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66 Austin Healey fuel pump replaced
- Thread starter timmer2002
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I think it was about vapor locking not fire hazard.
RAC68
Darth Vader
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Hi All,
I have always stood in ah at the ingenuity so many have extended to the implementation of our fuel pumping system. As many of you know, I still have a points SU pump in my BJ8 Phase 1 but back in the mid 1980s, was convinced by a friend to replaced the Square bodied SU with the newer round-bodied unit used by the phase 2. Looking back, there was no necessity to do this as the pump, as with its replacement, could have been easily modified to last well past today. The modifications I have executed through the years were quite simple and included:
1) Conversion to neg. ground (no physical change needed for the SU pumps I had/have)
2) Extended point life indefinitely by addition of a Transient-Voltage Suppression diode (TVS @ $1.50). This diode is placed across the points to limit voltage passing across the points to a max of 21 Volts. Without this diode, the effects of the pump's coil could raise voltage passing across the points to multi-hundreds of volts and could cause premature points failure. with the TVS, voltage is limited to 21 volts (high enough to clean points but low enough to be below burn potential) with all access voltage gated to ground.
3) Fuel pump Inertia Switch to shut off fuel flow in case of an accident (cuts power after heavy blow or car turnover).
Due to these additions, my points pump has worked well and with little consideration for the past years and is expected to continue into the future. However, keep in mind that I have focused on the electrical longevity of the pump and their are still other components (i.e. diaphragm etc.) that still warrant aging concerns. Yes, 2 pumps can be better if one fails but also brings added complexity. New solid state pump replacements can also reduce concerns but that has not proved to be a securing move in the past for when they fail, unlike points, there really dead.
Well, just my thoughts,
Ray(64BJ8P1)
I have always stood in ah at the ingenuity so many have extended to the implementation of our fuel pumping system. As many of you know, I still have a points SU pump in my BJ8 Phase 1 but back in the mid 1980s, was convinced by a friend to replaced the Square bodied SU with the newer round-bodied unit used by the phase 2. Looking back, there was no necessity to do this as the pump, as with its replacement, could have been easily modified to last well past today. The modifications I have executed through the years were quite simple and included:
1) Conversion to neg. ground (no physical change needed for the SU pumps I had/have)
2) Extended point life indefinitely by addition of a Transient-Voltage Suppression diode (TVS @ $1.50). This diode is placed across the points to limit voltage passing across the points to a max of 21 Volts. Without this diode, the effects of the pump's coil could raise voltage passing across the points to multi-hundreds of volts and could cause premature points failure. with the TVS, voltage is limited to 21 volts (high enough to clean points but low enough to be below burn potential) with all access voltage gated to ground.
3) Fuel pump Inertia Switch to shut off fuel flow in case of an accident (cuts power after heavy blow or car turnover).
Due to these additions, my points pump has worked well and with little consideration for the past years and is expected to continue into the future. However, keep in mind that I have focused on the electrical longevity of the pump and their are still other components (i.e. diaphragm etc.) that still warrant aging concerns. Yes, 2 pumps can be better if one fails but also brings added complexity. New solid state pump replacements can also reduce concerns but that has not proved to be a securing move in the past for when they fail, unlike points, there really dead.
Well, just my thoughts,
Ray(64BJ8P1)
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RAC68
Darth Vader
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Hi Vette,
I can understand having 2 pumps for security and, in the boot, I carry a pump head section as a replacement if my pump does go bad. As I see it, it takes a few minutes to pull the right wheel and unscrew the head from the pump and replace it with another as the head, containing the trigger, is the most prone to failure. The head I carry is the Optical Trigger a few friends and I created when everyone was experiencing a rash of SU solid state head failures and before I found the Transient-voltage suppression diode @ $1.50. Although the Optical Trigger for the SU pump did perform very well, when considering the life and performance extended to points by adding a TVS, economically it didn't make sense to continue the effort and now it is carried as my backup. It was a good example for me to learn how to make a printed circuit board and with learning errors and components, the project cost less then $25 if I remember correctly.
All in all, the Optical trigger is reliable and self adjusting but, as with any solid state device, if it fails it is dead. With points, I have a good chance of getting it going and arrive at my destination.
Keep in mind that if you have 2 pumps in series (main and backup), any electrical issue causing your main to fail can also affect your backup.
Just my thoughts,
Ray(64BJ8P1)
I can understand having 2 pumps for security and, in the boot, I carry a pump head section as a replacement if my pump does go bad. As I see it, it takes a few minutes to pull the right wheel and unscrew the head from the pump and replace it with another as the head, containing the trigger, is the most prone to failure. The head I carry is the Optical Trigger a few friends and I created when everyone was experiencing a rash of SU solid state head failures and before I found the Transient-voltage suppression diode @ $1.50. Although the Optical Trigger for the SU pump did perform very well, when considering the life and performance extended to points by adding a TVS, economically it didn't make sense to continue the effort and now it is carried as my backup. It was a good example for me to learn how to make a printed circuit board and with learning errors and components, the project cost less then $25 if I remember correctly.
All in all, the Optical trigger is reliable and self adjusting but, as with any solid state device, if it fails it is dead. With points, I have a good chance of getting it going and arrive at my destination.
Keep in mind that if you have 2 pumps in series (main and backup), any electrical issue causing your main to fail can also affect your backup.
Just my thoughts,
Ray(64BJ8P1)
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I can understand this if you mean "in series" electrically, but they can't be wired in series and work. If plumbed in series, either pump can pump through the other.
RAC68
Darth Vader
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John,
Sorry I wasn't as clear as I thought but you did presume correctly. The pumps are in searies and I was thinking that the electrical connections would be centered from a single feed before the intrusion of a selector switch. Circuit power issues would be sunted to the selected pump and if the issue caused the pump to fail then their is a good possibility that the selection of the backup would expose the backup to the electrical issue as well.
Maybe it would be best if each pump was wired to a separate circuit and each controlled with an on/off switched.
Again, you were correct and I was not as clear in presenting my thoughts as I thought.
Sorry I wasn't as clear as I thought but you did presume correctly. The pumps are in searies and I was thinking that the electrical connections would be centered from a single feed before the intrusion of a selector switch. Circuit power issues would be sunted to the selected pump and if the issue caused the pump to fail then their is a good possibility that the selection of the backup would expose the backup to the electrical issue as well.
Maybe it would be best if each pump was wired to a separate circuit and each controlled with an on/off switched.
Again, you were correct and I was not as clear in presenting my thoughts as I thought.
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Ray,
I had both my pumps "fail" in that the ground wires were attached to the same bolt, which became loose. My O2 meters told me both carbs were starving. I then ran the grounds to separate bolts.
If one ran two circuits to the pumps, could you use a DPDT switch instead of two separate switches?
red57
Jedi Knight
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I have mine wired as two separate circuits. I'm pulling fused power (with the key on) from the fuse panel to an on/off/on switch under the dash, then two inline fuses and separate wires to the pumps. So, if one pump dies or the fuse blows or the wire gets pinched, I flick the switch and not only a backup pump but a backup fuse and wire too.
I got overly concerned about shorting the wires down the frame because several years ago on a dirt road in the Yaak Valley in Montana on our way to Calgary for a vintage race, I drove over some exposed tree roots that one of the wire loom clips hooked on and rotated it enough to cut through the wire loom and into the fuel pump wire. Smoke everywhere. A that time I still had a stock unfused fuel pump circuit and the whole bundle of wires burned to a crisp before I realized what was happening and the result was replacing several feet of the rear wire harness under the car at the edge of the dirt road (my buddy went exploring and found a fellow nearby with a dead junker in the yard who allowed him to cut out some sections of it's wire harness to make my repair)
Dave
I got overly concerned about shorting the wires down the frame because several years ago on a dirt road in the Yaak Valley in Montana on our way to Calgary for a vintage race, I drove over some exposed tree roots that one of the wire loom clips hooked on and rotated it enough to cut through the wire loom and into the fuel pump wire. Smoke everywhere. A that time I still had a stock unfused fuel pump circuit and the whole bundle of wires burned to a crisp before I realized what was happening and the result was replacing several feet of the rear wire harness under the car at the edge of the dirt road (my buddy went exploring and found a fellow nearby with a dead junker in the yard who allowed him to cut out some sections of it's wire harness to make my repair)
Dave
Last edited:
RAC68
Darth Vader
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Hi All,
Steve, As you are astutely aware, a DPDT switch will have 2 inputs (+/-) that will be connected to one of 2 different sets of +/-. In your DPDT circuit configuration, your DPDT switch would connect a single source of power to 1 of 2 different pumps (i.e. Source +/- to switched to 1 of 2 pumps at a time). This would perform well as long as the source of power (original +/-) stays connected to the switch and the switch is connected to at least one functioning pump. However, you still have the potential of a ground or power connection being lost resulting in the functional elimination of both switch and both pumps as mentioned.
Now lets consider common probability and acceptance of personal responsibility to save on costs and complexity. When considered the loss of power or failure of a critical component, a Full Fault Tolerant environment would require a fully redundant configuration and an intelligent facility to immediately identify the source of fault and a pre-prescribed response. Although you would want Full Fault Tolerance when dealing with a critical environment, of which Dave approaches when racing, I expect you would be more incline to have a relatively lower cost response on your Healey.
The design of a use-and-cost reasonable Fault Tolerant system imbedded within your fuel pumps seems as you have stated. In your configuration, you seem to have a concern for the longevity of the pumps and, your consideration of on-the-fly substitution of one pump for the other, concern-satisfying at a risk-reasonably cost. So, I expect you would rather lower your expense by supplying the needed analytical intelligence in determining the source of the fault and responding by addressing an appropriate fix (i.e. tighten ground/power contacts, etc.) or activating the correct throw of the DPDT switch to maintain an active pumping operations. Since the probability of fault is quite low in the supply of power and much greater in the operation of your pumps, a DPDT providing a single power source to 1 of 2 fuel pumps seems to be a reasonable configuration.
To see how my evaluation differs, my casual use of my Healey and reliability experiences with my slightly modified SU pump, seems to be higher then yours and I have chosen a much lower cost solution at an increase in personal responsibility and inconvenience. Should I encounter a faulting pump operation, I must analyze what is happening and chart my actions to remediate the condition (determine the pump's fault and possibly replace the pump trigger, possibly at the side of the road).
All in all, I would use a DPDT switch with 1 power source and 2 pumps,
Ray(64BJ8P1)
Steve, As you are astutely aware, a DPDT switch will have 2 inputs (+/-) that will be connected to one of 2 different sets of +/-. In your DPDT circuit configuration, your DPDT switch would connect a single source of power to 1 of 2 different pumps (i.e. Source +/- to switched to 1 of 2 pumps at a time). This would perform well as long as the source of power (original +/-) stays connected to the switch and the switch is connected to at least one functioning pump. However, you still have the potential of a ground or power connection being lost resulting in the functional elimination of both switch and both pumps as mentioned.
Now lets consider common probability and acceptance of personal responsibility to save on costs and complexity. When considered the loss of power or failure of a critical component, a Full Fault Tolerant environment would require a fully redundant configuration and an intelligent facility to immediately identify the source of fault and a pre-prescribed response. Although you would want Full Fault Tolerance when dealing with a critical environment, of which Dave approaches when racing, I expect you would be more incline to have a relatively lower cost response on your Healey.
The design of a use-and-cost reasonable Fault Tolerant system imbedded within your fuel pumps seems as you have stated. In your configuration, you seem to have a concern for the longevity of the pumps and, your consideration of on-the-fly substitution of one pump for the other, concern-satisfying at a risk-reasonably cost. So, I expect you would rather lower your expense by supplying the needed analytical intelligence in determining the source of the fault and responding by addressing an appropriate fix (i.e. tighten ground/power contacts, etc.) or activating the correct throw of the DPDT switch to maintain an active pumping operations. Since the probability of fault is quite low in the supply of power and much greater in the operation of your pumps, a DPDT providing a single power source to 1 of 2 fuel pumps seems to be a reasonable configuration.
To see how my evaluation differs, my casual use of my Healey and reliability experiences with my slightly modified SU pump, seems to be higher then yours and I have chosen a much lower cost solution at an increase in personal responsibility and inconvenience. Should I encounter a faulting pump operation, I must analyze what is happening and chart my actions to remediate the condition (determine the pump's fault and possibly replace the pump trigger, possibly at the side of the road).
All in all, I would use a DPDT switch with 1 power source and 2 pumps,
Ray(64BJ8P1)