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454 fuel pump question

R

realcaptron

Regular Contributor
Guys, I have the older 454s with Holley 4160 750 c.f. marine carbs and mechanical fuel pumps. I'm contemplating replacing the pumps with electric pumps, thinking this would eliminate the diaphragm failure/leak possibility. Is conversion to electric a better/safer idea than simply replacing my existing mechanical with new ones? Both engines are running great and pumps are fine now but with unknown service hours on very old motors. Just trying to be pre-emptive. And....which and what size electric pump do you recommend for these motors with these carbs?
 
Mechanical pumps stop when motor stops.----You need to add a safety set-up so that an electric pump does not create an explosion hazard.
 
Doing that conversion would be OK.
You would remove the mechanical pump along with the push rod, and install a block-off plate and gasket.

The electric fuel pump pressure will be in the range of 4 to 7 psi for carburetors.

Carter offers a decent pump. You will find this pump being marketed under several brand names.
https://www.summitracing.com/parts/crt-p4389

These can be mounted in the same location as was the mechanical pump.

The electric fuel pump will require:

......... a N/O (normally open) LOP (low oil pressure) switch as required by the USCG.
This ensures that the electric fuel pump will stop working in the event of engine stalling.... worst case being a severed pressurized fuel line!

........ a "start-by-pass" circuit in order to energize the pump during cranking (prior to oil pressure).

........ Or..... a momentary helm switch that would energize the pump prior to start up. (one for each engine)
The nice aspect of this is...... you will be able to energize the fuel pumps and prime the fuel bowls before you begin cranking.
Less cranking = longer battery and starter motor life!

Once the engine fires up and the oil pressure comes up, the N/O LOP switch will close the circuit and will send power to the pump.


My preference would be in using a 5 pin relay switch that would be triggered by the LOP switch AND/OR by the momentary helm switch (if you go that route).
Once triggered, the relay would send power to the fuel pump.



.
 
Last edited:
RicardoMarine said:
Doing that conversion would be OK.
You would remove the mechanical pump along with the push rod, and install a block-off plate and gasket.

The electric fuel pump pressure will be in the range of 4 to 7 psi for carburetors.

Carter offers a decent pump. You will find this pump being marketed under several brand names.
https://www.summitracing.com/parts/crt-p4389

These can be mounted in the same location as was the mechanical pump.

The electric fuel pump will require:

......... a N/O (normally open) LOP (low oil pressure) switch as required by the USCG.
This ensures that the electric fuel pump will stop working in the event of engine stalling.... worst case being a severed pressurized fuel line!

........ a "start-by-pass" circuit in order to energize the pump during cranking (prior to oil pressure).

........ Or..... a momentary helm switch that would energize the pump prior to start up. (one for each engine)
The nice aspect of this is...... you will be able to energize the fuel pumps and prime the fuel bowls before you begin cranking.
Less cranking = longer battery and starter motor life!

Once the engine fires up and the oil pressure comes up, the N/O LOP switch will close the circuit and will send power to the pump.


My preference would be in using a 5 pin relay switch that would be triggered by the LOP switch AND/OR by the momentary helm switch (if you go that route).
Once triggered, the relay would send power to the fuel pump.



.
Click to expand...

So Rick, let me ask you this. Would your preference be new mechanical pump or electric coversion?
 
Your concern over the diaphragm failure may be a bit over-weighted.....there is a safety feature to minimize the likelihood of any major danger in the mechanical pump. I'd say you will add more points of failure swapping over to an electrical pump....and you can buy two mechanical pumps before you get one conversion completely installed.....so I wouldn't view the conversion as cost effective.

Just my 2¢......
 
makomark said:
Your concern over the diaphragm failure may be a bit over-weighted.....there is a safety feature to minimize the likelihood of any major danger in the mechanical pump. I'd say you will add more points of failure swapping over to an electrical pump....and you can buy two mechanical pumps before you get one conversion completely installed.....so I wouldn't view the conversion as cost effective.

Just my 2¢......
Click to expand...

Always value your input Mark. That's a good 2 cents. My concern is primarily that my starboard side has the clear hose running from barb on pump to spark arrest or. But my port side does not. And the port spark arrest or is identical marine arrest or as the starboard side but lacks the bracket with barb for any such overflow hose from pump. On digging into this, I think I am seeing evidence on line that a really old, original 1976 crusader with a Holley carb may have been factory delivered without a fuel pump overflow fitting, and that the mechanical pump as installed in 1976 may not have been manufactured with an overflow vent, yet still be a marine rated pump. This would require old timer knowledge of standards at the time. Common sense tells me if it's original, even if marine, it's overdue, but still it would be comforting a bit to know it is still as originally intended for use in a boat.
 
realcaptron said:
Always value your input Mark. That's a good 2 cents. My concern is primarily that my starboard side has the clear hose running from barb on pump to spark arrest or. But my port side does not. And the port spark arrest or is identical marine arrest or as the starboard side but lacks the bracket with barb for any such overflow hose from pump. On digging into this, I think I am seeing evidence on line that a really old, original 1976 crusader with a Holley carb may have been factory delivered without a fuel pump overflow fitting, and that the mechanical pump as installed in 1976 may not have been manufactured with an overflow vent, yet still be a marine rated pump. This would require old timer knowledge of standards at the time. Common sense tells me if it's original, even if marine, it's overdue, but still it would be comforting a bit to know it is still as originally intended for use in a boat.
Click to expand...

IMO, the only advantage to going electric, is the better priming ability at startup. All other factors are negative. Reliability, complexity, mounting, cost, safety. The mech pumps have a very long life.
 
diver_dave said:
IMO, the only advantage to going electric, is the better priming ability at startup. All other factors are negative. Reliability, complexity, mounting, cost, safety. The mech pumps have a very long life.
Click to expand...

Thanks Dave. I think I'm gonna stay mechanical after all. Now to put you on the spot, what's your opinion on the port side pump I have with no overflow vent fitting? Is it possible that there were or are marine mechanical pumps designed without overflow vent fittings?
 
realcaptron said:
Thanks Dave. I think I'm gonna stay mechanical after all. Now to put you on the spot, what's your opinion on the port side pump I have with no overflow vent fitting? Is it possible that there were or are marine mechanical pumps designed without overflow vent fittings?
Click to expand...

Just adding a comment here, these engines are running beautifully
I give them 2 cold start pre ignition throttle pumps and turn the key for instant ignition and smooth idle. I think I have them dialed in.
 
2X on DD's primer observation adding that its only an issue if you don't use the boat frequently.

I can tell you that the now-vintage I/O unit I learned a lot on was installed in 1968....and it had the TYGON sight tube from the pump to the carb. We didn't get it until ~ 1976 and I can't tell you if it was original or had been replaced.

either way, I'd say you have committed yourself to upgrading the pump to current standards. What you have on there may have been ok - I have seen more than one sight tube fitting broken off or it could be an auto pump.

As far as the fitting on the carb...personally, I think the barb on the exterior of the flame arrestor is BS.....from what I saw of the newer holley units, they now have a hose barb fitted to the side of the primaries...and it cant be hard to retrofit this on an older unit....and it is clearly superior to the barb scheme.....
 
makomark said:
2X on DD's primer observation adding that its only an issue if you don't use the boat frequently.

I can tell you that the now-vintage I/O unit I learned a lot on was installed in 1968....and it had the TYGON sight tube from the pump to the carb. We didn't get it until ~ 1976 and I can't tell you if it was original or had been replaced.

either way, I'd say you have committed yourself to upgrading the pump to current standards. What you have on there may have been ok - I have seen more than one sight tube fitting broken off or it could be an auto pump.

As far as the fitting on the carb...personally, I think the barb on the exterior of the flame arrestor is BS.....from what I saw of the newer holley units, they now have a hose barb fitted to the side of the primaries...and it cant be hard to retrofit this on an older unit....and it is clearly superior to the barb scheme.....
Click to expand...

Thanks Mark. I'm gonna call Holley tomorrow and ask them about optional fitting to carb on that. And get a new pump.
 
its probably not an option for what you have as it is.....you just need to know where to bore the hole and then tap it, clean it out, and put the fitting in. If I can 'grab' a pic of what I saw recently, I'll let you know.

on the pump, my log shows an AIRTEX 60502 as the last mechanical pump I put in....
 
makomark said:
its probably not an option for what you have as it is.....you just need to know where to bore the hole and then tap it, clean it out, and put the fitting in. If I can 'grab' a pic of what I saw recently, I'll let you know.

on the pump, my log shows an AIRTEX 60502 as the last mechanical pump I put in....
Click to expand...

Thanks
 
......................
realcaptron said:
So Rick, let me ask you this. Would your preference be new mechanical pump or electric conversion?
My first response was aimed at you doing the electric pump conversions.
realcaptron said:
I'm contemplating replacing the pumps with electric pumps,
Click to expand...

For simplicity, I would probably stay with the mechanical fuel pumps given that you have Holley carbs.
If you had Q-jets, I would suggest the electric fuel pumps and the momentary helm switches. (Q-jets tend to evaporate fuel more quickly, and could use the priming capability of the electric pumps)
Click to expand...

diver_dave said:
IMO, the only advantage to going electric, is the better priming ability at startup.
Yes, and even better with the momentary helm switch.

All other factors are negative. Reliability, complexity, mounting, cost, safety. The mech pumps have a very long life.
Keep in mind that the industry did away with the GM mechanical fuel pumps years ago.
Click to expand...

realcaptron said:
Just adding a comment here, these engines are running beautifully
I give them 2 cold start pre ignition throttle pumps and turn the key for instant ignition and smooth idle. I think I have them dialed in.
Unlike some carburetors, Holley carbs can be at rest for a longer period without undergoing fuel bowl evaporation.
Click to expand...
 
makomark said:
its probably not an option for what you have as it is.....you just need to know where to bore the hole and then tap it, clean it out, and put the fitting in. If I can 'grab' a pic of what I saw recently, I'll let you know.

on the pump, my log shows an AIRTEX 60502 as the last mechanical pump I put in....
Click to expand...

Mark, another dumb question. Is it advisable to pull the old pump off first to verify exactly which new mechanical to buy or are they all pretty much standard to fit that block? I think I saw reference to some on eBay indicating "long" or "short" arm. And Holley sells a supposed matter pump for my carb on their website, but of course it's a bit pricier than other stuff I'm seeing in eBay for a crusader 454.
 
There is nothing magical about the Marine version of the BBC mechanical fuel pump.

All use a mechanically operated arm (cam driven) that operates the diaphragm.
All arms pivot on a rather crude pivot shaft.
All incorporate inlet and outlet check valves.
The Marine version gives us diaphragm burst protection by giving the leaking fuel a means of being directed towards the carburetor...... be it to the flame arrestor or directly into the primary venturi area.
Most of the better units give us the ability to re-index the body for port orientation.

I'd look for one that was made in the USA.



.
 
RicardoMarine said:
There is nothing magical about the Marine version of the BBC mechanical fuel pump.

All use a mechanically operated arm (cam driven) that operates the diaphragm.
All arms pivot on a rather crude pivot shaft.
All incorporate inlet and outlet check valves.
The Marine version gives us diaphragm burst protection by giving the leaking fuel a means of being directed towards the carburetor...... be it to the flame arrestor or directly into the primary venturi area.
Most of the better units give us the ability to re-index the body for port orientation.

I'd look for one that was made in the USA.



.
Click to expand...

Thanks for your feedback Rick. Another friend of mine on the forum has been helping me as well via pm. So putting this out there for public consumption. If we all think "old school", go back maybe 40 years or as recently as 20 years...I have Holley 0-9015-1 750 marine carbs that are still available brand new from Holley or many other sources. I called Holley tech support today and asked specifically where on that carb does overflow from fuel pump go. Response was to the arrestor. And was given a part number for Holley marine flame arrestor. Currently on the website and available. it is pn 720-11 or 720-12. Both come with no overflow vents but instructions to hook up overflow vent to the arrestor. Then find Holley pn 720-33. It is an externally mounted bracket quite similar to what I currently have on my starboard motor, but the hose fitting for overflow is 1/2" ! And the Holley tech rep insisted that my specific carb is intended for externally mounted overflow to the arrestor. Holley is a big company and I would think they know how to be in full compliance with uscg regulations or be exposed to great liability. The peculiar part is that thye have other marine carbs WITH hard fittings for overflow into the top of the body. I don't get it.
 
I've put Edelbrock Performers (Marine) which have an input above the throttle blades. I'm pretty sure all marine carbs have those, I think the idea is that the sudden fuel dump will flood the engine and kill it. The original Quadrajets were worn out, and though I had them worked on by a carb guy, he told me that the typical problem was that the shafts were worn, leading to vacuum leaks and poor running.
 
srfdude said:
I've put Edelbrock Performers (Marine) which have an input above the throttle blades. I'm pretty sure all marine carbs have those, I think the idea is that the sudden fuel dump will flood the engine and kill it. The original Quadrajets were worn out, and though I had them worked on by a carb guy, he told me that the typical problem was that the shafts were worn, leading to vacuum leaks and poor running.
Click to expand...

Here's my dilemma....I have 2 great running engines and apparently good working Holley 4160 marine carbs. But these carbs do not have any hard fitting for receiving fuel overflow from pump. None. Holleys approach to that issue at that time was a 90 degree bracket held down under the arrestor wingnut with a hose barb screwed into the face up against (1/2" away) the outer ring of the arrestor. I'm considering some sort of modification to thst arrangement thst would result in an insertion of some type on It either the arrestor grid or thru the top of the arrestor. I'm just not sure which is best approach but I do know I do not want to throw 2 perfectly good Holleys in the trash and replace with 2 new $500 carbs for the sake of a hose barb.
 
diver_dave said:
I would not violate the flame arrestor. I'm not sure what I would do, but not that.
Click to expand...

The reason this forum is so valuable to me is getting feedback from you guys to talk me out of stupid mistakes. Mark has been advocating drill and tap the carb body near the top away from any internal channels and screwing in a barb fitting. That's probably the smart approach.
 
makomark said:
Ron:

did you ever get the number off the carbs? Do they have the "inverted J" vent tubes?
Click to expand...

yes, both carbs are stamped 1-9015-1 , which shows up all over the place as a marine 4160 750 cfm. Yes, the inverted j-tubes are present on primary and secondary side. I think the issue here is probably just vintage. I examined yesterday again and discovered that the casting resembles the currently available new 1-9015-1 Holley carb BUT it does not have the angled little spot on primary side by the float bowl over the throttle linkage where a convenient drill and tap could occur for a hose barb.
 
thanks...thought you had verified those data points but wasn't sure....based on the last link, I'd say the factory 'update' barb is NOT tapped but just a press in....aka it is friction fit....
 
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