Abarth X1/9 Fuel pump issues

TonyK

True Classic
The stock Abarth Fiat 500 platform uses a fuel pump that is located in the fuel tank. Gone are the days of having a fuel rail that has a pressure regulator connected to the rail and makes reference to the plenum pressure or vacuum. The ECU calculates the injector open duration based on MAP values. In simple terms, if the plenum is at 26 PSI boost and the fuel pressure is 36 psi then the Delta value is only 10 PSI. To get the required amount of fuel the injector must stay open longer. When the engine is operating under vacuum -10 PSI the Delta value is now 46 PSI and the duration of when the injector is open must be shorter. In the build that I have done I used a Bosch type external fuel pump. The problems with these pumps is that the rotor in the pump appears to be made of soft material and the pump wears out the slots in the rotor and fuel flow is starved. The issue I have now is trying to find a good pump. What I am saying is when I went to Car Quest they offered a Bosch pump for $300 when I asked is it a Bosch Pump or a Chinese knock off that will fail, they could not answer the question. Knock off pumps seem to last only about 3000 miles and present sudden drop in power followed by a surge and it repeats it's self. Like riding a bucking Bronco. The Abarth engine requires 59 PSI at the rail. The current pump in the car has an output of 72 PSI and a fuel regulator is used and set to 59 PSI. If anyone knows of a good quality pump please let me know. The knock off Bosch just isn't cutting it.

I have attached a few pictures of the fuel pump location on the Abarth X1/9.

Comments most welcome.

TonyK.

Grimsby Ontario Canada.
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kmead

Glutton for punishment
Any chance you could use the OE Fiat in tank pump? I have seen where people install a modified version of an in tank pump in older fuel tanks. I recall Ditchdigger doing so for his 850 FI conversion, there are others I have seen.

Or is the OE pump too large in diameter to fit into the relatively narrow X tank?
 

TonyK

True Classic
Thanks Jim, there is one that would be direct replacement. However $158 USD converts to $204 CND, plus $50 shipping and 13% sales tax is $287 CND. On the bright side Holley is a good product and I can only hope it isn't a knock off made in China.

Thanks again.

TonyK.

Grimsby Ontario Canada.
 

TonyK

True Classic
New fuel pump installed and no start. I have push button start in this car so a broom stick and with the rear engine cover up I watched to see if the fuel pressure gauge lit up or not. It did not. No fuel pressure. Taking a look at the pump I must have rotated it before I connected the + and - terminals and yes the polarity was reversed. A 20 minute job to reverse the feed wires to the pump and I now had fuel pressure and the car started. Performance was good and the pump is a lot more quiet than the pump that I had removed. With the modern Fiat 500 platform first check is to put a code reader on the ECU and see what codes are being posted. Currently, fuel tank level not changing, Evap emissions small leak. Neither are in the build. Both have nothing to do with the engine dropping off under load. Hence fuel problems must be supply that are exaggerated by the fact that I am running an Open Flash Tablet tune that takes the boost from 18 PSI stock to 26 PSI on the 177 HP tune. I ran the car on a trip into town for dinner with the greatest of reluctance, the return home requires a steep hill climb of 14% grade and 400 feet of elevation. No issues on the climb, but I held the boost to 20 PSI until I made it to the top of the hill. I pulled 26 PSI a few times on level ground without the engine dropping off. Jim I will need to order that Holly pump and bite the bullet on the cost. Thanks for the information.


TonyK.

Grimsby Ontario Canada.
 

TonyK

True Classic
Any chance you could use the OE Fiat in tank pump? I have seen where people install a modified version of an in tank pump in older fuel tanks. I recall Ditchdigger doing so for his 850 FI conversion, there are others I have seen.

Or is the OE pump too large in diameter to fit into the relatively narrow X tank?
It is possible as the pump is small. As always a lot of modification would need to be done. I sold one of the pumps already the other I have in a fuel cell for the engine test body to run the engine when I am preparing it for a swap. The external appeared to be the easiest solution with the swap. As you know there are a lot of changes that need to be done for all of this to work. For now with new pump installed all is good.

TonyK.

Grimsby Ontario Canada.
 

JimD

Waiting for Godot...
Moderator
Thanks Jim, there is one that would be direct replacement. However $158 USD converts to $204 CND, plus $50 shipping and 13% sales tax is $287 CND. On the bright side Holley is a good product and I can only hope it isn't a knock off made in China.

Thanks again.

TonyK.

Grimsby Ontario Canada.
I am surprised Holley doesn't have a Canadian dealer. Fi d a local performance shop and see if they carry Holley stuff. Good luck.
 

TonyK

True Classic
Any chance you could use the OE Fiat in tank pump? I have seen where people install a modified version of an in tank pump in older fuel tanks. I recall Ditchdigger doing so for his 850 FI conversion, there are others I have seen.

Or is the OE pump too large in diameter to fit into the relatively narrow X tank?
I looked up at Rock Auto what the in tank pump sells for and it is $320 USD plus shipping and Tax. Wow!

TonyK.

Grimsby Ontario Canada
 

kmead

Glutton for punishment
I looked up at Rock Auto what the in tank pump sells for and it is $320 USD plus shipping and Tax. Wow!

TonyK.

Grimsby Ontario Canada
Diggity. I figured you had one on the shelf from the forlorn carcass of the Abarth. Yeah, new car parts are not cheap.
 
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