I just bought a 99 7.3 from a person that had a problem and got discusted. He replaced the Computer and the oil pressure pump Not sure about the fuel pressure regulator. It will start if you spray fuel oil into the air filter hose but it smells very lean when it starts and it spews out smoke out of the exhaust (light color) It then dies and won't start unless you let it sit until the next day. It runs awful You have to race it in order to start 1600 RPM. I have taken it to a shop and they say the pump is bad but it was just replaced ?? It only has 80,000 miles .. After reading I'm thinking CPS but I'm not sure .. Any ideas what to check ? Could they have messed up the pump instlation ?
Don H
Sounds like the fuel pump is bad since you replaced the high pressure oil pump. Scan for any codes and get a fuel pressure test done. If you look directly underneath the drivers side door on the frame rail is the pump. Cycle the key to the wait to start position and see if you can hear the pump running.
Yes we checked that It the pump is running and it fills the fuel filter up too. I have no scanning tool and the shop I took it to wants to start throwing parts at it I told them to hold on Lets get some information.
Yes we replaced the filter I'm not sure what the codes were that he had but I think he said something about low fuel pressure . I told him the pump had just been replaced but I suppose it could be defective .
If you can get #5 o-ring boss hydraulic fitting, hydraulic hose, and a 0-5000 psi gauge (cost ~25.00-30.00) remove a oil gallery plug in the head, and connect gauge. Pressure should get over 500psi in a crank or two, if not, there could be a problem with the IPR injection pressure regulator sticking open, or other HPOP system fault.
I remember he told me he checked the pressure at cranking and it was 400 pounds but the batteries were low too I'm not sure if he checked for split O rings
Can anyone tell me what drives the high pressure fuel pump Is it a gear off of the cam shaft? Does the fuel pressure regulator just regulate the fuel pressure output from the fuel pump ? How does the fuel flow from the tank to the electric fuel pump to the fuel filter to the high pressure pump to the injectors ? The cam sensor tells the injectors when to open & close by the posisition of the cam ? I'm only trying to understand how this works . If the pressure is low at the pump at start up it could be a restriction between the filter & pump ? Or a bad pump? or pump just not putting out enough pressure ?
Don :doh:
Can anyone tell me what drives the high pressure fuel pump Is it a gear off of the cam shaft? Does the fuel pressure regulator just regulate the fuel pressure output from the fuel pump ? How does the fuel flow from the tank to the electric fuel pump to the fuel filter to the high pressure pump to the injectors ? The cam sensor tells the injectors when to open & close by the posisition of the cam ? I'm only trying to understand how this works . If the pressure is low at the pump at start up it could be a restriction between the filter & pump ? Or a bad pump? or pump just not putting out enough pressure ?
Don :doh:
Actually what you are talking about is the hpop or high pressure oil pump it is gear driven on the front of the motor. This is fed by engine oil which it in turn boosts the pressure to around 3500 psi give or take some. You need around 500 psi for the injectors to fire. What this does is hyrdraulically fires the injectors or the mechanical part of the equation. The fuel flows from an electric pump on the frame rail right underneath the drivers side door. You want at least 50 psi from the fuel pump. The cam sensor in a nutshell lets the pcm know the engine is running so fuel will continue to flow since the diesel doesn't have an ignition system like a gasser. If you have low pressure at the hpop it could be a leak so really you need to have some diagnostics run with a scanner to verify.
Above the harmonic balancer and below the water pump kinda on the passenger side. Very easy to get to, takes a 10mm socket, remove one bolt and unplug one plug. They now cost around $20, used to cost around $180. Anytime I have a runability issue I take 2 minutes to swap my CPS with the spare in the glove box.
Don H, you need to find a mechanic with a scanner and the know how to use it properly or borrow one yourself. You can plumb into the heads to check both fuel pressure and high oil pressure. Fuel needs to be above 50 psi, if not since the pump has been replaced I would look closely at the fuel pressure regulator on the side of the filter bowl. HPOP needs to be around 500 cranking, if not look closely at the IPR on the bottom of the pump, it has a tinnerman nut and a wire plug going to it. The pumps themselves rarely fail. Again good diagnostics with a scanner can save lots of time and parts.
Also the batteries need to be very good for a PSD to start and run.
Well I got the truck back and they replaced the pump and the regulator 78000 miles and third HPOP pump It runs but now skips I guess I have a injector peoblem .
I believe I was taken
being that they changed the hpop out there may be some air still in the high pressure oil lines it nomaly takes a while to get all of it out. I would run it a little while to see if it clears up before I shell out for injectors.
I guess theres no bleeding them huh ? I have driven it 40 miles I would have thought this would have been enough time but I will add some injection cleaner and see what happens before I replace anything .
The HPOPs are built really well. I would really doubt that an HPOP failed once but 3 times is near crazy. Did the same shop work on the truck each time?
whe I installed the dual hpop system on my rig it took foever to get the truck started and then it ran like crap for about 3 or 4 days, but it cleared up and all is well.
I bought the truck not running The HPOP had been replaced and they couldn't get the truck running so the shop replaced the HPOP and the computer Still wouldn't run so the owner bought a new truck. That was 6 months ago I bought the truck 3 weeks ago and didn't know much about it then so I took it to a shop that checked it and said the HPOP was bad I told them it had just been replaced but they insisted it was bad . Well they replaced it along with a regulator and a Cam sensor Now it runs but I have another problem .. ( Skips ) I told them I find it hard to believe the truck went through 3 pumps in 78000 miles but it is running. I paid the core and kept the pump I may have it checked to be certain it was gone .
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