missile2511

Hey guys, I'm back. Does my 1983 M28/11 with CIS injection need a low pressure fuel pump in the tank to feed the high pressure pump. This car was AFC injection and has the wrong high pressure pump and no low pressure feed pump. Will I get away without the low pressure feed pump in the tank and if I need one, where can I find the hose hook up to go from the low pressure feed pump to the high pressure pump?

ROG100

It will depend on which market your car was built for. If it was a European car it will not have an in tank pump. You need just the filter in the tank - check the hose from the external pump that runs into the tank. If there are wires going into the boss screwed into the tank you may have an in tank pump.

missile2511

The engine is euro, but the car is not. The car has no pump in the tank and is a 1984 with AFC injection originally. I just changed engines and am now in the process of finalizing the CIS system in an AFC car.

ROG100

Euro M28/11 with stock CIS will be fine with an external pump and an internal filter screen.

missile2511

Roger,
Do you have the external fuel pump and filter for this car?

docmirror

You will need a CIS fuel pump now. I think the orig AFC fuel pump is lower pressure. Get the PN off the orig pump so you can match the fittings up, then get the CIS pressure pump with the right fittings. Roger can supply all of them.

CIS pressures are important. Suggest you get the CIS pressure test kit at the same time. will save you a lot of futzing when the car is running by getting the pressures set correctly. Bad pressures on the CIS have led many people astray. Also make sure you have a long 3mm Allen T wrench or equiv to adjust the CIS A/F metering.

R.Pires

Hi,

Roger will confirm this, but my 83 Euro S with an M28/11 and CIS has originnaly

In tank filter 928 201 081 04
Fuel pump 911 608 102 02
External fuel filter 928 110 147 05

Hope this helps

Regards

jpitman2

My car, as below, NEVER had an in-tank pump- C16, UK delivery model. When I got it in Saudi, it had an S4 external pump (based on its Bosch no), and never missed a beat (due to pump) in temps to 120F. Delivered 75psi and spec volume rate for 7 Years in my hands, before I replaced the pump as a precaution, while I was doing other tank and pipe work.
Therefore I believe that the original L-jet pump should work, unless you are in a hot and high environment and asking for high outputs. I doubt anywhere in Maine qualifies as HOT for this circumstance. Only test is to measure the pressure at the WUR (tap closed), and delivery - 1360cc/30 secs. If it can do these, you should not suffer problems caused by the pump's characteristics.
AFAIK the pressure difference between L and LH systems is quite low, so either type pump should work. I have been told the filter for CIS is NOT the same as for L, LH, due to the higher pressure used in CIS, so you may be well advised to specify model when ordering a filter.
jp 83 Euro S AT 55k

docmirror

JP, the OP had/has a car with AFC originally. Not L or LH. Unless you are referring to AFC as L-Jetronic?

I don't know for sure, but I think the pressures for AFC are quite a bit lower than CIS. Also, no one has any idea what fuel pump is currently in a 30YO car. It may have been changed in the past.

Anyway, if it is the AFC pump, it may put out enough pressure for CIS, but it prolly won't.

FBIII

On the Ljet wouldn't the fuel pressure be determined principally by the fuel pressure regulator and to a lesser extent by the fuel pressure relief valve. On a cis car the maximum fuel pressure would be regulated by the relief valve. I wonder if there is a different part number for cis relief valve vs the later electronic systems relief valve.

jpitman2

Docmirror, you are trying to confuse me here. What do you mean by AFC ? AFAIK, there were only 3 injections systems used on 928s - CIS (aka K-jet), L and LH-jet. Is AFC another name (being Air Flow Controlled ?) for CIS/K-jet ? My info shows L-jet ran pressures around 40psi, and LH maybe a little higher (45?), but CIS runs 65-75 system pressure.
For FBIII, all the systems are controlled by a pressure regulator - in CIS its inside the fuel distributor; in L and LH its done by external regulators that are modulated by engine vacuum, to reduce pressure at high vacuum. The only other valve I know of is the check valve at the pump, whose only job is to STOP pressure dropping as the engine cools.
jp 83 Euro S AT 55k

docmirror

I'm not trying to confuse anyone here. I'm calling it was Porsche calls it in section 24 of the WSM, starting on page 24-01 "AFC equipment table" etc, and what the OP put in his post #1...

Since the A in AFC = air, and the L in L-jetronic equal Luft, and since air = luft I guess it's the same thing. As I pointed out in post 6, and you have also pointed out in post 11, the pressure is different. However, in post 8 you stated that your L-jet pump was suitable for a CIS application due to it providing 75PSI of pressure.

I don't know which PN you had, or if it was in fact a AFC or L-jet pump, or if it was modified or if it was a standard pump that happened to put out 75PSI.

What I DO know, is that AFC pressures are 36.75PSI(2.5bar), and CIS pump pressures should be about 90PSI, thus my posting. If YOU guarantee CIS (K-jet) will work with an AFC pump, or an L-jet pump I will defer to you. I would not do it, but that's why there's an internet.

YMMV, things are closer than they appear, contents may have settled, don't try this at home, professional driver on a closed course, and mind the gap.

jpitman2

I seem to recall seeing CIS/K-jet called AFC somewhere, thats what confused me. If you think about it, ALL the injections systems above are AIR FLOW CONTROLLED, as they respond to air flow movement. They just try to assess the air flow, convert it to a mass value, and apply the appropriate fuel supply.
I have a Bosch file of their part numbers for equipment supplied to various makes of car, and the pump that was on my car was listed for an S4 (up to 88) 0 580 464 045.
The proper Bosch no for CIS is listed as 0 580 254 053.
Do a search for "boschefi_vehicleapplications.pdf" on the web.
As I said before, the 0 580 464 045 pump ran fine in my car for nearly two years in Saudi in my hands in temps up to 120F, and another ~ 4 years back home in temps from 50 - 100F. When I replaced it with the proper pump for CIS, the behaviour of the engine did NOT change one wit.
Obviously I cant guarantee anything anywhere, BUT if the OP can get 65-75 psi at the WUR with valve closed, AND the specified delivery rate (1360cc/30 secs) on the current pump....where is the issue ?
Somebody here once said that pumps produce FLOW, they dont produce PRESSURE, its the downstream equipment that controls pressure.
jp 83 Euro S AT 55k

docmirror

Well since you seem to recall it somewhere -- that settles it.

As for what pumps do, that depends on the pump. The turbine pump(non-displacement) for the fuel and Oxygen on a liquid rocket provide/produce gobs of PRESSURE at zero flow rate until the match is lit, and the fuel/LOX valves are opened, when they then provide/produce gobs of FLOW as the pressure goes down dramatically. So, when 'somebody' says something about pumps, I guess I would discount that as once again - the reason there is an internet.

ROG100

No worries as correct parts have been supplied