the timing. As for pulling thick VO, thats why all the heat exchangers possible should be used,tank,filter and i use vegetherms which heat it up to 100 o C . Of course there is a school of thought which says we could heat it up to 300 o C but then you're going to have other issues. Only if the oil is heated that much will the VO come close to diesel viscosity. In most applications the VO is still 2-3 times thicker. So matter what you do, there are comprimises to be had when using VO.I appreciate your opinion, and am always trying to make conversions better for my customers.
around 30-50 psi at idle and up to 100-150 psi at high RPM for a VE pump, I really dont think that the 4-10 psi lift pump can affect the timing.If its really affect, Its a little help in high rpm, not the inverse, but with a good pump adjustment, no need a lift pump on VE TDI.
i've been thinking that the little solid state fuel pumps might not be able to flow enough fuel for high rpm if the pump is set up to deliver lots of fuel... they have anti siphon valves etc so if the pump were to lose power, the injection pump would be starved... a set of lines with check valves could take care of that though
Quote from: "jtanguay"i've been thinking that the little solid state fuel pumps might not be able to flow enough fuel for high rpm if the pump is set up to deliver lots of fuel... they have anti siphon valves etc so if the pump were to lose power, the injection pump would be starved... a set of lines with check valves could take care of that though That's what I have and fuel can be sucked through mine.
Last week my customer came back because we decided that his PD probably should use a lift pump, because the OG system has one. So i go and wire it all in so that the og one runs on diesel and shuts off while the extra one runs on VO. Well while figuring everything out and reading some of the PD course lit again i see that the OG lift only works to circulate the fuel through the cooler when it hits a certain temp. So all to say that this is all bull*** because the OG pump isn't even there to push fuel to the front. BTW he drove his car for 3500 kms before i did install the second pump with no running issues.