jmartins

Hi!

I'm using one CIS pressure kit to check my car's system and control pressures.

I'm flowing the instruction manual and several posts and videos.

I left the car rest for some days before testing and got the following results @ 25C room temperature:

Control pressure = 2.4 BAR / ~35PSI
System Pressure = oscillating between 4.8 and 5.4 BAR / ~65 and ~75 PSI

Apparently, all pressures are Okay, but after this test, I'd never got the same results letting the car rest for some hours. Is it normal?

Thank you!

JL

jmartins

OOOOOOOOOPSSSSS!

It's a 78 EURO!

JL

Jadz928

Could you explain further?

checkmate1996

Ok - Cold control pressure seems a bit high at 2.4bar for only 25c.
System pressure should NOT be oscillating back and forth. That sounds to me like you have a leak somewhere. System pressure should be rock steady.
What's your leak down pressure/time?
You don't need for the car to 'rest'. You are trying to get it the engine to cold temperatures. Also what is your warm pressures?

docmirror

Remove the electrical plug on the WUR. Take the pressure reading. Then reconnect it and run the car(if you have the right thru adapter hoses) while taking the next reading. The WUR will gradually change the pressure as the car warms up.

Strangely, higher pressure means lower fuel delivered, or higher(leaner) air/fuel ratio. It's the cold start, or choke program of the mechanical injection.

Chances are your WUR is simply worn, and old, and getting out of spec. They can be rebuilt if you locate the link to Birdman's Ferrari page, where he shows how to disassemble clean and test the WUR. If you can get a new gasket for it at the same time, that's better.

jpitman2

First question is, do you have a problem with cold starting, hot starting, driveability, or power, or MPG? if No to all of these, what are you worried about? Watson gives cold control as 17psi@50F, 30@75F, 44@100F. 25C is 87F, so your 35psi is not unreasonable IMHO. As above, system should not fluctuate - mine was rock steady last I looked, at 75psi.
Try to avoid the 'if it aint broken fix it till it is' game.

jp 83 Euro S AT 55k

jmartins

Thank you guys for the reply!

I'll rebuild my FD and WUR... I hate this fuel injection system!

Next problem, and I'll convert it into electronic fuel injection!

JL

jmartins

Just rebuilt the Fuel Distributor with the popular kit found at Ebay.

Residual pressure according to Service Manual ~ 1.8 BAR

Now I have the both system and control pressures at 75 PSI.

Is it time to rebuild the WUR?


Thanks a lot!

Ad0911

Rebuild the fuel distributor in 1 day! Wow, I have to get me one of those sets! I think after 35 years the car deserves that. Could you post a link?

jmartins

Here is the link.

It takes about 1 hour to rebuild. Pay attention to not mix the internal springs and base. Number them and place them at same place when reassemble.

http://www.ebay.com/itm/171282471642...84.m1497.l2649

jmartins

After one month fighting with FD, WUR and everything else, I finally found the problem:

1 - Fuel Distributor out of specifications... ended buying a Bosch refurbished one to resume the long history;

2 - WUR clogged, disassembled and left 2 weeks at jar filled of fuel injector cleaner. Many ultrasonic bath sessions and O-ring changed. Now it´s working fine;

3 - Some fuel lines from FD to injectors clogged;

4 - Discovered that the injectors I bought as new and original was "OE replacements" and almost all of them was clogged. Bought new Bosch Original set at Bosch re-seller.

5 - Fuel return line clogged - here a big problem - not changed yet, but will do soon.

Now I have the following numbers:

Room temperature: 21.8C 72F
Cold Control Pressure: 31PSI - 2.2BAR
System Pressure (little low): 60PSI - 4.3BAR
Rest Pressure: Normal
Warm Control Pressure: Not tested yet

Ad0911

When you select year/make/model for this item the reults sys the part is not compatible ith the Porsche 928 4.5L. It is ompatible to the Mercedes Benz 450SLC. What makes this set of gaskets incompatible?

jmartins

My FD is alloy adjustable and part number is 0438100112 very similar to 0438100111 and 0438100088 (the one used by Mercedes Benz 450SL). I think they differs only on outlet fuel pressure.

Porsche used both cast iron and alloy (I think due to availability at assembly time) and they are very different. The cast iron ones are not adjustable and uses stainless steel gasket instead of rubber.

I would suggest you to ask the seller by part number.