Electric pump or not

I went to the trouble of making up the factory wiring for an electric fuel pump oil pressure safety circuit once. I think it was the 75 spider that came with an electric pump so I used the wiring diagram to figure it out. It uses a relay that takes the ground signal from the oil light sending unit to trigger the relay. Had to find the correct relay to do this.
 
While I agree it is a good idea to have all these safety features, I must say I've never done any of them on any of my vehicles. But that's more a personal choice than smart thinking. :rolleyes:
 
Speaking of inertia switches. I recall VW has one that is quite small and not very noticeable. I also came across one from a Toyota/Scion vehicle that is small and compact. And I'm sure there are other little ones if keeping the engine bay clean is a goal. However I don't know how any of them compare performance wise to the more common Ford item (which is huge and gangly looking in my opinion). Prices also seem to range widely for various ones.
 
Ha! Indeed it is mine, but it's no problem. FWIW & hopefully without jinxing the Special, it could be the only engine bay mounted FP in a 124 I've seen work well long-term. In 124 Sports, I usually mount a FP close to where the original ('74-'76?) pumps were mounted in the trunk as low as reasonable. I've heard of people mounting pumps below the car generally where the FI cars have the FP located (which was the recipe I used on my '79 X1/9...low mounted where the FI pump is located). Ford inertia switches are wonderful: front kick panels of trucks/vans, trunk L/R in Taurus or Crown Vic sedans....if you're a real cheapstake, bring the 8mm socket, dykes & take 20 back from Pull-a-Part & sell a few on Ebay or something...either way, they're simple and cheap. I've never tried the relay approach as it seems like an over-engineering exercise, but that's just my POV.
 
twincam69 said:
For a car that’s only driven occasionally, I really like the electric pump. Here’s the install on my ‘75.
View attachment 70332
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A question from a newbie: my mechanic replaced a previously installed electric fuel pump in my newly acquired ‘74 X1/9 (1300) with a mechanical one to solve an issue we were having tuning the carb. I read through this post and it seems there is a preference for good quality electric fuel pumps. Are there trade offs or what we should have done is find a better electric pump?
 
LexZ said:
A question from a newbie: my mechanic replaced a previously installed electric fuel pump in my newly acquired ‘74 X1/9 (1300) with a mechanical one to solve an issue we were having tuning the carb. I read through this post and it seems there is a preference for good quality electric fuel pumps. Are there trade offs or what we should have done is find a better electric pump?
Click to expand...
The main problem I’ve seen with electric pump installation is that the pump that was chosen had output pressure that was too high for the Weber carb. That can be solved with a regulator or just choosing a low pressure pump like I have.
 
twincam69 said:
The main problem I’ve seen with electric pump installation is that the pump that was chosen had output pressure that was too high for the Weber carb. That can be solved with a regulator or just choosing a low pressure pump like I have.
Click to expand...

Thanks. Should we switch and buy a low pressure pump? My preference would be to find a solution favoring dependability and drivability over maximizing power or authenticity. Are there tradeoffs or is going back to (the right) electric a no brainer?
 
LexZ said:
Thanks. Should we switch and buy a low pressure pump? My preference would be to find a solution favoring dependability and drivability over maximizing power or authenticity. Are there tradeoffs or is going back to (the right) electric a no brainer?
Click to expand...
A mechanical pump is a good, reliable solution which can last a long time. The two on my 1969 and 1970 Fiats are OE from the factory parts and continue to give good service.

An electric pump adds several additional points of failure due to the wiring in addition to the quality of modern pumps which has become decidedly sketchy.

Personally, on a carbureted car I am more than happy with a mechanical pump. I personally would not change to an electric, period.

The other factor to strongly consider revolves around safety. An electric pump will keep running as long as the ignition is in the on or start position depending on how you wire it up. A mechanical pump stops pumping as soon as the engine stops. In an accident you may not have the presence of mind to turn off the ignition switch.

An electric pump can be wired to only run when the engine is running, has oil pressure or be shut off by a major event using an inertia switch. One could choose to do all of these things. The caveat is each system adds a failure point which can sideline the car. There are a number of ways to do this which we can delve into if you are interested.

Regardless of either the above issues, make sure the nipple for the fuel line is secure in the top of the carburetor. On old zinc castings the two dissimilar metals of the nipple (brass) and the top of the carburetor (zinc) can cause the brass part to come out and the pump will merrily spray fuel all over the top of the engine and the overly warm exhaust manifold below.

This can be fixed by intentionally removing the brass nipple and affixing it in a more permanent fashion by tapping the parts or roughing up the parts and epoxying them together.

Watching your car burn is not a fun way to spend part of a drive.

PS Buy a good quality fire extinguisher and place it in the car where you can easily get at it. (A bracket in front of the passenger seat or in the trunk are both good options).
 
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I agree with @Karl on this one. I use the stock mechanical pump to feed my DCNFs. No issue with capacity, and the reliability of the mechanical pump is pretty good. If I ever did switch to electric, I would definitely add the necessary devices to make sure it shut off in the event of an accident.

The one mechanical pump failure mode that I am aware of is that the return spring can rust and get shorter. This shortens the pump stroke and it will eventually get to the point where it can't deliver as much fuel as the engine needs. The symptom that led me to finding this problem is that the car would have trouble maintaining highway speeds and eventually could not do over 40 mph on flat ground. Once I pulled the pump out, it was obvious what the issue was as the spring had rusted down to about half of its original length. The two pumps that I had fail that way were from the 70s (factory pump and replacement for it). Hopefully, they are using better material for the spring now.

The other issue with the mechanical pump has to do with using it with carbs that vent to the air (like DCNFs). Depending on how long the engine has sat, and how warm it is, you can lose all the gas in the float bowl due to evaporation. With a mechanical pump, that means you will be cranking a bit longer to fill the bowl than if you had an electric pump. I prefer to view that as a test of battery capacity before I drive off.
 
LexZ said:
Thanks. Should we switch and buy a low pressure pump? My preference would be to find a solution favoring dependability and drivability over maximizing power or authenticity. Are there tradeoffs or is going back to (the right) electric a no brainer?
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The following is a great thread, although it is for an 850 application, the basic wiring work would be similar on an X.

Jeff Stich’s approach is clean, well thought through and very well executed.

850 electric fuel pump conversion (safety switch)

As part of the ever-ongoing rebuild of my 850 Sport Coupe, I'm converting the fuel delivery system from a mechanical pump to an electric pump. When I've done this on my 850's in the past, I simply ran a wire from the "+" terminal on the ignition coil to the electric pump in order to power the...
xwebforums.com
 
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I’m good with either a mechanical or electric pump. My cars sometimes sit for a while and I find the electric pump gets fuel to the carb (or carbs on my ‘60 Vette) without an inordinate amount of cranking. If your mechanical pump is serving your purposes and your use of the car, I would leave it alone.
 
kmead said:
A mechanical pump is a good, reliable solution which can last a long time. The two on my 1969 and 1970 Fiats are OE from the factory parts and continue to give good service.

An electric pump adds several additional points of failure due to the wiring in addition to the quality of modern pumps which has become decidedly sketchy.

Personally, on a carbureted car I am more than happy with a mechanical pump. I personally would not change to an electric, period.

The other factor to strongly consider revolves around safety. An electric pump will keep running as long as the ignition is in the on or start position depending on how you wire it up. A mechanical pump stops pumping as soon as the engine stops. In an accident you may not have the presence of mind to turn off the ignition switch.

An electric pump can be wired to only run when the engine is running, has oil pressure or be shut off by a major event using an inertia switch. One could choose to do all of these things. The caveat is each system adds a failure point which can sideline the car. There are a number of ways to do this which we can delve into if you are interested.

Regardless of either the above issues, make sure the nipple for the fuel line is secure in the top of the carburetor. On old zinc castings the two dissimilar metals of the nipple (brass) and the top of the carburetor (zinc) can cause the brass part to come out and the pump will merrily spray fuel all over the top of the engine and the overly warm exhaust manifold below.

This can be fixed by intentionally removing the brass nipple and affixing it in a more permanent fashion by tapping the parts or roughing up the parts and epoxying them together.

Watching your car burn is not a fun way to spend part of a drive.

PS Buy a good quality fire extinguisher and place it in the car where you can easily get at it. (A bracket in front of the passenger seat or in the trunk are both good options).
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Great response, much appreciated. Already have the extinguisher - just in case…
 
I like the responses from this thread. as far as reliability, I have had mechanical pumps in my carbed cars most of the time. The real reason I posted this was because in the spider, the starter is way easier to get to without the mechanical fuel pump in the way. Now, how often does one need to get to the starter? not much. I do know I have at least one more time I need to get to it when I swap it out for a gear reduction started, (but that is not in "get it on the road" budget). So not often and could just pull the fuel pump if I needed to get to it. But the engine has been sitting, except for one start up before I tore it down, 2 years ago, and when we did it then the pump was non functional so it would need to be replaced anyway. I chose, and I truly believe it is a 6 one way 1/2 dozen another, to go electric. Working on the wiring now. I already have the inertia switch, and also contemplating on also tying in the oil pressure sensor as well, but probably not. All my cars, even my newer ones have a small extinguisher in them. I personally havent had to use one nor have had a fire, but I do work for an insurance company and see how many cars have fires. usually could have been stopped with an little extinguisher and not had the car engulfed. Also all of our auto adjusters have them in their cars as well. Seeing that they see the root cause of most accidents, I trust their knowledge of safety in a car.
Recap, IMO unless you have a reason to swap, the mechanical pump is the way to go.

Odie
 
Nice thread and it states both options (electric or mechanical) would work well when all things function properly. I personally prefer the electric pump but that's just me.

I will make one point, if you carry a fire extinguisher then putting it in the trunk seems counter intuitive. Will you have the presence of mind while in panic mode as you see your car is on fire to release the trunk latch (or in a 124 grab the keys to unlock the trunk)?
 
carl said:
Nice thread and it states both options (electric or mechanical) would work well when all things function properly. I personally prefer the electric pump but that's just me.

I will make one point, if you carry a fire extinguisher then putting it in the trunk seems counter intuitive. Will you have the presence of mind while in panic mode as you see your car is on fire to release the trunk latch (or in a 124 grab the keys to unlock the trunk)?
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LOL exactly! I have seen people do that as well. No common sense. I will admit, on my newer cars it isnt as quickly accessible as my older cars but not in the trunk. in my X it is mounted between the seats on the firewall. Havent figured where it will live in the spider. My last spider is was on the floor behind the passenger seat. Probably where it will end up in the current.
 
carl said:
Nice thread and it states both options (electric or mechanical) would work well when all things function properly. I personally prefer the electric pump but that's just me.

I will make one point, if you carry a fire extinguisher then putting it in the trunk seems counter intuitive. Will you have the presence of mind while in panic mode as you see your car is on fire to release the trunk latch (or in a 124 grab the keys to unlock the trunk)?
Click to expand...
Practice.

Especially as one needs to pop the engine lid anyway, pull both handles at the same time.

I am apparently too planful or more likely know Murphy all too well.
 
kmead said:
Practice.

Especially as one needs to pop the engine lid anyway, pull both handles at the same time.

I am apparently too planful or more likely know Murphy all too well.
Click to expand...
what if the fire is in the trunk as one of the fuel lines broke and a spark from the battery started the fire. :) wear kitchen mitts?

Odie
 
Don't forget, when you lift the engine lid you provide everything the fire needs to get REALLY BIG!

I suggest you clowns don't buy $20,000 Fiats. Buy beaters like I do, insure it and walk away from it when it's on fire....maybe dial 911 to report a car fire.
 
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