924Board.org

[dogleg]

Hi

i have an 81 924.starting fine,passing all emissions tests but not running perfect when driving.small miss fire under small throttle load.
so far i have fitted new injectors,plugs,plug leads,rotar arm,distributor cap,electric coil,fuel filter,air filter and oil changed.
all my earths are good checked and replaced any bad vac/intake rubber hoses.
compression tested 200 psi on all cyclinders.

bought a set of the cis fuel pressure gauges.i have connected it to the top of the metering head unit and am getting a reading of 72 psi operating pressure.
with the fittings supplied and the instructions cant see a way to connect them to the WUR to get warm up pressures.could someone please post a pic of these gauges as they should be connected to read all pressures.

ive tried a few searches here and on you tube for pics to no avail!
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1981 924

[Fasteddie313]

You connect one side of the gauge set to the fuel distributor wur line port, the side without the valve..
Then you connect the valve side to the WUR line you just took off the distributor, your just putting the gauge setup in the middle of the WUR line really..

Distributor-tester (gauge side)-tester (valve side)-WUR line..

Withe the valve open it just completes the WUR line and you see control pressure, close the valve and it shuts off the WUR and you see system pressure, shut the pumps down with the valve open or closed and you see residual pressure..

Remember the valve side goes toward the WUR..
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80 Turbo - Slightly Modified

[maybeoneday]

yeah what he said.

basically its the same place as where u have it just open the valve to get control pressure. I need to chase up the cold start and warm up equip on my car and I can take some pics for u. I will post some pics in the morning if no one else has yet
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1977 924 NA Auto

[maybeoneday]

Hope this helps, also a good way to check if I am hooking it up in the best way (or even the right way). But from what I gather its the same for system and control pressure just that the valve is open for control and closed for system. On my car right now they both read the same, this is not good and from what I gather about CIS this indicates a blockage in the WUR or its lines (But I still have much to learn about CIS).
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1977 924 NA Auto

[Fasteddie313]

Looks right, blow through your tester with the valve open to make sure your blockage isn't in the tester, just to be sure..

Sweet green you have there..
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80 Turbo - Slightly Modified

[Fasteddie313]

from the Porsche 924 Technical Specifications Booklet

1976-1984 Porsche 924 NA Fuel System Specifications
(all markets except as noted below)
Electric fuel pump Delivery rate: Min. 750 cm3/30 s
System pressure test value: 4.5...5.2 bar
Adjust, value: 4.7...4.9 bar
Control pressure cold (approx. 20° C): 1.3...1.7 bar
Control pressure warm: 3.4...3.8 bar
Leak test
Min. pressure after 10 min.: 1.7 bar
Min. pressure after 20 min.: 1.5 bar
Opening pressure of inject valves: 2.5...3.6 bar

1980-1982 US, Canada, Japan 924 NA
All the same as above EXCEPT for:
Control pressure cold (approx. 20° C): 1.7...2.1 bar

Credit to ideola..

Oops wrong CIS thread... But I'll leave it here anyway..
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80 Turbo - Slightly Modified

[dogleg]

thanks for the replies

just had another go at this and i have now connected to the larger bango bolt (UPPER)position at the WUR is this the correct position or should i be on the lower smaller bolt?dont have the fitting in the set i got to connect to that..im getting 5 bar (72 psi) straight away with or without the electrical plug connected.when i shut the tap the gauge needle alters very slightly but basically reads the same.
currently the car is starting up easy from cold but running badly untill it warms up a bit.then its drivable but has a misfire in it.misfire is exactly like a bad plug lead but as said before ive replaced everything electrical except the distributor its self.dont think the distributor could give the misfire but im am tempted to swap one into it just to eliminate it.

any pics of the cis gauges connected to a 924 would be great?
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1981 924

[dogleg]

found a few you tube clips on line and i think i do have the gauge connected correctly.i seem to have 5 bar system pressure and control pressure.is it possible the car would run fairly normally when hot with 5 bar instead of 3.5 bar?
im assuming my wur is my problem if im not getting any control pressure what so ever?

going to leave the car sit and go cold overnight to recheck the cold start pressure again in the morning,just to be sure the figures im getting are correct.
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1981 924

[ideola]

How to connect & operate the Hoffman CIS Test Kit
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erstwhile owner of just about every 924 variant ever made

[dogleg]

ideola and others thanks for all the assistance.

started the car from stone cold this morning (14 degrees c air temp)and im getting full system pressure 5 bar at the wur.think this means either my wur is blocked or faulty or one of the fuel lines are blocked.

im surprised the car will run from cold on 5.0 bar when it should be 1.5 bar.is this possible?
going to strip out the wur and maybe try a spare one in it tonight to see what pressures i get then.
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1981 924

[dogleg]

fitted a replacement wur and what a difference.cold start control pressure 1 bar (might be a tad low) going to 3 bar. system pressure as before 5 bar.
engine sounds nice.test drive tomorrow but all looks good.

thanks again for all the info.
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1981 924

[maybeoneday]

looks like we are struggling with the same beast at opposite ends of the globe. hopefully mine will be finished by summer and yours before the end of it.
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1977 924 NA Auto

[dogleg]

does seem ilke it! hopefully yours will be a straight forward fix.good luck with it.
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1981 924

[dogleg]

used into work this morning 45 miles running sweet.
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1981 924