Adding electric fuel to eliminate hard starting

When my 360 V8's sits for over a week they are very hard to start with the mechanical fuel pumps. Jeff I saw you mention once that you added electric fuel pumps to fill the carburetors to avoid this problem. Can you or anyone else explain how to install the electric fuel pumps to eliminate this condition. I don't want to switch to electronic pumps exclusively just augment the mechanical pumps I have twin 360's in aTrojan f32

Lottanerve

here is the prob my opion.you need to have some kind switch to shut it on and off.if youforget to shut it off now you have two pumps way to much pres. on the carb you will bend the float arm in carb and have a flooding condition. in the electric pump it runs off ing switch and uses the an oil pressure switch for safty end stalls pump shuts off. I could tell you how too but I think you should think it over good luck

I know that these are Chrysler engines, but here's a story.

GM discontinued their V engine mechanical fuel pumps in/around 1991, in lieu of electric fuel pumps (not electronic).
The cylinder blocks were no longer fully machined for a mechanical fuel pump.
This meant that the Marine industry had to also begin using the electric fuel pumps for the GM engine installations.

The common electric fuel pump (for carbureted engines) became the Carter brand.... also labeled as Merc, Volvo Penta, etc.
This pump was commonly mounted in the same area as where the mechanical fuel was previously.



Now... a mechanical fuel pump is engine driven. Engine runs/fuel pump operates. Engine quits/fuel pump quits.
USCG likes this idea.

An electric fuel pump must have a means of cutting electrical power if the engine was to quit.
This is done via a N/O low oil pressure switch in the pump's power circuit.
But there's a problem with this!
During start-up (prior to oil pressure being reached), nothing sends power to the pump.
The system now requires a Start-by-pass circuit.... of which is easy to do via a relay system.

Now... here's what will benefit you.
It's perfectly legal to have a helm located momentary switch for this fuel pump (must be momentary) that will by-pass the N/O low oil pressure switch circuitry.
This will allow you to operate the fuel pump before the starter motor has even been engaged.
This will also allow you to forgo the Start-by-pass circuit (optional) as long as you remember that priming is necessary.

Just make darn sure that you incorporate the N/O low oil pressure shut-off circuit, or you will be violating USCG regs.

This is a fairly straight forward installation.


BTW.... if you intend to augment the mechanical pumps via the electrical pumps, one of the pumps would be feeding the suction side of the other.
Technically... this would work due to the pump's check valves.
However, you may want to check and see if there would be any issues with pressure feeding the suction side of either the mechanical pump or the electric pump.

My gut feeling is.... it would not be allowed.


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I Tee'd a small electric pump into the fuel circuit of each of my carbs, right at the carbs. (A check valve prevents backflow.) I switch on the "boost pump" on during the 4 minutes of blower running, then off when I fire 'em up. Works very well.

Jeff

fastjeff said:

I Tee'd a small electric pump into the fuel circuit of each of my carbs, right at the carbs. (A check valve prevents backflow.) I switch on the "boost pump" on during the 4 minutes of blower running, then off when I fire 'em up. Works very well.

Jeff

Click to expand...

Lottanerve, I fully understand what Jeff has done, and I'll agree that it will no doubt work.

However...... if you were to replace the mechanical fuel pumps with the electric, and would comform to all USCG regulations... including the approved electric fuel pump power circuits...., you will have eliminated any risks and liability regarding a failure.

A major failure that might cause an explosion, fire, life safety, environmental impact, etc..... would no doubt lead to a violation/citation, insurance issues, and potentially expensive environmental clean-up costs.



IMO..... I'd simply replace the mechanical pumps with the electric pumps, implement the approved electrical circuits, add the momentary helm switches (for priming purposes), and be done with it.

You may even sleep better at night!



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