Fuel Pump Replacement

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This topic contains 12 replies, has 6 voices, and was last updated by  kentt 1 year, 8 months ago.

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #236041

    53tdreplica
    Participant

    @53tdreplica

    I have a 1953 MGTD replica with a 1974 Mustang 2.8L 6-cylinder engine.  The mechanical fuel pump has expired and I am considering replacing it with an electrical fuel pump.  Good idea?  If so, any details for the replacement process?  Suggestions for what would be a good electrical fuel pump to purchase to get the best from this engine?  Thanks in advance for your inputs.

    Andy

    #267401

    greg-press
    Participant

    @greg-press

    I to thought about replacing my mechanical with a electrical mine is a VW engine . I was advised by someone on here not to do it stick to the mechanical I am glad I did .      

    #267402

    kentt
    Participant

    @kentt

    This is the electric pump I installed on mine.

    Carter Low Pressure Pump

    Too soon to provide much feedback…

    EDIT: Should you choose to use an electric pump, here’s some good reading on installing and wiring it. Though it’s a VW site, the wiring is the same in principle. For safety reasons, I used the suggested Bosch relay that shuts the pump off when the engine stops running.

    Electric pump wiringKentT2016-03-11 22:17:00

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #267403

    53tdreplica
    Participant

    @53tdreplica

    Thanks for the info.

    #267404

    toller
    Participant

    @toller

    Two cautionary notes I picked up from research when I installed an electric fuel pump. 1) install regulator to adjust fuel pressure to 2.5 for a carb (PICT 34) 2) use a two relay electrical setup with a NO and NC is series circuit. The NO contact is controlled by the ignition switch and the NC by the low pressure oil sensor. Logic for electrics was if car is involved in accident and ignition switch is not turned off fuel pump will continue to pump fuel to engine. If engine is stopped oil pressure sensor drops to zero and power to second relay is shut down so fuel pump stops. I uploaded a copy of circuit design in previous postToller2016-03-13 07:32:57

    David B Dixon
    Port Perry ON CA
    Sabine

    #267405

    kentt
    Participant

    @kentt

    The Bosch relay I described does the same thing, using only one relay, by monitoring the tach signal from the coil. It only pumps when the engine is running.

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #267406

    toller
    Participant

    @toller

    In my research saw reference to Bosch relay but did not realize that it had the safety feature that you have explained. I thought it was just a brand that they were referring to. I used $10 relays and a bit more wire to accomplish the same safety configuration. Never the less the important take away is that when changing from mechanical to electric fuel pump you have to be able to interrupt the power to the pump when the engine stops

    David B Dixon
    Port Perry ON CA
    Sabine

    #267407

    edsnova
    Participant

    @edsnova

    Good info, guys. Never thought of this as I did the Soob Job. Now I’ll need to check and make sure the Subaru wiring incorporates this feature. I think it must, but I don’t know.

    #267408

    kentt
    Participant

    @kentt

    Similarly, the Carter low-pressure pump I linked does not require a separate pressure regulator. It is internally regulated not to exceed 4 psi. A stock mechanical VW pump can produce up to 7.5 psi at high RPMs (with a mechanical pump, pressure is proportional to engine RPM), and the stock carbs handled it fine, though the 28 PICTs and the later 34s both had an “anti-diesel” solenoid that internally shut off fuel when the ignition was turned off, preventing the still turning engine from sucking more fuel through the carb, causing run-on with a hot engine…KentT2016-03-13 13:11:47

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #267409

    happyjack
    Participant

    @happyjack

    Hey Kent,

    Great post on the electric fuel pump relay issue.  I have electric fuel pumps in both the Bugeye and the BCW Tdr — neither car has a cut out relay as you described.  So, I need to rewire both cars to add this safety feature….
    Do you happen to have the part number for the Bosch fuel pump relay?  or whatever model works with our cars?
    Thanks,
    Happy Jack

    #267410

    kentt
    Participant

    @kentt

    HappyJack wrote:
    Hey Kent,

    Great post on the electric fuel pump relay issue.  I have electric fuel pumps in both the Bugeye and the BCW Tdr — neither car has a cut out relay as you described.  So, I need to rewire both cars to add this safety feature….
    Do you happen to have the part number for the Bosch fuel pump relay?  or whatever model works with our cars?
    Thanks,
    Happy Jack

    The original Bosch relay for 75-79 Rabbit ID VW #0 332 514 120

    It conveniently has a mounting tab with hole that lets you screw it to a firewall, bulkhead, etc. Less expensive aftermarket ones may or may not have the mounting tab, so look closely at pics.

    One downside of using this relay is that you can’t prime the carb (if the car has been sitting for a long time) simply by turning on the ignition switch. It will only pump if you are cranking the engine, or if the engine is running — the coil must be firing for the pump to run. So, if the car has sat long enough for the fuel bowl in carb to be dry, it may take a bit of cranking to get it started the first time…

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #267411

    happyjack
    Participant

    @happyjack

    Thanks Kent for the Bosch part number.  Kind of pricy new (but I know, I know, SAFETY….) however, I found them listed for sale on The Samba ads for $30 plus shipping.  Before I pull the trigger and order 2 [one for Emma (BCW Tdr) and one for Merlin (bugeye)] I’m going to check with my local VW recycler/scrap yard/mechanic to see what he has in his junk pile. 

    Now that your workshop building is well on its way to being outfitted you can meet us in Carlisle this year?  

    Happy Jack
    #267412

    kentt
    Participant

    @kentt

    I bough mine off Samba.

    Too much work remaining for Carlisle, I’m afraid. Maybe Virginia Beach…KentT2016-03-20 19:08:20

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

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