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Robert R
Robert R, ASE Certified Technician
Category: Jeep
Satisfied Customers: 4538
Experience:  ASE Master Certified, Jeep Certified
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I need a procedure to test the fuel Quantity solenoid on a

Customer Question

I need a procedure to test the fuel Quantity solenoid on a 2008 jeep Grand Cherokee 3.0 OMG 642 engine. I have good fuel pressure at the filter and it holds the prime. Just nothing comming out of HP pump. I assume the solenoid is returning to tank.
JA: How many miles are on the car? Have you had the fuel pressure tested recently?
Customer: I just tested the low pressure side and it was 50. there is no high pressure comming out of pump. nothing to test.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes. I am a HD Mechanic. just no experience on this engine. I need a procedure to check the 2 pins in the harness to ensure the power is correct before I replace solenoid.
JA: Anything else you think the mechanic should know?
Customer: No, that should be enough for a test procedure.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Jeep Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Jeep
Customer: replied 1 year ago.
When can I expect an answer. I have the jeep apart and the solenoid in my hand?
Customer: replied 1 year ago.
I just did a little testing........ Key off: 477 ohms across connector, (pin to pin) no voltage at either, 401 ohms to ground on yellow tracer wire, 555 ohms on black tracer.
Key on 346 ohms across connector (pin to pin) .375V on yellow, 0 on black, 371 ohms to ground on yellow tracer wire, 53.4 ohms on black tracer
Actuator: 2.9 ohms pin to pin.
Hope this helps.
Glenn.
Expert:  Robert R replied 1 year ago.

Hello, welcome and thanks for asking your question. My name is*****'m a Certified Auto Technician with 29+ years experience. I will do my best to assist you. please keep in mind that I may need to ask questions of you before I can answer. When you reply please feel free to add as much detailed information as possible pertaining to your concern.

Did you remove the solenoid from the fuel rail?

What is the vehicle concern that you suspect the Fuel Pressure Solenoid?

Has it been scanned for codes? If so, can you post them here?

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
I have provided my test specs previously. there is no fuel comming out of HP pump. The harness doesnt seem to be providing enough power to activate the solenoid, Tested actuator on 12 power supply and it shifts. Perhaps there is another sensor that controls that voltage.
Thanks.
I have a open file, but it has not provided me test procedure. the file number is *****
I have no fuel coming from the HP pump. The supply pump is producing plenty of pressure at filter.. The fuel solenoid is not getting enough power from the harness to close the solenoid and close the return passage. What could effect the supply voltage.
Expert:  Robert R replied 1 year ago.

Before we continue I need to make sure that we are on the same page and talking about the same solenoid. Are you referring to the Solenoid that is mounted to the Fuel Injection Pump or the one mounted to the Fuel Rail?

Customer: replied 1 year ago.
The 1 on the pump.
Expert:  Robert R replied 1 year ago.

Ok, That is the "Fuel Quantity Solenoid". This solenoid is Normally Closed, meaning that when it is not receiving power, the fuel injection pump is delivering maximum fuel. This solenoid is NOT a fuel cutoff solenoid. It only reduced fuel volume delivered to the fuel rail when the ECM modulates voltage to this solenoid. It will NOT receive power with the ignition on and cranking the engine. It only operates after the engine is running.

Here is a document explaining normal operation of the Fuel Quantity Solenoid --->> Click Here to view <<---

You stated that the injection pump was not delivering high pressure, how did you determine this? Was there any flow at all from the injection pump? Do you have access to a scanner that can read the datastream on this Sprinter?

Keep me posted...

Thank you,

Robert

Expert:  Robert R replied 1 year ago.

This solenoid along with the "Fuel Pressure Solenoid" controls rail pressure and keeps this pressure at a constant pressure as requested by the ECM. It also helps to reduce the fuel pressure pulsations that would normally be caused by the individual injectors opening during injection of the fuel.

At this time, I'm assuming that the vehicle doesn't start. How many miles on the odometer?

When you checked for fuel flow from the injection pump was there absolutely ZERO fuel coming from the injection pump or a very little volume amount?

Customer: replied 1 year ago.
Tha nks for the info. I only have a cheap scanner. I tested the pressure at the filter and there was 50+ psi. I removed the high pressure line at the top of the HP pump and there is nothing comming out durring cranking. I had this engine out to change a cylinder head and it was all working fine. Did not touch the pump.Is it possible it is passing that solenoid?
Expert:  Robert R replied 1 year ago.

Which head was changed out? Did you remove the injection pump during the process?

When cranking the engine does it sound strange like intermittent compression loss?

Expert:  Robert R replied 1 year ago.

I've never had a solenoid stick open. It would have had to had water contamination in the fuel in the past to cause the Fuel Quantity solenoid to stick open.

If there is no fuel coming from the injection pump whatsoever, I would start looking for a possibility of a broken camshaft on the driver head. The Injection Pump Drive sprocket is built as part of the camshaft assembly and may have sheared the injection pump drive sprocket at the point where it attaches to the camshaft. I've seen this a few times in the past. I had this happen once and one strange symptom was intermittent compression loss. This was caused by an intermittently rotating camshaft on the left side....

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
I changed the right side head. Is there a coupling in there tha But yes I do hear a sound like that.
Expert:  Robert R replied 1 year ago.

The camshaft has a toothed drive gear that drives the injection pump. You will need to remove the left valve cover to inspect the Intake Camshaft (I believe) for signs of breakage right at the point where the drive gear is attached. You may need to rotate the engine to see if both cams are rotating after removing the valve cover...

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
I just checked the solenoid. It is N/O without power.
Expert:  Robert R replied 1 year ago.

It's set up where it delivers fuel fuel flow to the pumping chambers when no power is there. When power is there it redirects the fuel from the INLET port to a return port that leads back to the inlet port.

Customer: replied 1 year ago.
Do the electrical values look correct I sent. It is a pile of work to get the valve cover off and that side wasnt touched perhaps it would be easier to pull the pump.
Expert:  Robert R replied 1 year ago.

There is no published service info for electrical testing of the solenoid itself. The manufacturer has you test the wiring, and if ok replace the FQS as a process of elimination..

See the following diagnostic procedure for additional info...

--->> Click Here to view <<---

I was just thinking and I realized that the injection pump should still be spinning even if the camshaft has broke. The cam drive is driven off the exhaust cam which is driven off the timing chain. At this point if there is NO flow from the injection pump it is likely bad and needs to be replaced.

Customer: replied 1 year ago.
Robert, thanks again for the details. I just read in 1 of the attachments you sent, that when the ignition is turned off it diverts the fuel to the return passage. That means with no power the fuel does not go through the HP plunger. It is still looking like a power problem if this is the case. Is this how you understand as well?
Expert:  Robert R replied 1 year ago.

Ok, it appears you're correct. Has the vehicle been scanned for codes? If you can post the codes retrieved here, I will get the correct diagnostic procedure so you can check the wiring for the Fuel Quantity Solenoid...

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
I just performed the test procedures you provided. When I remove the ecm harness and perform the 2 tests. It exceeds the guidelines you provided.
Expert:  Robert R replied 1 year ago.

Which steps of the procedure exceeded the specs? Also what were your test results?

Were you able to retrieve codes from the vehicle so I can make sure you are running the correct diagnostic procedure?

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
Despite the test results I tried cranking the engine with harness off solenoid and with 12 volts. Neither produced fuel from pump I pulled pump and drive gear is turning fine. I loosened all the injectors and turned over and all cylinders aare making compression. No broken cam... I am taking the pump apart but so far it looks good. Is there another solenoid in the fuel system that divert or block fuel when cranking. I know the supply pump makes 50+ when the key is on. Not sure when I am cranking. The only other place it could go is through the small return hose. What is the solenoid in the fuel rail do you talked about. Meanwhile I will check the rest of this pump out.
Customer: replied 1 year ago.
Pump is all back together. Nothing wrong inside. Is there anything that would over ride the primary pump for shut down?
Expert:  Robert R replied 1 year ago.

From every thing you are describing, I still have to suspect a faulty Fuel Injection pump. Basically there is nothing else in the fuel system that can block fuel flow from the fuel filter to the Injection pump. If you have verified that fuel is getting to the injection pump with a pressure of 50 psi, I would have to assume that there is no other possibilities for no flow from the injection pump. This leaves the ONLY possibility being the injection pump itself. I would have to say that it is definitely possible for there to be an internal crack causing no flow from the pump..

I do have another question for you, hopefully you will answer it. Any questions I have for you help me to point you in a better direction.

When you say no fuel flow, do you mean absolutely ZERO fuel flow or do you see fuel dribbling out from the fuel injection pump output port?

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
It looked like it dribbled. I only checked the supply pump pressure with key on. Not cranking. I am going to test that now. At filter outlet and then at the return line comming out of HP pump. The pump looked fine inside. Could test the pressure relief cartridge in it though.
Expert:  Robert R replied 1 year ago.

The solenoid in the fuel rail is the Fuel Pressure Solenoid. This can fail and cause excessive fuel return flow and hard or no start condition. This is ONLY a possibility if the injection pump is delivering fuel...

Keep in mind that the injection pump does not deliver a large volume it only delivers high pressure. If it is dribbling when cranking, that may well be enough flow, the problem may be somewhere else on the high side such as the Fuel Pressure solenoid or one or more bad injectors returning too much fuel...

Let me see if I can find a spec for fuel injection pump delivery volume so you can run a test on it

Customer: replied 1 year ago.
Right now all my testing is done with the jumper pipe off between the HP pump and fuel manifold. There is defnately not enough volume to even blead the system to injectors. Is there any relays or sensors that control the primary pump. It has to be something simple. It was working fine before I pulled the engine. 1 other note the steering wheel lock does not work. It may have been like that before. This unit gets towed behind motor coach.
Expert:  Robert R replied 1 year ago.

I can't find a spec for injection pump flow but you can run a test anyway. Do this, get yourself a graduated cylinder that can measure around 100 ml of fuel. Point your jumper pipe into this grauated cylinder or a catch cup. Crank the engine until you get fuel at the outlet of the jumper pipe. Drain the container and put it back under the jumper pipe. Crank the engine for a total of 30 seconds splitting it up into 2 or 3 equal increments. Do this at least 3 different times catching and measuring the fuel each time. Average your readings. If you have at least 75 ml of fuel in this 30 seconds as an average output, your injection pump is fine.

post back the results and we can go from there...

Thank you,

Robert

Customer: replied 1 year ago.
I just tested. I have only 14 psi during cranking at filter outlet hose, 60 with key in on potion. Presume is going somewhere. I am sure that's the problem.
Customer: replied 1 year ago.
I cleared all the codes and cranked it over. I got R0091 Fuel pressure regulater control circuit low & 003 Fuel volume circuit low.
Expert:  Robert R replied 1 year ago.

I'm not certain that 14 psi is bad while cranking, the main thing the injection pump needs is fuel volume. Injection pump is not required to receive the fuel under a lot of pressure to start the engine.

Here is some service procedures for the two codes posted, run these charts and keep me posted...

P0003 ---->> Click Here to view <<---

P0091 --->> Click Here to view <<---

Here is a star case pertaining to Sprinters. This info also pertains to the 3.0l Diesel in the Jeep Grand Cherokee. --->> Click Here to view <<---

Run these procedures and post back the results.

Thank you,

Robert

Customer: replied 1 year ago.
Thankyou for the last links. I think we are getting somewhere. I believe it is a volume problem to the HP pump. I tested the pressure before but not the volumne. is there any relays other than fuse 21 that controls power to the fuel pump. maybe the pump is lossing power.
Expert:  Robert R replied 1 year ago.

Ok, Here is the wiring diagrams for the fuel pump circuit, also the connector pin chart for the relay. The relay is in the PDC under the driver seat.

Page 1 --->> Click Here to view <<---

Page 2 --->> Click Here to view <<---

Connector Pinout --->> Click Here to view <<---

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

Customer: replied 1 year ago.
I have I fuse panel under dash and the PCM and IPM are under the hood. I see a seperate fuel pump moduLe noted on drawing. Is that under the seat. What about auto shut down? Is there someway to check that?
Customer: replied 1 year ago.
The steering wheel lock is not functioning. Is there any way that could effect fuel pump voltage?
Expert:  Robert R replied 1 year ago.

Sorry, Incorrect, The fuel pump relay is in the PDC under the hood not under the seat. For some reason I keep thinking Sprinter every time I am dealing with a 3.0l Diesel....LOL

The Fuel Pump Module you are seeing on the wiring diagrams is the actual Fuel Pump Assembly in the fuel tank. Chrysler calls it a Module but it is just a fuel pump and fuel level unit assembly.

Steering lock will not affect fuel pump voltage. What is the steering lock doing? Are you able to turn the key when it doesn't function?

Let me research the ASD for you...

Thank you,

Robert

Customer: replied 1 year ago.
I think we can rule out mechanical component failure. Thst pump is expensive. Broken cam even worse. Just need to figure our where the electrical glitch is. When the key is off and out off the ignition the steering wheel is not locked. It may have been modified for towing purpose's.
Expert:  Robert R replied 1 year ago.

Try rotating the steering wheel 360 degrees and let me know if it locks any where around the rotation of the steering wheel.

How many miles are on this vehicle?

Customer: replied 1 year ago.
It has about 70,000$ No it does not lock.
Expert:  Robert R replied 1 year ago.

As long as it doesn't stop the ignition switch from turning to the "On" position, I wouldn't worry about the steering lock...

I recommend to run an injector return flow test, I think I posted a document above that outlines a simple injector return flow test.. Run this and keep me posted..

Let me know about the results of the code testing...

Thank you,

Robert

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Customer: replied 1 year ago.
I hAve to get the pump operating before I can check rturn flow. I pinched off the line st the return tee ans it made no difference. I am convinced it has to do with the electric pump power signal bring interrupted. Yes key turns on and shifter moves.
Expert:  Robert R replied 1 year ago.

I know you must get the Injection pump operating but what I am trying to get across to you that in fact a dribble from the pump may seem not enough fuel but it may well be. I was hoping that you would be able to run an an injection pump flow test by measuring the amount of fuel collected in 30 seconds. If this amount collected is at least 75 milliliters that would likely be enough fuel (75 ml is definitely NOT a lot of fuel) Run this test and post back the results..

Keep me posted...

Thank you,

Robert

Expert:  Robert R replied 1 year ago.

Pinching off the return line will NOT change anything as you found out. Pinching the return line off is NOT a good conclusive test. You will need to run an injector return flow test after you run the injection pump flow test. Let me know what your results are for the injection pump flow test and we can go from there...

Thank you,

Robert

Customer: replied 1 year ago.
I just jumpered the the fuel pump relay between pin 30 and 87 and there is plenty of fuel coming from hose now.going to hook the lines all back up, jumper it and crank the engine. I suspect I will get fuel from HP pump now. But I still will need to find what's interrupting the pump circuit.
Customer: replied 1 year ago.
I have 1 more question. #30 is hot all the time. Not switched. Is that correct?
Expert:  Robert R replied 1 year ago.

Ok, Let me know if you get it started by bypasing the relay.

Correct, pin 30 is B+ and NOT switched voltage...

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
Got fuel to the injectors now. I only have 3.7 volts on the #86 pin of relay with key on. I dont see anything in the draawing between the battery power and relay. It looks like it should be 12Volts.
Expert:  Robert R replied 1 year ago.

Yes, Pin 86 of the relay should receive 12 volts. This is fused 12 volts so check the fuse to be sure. The diagram shows the fuse number...

Customer: replied 1 year ago.
That is powered by fuse 16 according to drawings and hot all the time. I don't see anything between the fuse and relay, but it appears it also sends power to water in fuel sensor. I pulled that connector but still only 3.7.V
Customer: replied 1 year ago.
Can you verify which connector I should be taking the harness readings on.
Customer: replied 1 year ago.
I Just found another quirk. At the fuel pump relay base. Key off 12V power at #30 only. Key on 12V at #30 & #85 and 3.5V at 86.
Customer: replied 1 year ago.
Robert, I really need your help. The test procedure document has a different ECM conector, 2 smaller on the side. I am sure the numbers work out but do sure tracing by colours doesn't work. Do you have the ECM pin out doc?
Thanks
Expert:  Robert R replied 1 year ago.

Please post the last 8 digits of the VIN and I'll get the correct ecm pin chart for you

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
Did you see the photos of the connectors I sent?
8C528353
Also I noticed the Fuel Pump relay is reversed and the 12 volt switched power is on 85 not 86. 86 seems to have 3.5 back feed.
Expert:  Robert R replied 1 year ago.

Yes. Which connectors are those?

Let me run the vin so I can get your ecm connector pinout.

It will be fine if 85 and 86 are swapped, the most important thing is that you have a complete circuit between 85 and 86. We just need this to activate the relay so it shouldn't matter which way the current goes through the relay coil. To check for back feed on 86 disconnect the ECM and check resistance of the wire from end to end, also check for a short to power (the 3.5 volts) and for short to ground. If you find that this wire is good it may be that the ECM is sending this 3.5 through this circuit. So will the ECM not turn on the fuel pump relay at all? You stated earlier that you were getting 50 psi fuel pressure. Just confused about this part.

Give me a bit to get the correct ECM pin chart.

Be right back

Customer: replied 1 year ago.
Those connectors are off the ECM. I will ohm out every wire as soon as I have the pin out for the ECM/harness.
I jumpered the fuel pump relay to get the pressure and volumne check done
Expert:  Robert R replied 1 year ago.

Those are not the ECM connectors. The ECM is located under the battery. I'm posting the ECM Connector Pin Chart and it will show the ECM location on the last page...

Click to view

Post the results of the pressure and volume test

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

Customer: replied 1 year ago.
OK thanks. I never had those wires off. I had the engine connector harnesses only.
Customer: replied 1 year ago.
I cant open the pin out you sent,
Expert:  Robert R replied 1 year ago.

What happens when you click the link?

Customer: replied 1 year ago.
I got it. It just took a while Do you have a schematic of the ASD circuit. that appears to control the fuel pump that I cannot see.
Thanks for all this help. We will get it.
Expert:  Robert R replied 1 year ago.

Here are the ASD Circuit diagrams and connector pin chart

Page 1 --->> Click Here to view <<---

Page 2 --->> Click Here to view <<---

Page 3 --->> Click Here to view <<---

Page 4 --->> Click Here to view <<---

Connector Pinout --->> Click Here to view <<---

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

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Expert:  Robert R replied 1 year ago.

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Customer: replied 1 year ago.
I have been busy with my oilfield buisiness and not had a chance to work on Jeep. I still have the 3.7 volts on the relay gnd for fuel pump. Any ideas.
Expert:  Robert R replied 1 year ago.

The only thing I can suggest is to disconnect the ECM connector and check the wire using an ohm meter. You will also need to check for short to power using a voltmeter. If you have a short and can't find the actual short, it is acceptable to run a new wire and cut out the bad part of the circuit...

Keep me posted...

Thank you,

Robert

Customer: replied 1 year ago.
I have tested all the wires. It appears to be getting through the ECM. There must be a sensor telling it to send signal.when the engine is not running it is reading 330 psi fuel rail pressure. If I pull the harness from sensorit still reads 330, but the sensor voltage changes from .5 to 5.
Expert:  Robert R replied 1 year ago.

That 330 psi may just be a default value that the ecm is showing when the sensor voltage is beyond a certain threshold. I've seen that several times, it's nothing to worry about.

If the Fuel pump relay still won't power up then I would have to assume there is an internal failure in the ECM causing it to not engage the fuel pump relay via that wire that is showing the 3.5 volts. What happens if you just ground this wire and see if it turns on the fuel pump relay. If it does, then the ECM is bad and will need to be replaced...

Keep me posted...

Thank you,

Robert