Lift pump upgrade for zd30 di

[find_adam]

Hey im.not sure if its been done but has anyone added a low pressure (6psi) lift pump inline between the main tank and fuel pump . I think it may increase power by delivering fuel under slight pressure.
Anyone think im.wastong my time ?

[mudski]

Hi mate. Adding a lift pump is a good idea but it won’t give you anymore power. It’s all limited at the injector pump.


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[RJames]

I had to replace the injector pump ($$$$) due to the hand primer pump diaphragm leaking air into the fuel line from the suction and causing cavitation in it. The pump overhaul guy was against lift pumps for the ZD30 engine as he said their capacity was usually too low to keep up with the injector pump which recirculates a large part of the volume for cooling. Maybe a large capacity lift pump would have prevented this but I could not find out how big a pump to get.

[PeeBee]

I had to replace the injector pump ($$$$) due to the hand primer pump diaphragm leaking air into the fuel line from the suction and causing cavitation in it. The pump overhaul guy was against lift pumps for the ZD30 engine as he said their capacity was usually too low to keep up with the injector pump which recirculates a large part of the volume for cooling. Maybe a large capacity lift pump would have prevented this but I could not find out how big a pump to get.

RJ, I went down the track of resolving what you are talking about for my Chev conversion. I run an in-line pressure transmitter to measure fuel pressure, plus run in-line flowmeters on the supply and return lines. This gives me the info to profile the size- volume and pressure- required for the lift pump. I ended up settling with a nominal 150lphr pump rated at 16psi, as this gives me an oversupply at WOT of 50lphr and 10psi. The positive pressure to the pump changed the driveability of my truck totally when running as a N/A. I don't know how it translates to the 3.0L motor though. I can't say it had anything to do with a power increase, but it certainly didn't allow the pump to starve. The engine felt different to drive, more responsive is perhaps the term. Maybe it wasn't allowing any cavitation, which is air into the mix - don't know, but as mudski says it isn't a direct player on performance, maybe a support device.

[RJames]

Hi PeeBee
Thanks for the input. In this case, overkill is probably not a bad thing! I have seen threads that mention the benefits of positive pressure to the injector pump but Nissan won't talk about any modifications at all - understandably I suppose. My Patrol is used for towing a caravan and any sort of steep or long climb makes it seem to lose power - I can live with it but it would be great to find a fix.