Good morning friends long time lurker of the forum and now I own a bunch of heavy equipment in the tree industry and could use a pointer. I have a truck with a 1995 dt466 NGD all mechanical. Bosch P3000 pump. In frame rebuild done last year around June or august After that it would start right up every time off to the races. Now, it’s extremely hard to start. It started when it was cold out, but it doesn’t matter - if it’s 60 degrees or 20, it cranks for ever. Occasionally holding wide open would help. Sometimes we can’t get it to start at all. I replaced every fuel line on the truck. Return lines, feed lines, lines from tank, not one hose on it leaking or sucking air at this point. New primer pump. Primer pump used to get rock hard but now it never seems like it does... replaced it 3 times to make sure I didn’t get a bad pump. It is pushing fuel though. next item in line was the lift / transfer pump, same thing mounted to the block on a 5.9 Cummins but it goes on the side of the injection pump. Replaced that because I thought I was getting fuel in my oil. Making a little oil and it’s not coolant. Looked like fuel was getting past the stem. So that’s new, thought that could be sucking air making it hard to start. Primed it up drove around truck always runs perfect once it’s going. If it sits overnight, good luck getting it to start. At this point, I’m thinking it might not be a “priming issue” although I am thinking about putting a 12v inline fuel pump on it. 8psi. Is it bad to send 8psi to the transfer pump? Factory setup has no electronic pumps. could something in the injection pump be faulty making it hard for us to make pop off pressure when first cranking? Granted, sometimes it fires up no issue at all as soon as it rolls over. I don’t think it’s injector related, it runs perfect no smoke lots of power. Appreciate any insight.
I would look at the inlet check ball between fuel tank pickup and primer pump
There should be an external solenoid mounted on or near the fuel injection pump that pulls the shutdown lever to the run position. Unless you have a manual pull cable with a Tee handle for shutting the engine off. If your truck has a shutdown solenoid make sure it is working. There are 2 different solenoids. Both solenoids have 2 coils a pull in coil and a hold in coil. The early type had 2 wires to it a 12v ignition switched power and a ground. When the solenoid pulls in the plunger all the way there is a switch in the solenoid that disconnects the pull in coil so it does not burn out. The internal switches would fail and the engine would not start. The later solenoid had 3 wires to it. A 12 volt switched ignition wire a ground and a pull in wire that connects to the output side of the starter solenoid. When the starter is energised it sends power to the solenoid to pull the plunger in. The pull in coils would periodically fail and cause a no start condition.
Or you could just put a new pressure relief valve on the injection pump. Bob
I'm going to second the stupid little rubber check ball first. They are a known problem. the break down and lose pieces and the seal they are supposed to make is never right after. It is right behind the primer pump before the hard line. IIRC there is a plastic cap over the top of it.
Does it smoke when cranking could be leaking injector
X2 on bluox's comment. You stated that you replaced all the fuel lines. In that operation did you happen on a little plastic bowl strainer just forward of the bulkhead on the left side? That whole thing is made of plastic. Wouldn't be hard to damage. Additionally, sometimes those things are fitted with Racor or diesel pro fuel/water separators hidden to the rear of the fuel tank/step/battery box. Sometimes inside the wheel house under the hood directly below where your clutch linkage is/should be. Anyway, the point is, don't miss hidden filters or rock catchers. If you can say with 100% certainty that you haven't missed anything, look at that overflow valve, common failure.
I would start at the OVERFLOW VALVE.. it’s located at the fuel return line..on the pump.. it’s a spring loaded ball.. The supply pump should produce 1.5 bar to the pump inlet..
thank you ALL for the answers. I had begun to suspect this overflow valve after reading up on the pump schematic. International dealer gets crazy stupid 5x/6X what you can find online for part prices, should the one from a 5.9 Cummins / p7100 be suitable for this p3000? Seems those are easy to come across. Looks identical. ‘between the fuel tank pickup and the primer pump is a fuel water senator and a rock catcher. Not sure where this check ball would be? we deleted that when I swapped this motor in, it’s all mechanical. No failure here ‘next on the list.. seems very likely. I do know where there is a plastic cap. I will take pic and report back. GuEssing this thing could suck air? It’s on the top of the filter head , yes? No smoke ever runs great I really don’t suspect a leaking injector. fuel water separator is new... overflow valve next. I know where the rock catcher is but I haven’t opened it. Since you are the pump guy.. I have to ask, do you know where to get an oil feed line for this pump. It’s a little different than a p7100. It looks to have a restrictor portion to dumb down the oil pressure, I think, so I didn’t want to replace it with just anything. But international dealer can’t seem to find what I’m after. Has a small seep leek
The P7100 overflow valve is set to a higher opening pressure BUT that’s what u want.. IF u can hold fuel pressure in the gallery longer, u can actually increase fuel delivery to the engine... Last time I priced an ovflo valve. they were almost 200.00 I don’t know a thing about oil lines.. I’m a fuel guy.. but the thousands I’ve had my hands on, there was no restrictions
motor is rated right below what the clutch will hold, so I’m not sure I do want to increase fuel delivery, but I’m going to try one out... I ordered one offline with good reviews for $18.00
The 200.00 one is a Bosch.. Can u post the site where u found one for 18.00.?? I’m always up for a sale..
ZM Overflow Valve for Dodge Ram 2500 3500 1994-1998 P7100 OFV030 OFV-A 5.9T Diesel https://www.amazon.com/dp/B07T13TKTZ/ref=cm_sw_r_cp_api_glc_fabc_xk5aGb0QD55C6 I am all about buying name brand stuff but a little spring in a valve type thing we’ll give it a shot lol. I see Bosch ones on there also for $40.00 but they say 98-02. Which I think is vp44 territory.
Thing I’m pointing to with pinky finger? Any chance you have a part number. I have this 95 engine in a 2005 intl that had a 6.0. Little Frankenstein hard for dealer to get me parts as I don’t have the vin for the donor truck
That's a compucheck test port fitting to hook up a pressure gauge. Bob
No expert, but that's not the check valve I was talking about, that's a over flow (to much pressure) The check valve should be inline with the fuel line like funwithfuel mentioned
if you look two posts up. The thing I’m pointing to is the only thing I can see that’s in between the tank and the rock filter is attached there. He said rubber plug over it. it’s before the pump and before the primer. I thought it was a test port also. Thought it might be the elusive drain back valve thing. EDIT : I’m thinking about putting an inline pump near the fuel water separator on a switch so you can “Prime it” with that. Think that will bring any harm to the transfer pump?
If you prime it before trying to start. will it start?
I can’t get it to prime without pressurized fuel tank and then bleed everything out one by one and then with some extended cranking I can start it. I think I understand where the check ball is now though. On top of the rock catcher. Primer pump will not pull fuel unless I suck on line and get fuel to it first and even then spits air once it starts it will re start all day
Either you've got a bad overflow valve or your sucking air. Have you taken the bowl off the rock catcher? Have you verified that the o-ring is sealing and not allowing fuel to drain back. You said you pressurised the tank to get a prime. Are you gauging this pressure? Beyond 5-6 psi, you run the risk of ballooning your tank. If you're pressurizing, cap the return line. This will cause fuel pressure to act on the suction side. Look for anything collecting fuel. If no fuel escapes, no leaks. If you look at fuel lines to and from injection pump body, you will have a banjo line from the lift pump . That's inlet and will have a hollow screw. The return fitting will be your overflow. It will either be a banjo screw with a spring loaded plunger or it will be on a stand-off valve with a hollow screw. In that case the stand-off will be the overflow.
Unscrew that "+" sign and the check ball is in there. Atleast that is where mine is located on my DT530E.
Okay so it’s the stand off valve with hollow screw. I order the banjo style one I read that it can be used in place of the stand off style overflow valve unless you know that to be false. International dealer having a hell of a time looking up parts for me so I’m kinda stuck ordering Cummins stuff off eBay I think I’m sucking air before the primer ball because I can’t get it to pump up hard at all. If I crack the lines and bleed them it’s like, continuously pushing fuel and air. That primer ball used to get rock hard and it would fire right up. I am going to get that rock catcher off soon. In hospital right now wife having a baby lol as soon as we get this baby delivered I’m going to unscrew it and see. I’m hoping that is it. It definitely drains back to the tank overnight.
If primer pump won't "firm up" your overflow valve is leaking. That's why it'll run the rest of the day. Its running off the overflows orifice once its running. If nothing leaks when pressurizing, you ain't suckin air. If it sucks air, it WILL leak fuel .
I have used the overflow banjo on top of weak overflow nipples, so no problem there.
When I “pressurize” I get the compressor up to like 15/20 psi and I take a red rag block the full cap and a blow gun and barely shoot air I don’t think I’m putting more than 5psi in there just enough to get it to the pump. But I mean it feels like that primer pump isn’t pulling anything but air these days. You can pump and pump indefinitely 100-200 pumps and it still feels like air no change in resistance like you used to get and you can tell it’s moving fuel I’ll put the overflow on it and check out the check ball and report back. You guys are super helpful. Kudos
Got the baby situation under control and maybe the dt466 too! Put the overflow banjo $18.00 special on the bad overflow nipple yesterday, this morning 5 pumps on the hand primer and she fired up. Also replaced that check ball, but it looked to be in fine shape. hoping this is a permanent fix. If it gives me any more grief I am thinking I will just put the in line pump on it.
good to hear! glad it worked out even if I missed the mark with my suggestion!
Don’t beat yourself up Red.. If everyone was a magician, I wouldn’t stand out as the diesel fuel injection “Sorcerer”.. lol
You do seem to be pretty talented with your Magic powers!