Diesel JD
Full Access Member
John Deere used db4 pumps on many engines, Ive seen some timing ring and lock pin failures, not many but usually on a unit that was poorly maintained, when the fuel filter gets plugged the pump can pull in air and my friend has seen the pin hammered almost gone.
remember the pop pressure is 2100 ish, injection pressure can be as high as 12k on some applications, like a direct injection Deere.
Lets see how Kens repair goes and give it some time before condemning.
And the aerated fuel is likely the problem, remember , custom race /performance items seldom work out of the gate the first time ,unless you have unlimited R&D budget.
Russ, NMB2 was trying to explain to me how air intrusion can cause this kind of damage, something about how the air causes the advance piston to get beat up. Your pump guy says the same thing. If this ever happens to a stock-ish pump I'm probably a good candidate since I seem to plug filters more frequently. Do you think for my benefit and everyone else's we could discuss a bit more how exactly air intrusion beats up the advance piston? I guess the thing I should do is have a fuel pressure gauge. I keep discussing this with gatorman since he has a good setup. Does anyone else have a fuel pressure gauge or gauges? Mostly interested in protecting my pump, but for a stock pump Justin's fix seems like big bucks...for a DB4 I would probably mostly copy his system AND have a gauge, just cause it's a big investment. As far as the comments about Calvin and the DB4 hybrid, he can correct me if I'm wrong but I think his guy used the innards of a DS4 not a DB4 and the failure point was the pump shaft snapping. I also remember Motrack and RKoch discussing DB4 pumps. For those who recall, RKoch did some outside the box turbo kits as well but they were always remote mounts and used DT466 or T444E turbos, and Motrack was a huge IDI fan and an old Deere mechanic. Unfortunately both those guys are harder to get hold of than Ken on his worst days. Also worth noting that Ken has greatly improved his customer service since people on here were using his products. He's been available to Justin to help solve this issue. None of us can really say how reliable the DPS DB4 pump is, but if we get some good mileage on the NMB2 build and the other 2 with no further failures, I'd be willing to assume it was a random weird thing caused by the air intrusion like Ken said. If we keep seeing failures, obviously something else will need to be developed for these HO builds. Sorry for the Hijack Eric, hope you can give that thing some more fuel, whatever route you choose to go and congrats on getting it started up.