Electric Fuel Pump for IDF:

[thechadzone]

So my IDF set-up is super kickass, but the engine sputters just after I I make a hard, or even somewhat hard turn, and it lurches a bit at the lower RPMs. I'm thinking that it's starved for fuel? I'm using only the stock mechanical fuel pump from the 2 liter motor.

I'm pretty sure I should be using an electric fuel pump, but should it go between the fuel tank, and the intake side of the mechanical fuel pump, or between the exit of the mechanical fuel pump, but before the carbs? Should I wire it to the coil, or is there a better option? I"ll be sure to use a pressure regulator...

Did the original dual carb'd "Sport Spider" with the 40 IDFs use an electric fuel pump? Did the 124 Abarth?

I tried searching for other threads on this, but I didn't find much. However I am not very smart...

Thanks in advance for your input.

[kmead]

The standard Euro IDF equipped cars used a mechanical pump. You may want one but they are not needed.

Carbs don't need tons of pressure, @2-3lbs versus 45+ for fuel injection.

The symptoms you describe sound like the floats are not properly set. If the float level is too low you won't have enough in the bowls to fulfill the need. In the case of poor performance while turning, it can cause a jet to get no fuel as the small amount of fuel in the bowl sloshes away from the inlet for the various jets.

Electric pumps push rather than pull so it should be mounted low near the fuel tank and push the fuel up to the engine.

[thechadzone]

Thanks for the reply. I didn't think that the Euro IDF equipped 124s used an electic fuel pump... The fuel filter that I'm using is the standard "cheapie" directional plastic one, and I've placed it about six inches before the fuel line goes into the first of the two carbs. It's clean, but will it affect the flow of fuel enough to contribute to the described problems? Is there a better place for a fuel filter, and/or a better filter?

Also, what spec is the suggested float height for IDFs used for this application? I've adjusted float heights on motorcycle carbs, but never on a non-bike carb. Tips are appreciated...

[kmead]

I have sent you a pile of info, but likely the most direct item is this link (I included the PDF of the site already):

http://www.piercemanifolds.com/Float_Level_1.pdf

In addition you may need to adjust the accelerator pump or look at the quality of the diaphragm of the accelerator pump. Not enough fuel from the accelerator pump can give a bog when first tipping into the throttle.

I would also look at your distributor advance, you may or may not have the dist properly timed or the vac advance may be stuck or not working due to lack of vacuum.

[sptcoupe]

The floats are pretty straight forward to adjust. Just two lightweight metal tabs that can be GENTLY bent to adjust the total arc of the floats. The arc should be a total of 22mm. In the "closed" position, the distance between the top of the float and the bottom of the carb top should be 10mm (with the gasket in place). In the "open" position, it should be 32mm. This will likely work fine for 90 percent of the normal set ups seen on IDF equipped cars.

I don't know what other mods you have made to your 2.0L, but a stumble on tipping the accelerator is usually caused by too-small bleed a back bleed valve. This is the valve in the bottom of the float bowl that determines how much of extra the gas pumped into the venturi by the accelerator pump actually gets intot he venturi, and how much is routed right back to float bowl (there is only one per carb) If you have 80's (the usual), swap them out wih 50's or 30's for an otherwise stock motor, and 20's or 00's for one with cams, a header, big valves, etc.

I always recommend an electric fuel pump with dual IDFs (although I don't think that is your problem). They are sensitive to fuel pressure, and an electric pump with regulated fuel pressure eliminates a lot of siisues that are hard to diagnose and a PITA to chase down. Hook it up with a fuel pressure regulator (it doesn't have to be expensive, just one of the universal, in-line models), and set it for 2.5 lbs on an otherwise stock motor, and 3-3.5 lbs on a heavily modified one.

You should also check the pump jet size. The usual 40s or 45's should be swapped out for 50's or 55's on modified engines. Contarty to popular brlief, larger pump jets do not increase/decrease the amount of extra fuel delivered by the accelerator pump, just the time it takes for the fuel to be delivered into the venturi. A larger jet delivers it faster, a smaller one, slower. The deeper your engine breathes, the faster it will normally want to get that extra fuel.

[mdrburchette]

My 2 cents: I'm running two Spiders with 40 IDFs and mechanical fuel pumps. Both also have a regulator since the mechanical fuel pump pumps 5 to 7 lbs of pressure.

[sptcoupe]

If your motor is not highly modified and you aren't regularly running it 7000 + rpms, then mechanical fuel pumps normally work fine. As Denise points out, the important point is that you have to regulate the fuel pressure to ensure consistent performance. I don't think you have a fuel pump problem.

[FMO]

Hi dear Spider people

I am running a electrical pump to my 44 IDF, and the engine is running like a champ above 7200 rpm without any problems.
But I dont know how much pressure it deliver, I use the same pump as I did when I got the car with 34 DMSA.

Regards
FMO

ps: The winter is coming to Norway, and I have to put my spider in garage for the next 5-6 months

[thechadzone]

Thanks to each of you for your thoughts on this. I'll have to check my invoices from Pierce Manifolds to see what I've got in there for jets & guts, and I think I'll also have a look-see at the floats. I might as well add a pressure regulator while I'm at it...

The only mods I've got on the 2 liter besides the IDFs are the 1.8 head upgrade and exhaust flowing freely to the Monza twin tip. As long as I keep it in a straight line and/or step on it, it really takes off! I was actually able to whoop-up on a BMW 320 in a friendly road race around the lake a couple weeks ago. It turned out that we were both headed to the same marina, and we got a chance to show off our respective cars. His looked better than mine, but I DID kick his ass...

[mdrburchette]

but I DID kick his ass...

And that's all that really matters, right?

[ga.spyder]

Well said,Denise.Looking good is an option...ass whooping is required!!

[Tappy]

... It turned out that we were both headed to the same marina, and we got a chance to show off our respective cars. His looked better than mine, but I DID kick his ass...

Ok you won from the start having a fiat spider , its a car for car lovers A BMW is just for mainstraim, instand "cool" guys

[MNspiderman]

Here I have some loose change I can give you too. Being I have a set of 44IDF's on my car. Even after rebuilding the carbs, I noticed fuel trickeling into one of the throttle bodies. I have an electric fuel pump from Kragen. Which is now Orieleys Auto parts. Its just one of those small round things which works great. But it has like 4-6psi's. way too much. So I purchase a chrome plated fuel pressure regulator from the same store. Kinda cool if you ask me. you simply turn a big dial and you can go all the way down to 1psi until you see your fuel stop trickeling into your throttle body. BUT... This is just my theory now, no real evidence so tell me if i am wrong. Just a theory..... I do not have a waffle intake I have a ported out aftermarket intake and when I look at my carbs from the front with the hood off. the carbs are not square with the engine they lean about 4 degrees outwards. Its hard to notice in the photo but they do lean outwards. so instead of being 90 degrees they are about 94 degrees. which is a lot in my book of theorys so I lowered the float level about an 1/8 of an inch to compensate for the angle that the carbs are leaning outwards. Now, I have no problems of any kind. These carbs aren't specifically made for a fiat, they are made for all cars and i am assuming that they are to be square and flat. If not, you need to compensate here and there for your own best results. Thats my two cents.