General Electric fuel pumps

[phoenix1]

Hi. Just a small comment about electric fuel pumps.The required amount of fuel even for a tuned engine fitted to these cars would be amply supplied by a good standard fuel pump.I am writing this because I had an Expensive car catch fire due probably due to leeking fuel (not enough left to say definitely ) the problem
With electric pumps and mine was very high pressure is they don't stop when the engine stops. The flames on my car although a front wheel drive were over the roof before I got it stopped and even plumbed in extiguisher did no good.The car I lost was a ford cosworth and not covered by insurance so it was a big loss.

On another topic replying to a recent post I have a 650cc engine with the none cable operated starter and I am trying to work out a way to use the redundent lever to operate the heater flap . Has anybody tried this or should I leave alone.

 

[AndrewHarvey]

I've fitted a Facet red top and Malapassi filter regulator.
Its wired through a separate fusebox powered by the ignition circuit. I also have a dash mounted battery kill switch.
The tracker fitted allows the fuel pump o be switched off in the event of it being stolen.
The engine is noticeably quieter with the pump removed.
I have a breather fitted where the pump resided - allowing a hose from rocker cover to crankcase.
The electric pump allows me the flexibility of pressure adjustment when tuning on the rolling road.

 

[the hobbler]

I totally agree with 'Phoenix'--the standard manual pump will amply supply all the fuel required for even a fairly well tuned 650 engine. Abarth only ever used the standard pump, even on the '695SS', and don't forget, Fiat put a fuel-return system on the 650cc engine '126s' to return the surplus fuel. On top of the reasons/concerns voiced by 'Phoenix', I am a great believe in the KISS principal----Keep It Simple Sucker!

 

[phoenix1]

I would add as long as the float chamber is full it dosn't matter about the fuel pressure. The only time it would is if you were using fuel injection which requires much higher pressure.I used to run a 1600cc ford engine for competition with twin 40 dcoe carbs with the standard mechanical pump which was adiquate and about the same physical size

 

[jackwhoo]

Too much pressure to a carb can cause the float valve to leak causing too high a fuel level or even carb to over flow.
Fire risk etc .

 

[fiat500]

Too much pressure to a carb can cause the float valve to leak causing too high a fuel level or even carb to over flow.
Fire risk etc .

It sounds like, as with everything on the Fiat 500, the original non-CAD specification of the engine, balances all factors to produce the best "compromise" (a million times better than most compromised designs).
I think one of Andrew's points is the most pertinent in that removing the pump also takes away some of the (lovable?) clatter.
But I would follow Tom's advice to keep it simple (ie. as it is) unless you're the type of person who likes to create and then find solutons to engine problems; from my observations here, the car already comes equipped with enough of those to keep most people "happy".

PS. Andrew AndrewHarvey ditch the "rolling road" idea and get it rolling on the road. I want to see that thng shake off the cobwebs.

 

[Bigvtwin996]

as I have nothing better to do these days here my bit...
I agree the 500 is a perfectly spec'd car, it does everything it should as it was designed to do ( 50 years ago).. and can provide many miles of problem free motoring...
but we are all used to something different...all production cars probably have electric fuel pumps, they are also very easy to easy to test and quiet.. no need to crank the engine..
I see little point in changing to an electric one and be honest and mechanical ones are quite serviceable and thus cheaper...
but I may change to de clutter the engine bay... and there is a little problem with fuel in the pump getting hot... but who knows I drove mine very little before it needed some work...
as an add on.. why does everyone seem to fit an inline fuel filter within the engine bay?
it should be fitted before the pump to stop any crud reaching and blocking the pump.... but the later cars F onwards (100% sure R's do) I believe have a filter built into the pickup within the tank, and the mechanical pump also has an internal filter, is the extra one for reassurance? is fuel from modern garages so bad? or that the pipes between the tank and the pump may be so old as to break down and block the pipe... well clean them... or replace them.

I am not saying that we should not update or improve these cars using technology that was not around when they were designed and "lessons learnt" from 50+ years of advancement... I have 123 Distributor I intend to fit.. simply because I don't want to clean points any more... but we do look for faults that may not exist.
I have a friend who brought an M3 BMW and was convinced he could tune it better than the team of engineers and £millions spent by BMW, needless to say.. it had to go to a specialist to be reset as the 12mpg and erratic running were somewhat of a problem...

My car does have a 650 engine.. and I defy anyone to drive a 479cc car and not think "Ohhhhhh ****ttttttttttttt I'm going to dieeeeeeeeeeeee" but it will be put back in at some point...

 

[jackwhoo]

In my opinion nothing wrong with fitting an electric fuel pump just make sure it is an electric pump suitable for a carburetor.

 

[fiat500]

I have run my car for three years and approximately 64 tanks of fuel relying on the three, factory-fitted, extremely​ fine filters mentioned by BigV. It has never suffered any type of fuel blockage. For those who would say, "But what about my dirty tank?", take it out and clean it; it's a very easy job.
PS. My 123 is currently in the garage attic which has improved my Fiat's smooth running significantly.

 

[jjacob]

The reason for the typical clear view fuel filter being installed is that it filters out finer particulates than the mesh in the tank pickup or fuel pump.
It should be installed before the fuel pump, best in the engine bay as when you change it you do not want gas spilling into the trunk area.
John

 

[fiat500]

The reason for the typical clear view fuel filter being installed is that it filters out finer particulates than the mesh in the tank pickup or fuel pump.
It should be installed before the fuel pump, best in the engine bay as when you change it you do not want gas spilling into the trunk area.
John

But that makes no sense to me John. Fiat presumably knew the diameter of the smallest orifice or passage in the carburettor and would have sized the mesh in the carb inlet at least, to be sufficiently fine to remove particles that would have the potential to block these. If that wasn't the idea there was no point having that filter.
It would make sense to have sized the pump filter-mesh to remove slightly larger particles which might block the carb filter too quickly. I would hazard a guess that the tank pickup would have had an even coarser mesh, although very fine at that.
I doubt that anyone with an inline filter fitted knows the specification of that filter. But if it is finer than the one in the carb or pump it makes them redundant. If it is correctly specified, intermediate between the size of the tank pickup and the pump filter, then it will do a good job of reducing the chance of a complete blockage of the pump flter in outrageously dirty fuel conditions but is not needed.
I am not suggesting that an inline flter is a bad idea, just that it is not necessary; so I can't see any validity in the argument that it provides an essential improvement to the filtering of fuel.

 

[jjacob]

Hi Peter,

No the filter mesh in the tank and the fuel pump is not as fine as a regular fuel filter and will pass very, very small fine particles.
You have to remember that these cars were built to price. Adding on a fuel filter, even at only $1.00 USD would have cost Fiat millions of dollars over the production life of the car. So they left it off for the same reason there was no real gas gauge on the standard F model, along with other items you might find on a car costing a few hundred dollars more.
Considering how cheap a new gas filter is, it seems to be good insurance.
Just my opinion!

Best regards,
John

 

[Vitesse]

I think the general consensus of opinion Peter is that to add any filter will "potentially" add to cleaner fuel reaching the carb, it can't do any harm.

I do disagree with John about the placement of the filter though. Putting it in front of the pump is going to "potentially" restrict flow to the pump. It is reliant on gravity for fuel to reaching the pump. It's like sticking a resistor on a piece of wire and passing a voltage through it, you are going to get a voltage drop. Because the fuel pump is a push pump it makes a lot more sense to place a filter between the pump and the carb because fuel will be pushed (forced) through it by the pump. You are not really interested in keeping the pump clean as it has its own filter already and I have never seen a particularly dirty filter inside a pump. The vast majority of filters I have seen are between the pump and the carb.

One thing I do stay clear of is plastic filters, it's not good idea to place a plastic filter that is full of fuel inside the engine bay. I have read stories of them blowing up like a balloon due to the heat in the engine bay. I have never personally experienced it but it makes sense for a few extra pounds to install one made of glass and metal, just to be on the safe side.

Tony

 

[AndrewHarvey]

To add a further point - when i removed the sender unit in the tank , the fine mesh was completely blinded.
I've read of old 500's rubber fuel lines breaking up and drpositing debris into pump and carb.
As a precaution (warning - more of Andrews's mods....) i removed the sender / fuel supply filter - bought an eletric pump and racing spec filter / regulator....replaced all rubber fuel lines...placed small glass superfine filter before carb.
Its going to upset my purest friends - but ive had great fun building "my" car.

 

[fiat500]

Hi Peter,

No the filter mesh in the tank and the fuel pump is not as fine as a regular fuel filter and will pass very, very small fine particles.
You have to remember that these cars were built to price. Adding on a fuel filter, even at only $1.00 USD would have cost Fiat millions of dollars over the production life of the car. So they left it off for the same reason there was no real gas gauge on the standard F model, along with other items you might find on a car costing a few hundred dollars more.
Considering how cheap a new gas filter is, it seems to be good insurance.
Just my opinion!

Best regards,
John

Obviously I grasp that argument; that the car was a compromise built to a price...most cars are, I'm not sure that it follows that an inline fuel filter was omitted for that reason. They actually fitted three filters in the fuel-line!!!
They also (unnecessarily?) chose to fit an individual dashboard switch so that you could choose to turn off or on the fairly ineffective speedometer light so that you could or couldn't see that the fuel gauge didn't exist. They also omitted the additional two cylinders that most cars had at the time. All of these things may or may not have been decisions that were affected by financial constraint. But I am fairly sure that they knew what they were doing.
As Tony points out, fitting a fuel filter is not without the potential to cause problems of its own. I also wonder how you would decide when to replace it. I agree that for the negligible cost and simplicity of fitting an inline fuel-filter, why shouldn' you? All I am saying is that I think that you gain nothing by doing so,

 

[Bleeding Knuckles]

Greetings all, I would just add that modern day fuel is quite a nasty cocktail and even with additive it will play merry hell with the 500 fuel tank That's added to the history of the tank rotting from the inside over time I have a pierburg electric pump and I carry a spare too - can be pricey though!! There is no way I would subject that pump to dirty fuel as so much relies on it. I do use a simple plastic inline filter (in the front bay directly before the pump) and the carb has a filter too. All of my flexible fuel pipe was removed and replaced with stainless steel braided pipe as a precaution it may sound all I bit manic, but the thought of breaking down due to dirty fuel is a bit beyond the pale

Ian

 

[jjacob]

Have to disagree Tony with the location of the fuel filter. If you put it after the fuel pump you are pushing and trapping most of the fuel debris in the fuel pump. I would agree that if you never change your fuel filter that putting it in front of the fuel pump would eventually cause problems for the pump. But anyone who owns these cars now will most likely take care of the car. However, how many people have ever cleaned out the filter screen in their fuel pumps? Probably never. A cheap fuel filter located before the fuel pump is a maintenance item no different than changing plugs or oil. Changed out every so often and there are no issues.
John

 

[Vitesse]

Well we'll have to agree to disagree John. You quote maintenance as a reason but part of the maintenance recommendation every 6000 miles is to indeed check the filters in the fuel system. "Clean the filters. There is one in the pump, reached by undoing the screw holding the domed cover on top".

Therefore checking the filter in the pump is also no different to changing plugs or oil. In fact I would argue it's a lot simpler that changing an inline filter. Which sort of backs up Peter's argument, are they really necessary if people are doing their maintenance correctly and at the right intervals?

 

[Franko500]

My personal view is the manual fuel pump is sufficient to operate the 500/650 engine. As long as you take the following precautions:

1. Make sure the tank has been cleaned out properly and has no signs of internal corrosion.
2. The tank sender unit filter is clean as they can get clogged up.
3. The fuel lines are replaced. The original flexi pipe was fairly rigid and less likely to deteriorate unlike rubber hose that can get damaged from taking it on/off of a metal pipe. Also some rubber hoses actually deteriorate due to the fuel itself.
4. Correct size jubilee/fuel line clamps are fitted. The wrong ones can cause damage to the hose.
5. The fuel pump has a very fine filter in it which looks to me to be finer than the holes in the jets of the carb. Therefore makes no sense to fit another inline filter between the tank and the pump. This filter on the domed cap pump can be removed and cleaned.
6. I don't really think an inline filter is required but if you do fit one then this should be between the pump and the carb due to the pressure being greater after the pump is far better than placing a restriction in the suction side.
7. The carb has yet another filter within the float valve, so in theory anything that gets past that should be able to go through the jets.
8. If you have done all that and still concerned, then use a filter in a funnel when filling the car up.

In the past the only thing that I have found that really blocks the fuel is small pieces of rubber that have come from the hoses.

 

[fiat500]

"Clean the filters. There is one in the pump, reached by undoing the screw holding the domed cover on top".

We've all driven this thread well off topic by now, but I will add more to that, that with the Savara pump which I have seen as original fitment on many cars in the past, but which in most cases is obviously long gone now, there is a tubular filter which is removed after unscrewing the removable inlet spigot on the pump.
It is a very compact pump with only four screws to secure the diaphragm and mechanism, but sadly I have been unable to restore this rare bit of originality as spares seem to be unavailable.