Any clever tips for upgrading classic to electric fuel pump?
Discussion
I've come to the conclusion that I want to fit a low pressure inline electric fuel pump to my classic to supplement the original mechanical pump. There's absolutely nothing wrong with the mechanical pump and I'm going to continue to use that to supply fuel to the carb... it's just that I'm sick of having to crank the engine for ages to fill the float bowl before the car will start after periods left idle.
It's the age old problem of fuel evaporating (or leaking!) out of the float bowl when the car sits for a few days unused... it's also not great when it's hot as the fuel boils off and creates the same problem....
To get around this, I'm planning to use a cheap eBay inline solenoid type pump - it doesn't have to do much, just pump fuel to fill the carb before the mechanical pump takes over once the engine is running... I could wire into the coil +ve via a relay to energise the pump whenever the ignition is on ... BUT there is a mild safety concern about continuing to pump fuel in the event of an accident. Added to which, I've experienced an event on another engine where the float stuck, the electric pump flooded and eventually strangled the engine to a stop and then continued to fill the hot engine with fuel before I worked out what had happened....
Ideally, I only really want the pump to run for 20 seconds or so when I first switch on the ignition. I don't mind if the pump then continues to run if the engine is running, but I'd like it to stop when the engine stops running. Seeing as we're looking at Goldilocks scenarios, I'd also quite like to be able to manually over-ride, so I can switch the pump on if the mechanical pump dies.....
So are there any clever relays or natty little devices out there in modern car land that classic car luddites like me might not have come across to achieve my aim?
Basically, I quess I want some clever relay that energises for a burst when I switch on the ignition, then only energises if I ask it to or if the engine is running.... What is out there that can achieve that? or how would you wire that with basic relays and points ignition?
It's the age old problem of fuel evaporating (or leaking!) out of the float bowl when the car sits for a few days unused... it's also not great when it's hot as the fuel boils off and creates the same problem....
To get around this, I'm planning to use a cheap eBay inline solenoid type pump - it doesn't have to do much, just pump fuel to fill the carb before the mechanical pump takes over once the engine is running... I could wire into the coil +ve via a relay to energise the pump whenever the ignition is on ... BUT there is a mild safety concern about continuing to pump fuel in the event of an accident. Added to which, I've experienced an event on another engine where the float stuck, the electric pump flooded and eventually strangled the engine to a stop and then continued to fill the hot engine with fuel before I worked out what had happened....
Ideally, I only really want the pump to run for 20 seconds or so when I first switch on the ignition. I don't mind if the pump then continues to run if the engine is running, but I'd like it to stop when the engine stops running. Seeing as we're looking at Goldilocks scenarios, I'd also quite like to be able to manually over-ride, so I can switch the pump on if the mechanical pump dies.....
So are there any clever relays or natty little devices out there in modern car land that classic car luddites like me might not have come across to achieve my aim?
Basically, I quess I want some clever relay that energises for a burst when I switch on the ignition, then only energises if I ask it to or if the engine is running.... What is out there that can achieve that? or how would you wire that with basic relays and points ignition?
Edited by larrylamb11 on Sunday 2nd January 21:30
If you're fitting an electric pump, why retain the mechanical one at all? If you want it to look original, just take the guts out and put the body back on to the block with a blank sandwich plate to seal the block and 'dummy' tubes to maintain the pretence.
As far as controlling the pump is concerned, IF nothing is available off the shelf, then someone with the right know how could create a controller using an Arduino board - apparently quite simple (once you know how) and relatively inexpensive.
Have a look: https://www.arduino.cc/
Kim
eta Oh, and use a proper low pressure Facet pump, not an Ebay special would be my advice.
As far as controlling the pump is concerned, IF nothing is available off the shelf, then someone with the right know how could create a controller using an Arduino board - apparently quite simple (once you know how) and relatively inexpensive.
Have a look: https://www.arduino.cc/
Kim
eta Oh, and use a proper low pressure Facet pump, not an Ebay special would be my advice.
Understand your pain, I used to kill the battery trying to fill a pair of Webers on my Caterham back in the 1990's. Fitted a Facet solid state pump under the rear bulkhead and it's been working fine ever since. Ignition on a few seconds of clicks and its away we go. Did similar to my old mini rally car when I had it.
Only thing i'd say is rubber mount it as thenoise transmits through the car.
Only thing i'd say is rubber mount it as thenoise transmits through the car.
Why not just have the electric pump with a switch then you can turn the pump on for long enough to prime then turn it off. You could have a push button or sprung switch so you can't leave it on.
This is assuming a switched off electric pump allows free flow of fuel and doesn't prevent the mechanical pump from pumping!
This is assuming a switched off electric pump allows free flow of fuel and doesn't prevent the mechanical pump from pumping!
I fitted a Facet solid state cube pump to my escort, used to take a while for the mechanical pump to fill the twin Weber’s.
Have a look for a tachometric pump relay (I used a Volvo unit) these take a wire from the -ve side of your coil, as long as your coil is firing the relay stays energised.
Some relays have an initial ‘prime’ time too, although I just wired in a separate standard relay with a push button for when the car has been sitting for a while .
Have a look for a tachometric pump relay (I used a Volvo unit) these take a wire from the -ve side of your coil, as long as your coil is firing the relay stays energised.
Some relays have an initial ‘prime’ time too, although I just wired in a separate standard relay with a push button for when the car has been sitting for a while .
Could you not use a diesel glowplug relay?
Has a timer inside and turns of automatically.
Easy to wire a switch to bypass the timer and have the pump running all the time, you could also use a vw injection relay pump while the engines running and wire a switch inline to kill the pump as and when you wanted ( use an illuminated switch with a tell tale light to remind you its on/off).
Has a timer inside and turns of automatically.
Easy to wire a switch to bypass the timer and have the pump running all the time, you could also use a vw injection relay pump while the engines running and wire a switch inline to kill the pump as and when you wanted ( use an illuminated switch with a tell tale light to remind you its on/off).
In Porsche land a priming bulb is a popular mod. No need to wire it in. 
https://www.amazon.co.uk/ePathChina®-Primer-M...
Alternatively, if using an electric pump, a momentary on switch is fitted to the bottom edge of the dashboard and out of sight. Jump in the car, hold the button till the clicking stops, release and off you go !
https://www.amazon.co.uk/ePathChina®-Primer-M...
Alternatively, if using an electric pump, a momentary on switch is fitted to the bottom edge of the dashboard and out of sight. Jump in the car, hold the button till the clicking stops, release and off you go !
I rebuilt my mechanical pump using a rebuild kit I bought three or four years ago, and was disappointed to find that it was leaking after a year or so. So I took the plunge and replaced it with an electric pump and a pressure regulator. Prior to it leaking, it was working very well - replacing the two valves made the most difference, but the new diaphragm sorted out the pumping issues, which are particularly in evidence on my car as it cranks very slowly.
I have bought an inertia switch from, I believe, a Ford Fiesta with the intention of wiring it into the supply circuit. The only reason I've not done it yet is because I haven't got the electrical connector for it - the one I bought isn't correct. Others I know have bought them from breakers and got the last 6" of loom included to get around the issue.
I bought quite an expensive pump because I wanted one that was able to be sited in the engine bay for various reasons, not least that I didn't want to pull virtually all the interior out to get a wire to the back. The low-cost ones all need to be closer to the tank than I wanted to fit it, but if I do the other car I may go for one of the less costly ones and put it at the back.
I have bought an inertia switch from, I believe, a Ford Fiesta with the intention of wiring it into the supply circuit. The only reason I've not done it yet is because I haven't got the electrical connector for it - the one I bought isn't correct. Others I know have bought them from breakers and got the last 6" of loom included to get around the issue.
I bought quite an expensive pump because I wanted one that was able to be sited in the engine bay for various reasons, not least that I didn't want to pull virtually all the interior out to get a wire to the back. The low-cost ones all need to be closer to the tank than I wanted to fit it, but if I do the other car I may go for one of the less costly ones and put it at the back.
The pump is good and I'd prefer to leave it alone.... Don't fix what isn't broken being a worthwhile mantra on old cars!.... Yes, I could do away with it entirely and fit an electric pump, but I'm then building in an item that could fail and leave me stranded.... If I have the mechanical pump as the primary and the electric as the secondary/backup, I'm building in contingency that is more likely to get me home should I need it.
Thanks for the suggestions so far - I'm keen not to have it rely on having to press a button, or flick a switch.... I really want to make it as automatic and idiot proof as possible. Mrs LL11 is expressing an interest in piloting this jalopy on occassion, so I want her to be able to just hop in and for it to work... even if it's been sat on the drive for a fortnight unused. Hence wanting the pump to prime the carb on first turn of the ignition. It also needs to be safe.
The VW relay is an option. I like how they only run when they get the signal from the coil... but I don't know if it will prime long enough to fill the carb.
There must be a cheap, easy, safe solution out there, as I can't be the only person wanting to do this? or do people just run an ordinary relay and have the pump running whenever the ignition is on and hang the safety aspect....?
Someone mentioned inertia switch - what's the word on these? easy scrap yard fodder? and where do these modern devices normally hide?
Thanks for the suggestions so far - I'm keen not to have it rely on having to press a button, or flick a switch.... I really want to make it as automatic and idiot proof as possible. Mrs LL11 is expressing an interest in piloting this jalopy on occassion, so I want her to be able to just hop in and for it to work... even if it's been sat on the drive for a fortnight unused. Hence wanting the pump to prime the carb on first turn of the ignition. It also needs to be safe.
The VW relay is an option. I like how they only run when they get the signal from the coil... but I don't know if it will prime long enough to fill the carb.
There must be a cheap, easy, safe solution out there, as I can't be the only person wanting to do this? or do people just run an ordinary relay and have the pump running whenever the ignition is on and hang the safety aspect....?
Someone mentioned inertia switch - what's the word on these? easy scrap yard fodder? and where do these modern devices normally hide?
Skyedriver said:
PositronicRay said:
Are you sure the mechanical pump is good? Sometimes the diaphragm can leak.
Which car is it?
It's not so much the pump as the carbs and supply pipe drain and it takes a while to fill themWhich car is it?
I know wear on the finger or diaphragm can cause lacklustre performance.
The one I am looking at converting right now is a Scimitar. The carb is in the V of the engine and will boil pretty much dry at the end of a good run. Leave it a few days after that and when you try and start it it'll fire a couple of times as it uses the remaining fuel squirted in from the accelerator pump having pressed the throttle to set the auto-choke, then it churns for uncomfortably long as it mechanically refills the carb before bursting into life..... I can't let Mrs LL11 wrestle with that and then expect her to trust the car will start later.. If she doesn't trust it, she won't use it - fair enough really.
The other issue is that the battery is woefully tiny and the battery tray shaped so you can't fit a bigger one - anything I can do to make it start more quickly and easily is worth it.
The other issue is that the battery is woefully tiny and the battery tray shaped so you can't fit a bigger one - anything I can do to make it start more quickly and easily is worth it.
Pistonsquirter said:
The electric pump just needs an ignition switched relay. And an inline inertia switch to shut the pump off if you have an accident. Simple.
A prefilter wouldn't be the worst idea either.
This seems to be the easiest solution.... thus Mrs LL11 proof. Yes, the pump will run all the time, which I hadn't planned on, but the inertia switch provides the key safety device I was looking for.A prefilter wouldn't be the worst idea either.
I'll have a look at a heated rear window relay too, as that is an interesting idea.... One of those with the inbuilt timer ought to do exactly what I wanted one to do - prime at ignition switch 'ON' for a while, then switch off. Good suggestion.
Larry,
Much useful advice re starting above, but you also asked about stopping the pump in an accident. With some of the scenarios above that would seem unnecessary, but anyway.
Inertia switch. This is a switch that will break the pump circuit if subjected to a high-g shock as in a sudden stop, or if striking something else. I think all moderns that run fuel injection have them. One type is so common, and presumably successful, that it is fitted by many manufacturers, from Land Rover to Maserati. Those are two adjacent letters in the alphabet, but you'll get what I mean!
EG: https://www.ebay.co.uk/itm/294577509068?hash=item4... There are lots more of that ilk. There are also two types, with two and three terminals. The latter will light up a warning on the dash to show that the switch has triggered. You might think unnecessary, given what it's for, but running the kerbs on a corner has triggered mine. Without the light, I would have had a sudden engine failure for no good reason.
And, get one WITH the male connector from the loom, else wiring it in will be a pain.
John
Much useful advice re starting above, but you also asked about stopping the pump in an accident. With some of the scenarios above that would seem unnecessary, but anyway.
Inertia switch. This is a switch that will break the pump circuit if subjected to a high-g shock as in a sudden stop, or if striking something else. I think all moderns that run fuel injection have them. One type is so common, and presumably successful, that it is fitted by many manufacturers, from Land Rover to Maserati. Those are two adjacent letters in the alphabet, but you'll get what I mean!
EG: https://www.ebay.co.uk/itm/294577509068?hash=item4... There are lots more of that ilk. There are also two types, with two and three terminals. The latter will light up a warning on the dash to show that the switch has triggered. You might think unnecessary, given what it's for, but running the kerbs on a corner has triggered mine. Without the light, I would have had a sudden engine failure for no good reason.
And, get one WITH the male connector from the loom, else wiring it in will be a pain.
John
I've been thinking of similar fixes. Can anyone confirm whether mechanical and electric pumps are free-flow when not in use i.e. if put on a single line the the electric pump won't prevent flow when using the mechanical pump and vise-versa?
My car gets so hot under the bonnet that it vapourises the fuel when doing slow manoeuvres at the end of a drive e.g. reverse off road, get out to unlock gate, unload kids, reverse up driveway, getting out to unlock the garage door, reversing into the garage.. so maybe 2-3 minutes barely moving. If in the car you can feel it starting to go so a blip of the throttle will keep it running. If it stops then it won't be starting for at least 5 minutes, probably 10. Is mounting an electric pump near the tank a solution (I'd likely just use a toggle switch as I'd use the normal pump for actual driving).
It's a '65 Mustang so it's a car known for this, as under bonnet temperatures are high, the carb in the middle of the V etc. (a change to exhaust headers didn't help, and the uprated rad/fan moves more heat out of the engine into the engine bay). It's just one of those cars that doesn't have a exit route for hot air when not moving.
My car gets so hot under the bonnet that it vapourises the fuel when doing slow manoeuvres at the end of a drive e.g. reverse off road, get out to unlock gate, unload kids, reverse up driveway, getting out to unlock the garage door, reversing into the garage.. so maybe 2-3 minutes barely moving. If in the car you can feel it starting to go so a blip of the throttle will keep it running. If it stops then it won't be starting for at least 5 minutes, probably 10. Is mounting an electric pump near the tank a solution (I'd likely just use a toggle switch as I'd use the normal pump for actual driving).
It's a '65 Mustang so it's a car known for this, as under bonnet temperatures are high, the carb in the middle of the V etc. (a change to exhaust headers didn't help, and the uprated rad/fan moves more heat out of the engine into the engine bay). It's just one of those cars that doesn't have a exit route for hot air when not moving.
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