924Board.org

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

ok...i've had enough....my car runs like crap !

the 83 euro 924 NA:

today i went for a drive for a few hours...car started easy and i drove it around for a couple of hours withouth passing 3500 RPM....it ran ok.

However it still had that WOT or close to WOT problem:

when i give it some stick it feels like only 3 pistons are running...and over 4500 RPM it feels like the fuel cuts out and runs like only 2-3 pistons are firing.
If i slowly press the gas pedal it reaches 5000 RPM but then i need to WOT it and it just cuts out.

now...back to my story...

i met a friend with a Corrado G60 and we decided to go to the track for a spin...when i was near the track the car started to run even poorer...i could not press more than 2 cm on the gas pedal...because the engine woud die. Then at a stoplight the engine died on me

0and i had to push the car on the side of the road....it eventualy started...but very hard.

NOTE: when i was trying to start the car i pulled out one fuel injector jumpered the fuel pump and lifted the A/F plate...NOTHING came out.

After it started i took it home...but it ran in 2 pistons and sometimes in 3 pistons......at idle the car runs smooth...but when i give it stick it just dies.

My feeling is that there is not enough fuel going into the combustion chamber..

a couple of weeks ago i replaced with new ones:

-fuel filter
-fuel injectors
-air filter

Yestorday i mounted a free flow exhaust...60mm straight pipe from the midle of the car to the 944 final piece.(only one sound absorber...the 944 final piece.)

again...my feeling is that there is not enough fuel...and i think that when the engine is hot the WUR bleeds the pressure back into the tank.

what do i need to do tomorow morning ? unmount the WUR and clean it with compressed air ?
_________________
Supercharger and EFI kits
https://www.the924.com

Ozzie · Posted: Mon Aug 21, 2006 7:19 am Post subject:

The WUR will make it run rich if it is draining fuel. It would allow lower pressure on the air sensor plate and allow it to lift higher increasing the fuel to the injectors.
I'd suspect a faulty fuel pump/s?
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

hmm....may be....

i've tested the fuel pump one week ago and got over 8 bar of pressure.

here is a sketch of the way i tested the fuel pump

I will try and replace fuel pump tomorow...if i can find a donor just for a test.

The last fuel pump that i had simply died...the car did not start anymore...this one could be shot also...i will have to check it with a amp meter to see if it runs smoothly.
_________________
Supercharger and EFI kits
https://www.the924.com

Lizard · Posted: Mon Aug 21, 2006 8:23 am Post subject:

just making sure but you are sure that you are not just really low on fuel correct,

a fuel pump from a CIS VW, Merc, or Volvo should work for testing purposes as well,

it also could be spark related, as in the advance within the distributor is cooked, though you would still get fuel out of the injectors if that was the case
_________________
3 928s,

Ozzie · Posted: Mon Aug 21, 2006 11:41 am Post subject:

Also check the intank pump is working as this is supposed to 'prime' the main pump.
I think they were fitted from '79 on.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

the intank pump makes no difference if it works or not..i bought the car with the intank pump stuck and the car drive fine...sprinted nicely and all that...one day i decided to take a look and i realised that it was stuck...i made it work and there was no difference...still works now.

I'm not low on fuel...i put 5-10 liters every day in the car...i'm going to check today this too.

Well...i'm off to the garage to see whats up with the porky.
_________________
Supercharger and EFI kits
https://www.the924.com

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

ok...i removed the WUR....and like the last time i removed it and checked it....it seems fine...i opend it...and trough one of the holes i could easly blow air with my mouth....and trough the other one...the one with the "#" (filter) i could not...i mean...its hard to.

What i noticed this time is that i have a late WUR that also has a vacum port. However this port is not connected to anything....its just left open.
Anyway...the car ran fine with this vacum port open before so this is not a subject of weather this is causing the car to run like crap or not.

And i dont think that the WUR can affect the fuel sistem that much...the holes are too small for it to do any major pressure modification int the CIS.

next to check is the fuel pump...i need to see if it works smoothly or not.
_________________
Supercharger and EFI kits
https://www.the924.com

924RACR · Posted: Mon Aug 21, 2006 9:52 pm Post subject:

Did you adjust your mixture after installing your free-flow exhaust? It will likely need a slightly richer mixture, if it is indeed freer-flowing. Mine does.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Qky · Joined: 29 May 2006 Posts: 44 Location: Serbija

When already talking about fuel pumps!
I have one question!
I whas under the car, and so something!
& do't have idea, wtf is this!?
I have't take a picture, but ...!
Is this 2 fuel pump?

Lizard · Posted: Tue Aug 22, 2006 1:05 am Post subject:

yes that picture shows the two pumps,
_________________
3 928s,

Qky · Joined: 29 May 2006 Posts: 44 Location: Serbija

Zule · Posted: Tue Aug 22, 2006 3:23 am Post subject:

Yes it is normal on later models. My '78 for example has got only one pump, the one on the lower picture which is mounted outside of the fuel tank.
_________________
1978 Porsche 924, Euro, NA

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

yes its normal to have 2 pumps....for a porsche

i've put everything back togheder...car starts easy and runs acceptable...but when i give it stick it just trembles and looses power(specialy when warm). Havent got the chance to replace the high pressure fuel pump today but will do it tomorow. It feels like its not getting enought fuel....maby i need a way more rich setting since i have a high flow air filter now(K&N) and a free flow exhaust (60mm pipe i will post pictures tomorow)

Anyway after i try the fuel pump if the car still runs lilke this i will book a CIS debug session at a Bosch Service.
_________________
Supercharger and EFI kits
https://www.the924.com

Qky · Joined: 29 May 2006 Posts: 44 Location: Serbija

How to now what pump is "low presure pump"?
& what presure is it deliver?

Lizard · Posted: Tue Aug 22, 2006 9:26 am Post subject:

the pump that is in the tank (has the arrows in the picture) is the low pressure pump and runs at 35 PSI, it is only needed for really hot weather though.
_________________
3 928s,