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Gene · Posted: Sat Oct 29, 2011 8:57 am Post subject: 924 won't rev up

I replaced the fuel filter, system and control pressure are normal now but she won't rev up, runs ok at low speeds only, seems to be getting ok spark from cheap inline spark tester when I try to rev it up. Help

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

First, what year 924 do you have?

I ask because the early models had a distributor with points.

Second, did you put the filter on in the correct orientation? Arrow always points to the tank/pump.

Either way, with the ignition there should be an advance mechanism inside the distributor that needs to be checked that it is working properly.

Weak spark could be fouled plugs, bad wires, worn cap/rotor, bad/weak coil, poor electrical (power and ground) connections, weak battery/alternator.

If it isn't spark, then check the cam timing to ensure it is correct as some get them wrong from time to time.

If all of that seems to be fine then you should check that the air flap in the fuel distributor is moving properly. Perhaps the internals are gummed up as well.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Gene · Posted: Sun Oct 30, 2011 1:44 am Post subject: 79 924 won't rev up

Car is a '79, ele ign. Was running fine till I tried to climb a high mountain in July, it would only not bog down if I gave it half throdle, full gas petal and it would bog down. After comming out of mountains it ran fine but took a couple of days to completely come out of it. Ran good for 4 months till lately.Haven't done any work on car lately before last problem. Had already checked the coil resistance, sucked on advance to dis. and I hear the diaphram moving back and forth and have suction at hose. Cant be cam timing cause its an intermint problem, run fine for 4 months till the latest incident. Already replaced the plug wires,I had already checked the flap in the fuel dis. and the plunger had smooth action. Checked all vacume hoses and they are correct. I put the filter in the same way it came out and from photo in Haynes manual looks the same. I put a cheap in line spark tester on and it seems to be sparking when I try to rev it up but hard to tell if its getting correct spark with tester. Just replaced the control pressure regulator and have correct control pressure readings now but it still bogs down. Car runs fine up to about 3 grand or so. Don't know what else to check. Might want to add I did put in about a gal of very old gas in a full tank of fresh just before the last incidient so maybe this brough back the old problem, did check and back flushed the new fuel filter and drained out that gas but problem still presists.

Ozzie · Posted: Sun Oct 30, 2011 7:02 pm Post subject:

Check fuel flow.
Pressures may be OK but volume may be not enough at high revs and engine goes lean and bogs down.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Gene · Posted: Mon Oct 31, 2011 2:44 am Post subject:

Car had perfect fuel pressure the other night but next morning would barely run and about 50 LBS system pressure and control pressure, fuel pump sounded noisy so I put in another pump now it won't even start. Strange cause when I losened the pump fittings when replacing pump I had air escapeing along with fuel, don't know why the air was coming out.I bled the air out this time at the fuel filter. Also starting to wonder if the new rebuilt WUR has gone bad with these pressure readings. Oh the joys of fuel injection ! Give me a carb any day LOL !

the_mad_electrician · Joined: 16 Nov 2009 Posts: 1073 Location: Central Georgia

I'm not a fan of the K-jetronic system myself. Any fuel system that requires the air to move a plate in order to function seems counter productive to me. That being said if it would not have cost tripple what I paid for the car I would have switched to EFI instead of carbs. One advantage to carbs is there are a lot fewer parts to fail.
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81 924 N/A

2004 Ranger "Edge"

2005 Mazda 6

Gene · Posted: Mon Oct 31, 2011 3:04 am Post subject: '79 924 fuel pressures issues

What did that weber cost you and who sells them ?

Ozzie · Posted: Mon Oct 31, 2011 8:31 am Post subject:

pressure does not equal volume.

an example- turn on the garden hose so it is running out very slowly.
put your thumb over the end of the hose and the pressure will slowly build up and start spraying.

do this again with the hose turn on full.
Is there a difference?
the pressure is the same. flow rate is different.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

the_mad_electrician · Joined: 16 Nov 2009 Posts: 1073 Location: Central Georgia

Do a google search you'll find plenty of place with them, new expect to spend at least $1000 because you'll have to get a new fuel pump. I peiced mine together from used stuff the only I have that is new is the fuel pump and I used a Carter pump Summit had it was around $70. I have abouit $600 total in my setup
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81 924 N/A

2004 Ranger "Edge"

2005 Mazda 6

Gene · Posted: Tue Nov 01, 2011 2:41 am Post subject: '79 924 fuel pressures issues

Ozzie, yes I agree with you about the pressure. I've been planning on doing the volume test but so busy putting a VW engine together haven't had the time. Both legal vehicles went bad on me within a day if each other, bottom end of my Harley went out the month before and both Rabbit convertables in storage won't start, CIS problems with them also cause they sat for 2 years, learned my lessen there, no matter how busy I am " Start Them More Often" !!

Ozzie · Posted: Tue Nov 01, 2011 6:26 am Post subject:

No worries Gene.
air in the lines at the fuel pump?
these are self purging and will get rid of the air fairly quick.

if the lines are bad the pump will suck air.
If yours has dual pumps then the intank pump could be faulty.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Gene · Posted: Wed Nov 02, 2011 2:00 am Post subject:

Yes thats what I thought that it would get rid of the air, seemed strange I was getting all that air on the pressure side of the pump when I undid the fittings so yes will have to check the inlet hose. Had to replace the Rabbit convertable inlet the other day cause I had clamped shut the line when removing the pump and damaged it. Lucky here as all my (4) VW, Porsche injection vehicles only have one pump. Should have the VW pickup engine back together today so I can get back to the 924.

Gene · Posted: Mon Nov 14, 2011 5:12 am Post subject: '79 924 fuel pressures issues

Well did the fuel volume test on the car and it passed so thats not the problem. Fighting with the company that sold me the rebuilt WUR as I had good control pressure at first but now back to contnrol pressure the same as system presurre. And when the control prossure was ok it still wouldn't rev up so thats another issue. Looks like I might have to spend the money and get another fuel dist.

Ozzie · Posted: Mon Nov 14, 2011 6:38 am Post subject:

If the spray pattern and fuel flow increases from the injectors when the plate is lifted the fuel dissy is working fine.

Check spark, leads , valve and ign timing.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance