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new electric fuel pumps

eyechaser

New member
just purchased a 79 trojan last year and we have been going thru it fixing all the previous "jerry rigged" things. we had a rpm issue last year so we rebuild the carbs on the twin 318's but have not had a chance to test them yet as it is still on blocks. going thru the fuel system they had a electric pump by the tanks that appear to be just cheap transfer pumps like these https://www.amazon.com/AUTOPARTS-El...-c5b0dbebe95a&pd_rd_w=vLM5t&pd_rd_wg=mJR1f&pf. we want to install new ones after the separator but are unsure of which ones to get. we have no idea why the mechanical ones were removed. any suggestions?
 
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just purchased a 79 trojan last year and we have been going thru it fixing all the previous "jerry rigged" things. we had a rpm issue last year so we rebuild the carbs on the twin 318's but have not had a chance to test them yet as it is still on blocks. going thru the fuel system they had a electric pump by the tanks that appear to be just cheap transfer pumps like these https://www.amazon.com/AUTOPARTS-El...-c5b0dbebe95a&pd_rd_w=vLM5t&pd_rd_wg=mJR1f&pf. we want to install new ones after the separator but are unsure of which ones to get. we have no idea why the mechanical ones were removed. any suggestions?


Those pumps are not correct. I would say that the volume is also inadequate for your engines.

They should also be installed between the fuel filter cartridge and the line running to the carburetor!

You will want a Marine approved electric fuel pump for carburetors.... i.e., 4 to 7 psi.

In order to be USCG approved, you will need to install a LOP (low oil pressure) switch that interrupts the fuel pump's power supply in the absence of engine oil pressure.
This is a safety feature that prevents continued fuel supply in the event of an engine stall that may be caused by a fuel line breach.

You will also want to incorporate a "start-bi-pass" circuit that will operate the pump prior to oil pressure.

In lieu of the "start-bi-pass" circuit, you can add a helm located "Momentary Switch" that will trigger the relay and therefor operate the pump.
Either will work, and neither are a USCG requirement....... but the key is to have a "Momentary" helm switch.

Most of us will incorporate a relay, and will trigger the relay via the LOP and the SBP circuit.
When wired correctly, we eliminate the potential for any circuit back-feed.



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thanks for the reply. yes we are installing the safety switches and oil pressure cut of.just unsure of what pump to get for the 318's. is the carter[h=2]180-P4070 the correct pump?[/h]
 
thanks for the reply. yes we are installing the safety switches and oil pressure cut of. just unsure of what pump to get for the 318's. is the carter180-P4070 the correct pump?

I believe that the carter 180-P4070 pump will work.

by the way...... the LOP switch needs to be a N/O (normally open) switch. One that closes when oil pressure is achieved, and opens when pressure drops below a certain PSI.


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well we decided to go with the new mechanical pumps instead

That would be the simplest route to go.

One nice thing about the electric fuel pump is the ability to prime a carburetor that has been sitting for a while.
With a momentary helm switch (that triggers the fuel pump relay), the pump can be activated prior to engine cranking.
These can also be mounted "off engine".


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ok the new mechanical pumps are in. all new fuel line and separator. carbs just rebuilt, new plugs wires and dist cap. both start right up and run great at 1000 rpms but when we back them down to idle speed the both die. monkeyed with the air adjustment but no difference. any ideas?
 
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