mechanical fuel pump with IDFs - why not?

[Sparky]

For all the posts talking about electric fuel pumps failing, would a new mechanical pump be more reliable?
I'm using twin EMPI style IDF 40 carbs with the EMPI fuel pressure regulator.
Does anyone know if there is a maximum rpm they can be run up to or other shortcomings?
Are they incompatible with our ~10% ethanol that's in all the gas now?

[engineerted]

I believe other out there still use the stock mechanical pump. I did originally, but moved on to the electric pump. I did not like cranking the engine for extended periods to pump fuel to the carbs, mostly after the car setting for more than a week. Electric pump are very reliable if mounted in correctly, rubber isolated (mostly for noise) and at or below fuel tank fluid level.

[chrisg]

The factory (European) IDF/1608 would have used a mechanical pump. In theory & for a daily driver, I would figure it's a matter of preference & the fuel pressure can be regulated (I don't know if or how it was in the full European setup....I had a European 1608 car once, but it already had an electronic pump on it when I got it.

[MattVAS]

Well electric pumps are just better, and that is from someone that sells both.
1. You don't need the regulator if you have an electric pump.
2. You don't need a one way valve in the fuel line.
3. You don't need to crank the engine for prolonged amounts to pump the fuel up to the carbs.

The cons are low pressure fuel pressure regulators (these are ones used on carb setups) are notoriously unreliable. One way valves are prone to failure as well and that causes the extra engine cranking. Also the fuel will go away no matter what since most people don't drive them enough keep the fuel up at the carbs no matter one way valve or not. And lastly electric pump can usually blow by a fuel vapor lock, this is pretty rare on Fiats but when it happens it always has a mechanical fuel pump.

I've never kept a mechanical fuel pump on a Fiat.

[Sparky]

Hey Matt, I've never heard of someone running IDF carbs without a fuel pressure regulator?
Do you have some recommendations on pumps? I haven't come across any lower pressure pumps that didn't have a fair number of failures reported. By contrast, I haven't heard of anyone with a newer mechanical pump that's been stranded due to failure, but maybe they're just too rare to get a decent sample size.

[chrisg]

I recently installed a Carter fuel pump on my 79 X1/9....probably going to swap to that pump (4070?) on other Fiats as well, at least the others that have dual carburetors.

[gjones1967]

Sparky,

How are those EMPI carburetors? What is the performance against the Weber’s? Just curious as I am currently restoring a 78 and planning on using IDF 40’s. There is a huge price difference

[Sparky]

I can't comment on the carbs performance yet as I'm still putting the car together. The build quality seems fine. I'm using Weber jets, venturis, etc... Unlike the 'proper' Webers, I had to cut the shafts down between the carbs and fit a balance linkage.

[AndyVAS]

The primary cause of failure of the electric fuel pump is poor installation. When installed correctly they don't fail very often at all. You want the electric pump mounted low and close to the tank. Hence why newer cars mount them in the tank with the pickup screen on them.

[wetminkey]

I have to agree with the opinion that e-pumps work just great, but they are easy to install incorrectly, and you can sure find some really cheap ones out there, too.
My engines with e-pumps start nearly immediately,...even in the cold. And, despite having a few cars with them, for a good number of years, I've never actually had one quit,...
Years ago, the mechanical diaphragms used to fail after a number of years. But better synthetics now,...
Follow Andy and Matt's advice while installing,...they describe how it's done properly.
Todd.

[grrrdot]

FWIW I ran a mechanical fuel pump on my 124. Within two years I went through three different pumps, each failed for various reasons.
I then bought a vane style pump and regulator, 5+ years now with no issues.

-G

[chrisg]

The 1974 124s had an electric fuel pump, so that mounting location can be a good reference, I suppose. It's the low location in the trunk that I always use.

The potential to spew fuel into the crankcase while still also pumping is probably the biggest factor I my mind. I also prefer to be able to fuel prime the carb and then turn the key vs a few starter cranks before it has enough fuel.