Sorry to hack your thread, I just want to ask you something, I have the CP4 and I've been reading on this to make sense of the issue, to avoid an issue on my 2016 Dmax, should I use a lift pump and additive? It seems everyone has a different opinion on this, my truck is bone stock and not planning on doing any tunning or deleting for now, I just came out of warranty and want to avoid a catastrophic issue, have a kid in college and dont have the extra $ to spend on not essentials, you seem to know what are you talking about, please advise.
the design of the pump is kind of the issue overall, wear particles in the pump get sent down the high pressure rails instead of returned to the tank, so the way as far as i understand to increase the life of the pump would be to limit the internal wear as much as possible. Based on the Spicer study biodiesel seems to have the best overall lubricity characteristics, so if you can get that where you are, run that. It will exceed the lubricity rating required by the pump. If you cannot get bio diesel, or just want peace of mind you can add an additive like Optilube or a different additive as well. Optilube did well in the previously mentioned study, some additives on the market actually reduced lubricity, so not all additives are equal. The lift pump will reduce some load on the pump, how much, well thats debatable, but the added filtration and water separation will reduce the overall amount of grit and water that goes through the pump and injectors which should extend the life of both. The CP4 by design will not last forever and every pump will eventually fail for the same reason. This is not untrue of the CP3 though, the difference is the CP3 will generally outlast the rest of the truck and drive train before letting go, where as the CP4 based on owner reviews appears to not be nearly as robust. That said, i believe the reports of failures galore are highly over exaggerated. Forums tend to consolidate people with problems, as you seek out answers for your issues. Its less likely that someone seeks out a forum to tell everyone how well there truck is working, and much more likely they are there to complain about a problem, so the poll on this forum is heavilly biased towards the side of failures. Even then, the poll only shoes a 10-12% failure rate and theres not really a major difference based on miles driven so to me, it kind of sounds like if you get a good pump your probably ok for a while. Personally i would run biodiesel if you can get it, add a little optilube to each tank and if you decide you want the peace of mind that comes with the extra filtration of the lift pump, get a 95 GPH pump and drive the wheels off the truck. If you really do not want the stress of the CP4 though there are kits you can get that will switch it for a CP3 for about 2 grand including the CP3 pump. Install if you dont do it yourself is around 1500-2000 depending on where you go and what kit you get. You would still want to take care of the fuel system with the CP3 because the injectors still need lubrication, but the pump would return metal to the tank in the event of a failure and you would be much less likely to have to replace the whole fuel system.