Lift Pump failures
11-12-2008, 05:13 PM
#16
Chapter President
My opinion, get rid of the junk LP and do either an Airdog or Fass.
I ran the Holley blue on the frame with the stock LP for about 2 years. The Holley failed and the LP couldn't pull through it. So i bought an Airdog 100.
Might cost more upfront but will save you money in the long run.
I ran the Holley blue on the frame with the stock LP for about 2 years. The Holley failed and the LP couldn't pull through it. So i bought an Airdog 100.
Might cost more upfront but will save you money in the long run.
11-13-2008, 11:26 AM
#17
Guest
Posts: n/a
My opinion, get rid of the junk LP and do either an Airdog or Fass.
I ran the Holley blue on the frame with the stock LP for about 2 years. The Holley failed and the LP couldn't pull through it. So i bought an Airdog 100.
Might cost more upfront but will save you money in the long run.
I ran the Holley blue on the frame with the stock LP for about 2 years. The Holley failed and the LP couldn't pull through it. So i bought an Airdog 100.
Might cost more upfront but will save you money in the long run.
11-13-2008, 11:42 AM
#18
Registered User
I agree, just get a FASS LP and forget about it. I don't even hardly look at the fuel pressure gauge anymore it is so boring... up to 15.5 at idle, down to 12 @ WOT.
11-14-2008, 08:29 AM
#19
Registered User
afgunn...you are correct...the stock set up is as you say...Tank..LP...filter...IP. Running the filter pre-LP is the way to go. I have a similar set up as johnh...but I have only one pump. I like the redundancy in case of failure though.
11-14-2008, 11:10 AM
#20
Registered User
The ISC's I work on use basically the same lift pump as we do and they frequently run over 300k miles, the biggest difference being that we run the fuel through 2 filters before it gets anywhere close to the pump.
11-16-2008, 01:51 PM
#21
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Charlie
I just had to get into this discussion to help clear up a few misconceptions about fuel pumps.
Pumps do not suck fuel into them. The pump creates a vacuum (measured in inches of mercury),! An out side force is required to push the liquid into the vacuum chamber of the pump. That force is the pressure differential between the lower than ambient pressure of the pump vacuum chamber and the outside atmospheric pressure. In the case of your fuel pump, that force is the atmospheric pressure plus or minus the fuel column depending whether the pump is above or below the surface level of the fuel. The fuel flow is also reduced by the restriction caused by the size and length of the supply line, 90 degree fittings and filters between youir fuel tank and the pump.
The vacuum or pressure differential that the pump creates depends on the quality of the pump mechanism.
Vane type pumps. opposing gear pumps, plunger pumps, and diaphram pumps as well as gearotor pumps, all create a vacuum. The short comings of the vane type is excessive wear. Opposing gear pumps fight the incoming flow with the 'paddle wheel effect and centrifugal force which creates cavitation and vapor at higher RPM's. Vapor, being compressible retards timing. Check the torque curves of class 8 trucks, gear pumps are have been the pump of choice for years for the semi's. Next, plunger and diaphram pumps. These pumps start and stop the flow of liquid from the tank with every pump cycle, horrible cavitation especially at higher RPM's. Now look at the gearotor pump. This is a gear inside a gear. It creates a constant flow as the vacuum is continually expanding as it turns and has one tooth wear movement with each revolution of the assembly, higher efficiency with less wear. The gearotor pump mechanism can also be manufactured with the tightest tolerances to create the highest vacuum and flow. The gearotor is a much more expensive pump mechanism but it has the advantage of high efficiency plus long life.
One more thing about vacuum, a vacuum is created as the pump mechanism operates to create a flow from the outside of the pump to the inside of the pump. The flow is driven by atmospheric pressure trying to equalize and is a very limited pressure differential force. To give you an idea, At sea level atmospheric pressure is 14.73 PSI, at Denver, 5,280 feet (thus called Mile High) the pressure is down about 15% and at Eisenhower Tunnel, 10,000 feet above sea level the atmospheric pressure is down about 28%. All this really means is that the higher you go, the less possible pressure differential or vacuum available and consequently less potential fuel flow to the pump.
Back to the pump! All of the above means nothing if the pump does not operate/run. Take a look at the electric motor, the brushes, commutator plates, the bearings, and seal system. It takes a well designed and manufactured pump to pump diesel fuel for a long trouble free time. Want to know the quality of the pump, look at the warranty offered on the product. The warranty offered by the manufacturer will tell you a lot about quality without doing a physical examination of the motor/pump itself.
If you have any questions or would like to discuss any of the above, I can be reached at 573-230-8838 anytime.
Thanks for your time, I hope this helps.
Charlie Ekstam
PureFlow Technologies, Inc.
Home of AirDog, AirDogII, and Fuel Preporator for Class 8 Trucks.
Mon. - Fri. 8:00 AM - 5:00 PM at 573-635-0555
Pumps do not suck fuel into them. The pump creates a vacuum (measured in inches of mercury),! An out side force is required to push the liquid into the vacuum chamber of the pump. That force is the pressure differential between the lower than ambient pressure of the pump vacuum chamber and the outside atmospheric pressure. In the case of your fuel pump, that force is the atmospheric pressure plus or minus the fuel column depending whether the pump is above or below the surface level of the fuel. The fuel flow is also reduced by the restriction caused by the size and length of the supply line, 90 degree fittings and filters between youir fuel tank and the pump.
The vacuum or pressure differential that the pump creates depends on the quality of the pump mechanism.
Vane type pumps. opposing gear pumps, plunger pumps, and diaphram pumps as well as gearotor pumps, all create a vacuum. The short comings of the vane type is excessive wear. Opposing gear pumps fight the incoming flow with the 'paddle wheel effect and centrifugal force which creates cavitation and vapor at higher RPM's. Vapor, being compressible retards timing. Check the torque curves of class 8 trucks, gear pumps are have been the pump of choice for years for the semi's. Next, plunger and diaphram pumps. These pumps start and stop the flow of liquid from the tank with every pump cycle, horrible cavitation especially at higher RPM's. Now look at the gearotor pump. This is a gear inside a gear. It creates a constant flow as the vacuum is continually expanding as it turns and has one tooth wear movement with each revolution of the assembly, higher efficiency with less wear. The gearotor pump mechanism can also be manufactured with the tightest tolerances to create the highest vacuum and flow. The gearotor is a much more expensive pump mechanism but it has the advantage of high efficiency plus long life.
One more thing about vacuum, a vacuum is created as the pump mechanism operates to create a flow from the outside of the pump to the inside of the pump. The flow is driven by atmospheric pressure trying to equalize and is a very limited pressure differential force. To give you an idea, At sea level atmospheric pressure is 14.73 PSI, at Denver, 5,280 feet (thus called Mile High) the pressure is down about 15% and at Eisenhower Tunnel, 10,000 feet above sea level the atmospheric pressure is down about 28%. All this really means is that the higher you go, the less possible pressure differential or vacuum available and consequently less potential fuel flow to the pump.
Back to the pump! All of the above means nothing if the pump does not operate/run. Take a look at the electric motor, the brushes, commutator plates, the bearings, and seal system. It takes a well designed and manufactured pump to pump diesel fuel for a long trouble free time. Want to know the quality of the pump, look at the warranty offered on the product. The warranty offered by the manufacturer will tell you a lot about quality without doing a physical examination of the motor/pump itself.
If you have any questions or would like to discuss any of the above, I can be reached at 573-230-8838 anytime.
Thanks for your time, I hope this helps.
Charlie Ekstam
PureFlow Technologies, Inc.
Home of AirDog, AirDogII, and Fuel Preporator for Class 8 Trucks.
Mon. - Fri. 8:00 AM - 5:00 PM at 573-635-0555
Last edited by Fuel Preporator; 11-16-2008 at 01:58 PM. Reason: misspelled Eisenhower
11-16-2008, 02:25 PM
#22
My Carter 4601hp with soldered wiring on the frame rail has been 15psi idle/9.5psi or better WOT 5x5 since Sept.'04.
I fuel up slow to use the despensing pump's filters and use PS at the mfg's recommended dose every time I add fuel.
I fuel up slow to use the despensing pump's filters and use PS at the mfg's recommended dose every time I add fuel.
Last edited by Clunk; 11-16-2008 at 02:51 PM. Reason: pressure correction
11-17-2008, 09:01 AM
#23
Guest
Posts: n/a
I just had to get into this discussion to help clear up a few misconceptions about fuel pumps.
Pumps do not suck fuel into them. The pump creates a vacuum (measured in inches of mercury),! An out side force is required to push the liquid into the vacuum chamber of the pump. That force is the pressure differential between the lower than ambient pressure of the pump vacuum chamber and the outside atmospheric pressure. In the case of your fuel pump, that force is the atmospheric pressure plus or minus the fuel column depending whether the pump is above or below the surface level of the fuel. The fuel flow is also reduced by the restriction caused by the size and length of the supply line, 90 degree fittings and filters between youir fuel tank and the pump.
The vacuum or pressure differential that the pump creates depends on the quality of the pump mechanism.
Vane type pumps. opposing gear pumps, plunger pumps, and diaphram pumps as well as gearotor pumps, all create a vacuum. The short comings of the vane type is excessive wear. Opposing gear pumps fight the incoming flow with the 'paddle wheel effect and centrifugal force which creates cavitation and vapor at higher RPM's. Vapor, being compressible retards timing. Check the torque curves of class 8 trucks, gear pumps are have been the pump of choice for years for the semi's. Next, plunger and diaphram pumps. These pumps start and stop the flow of liquid from the tank with every pump cycle, horrible cavitation especially at higher RPM's. Now look at the gearotor pump. This is a gear inside a gear. It creates a constant flow as the vacuum is continually expanding as it turns and has one tooth wear movement with each revolution of the assembly, higher efficiency with less wear. The gearotor pump mechanism can also be manufactured with the tightest tolerances to create the highest vacuum and flow. The gearotor is a much more expensive pump mechanism but it has the advantage of high efficiency plus long life.
One more thing about vacuum, a vacuum is created as the pump mechanism operates to create a flow from the outside of the pump to the inside of the pump. The flow is driven by atmospheric pressure trying to equalize and is a very limited pressure differential force. To give you an idea, At sea level atmospheric pressure is 14.73 PSI, at Denver, 5,280 feet (thus called Mile High) the pressure is down about 15% and at Eisenhower Tunnel, 10,000 feet above sea level the atmospheric pressure is down about 28%. All this really means is that the higher you go, the less possible pressure differential or vacuum available and consequently less potential fuel flow to the pump.
Back to the pump! All of the above means nothing if the pump does not operate/run. Take a look at the electric motor, the brushes, commutator plates, the bearings, and seal system. It takes a well designed and manufactured pump to pump diesel fuel for a long trouble free time. Want to know the quality of the pump, look at the warranty offered on the product. The warranty offered by the manufacturer will tell you a lot about quality without doing a physical examination of the motor/pump itself.
If you have any questions or would like to discuss any of the above, I can be reached at 573-230-8838 anytime.
Thanks for your time, I hope this helps.
Charlie Ekstam
PureFlow Technologies, Inc.
Home of AirDog, AirDogII, and Fuel Preporator for Class 8 Trucks.
Mon. - Fri. 8:00 AM - 5:00 PM at 573-635-0555
Pumps do not suck fuel into them. The pump creates a vacuum (measured in inches of mercury),! An out side force is required to push the liquid into the vacuum chamber of the pump. That force is the pressure differential between the lower than ambient pressure of the pump vacuum chamber and the outside atmospheric pressure. In the case of your fuel pump, that force is the atmospheric pressure plus or minus the fuel column depending whether the pump is above or below the surface level of the fuel. The fuel flow is also reduced by the restriction caused by the size and length of the supply line, 90 degree fittings and filters between youir fuel tank and the pump.
The vacuum or pressure differential that the pump creates depends on the quality of the pump mechanism.
Vane type pumps. opposing gear pumps, plunger pumps, and diaphram pumps as well as gearotor pumps, all create a vacuum. The short comings of the vane type is excessive wear. Opposing gear pumps fight the incoming flow with the 'paddle wheel effect and centrifugal force which creates cavitation and vapor at higher RPM's. Vapor, being compressible retards timing. Check the torque curves of class 8 trucks, gear pumps are have been the pump of choice for years for the semi's. Next, plunger and diaphram pumps. These pumps start and stop the flow of liquid from the tank with every pump cycle, horrible cavitation especially at higher RPM's. Now look at the gearotor pump. This is a gear inside a gear. It creates a constant flow as the vacuum is continually expanding as it turns and has one tooth wear movement with each revolution of the assembly, higher efficiency with less wear. The gearotor pump mechanism can also be manufactured with the tightest tolerances to create the highest vacuum and flow. The gearotor is a much more expensive pump mechanism but it has the advantage of high efficiency plus long life.
One more thing about vacuum, a vacuum is created as the pump mechanism operates to create a flow from the outside of the pump to the inside of the pump. The flow is driven by atmospheric pressure trying to equalize and is a very limited pressure differential force. To give you an idea, At sea level atmospheric pressure is 14.73 PSI, at Denver, 5,280 feet (thus called Mile High) the pressure is down about 15% and at Eisenhower Tunnel, 10,000 feet above sea level the atmospheric pressure is down about 28%. All this really means is that the higher you go, the less possible pressure differential or vacuum available and consequently less potential fuel flow to the pump.
Back to the pump! All of the above means nothing if the pump does not operate/run. Take a look at the electric motor, the brushes, commutator plates, the bearings, and seal system. It takes a well designed and manufactured pump to pump diesel fuel for a long trouble free time. Want to know the quality of the pump, look at the warranty offered on the product. The warranty offered by the manufacturer will tell you a lot about quality without doing a physical examination of the motor/pump itself.
If you have any questions or would like to discuss any of the above, I can be reached at 573-230-8838 anytime.
Thanks for your time, I hope this helps.
Charlie Ekstam
PureFlow Technologies, Inc.
Home of AirDog, AirDogII, and Fuel Preporator for Class 8 Trucks.
Mon. - Fri. 8:00 AM - 5:00 PM at 573-635-0555
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