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Hi Pressure Fuel Pump Testing- low fuel pressure problems
I seem to be seeing this problem more frequently come in the shop and that is the Hi Pressure pumps failing on the direct injection engine. testing the supply side is simple enough but other than monitoring scan tool data I have had no real solution to testing and confirming a pump failure than to replace it with a new one..
Understanding the design is the first step , that is a mechanical pump pcm controlled by a built in regulator and a fuel pressure sensor.
I have a 2014 Jaguar XK 5.0 normally aspirated engine which uses 2 D.I. pumps. These pumps are about $400 each (aftermarket cheaper) and too much to eat if your diagnosis is incorrect. I've tried pumps off a pull-out engine only to have the same problem. This is a 10k engine swap and it's eating my lunch trying to get it out the shop.
I read it may have a timing chain misalignment on the lower chain drive and if not timed correctly could cause low pressure problems. I removed the lower oil pan and found a few pieces of the chain guide in the bottom of the pan. It also has a rattle (louder than the normal sound on the drivers side valve cover like a dry fire injector or chain rattle. Keep in mind I Paid $4000 for this "good motor" and the seller insisted it came out a good car. Its clean on the inside but way too much work taking apart to inspect the chains . I would have to pull the motor a second time. I am about to bite the bullet and install new pumps just to eliminate them from the equation. I had ordered them once and sent them back being unsure it would fix my problem.
Anyone have simular issues or advice to assist me in getting this out the shop? The tests on the solenoid and monitoring the scope pattern were inconclusive.
I will update this with the history and codes (only 1 code, low fuel rail pressure), new in tank pump, (attached fuel filter was on back order when new pump installed, was full of dirt, my guys installed the pump and saved the fuel to show me how cloudy and dirty it was. pressure is ok at fuel rail connector line but I don't know if there is a volume flow issue. This is the replacement engine that starts and runs but bucs on heavy accel and continues to measure very low pressure on the high pumps. The demand begins at 1460 on start-up then within the first minute drops to 0. I assume the pcm defaults into failsafe "Restricted Performance", obviously due to low fuel pressure. These pumps according to Jaguar have a high fail rate. Previous engine overheated from another common problem intake crossover plumbing blowing out. I have seen 2 engines like this that blew the fuel line to the pumps . I suspect this is because of the fuel system is a closed system with no return. The regulated pressure is fed back through the second line on the HP pumps. I will order new pumps this morning which will be my final option before pulling the motor back out again. It is nearly impossible to work on the motor "in frame", on the timing chains.
Do you see anything with Fuel trims? to help backup the rail pressure being low? From my understanding the Fuel Rail Pressure sensor does not fail often but it is possible. So if the Fuel Rail pressure sensor is reading low and Fuel trims backs up that assessment I would think you are pretty close to calling the pumps. But I have limited experience. just a bunch of reading.
Well being that the pcm monitors the fuel rail pressure sensor and if you unplug while running it does go (or at least it reads max pressure) max pressure about 2800psi for about 10 seconds before the pcm shuts it down (its too smart to be fooled) during that time it runs great. Now I'm not the sharpest knife in the drawer but I do understand how to read a scope. Never figured out how to command full pressure with my verus edge ver 21.4. Now have I understood how the fuel pump camshafts could e out of time when it runs great. I just spent $400 on some bosch oem (near oem) pumps. I will let you know what happens. This problem ain't going away. We'll visit it again. It will be good to have some more fire power in the tool box to address this when it rears it's ugly head again!
Fuel trims - short terms both banks high 17-21
fuel rail pressure HI- 74.26 psi, low pressure- 59.4
desired hi- 1450; desired low 105.7
computer is trying to max out available volume - fuel pump duty ratio 75%
she's giving it all she's got!
Fuel injector pulse width .35 ms all injectors
Cat temps pretty cold! 203 both banks.
what else you need to know- remember i did find a few chain gude pieces in the pan but they were small. cam- crank correlation ok- no codes, only code set is P0087-00 Fuel rail/system pressure too low
You may want to inject a valid signal into the fuel rail pressure sensor wiring to the pcm while being disconnectet. That way you can fool the pcm....
While powering up the then disconnected sensor you can read the sensor output to confirm high pressure. Depending on the circuit design - normally open vs. normally closed control valve - you may have to pulse this solenoid/control valve as well, normally open valves will go full gorilla when disconnected.
The difference between desired and actual low side pressure is considerable, you may want to make sure that the problem is not related to the low side pressure. You could watch out for what´s going to happen when - by an external source - the low side pressure is raised to a level the pcm is expecting to see.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
as far as the low side pressure, new pump from dealer, I know that pressure is correct. you can test it @ the line connector on the engine . pressure gauge installed in loop- not head-headed (damage to pump will occur if fuel has no where to go even know the pcm controls both power & ground- signals pulsed) I did feel uncomfortable in re-installing the original fuel filter in the tank. We dumped a ton of dirt out of it but being backordered had no choice. I know a pressure reading in specs does not guarentee the correct flow rate. but since I have no way to test it (well I guess I can do a 2-5 second key cycle test out of the open line from the low side pump and measure the volume flow compared to a known good vehicle. I'm, a jaguar tech so I have several here all the time.
Well the customer has been very patient and understanding even after shelling out 10k so far! He loves his car. I'm still cheaper than the dealer but this cars been her for 3 months. It's time to go home! I bit the bullet and bought the expensive Hi Pressure pumps today. They'll go on first thing in the morning. Will follow up afterwards.
initial start up pressure is around 1450psi, then it usually levels out around 800 psi, It maxes out around 2800 psi on demand, Pressure is monitored by the pcm via a fuel pressure sensor and controlled by solenoids on each pump regulating the on/off time of fuel delivery and the amount of high pressure return fuel back through the pump. All HP Pumps operate on this general principal and are of a similar design.
