85 6.9 IDI Will not run

[Olds64]

Two things first the facet pump is definitely not recommended anymore. Their quality has fallen off a lot and they really don't flow enough for our trucks.

Never read that before. Definitely order from a trusted supplier vs. Amazon. Everything is counterfeited these days.

x2 on contacting Justin at R&D. He's the expert when it comes to these old IPs.

Let us know how that spare IP runs.

 

[BMadScientist]

Well with the spare pump shipped it was right around $180 so at the very least I’ve got a cheap core. There’s also a local guy selling a CDD 110cc pump as well that I’ll be picking up tonight with a set of injectors. I’ve also got some parts on the way to try and spruce up the turbo as well to try and make use of the extra fuel.

 

[IDIBRONCO]

If a different IP gets your truck running right, get ahold of Justin again. He may offer to make it right since his is acting up.

I’m not thinking that it’s a fuel supply issue now. I had someone watch my fuel pressure at the pressure gauge which is on the pressure side of the regulator while I was running the engine and there was no pressure drop when the truck was running and would die down. This would indicate to me that the lift pump flow is more than adequate to the injection pump.

This is why my fuel pressure gauge is mounted inside the cab. It's an electric Autometer gauge. That way, I can keep an eye on it while I'm driving. I recommend that everyone does this along with a vacuum gauge to keep an eye on your vacuum pump. I'm not saying that everyone has to use an Autometer pressure gauge, just that everyone uses one.

 

[BMadScientist]

This isn’t all that pertinent to the diagnosis of this truck but I figured I’d go ahead and tell the story. I went out today and bought the used CDD 110cc pump today along with a set of CDD stage 1 injectors to hold onto as a spare set for later. I arrived at this shop on the outskirts of town and was greeted by Caleb who is a gentleman by all accounts. Him and I get to talking about his truck and what he had, he had a. 7.3 IDI with this pump and an HX35 turbo. Built motor with a logger cam and all sorts of other fun stuff in the motor. Reason he was selling the pump is he cracked one of the heads on his truck and it started drinking coolant. But him and I get to talking about my truck and as I start listing off details about my truck he cuts in and continues listing details off about my truck. Turns out he built the motor that’s in my truck. He built my truck side by side with his truck right around 2023. My truck has an AC compressor but was missing the AC lines coming off the compressor. Right hand on the bible he tells me that today is my lucky day. He pulls the ac lines that came off my truck out of his car and gives them to me along with the 4wd linkage for the truck as well. (The truck was originally a 2wd automatic but currently has a ZF5 with an NP205 but still has a non driven front axle. I’m working on getting a set of F450 axles for the truck to remedy this.) I just figured I’d up and share this information just for fun. He’s currently working on a P pump setup for his IDI and I believe one or more of his coworkers have a working P pump in their trucks as it stands today. I have no affiliation with these guys but everyone over at Jimmys Repair Service 24949 Conway Rd, Caldwell, ID 83607 in Caldwell Idaho were awesome to talk to.

 

[vertflyer]

This might be a dumb idea but if your PSD pump puts out 50-52gph @ 60psi and you turn down the pressure to 20psi how many gph is the psd pump putting out?

 

[BMadScientist]

vertflyer, I wasn’t ever able to find a definitive flow chart like those available for common aftermarket gasoline fuel pumps, I’ll try and attach the flow chart for the pumps im running in my 6.2 raptor swapped 2001 F150, but typically with this style of fuel pump flow rate goes up as pressure goes down and vice versa. I would suspect I’m getting more than 50-52 GPM with the pump getting basically “open flow” at 5-12 PSI which would in theory raise fuel flow given the lack of flow.

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[IDIBRONCO]

This might be a dumb idea but if your PSD pump puts out 50-52gph @ 60psi and you turn down the pressure to 20psi how many gph is the psd pump putting out?

vertflyer, I wasn’t ever able to find a definitive flow chart like those available for common aftermarket gasoline fuel pumps, I’ll try and attach the flow chart for the pumps im running in my 6.2 raptor swapped 2001 F150, but typically with this style of fuel pump flow rate goes up as pressure goes down and vice versa. I would suspect I’m getting more than 50-52 GPM with the pump getting basically “open flow” at 5-12 PSI which would in theory raise fuel flow given the lack of flow.

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Mu guess on this is that the pump won't have any more volume than it's capable of making. If it's only capable of making 60 GPH, as an example, then it can't make any more than that. I also don't know that the volume of flow would increase at all in this application since the pump itself is still putting out 60 PSI. It's the restriction of the regulator that reduces the fuel pressure, not an adjustment to the pump itself.

 

[BMadScientist]

IDIBRONCO, the lift pump is in no way putting out 60 psi with the regulator I have installed. It is a bypass style regulator. The lift pump is only seeing whatever pressure I have the fuel system regulated down to. To treat it as if it were a hydraulic system, the regulator would be holding the outlet side of the lift pump at whenever pressure I have the regulator set at, and as such functioning like a pressure compensated relief valve in a sort of way. There is not in any way 60 psi being put out of the lift pump so long as the fuel pressure regulator is functional. Anything more than whatever set point pressure I have regulated is sent right out the return. The lift pump is not outputting 60 psi because the pump does not create pressure, it creates flow. The restriction to flow (fuel pressure regulator) is what creates pressure. It is at the will of the fuel pressure regulator to create pressure, not the pump.

 

[IDIBRONCO]

Unless your regulator is integrated in the lift pump, then it is, in fact, putting out it's maximum pressure. Now it very well may be integrated. I'm thinking of external regulators that are used after the lift pump.

 

[BMadScientist]

I really feel that you have a fundamental misunderstanding of how hydraulic pressure works.

 

[ihc1470]

When testing hydraulic pumps with flow rators if you do not have it restricted you will have flow but little pressure. As you start restricting the flow the pressure will rise. You determine if the pump is good or bad by how many gallons/liters per minute it will flow at what ever pressure the system is designed for say 2000 pounds.

Same with a water system, you can flow 10 gallon a minute through a 1/2 inch pipe or a 4 inch pipe. You will see much more pressure at the end of the 1/2 inch pipe than the 4 inch but in both cases you will have 10 gallon a minute.

Now an application which in many ways is similar to this fuel system. I am a farmer and put on a liquid when I seed fields. The application rate is 5 gallon per acre. I have 36 openings for the fluid to pass through and if I recall those tubes are .093 in size. The pump is capable of 60 psi, I do not recall how many gpm. There is a fixed bypass valve in the system which returns the excess to the tank so that is a tee allowing flow in 2 directions. The system is computer controlled on the leg that goes to the application side. There is a flow meter and a regulator valve so the system is always applying 5 gpa so matter the ground speed. When applying the pressure gauge is reading maybe 2-3 psi. When the computer shuts it down when turning on the headlands it reads mid 50 as it can still bypass through the fixed valve. Now if I wanted to restrict the fixed valve even more I could get the pump up to 60 psi and then it would shut off because the pump has a built in pressure switch for protection.

The point is the pump can reach rated pressure if restricted enough but will not if there is not a restriction in the system. So my question IDIBRONCO is how can this diesel system get the pump up to max pressure when you have an open return line to the fuel tank?

 

[BMadScientist]

The only situation in which the lift pump would have 60 psi at its outlet and a lower regulated pressure after the regulator is if the fuel pressure regulator was functioning as a pressure reducing valve. It is not a pressure reducing valve. It functions as a relief valve. This is audibly confirmed by the pump flowing more and getting louder as I reduce the regulated pressure. In a deadhead situation, ie me running the pump right into the injection pump inlet the pump gets quieter because there is higher pressure and less flow. IDIBRONCO, I’m in no way trying to pick a fight or cause an argument. I’m a heavy equipment mechanic and have a really good understanding of hydraulics. I genuinely do appreciate your insight and help.

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[ihc1470]

IDIBronco I am not trying to pick a fight either, just showing pratical applications and normal testing procedures.

 

[IDIBRONCO]

Did you not, in your first post, say that this is a PSD pump that's rated at 60+PSI (rounded down to 60)? If it's rated at 60PSI for a 7.3 PSD, then why is it not rated at the same for a IDI application? The 7.3 PSD also uses a return system, doesn't it? What is the difference? Does the pump know what truck it's on? Where's the regulator on a '99-'03 7.3PSD?

 

[Nero]

Ive been watching this thread for a few days... Honestly it sounds like you may have damaged something on the internals of the injection pump by more than tripling the spec of inlet pressure. The dynamic timing of these pumps is controlled by case pressure, it may be that the timing got so advanced and maybe bent/distorted parts internally...

As for your fuel supply system you've done, there have been many debated systems and arguements had over them. We all can speak from experience that e fuel systems are not reliable on these engines, as the injection pumps require a very specific fuel pressure and flow.

Good luck.