1996 Dodge Ram 1500 Fuel Pump Quiz/ Question
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10-05-2010, 06:11 PM
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1996 Dodge Ram 1500 Fuel Pump Quiz/ Question
What would cause the RPM of the fuel pump to change when you apply the break? Basically at idle when I apply the break I can hear the fuel pump "Whining" slow down just a bit. I have an aftermarket fuel pump "Airtex"? I think with borg warner fuel injectors. I just put in a rebuilt pcm and a oem crank position sensor yesterday to fix a bucking a stalling issue. Turns out the guy that built the engine broke the crank position sensor connector on the harness, so to hold it together, he split the wire back on both sides of the connectors and ran a cable tie through the middle of the wire senching down, eventually causing the wire to pinch and not get a proper signal. Truck ran fine today so I think I am on the right track. I am now thinking that Dodges only like oem parts on certain things. I still have the factory injectors and think I need to put in a factory pump. The truck seems like at idle it may be border line on fuel volume even though pressure is more than likely in range. Just curious about the difference in rpm and if it is due to the pump not being oem along with the injectors.
#2
10-05-2010, 08:49 PM
#3
10-06-2010, 09:13 AM
What would cause the RPM of the fuel pump to change when you apply the break? Basically at idle when I apply the break I can hear the fuel pump "Whining" slow down just a bit. I have an aftermarket fuel pump "Airtex"? I think with borg warner fuel injectors. I just put in a rebuilt pcm and a oem crank position sensor yesterday to fix a bucking a stalling issue. Turns out the guy that built the engine broke the crank position sensor connector on the harness, so to hold it together, he split the wire back on both sides of the connectors and ran a cable tie through the middle of the wire senching down, eventually causing the wire to pinch and not get a proper signal. Truck ran fine today so I think I am on the right track. I am now thinking that Dodges only like oem parts on certain things. I still have the factory injectors and think I need to put in a factory pump. The truck seems like at idle it may be border line on fuel volume even though pressure is more than likely in range. Just curious about the difference in rpm and if it is due to the pump not being oem along with the injectors.
The reason for going with OEM over after-market on ALL sensor based systems and fuel pumps, alternators, generators and, basically anything that is considered a HI-REL (High Reliability) component, OEM is THE only way to go.
They are thoroughly tested and screened to FULLY meet OEM specs over the entire use range and environmental range as well. The ones that DO NOT pass OEM screenings are then sold off dirt cheap to brokers who, in turn, turn and sell them to 3rd party distributors. They work to more / lesser degree and, the reliability is no-where near the life of OEM parts.
I had gone through Bosch O2 sensors only to find one crapping out. Now, after learning from a component engineer friend of mine WHERE those are made and, WHO is assembling those, it's a wonder they even work at all as they are made in a sweat shop down in S. America. I recommend NTK ONLY as they are made in Japan and have been for YEARS and are OEM certified.
Borg-Warner is complete rubbish. I used a simple dizzy cap from them in a pinch. Let me tell you what happened with that POS. This was their "top end" cap and, it was nothing short of a pile. It was made so poorly that, the conductor for the coil had opened from the termination on the top to the spring-loaded button on the underside causing- no spark condition. Solid pin core design is the better choice and, you'll have to check to ensure that you're getting a good cap.
For the CPS, CKPS etc, I have used 4 aftermarket deals and NOT ONE of them worked properly.
Same with IAC valves, I bought three to find one decent one. I've had a TPS where, in one spot, it would surge.
Again, OEM is the only way to go.
Now, as far as what you're describing, IF INDEED you are certain beyond doubt that you can hear the fuel pump motor whine IN THE CAB whining- you've got a potential problem to start with.
If, the motor whine is going up and down while engaging the power brake system, there's another issue. The motor speed is intended to be constant RPMs regardless of rpms.
In order to verify the theory that the pump is whining down, you will need to take some measurements. If no measurements are taken, there's no way of knowing if this is really occurring or not.
TO TEST:
METHOD ONE: ELECTRICAL VOLTAGE DROP DOWN TEST
What this test is going to confirm is, whether or not there's a voltage drop at the fuel pump.
PROCESS STEPS:
- Backprobe the electrical connector at the pump. DO NOT REMOVE the connector for this test.
-TURN TO KEY <ON> measure voltage. Record the voltage under NO LOAD condition. This will tell you how much voltage is being sent to the pump under NO LOAD condition.
-<START> the vehicle and note voltage under RUNNING condition.
-INCREASE RPM and note voltage.
-APPLY the brake while releasing the throttle. Note if there's a voltage drop.
TEST METHOD TWO: FUEL PRESSURE VERIFICATION
What this test is going to confirm is, whether or not there is a drop in fuel pressure under varying loading conditions.
Repeat the same steps as above while recording the fuel pressure at the fuel rails.
Please post back as to whether or not you intend to test this or not. If so, I would like to see the results posted back into this thread for reviewing.
Regards,
CM
Last edited by cmckenna; 10-06-2010 at 09:16 AM.
#4
10-06-2010, 05:28 PM
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Regarding OEM parts:
The reason for going with OEM over after-market on ALL sensor based systems and fuel pumps, alternators, generators and, basically anything that is considered a HI-REL (High Reliability) component, OEM is THE only way to go.
They are thoroughly tested and screened to FULLY meet OEM specs over the entire use range and environmental range as well. The ones that DO NOT pass OEM screenings are then sold off dirt cheap to brokers who, in turn, turn and sell them to 3rd party distributors. They work to more / lesser degree and, the reliability is no-where near the life of OEM parts.
I had gone through Bosch O2 sensors only to find one crapping out. Now, after learning from a component engineer friend of mine WHERE those are made and, WHO is assembling those, it's a wonder they even work at all as they are made in a sweat shop down in S. America. I recommend NTK ONLY as they are made in Japan and have been for YEARS and are OEM certified.
Borg-Warner is complete rubbish. I used a simple dizzy cap from them in a pinch. Let me tell you what happened with that POS. This was their "top end" cap and, it was nothing short of a pile. It was made so poorly that, the conductor for the coil had opened from the termination on the top to the spring-loaded button on the underside causing- no spark condition. Solid pin core design is the better choice and, you'll have to check to ensure that you're getting a good cap.
For the CPS, CKPS etc, I have used 4 aftermarket deals and NOT ONE of them worked properly.
Same with IAC valves, I bought three to find one decent one. I've had a TPS where, in one spot, it would surge.
Again, OEM is the only way to go.
Now, as far as what you're describing, IF INDEED you are certain beyond doubt that you can hear the fuel pump motor whine IN THE CAB whining- you've got a potential problem to start with.
If, the motor whine is going up and down while engaging the power brake system, there's another issue. The motor speed is intended to be constant RPMs regardless of rpms.
In order to verify the theory that the pump is whining down, you will need to take some measurements. If no measurements are taken, there's no way of knowing if this is really occurring or not.
TO TEST:
METHOD ONE: ELECTRICAL VOLTAGE DROP DOWN TEST
What this test is going to confirm is, whether or not there's a voltage drop at the fuel pump.
PROCESS STEPS:
- Backprobe the electrical connector at the pump. DO NOT REMOVE the connector for this test.
-TURN TO KEY <ON> measure voltage. Record the voltage under NO LOAD condition. This will tell you how much voltage is being sent to the pump under NO LOAD condition.
-<START> the vehicle and note voltage under RUNNING condition.
-INCREASE RPM and note voltage.
-APPLY the brake while releasing the throttle. Note if there's a voltage drop.
TEST METHOD TWO: FUEL PRESSURE VERIFICATION
What this test is going to confirm is, whether or not there is a drop in fuel pressure under varying loading conditions.
Repeat the same steps as above while recording the fuel pressure at the fuel rails.
Please post back as to whether or not you intend to test this or not. If so, I would like to see the results posted back into this thread for reviewing.
Regards,
CM
The reason for going with OEM over after-market on ALL sensor based systems and fuel pumps, alternators, generators and, basically anything that is considered a HI-REL (High Reliability) component, OEM is THE only way to go.
They are thoroughly tested and screened to FULLY meet OEM specs over the entire use range and environmental range as well. The ones that DO NOT pass OEM screenings are then sold off dirt cheap to brokers who, in turn, turn and sell them to 3rd party distributors. They work to more / lesser degree and, the reliability is no-where near the life of OEM parts.
I had gone through Bosch O2 sensors only to find one crapping out. Now, after learning from a component engineer friend of mine WHERE those are made and, WHO is assembling those, it's a wonder they even work at all as they are made in a sweat shop down in S. America. I recommend NTK ONLY as they are made in Japan and have been for YEARS and are OEM certified.
Borg-Warner is complete rubbish. I used a simple dizzy cap from them in a pinch. Let me tell you what happened with that POS. This was their "top end" cap and, it was nothing short of a pile. It was made so poorly that, the conductor for the coil had opened from the termination on the top to the spring-loaded button on the underside causing- no spark condition. Solid pin core design is the better choice and, you'll have to check to ensure that you're getting a good cap.
For the CPS, CKPS etc, I have used 4 aftermarket deals and NOT ONE of them worked properly.
Same with IAC valves, I bought three to find one decent one. I've had a TPS where, in one spot, it would surge.
Again, OEM is the only way to go.
Now, as far as what you're describing, IF INDEED you are certain beyond doubt that you can hear the fuel pump motor whine IN THE CAB whining- you've got a potential problem to start with.
If, the motor whine is going up and down while engaging the power brake system, there's another issue. The motor speed is intended to be constant RPMs regardless of rpms.
In order to verify the theory that the pump is whining down, you will need to take some measurements. If no measurements are taken, there's no way of knowing if this is really occurring or not.
TO TEST:
METHOD ONE: ELECTRICAL VOLTAGE DROP DOWN TEST
What this test is going to confirm is, whether or not there's a voltage drop at the fuel pump.
PROCESS STEPS:
- Backprobe the electrical connector at the pump. DO NOT REMOVE the connector for this test.
-TURN TO KEY <ON> measure voltage. Record the voltage under NO LOAD condition. This will tell you how much voltage is being sent to the pump under NO LOAD condition.
-<START> the vehicle and note voltage under RUNNING condition.
-INCREASE RPM and note voltage.
-APPLY the brake while releasing the throttle. Note if there's a voltage drop.
TEST METHOD TWO: FUEL PRESSURE VERIFICATION
What this test is going to confirm is, whether or not there is a drop in fuel pressure under varying loading conditions.
Repeat the same steps as above while recording the fuel pressure at the fuel rails.
Please post back as to whether or not you intend to test this or not. If so, I would like to see the results posted back into this thread for reviewing.
Regards,
CM
After talking to another tech with Dodge I have also come to the conclusion that Borg Warner blows and am going to have my oem injectors flow tested, cleaned by ultra sound, have new screens put in them and have them certified for flow rate. As far as the testing goes, I need to buy a fuel pressure gauge which I will and do the tests. I have to wait probably a week as I just spent over a thousand on the wifes car and my truck. Fuel sender on hers. Chevy. And I only hear the whining down with the door open and yes it is the fuel sender, not the alternator or steering pump. Sorry I should have made that clear that I only heard it with the door open or window down.
#5
10-07-2010, 12:30 PM
Start taking voltage measurements at the pump. If it's whining down, this is indicative of a change in voltage to the pump motor thus, a drop in rpm speed when applying the brake which, if this is what is occurring, a drop in fuel pressure will be witnessed at the Schrader test port located on the fuel rail (providing you have such a test port - some rails did not include this feature)
CM
CM
#7
10-07-2010, 02:51 PM
I knew you were going to ask that question. I almost did earlier as, the reason being that, it's one thing that would drop voltage in correlation to braking. At time of braking, the engine rpm speed drops thus, the generator pulley speed slows thus, it may be putting out less voltage than the minimum requirements under that condition thus, causing a drop in fuel pump motor speed.
Now, if, this also occurs while parked, then, the other probable cause is a partial short on the brake CKT thus, dropping voltage in the system thus, affecting other CKTs.
By design, the fuel pump motor supply is constant and, should not vary more than a couple of volts under normal operating conditions. When the engine is not running, a nominal value of 12.XX volts is present at the fuel pump at time of KEY <ON> event. Upon starting, this voltage will rise ~ 2 volts as it's now being supplied off the charging system vs. the B+ voltage. Once running, this voltage is to remain steady regardless of a change in any other system.
Regardless of rpm and loading, the output of the generator should be consistent. It's a regulated output and, again, it is not intended to fluctuate with varying rpm / speed / loading conditions.
I went back and re-read the Original Post. It was stated WHILE IDLING this occurs. Another test would be to measure the charging system output at the BAT while depressing the brake while noting if there's a voltage drop or not.
Again, in order to assess this, there must be measurements taken in order to "see" what is really occurring.
CM
Now, if, this also occurs while parked, then, the other probable cause is a partial short on the brake CKT thus, dropping voltage in the system thus, affecting other CKTs.
By design, the fuel pump motor supply is constant and, should not vary more than a couple of volts under normal operating conditions. When the engine is not running, a nominal value of 12.XX volts is present at the fuel pump at time of KEY <ON> event. Upon starting, this voltage will rise ~ 2 volts as it's now being supplied off the charging system vs. the B+ voltage. Once running, this voltage is to remain steady regardless of a change in any other system.
Regardless of rpm and loading, the output of the generator should be consistent. It's a regulated output and, again, it is not intended to fluctuate with varying rpm / speed / loading conditions.
I went back and re-read the Original Post. It was stated WHILE IDLING this occurs. Another test would be to measure the charging system output at the BAT while depressing the brake while noting if there's a voltage drop or not.
Again, in order to assess this, there must be measurements taken in order to "see" what is really occurring.
CM
Last edited by cmckenna; 10-07-2010 at 03:22 PM.
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#9
10-07-2010, 06:32 PM
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Or one could go for the even simpler approach and get under the old thing and check that the ground is not loose and corroaded? I think I may have found it. Will let you guys know. Thanks for all the input. All though I have to say if it is not it I will begin the other methods suggested. The battery is new, yellow top optima and the battery connections ar tight and appear good. So we will see about the ground back on the rear of the bed.
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10-07-2010, 07:16 PM
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Ok so now I need a new meter, but when I apply the brakes, and turn on the headlight switch I can hear a definite change in the rpm of the fuel pump. Also when I turn on the A/C and all the above mentioned. Stupid digital meter, but if memory serves me correct the voltage regulators for these trucks are not in the alternators correct? They are in the PCM? Anyway are you guys suggesting that maybe my alternator is the culprit? It is the original even though the truck only has 134,000 original miles on it. I will have to go get a new meter. When my meter was working it said 12.8 at rest and 13.89 with engine on.