Jim bailey - 928 International

CIS runs at 5.2 Bar-5.8 Bar .... about 80 lbs of pressure

IcemanG17

Damm...thats high...but don't most of the CIS cars have 2 pumps to provide the additional pressure....

My 1988 only has 1 pump.....but I think my 89 has an in tank too...

Lizard928

Brian,
Most CIS cars, only have 1 fuel pump, and last I looked those pumps can provide over 92 PSI.

Jim bailey - 928 International

Correct they blow of the excess at the fuel distributor return it to the fuel tank. You can shim the needle to have higher system pressure like Mark did when he raced a modified 5 liter Euro 16 V with high flow heads to get it up over 400 HP at 7,500 RPM or so .

SharkSkin

Mine has two, most people don't think to look in the wheelwell for the second one.

Lizard928

I was speaking broadly

most cars with CIS only have 1 pump, 924, VWs, mercedies, audis, etc.

Angel84-928

Soooo, will a higher pressure (different year) fuel pump work on my '84?
Don't need one now but when it dies and I use my friend "Search" on Rennlist, it would be nice to have a straight forward answer.
Pros - Cons of using a different fuel pump?

Flint

I'd like to know this too. The pump on my '84 Euro died and since the Euros naturally tend to run lean, I wonder if a higher pressure fuel pump would help (possibly with a rising-rate FPR).

IcemanG17

7500rpm.....DAMM thats high for a 928 engine...... what else did he do to that motor to allow such high RPM's?

Jim bailey - 928 International

944 valves springs , carrillo rods , dry sump lubrication , Taylor drilled cranks for a start.

Lizard928

Angel, and flint, replacing the fuel pump with a unit that can produce more PSI will not help your cars at all. Fuel pressure is simply controlled by the fuel pressure regulator in the engine bay.

If you use a higher PSI rated pump, it will do the job without any issues, you may just not be using it to its full capacity.

RicerSchnitzzle

I replaced my Euro S pump with a less expensive Walbro about 3 years ago. Never an issue.

Jfrahm

I bought a Bosch fuel pump for my truck and it had a bad check valve causing excessive cranking. Replaced it with a Chinese knock-off that was perfect. Just one data point but there it is.

-Joel.

SharkSkin

Is it possible that a pump that puts out too much flow/pressure could overcome the bypass capability of the regulators on an LH system, resulting in too-high pressure?

Lizard928

Dave,

The simple answer to your question is NO.

It would take 2 or more Bosch 044 fuel pumps to do this, and thus far Noone has done that.