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'81 924 Turbo Won't Start

Update: Current situation and tests done
-----------------------------------------------------
1.) I have tested the fuel comming from the return line, this test passed...should pump at least 750ml of fuel per 30 seconds, pumps approximately 1000ml per 30 seconds.

2.) NO fuel comes out of the banjo fittings on the top of the fuel distributor (the ones that supply the 4 main fuel injectors), this test was performed with the lines to the injectors removed entirely. Weather I have spark or not, it cannot start with no fuel here.

3.) It will start for a few seconds when given a generous amount of starting fluid, then dies when starting fluid is depleted.

4.) I have rebuilt the fuel distributor twice, the second time without the gasket between the top piece (the one that has the fittings to the fuel injectors) and the piece dirrectly below it. When rebuilt in such a way, you can hear a high pitched wine accompanying a slow leak of fuel from where this gasket should be.

5.) Pushing/holding/jiggling the air meter plate on the fuel distributor has no effect on the lack of fuel going to the injectors.

6.) Engine will not caugh or sputter at all, just a cranking noise...no combustion is taking place at all

7.) It seems the charcoal canister had an internal rupture, I believe this may have something to do with the problem despite what I have been told by a few "back-yard" mechanics.


Original Post:
-------------------
I just got this car from my dad. He says that it stopped running while driving. It made a sound resembling a very bad valve train problem and slowly died. It has not started since. It will start for a second if you spray a huge amount of starting fluid into the intake, but dies as soon as it is gone. I tried hot wiring the fuel pumps, but it still will not start. Then I took off the 5th injector supply from the fuel distributor and turned the pumps on. A small amount of gas slowly dripped out of the port, there was a difference in the drip speed between off and on, but I have been told the car runs 60-70psi, so a slow drip would seem to be a problem.

Any ideas?


Last edited by KillerBug; 11-03-2003 at 09:29 PM..
Old 10-21-2003, 11:46 AM
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have you checked the timing belts? they are under the grey plastic cover below the distributor
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Old 10-21-2003, 12:32 PM
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Its an 81 931 with the 2 liter Audi motor much different from the 944 and the 924S. You might also want to check out www.924.org there are some guys over there that know alot more about the 931 than I do. If it runs ok with the starting fluid I would belive that the timing belt is ok since the 931 is an interference motor a bad timing belt will bend valves. If you suspect a fuel delivery problem then remove the return line put it into a container and jump the relay for 30 seconds. You need at least 750 cc of fuel. After that pull the injectors and put them in some empty plastic bottles. Then jump the relay and move the fuel meetering plate down and check the spray pattern and delivery.

None of the injectors should leak even a drop. The cold start valve (fifth injector) should not leak at all either.
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81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 10-21-2003, 08:02 PM
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Check to see if the fuel filter is clogged.
As noted above the 931 engine would self destruct if the belt went. So if the car turns over and runs when you introduce fuel I would suspect that the belts are ok for now. Though if you do not know when they were last changed I would change them to be safe.

If you jump the fuel pumps and get very little fuel out of the lines in the engine then there is either an issue with the pumps, the lines from the pump to the engine or the fuel filter. If you are checking it after the fuel dist it could also be a defective fuel dist. Check the flow moving forward from the pumps at each junction. Then if you can track and see where the actual flow issue originates.

Eric
www.geocities.com/eturbo924
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Old 10-23-2003, 06:09 AM
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I took the return line off the fuel distributor. Flowed 355ml in 11 seconds. Could not get the injectors out; they are rusted in place & soaking in penetrating oil now. I think it is the fuel distributor since clogged fuel injectors would not have caused such a sudden and serious problem, and even if one did go, it would still start. Does anyone know if they make rebuild kits?
Old 10-23-2003, 09:19 PM
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Crap I just tried to reply and it did not go through.

If the car fails the fuel supply test you need to check a few things first. Voltage supply (11.5 volts) and current consumption (8.5 amps) of the fuel pump. Also check the fuel accumulator, and fuel filter. The Haynes manual goes into alot of detail on these tests.

When cars sit for a long period of times they develop alot of crud in the fuel tank. If this is your problem then any parts you repalce or rebuild could fail quickly. There is also a screen and a second fuel pump in the tank. You may need to clean the screen and reline the tank.

You need to check these things before you attempt to rebuild the fuel distributor.

Rebuild kits are not available for the fuel distributor, but there are alot of Audi and VW fuel distributors that have the same internal parts and you can eaisly find any spare parts you need at the local junkyard. The only part that is unique to the 931 is the lower half of the fuel distributor housing. Take a look at www.924.org there is a procedure there for rebuilding the fuel distributor. I have rebuilt mine and once you have read the procedure post back I can give you some hints.
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Roger Hall

81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 10-24-2003, 06:41 PM
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Bug,

Sounds like your pumps are running with gas coming out the return. It might be a little high volume, but this sometimes depends on system pressure & heat on WUR.

Did you hot wire the pumps from the relay socket, this puts the fuse inline & means it is good? There are two other things that I can think of. The relay and overboost sensor. You can check the overboost sensor by grounding the wire to it & see if the car cranks.


Roger,

Thanks for tip on where to find info on rebuilding fuel distributor. Wife's has been sitting a few months & I'll probably have to clean the whole fuel system.


drew1
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wife has 924 turbo
Old 10-24-2003, 11:43 PM
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Drew,

Have you done a CIS pressure test? Have you pulled the injectors and check the spray pattern and fuel delivery?

Rebuilding the fuel distributor is possible, but I had a few problems and I would not recomend it unless you are sure the distributor is the cause of your problems.

When separating the upper and lower halves the procedure says to use a small hammer to shock the two halves apart. Once the two halves are separated about 1/4 to 1/2 inch stop using the hammer. Also be very carefull to not strike the seam where the upper and lower halves meet. Do not use anything to pry the two halves apart. The metal is very soft and the diaphram is very thin. A small ding, scratch, or dent will deform the metal and make it impossible to get a good seal. Once the two halves are separated the fuel meetering cylinder is still inserted into the upper half and it is a tight fit. Grab the upper half half with one hand and the lower half with the other hand, slightly twisting back and forth while pulling them apart.

I also cut the orings on the meetering cylinder slots. Make sure to grease them well when you reinsert them. and do your best to make sure they slide in evenly and dont get pinched.

I was having trouble getting the upper and lower halves to seal. I ended up using Meguires paint cleaner and a cloth polishing wheel on my dremel tool to polish the diaphram, and the surfaces of the upper and lower halves. Just a very light polishing and use some brake/parts cleaner before the Meguires starts to dry, its much eaiser to clean off before it hardens.

Lastly the Permetex Avaition Form a Gasket works well but I was having some difficulty applying it as the procedure states. I used some denatured alcohol and thined it out about 50/50. Then I got a set of paint brushes and the grocery store. The small ones that kids use for water colors. This worked well.

Good Luck, if you have any questions email me.
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Roger Hall

81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 10-25-2003, 07:48 AM
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Thanks Roger,

Haven't tried to run the car in last few months. Haven't done any testing. What I'm doing is rebuilding a core motor for it. I'm just thinking the fuel system will need a good cleaning before I try to fire the new motor up. I hate trying to crank & crank a new motor with no luck. And I want everything in good shape for the long haul. I have the O rings, shims, etc,for the pressure reg on the fuel distributor. I have a set of new 911 turbo injectors. From your advice, I may charge the battery, drain the gas, put in new, & test injection before pull I the old motor. If everything is good I won't tear into the guts of the fuel distributor. From your story looks like lots of opertunity to mess up.

In the car now, I'm still working on the exhaust. Got everything tacked together except the waste gate to exhaust pipe connection is not fabbed & located yet. Need to fab all of the hangers, tack in place, then weld it all up. In SE hot summers, the car ran hot when driven hard. So I got one of those Griffin Alum Radiators for it, now making brackets & plumbing it in. My wife wanted seats fixed, so they are recovered & while I was at it, I recarpeted. Still need to get a few pieces from upholstery place. The motor is coming along good. I fixed up a flow bench & have done intake ports, working on exhaust, & chamber cc. The motor is about ready for final assembly. Thinking about coatings. Like Nick posted, There is too much meat in JE pistons for rod side clearence, so I've had to work on them. I've got an old Conquest intercooler & a core 951 K26 so I'm looking at putting the cold side of it on the 931 so I can plumb to the intercooler. Maybe, I'll be finished by summer.

Where at 924.org is the fuel distributor rebuild, if I need it?

drew1
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Old 10-26-2003, 05:56 AM
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I couldn't find it in the tech section but here is a the link to the original post.

http://www.924board.org/viewtopic.php?t=4711search.php

Sounds like the project is comming along. Good luck keep me posted.
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81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 10-26-2003, 01:29 PM
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Update:
I have now rebuilt my fuel distributor twice, both times with the same result I started with. I also tried rebuilding it without the gasket between the top piece (the one that feeds the injectors) and the regulator piece, still no luck. NO FUEL comes out of any of the 4 cylinder supplies, but I do have fuel going to my cold start injector. If anything, I am running too much fuel pressure/volume, as I have a in-line pump, and have hotwired it and the in-tank pump together, bypassing all the crummy porsche wiring.

Since it is a continuous fuel injection system I am now considering another avenue: bypassing the fuel distributor entirely, with a modern electronic fuel pressure regulator. The only problem is that such a regulator would be vacuum/boost controlled, and would not feed more fuel for a higher RPM with a similar vacuum signal to idle. I am hoping this would not be a problem if I treat it like a race car all the time (which I do anyway!).
Is this a bad idea?

Also, I am considering blocking the fuel return line, removing all of the miscilanious fuel injection parts (such as cold start injector), and thereby forcing the fuel that goes in to go to the injectors. If I did this, would the jets before the banjo fittings be enough restriction to let the car run? (I don't mind running rich, I don't mind drivability problems, I just want her to run)

Last, I am considering going against my principals and installing a carburator. Does anyone know of a carburator that would bolt up where my throttle body is now, that would allow me to keep my turbo?
Old 10-31-2003, 01:14 AM
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You're not using the stock fuel pump? The CIS system pressures are extremely high and I doubt the fuel system would work without a proper CIS pump. System pressure should be between 85 and 95 psi for the system to work properly.

When you test the injectors, are you pushing on the air flow sensor plate?
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Old 10-31-2003, 03:09 AM
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It is a CIS fuel pump, same model #, and the car did run with it for about a year; it was just made in 2000 instead of 1980. I have tried pushing on the plate, leavingit alone, even moving it up & down as I try to start, same results (or rather lack of results). At this point I am so soured on CIS that almost anything would be preferable. (this is not my first catastrphic failure, it is just the first time I cannot afford to replace the parts)

I amnow also considering attempting to retrofit the fuel injection of an early 90's nissan/toyota/honda/etc 2.0 litre, as many of these vehicles can be converted to turbo without a new "chip" for the PCM. My only concern is finding some way to connect the new cam & crank sensors to the existing engine and I refuse to do the logical thing and simply swap out the motor for something I can trust.
Old 10-31-2003, 08:58 AM
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The cold start valve is electrically operated. My guess is that even with low fuel pressure when it opens fuel will come out. The fuel injectors are operated by pressure and require a minimum of 35 psi to open. Since you failed the fuel supply test I am pretty sure that your fuel filter is cloged or the fuel pump is bad.
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81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 10-31-2003, 04:49 PM
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One more time:

I get MORE fuel than specs, not less. If this is failing, I will reconnect the rotted porsche wiring so I don't get enough, but I don't think it will help, since the car died with that wiring installed.

Also, I have NO fuel going to the injectors (removed banjo fittings, didn't spill a drop)

Last, I was stating that the cold start valve have fuel going to it; I was not talking about fuel comming from it.
Old 11-01-2003, 07:53 PM
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Are you sure you are getting spark to the plugs, even a rotor that looks good could be bad.

drew1
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Old 11-02-2003, 08:46 AM
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I missread your post you are getting eoungh fuel. It is unlikley that all your injectors are frozen shut but with the rust you mentioned it is possible. The injecotrs are not expensive. Just a WAG but where your fuel return line comes off the fuel distributor there is a pressure valve. It is basically a spring, shim, and a meetering valve. When you took the distributor apart did you inspect and clean this assyembly? What did the inside of your distributor look like? Was it dirty or rusty? I think the only way to properly find the problem is to get a CIS pressure tester and hook it up at several points in the system and determin where the pressure is being lost. Your injectors should open a 35 PSI.

As for the carburator idea I think its a lost cause. I cant remember all the issues but running carbs with a turbo is difficult. There are carb kits for the N/A's but they require removing the throttle body and replacing the intake manifold. They are expensive and would require deleting the turbo.

As for converting to EFI it is possible but it will be expensive and the chip in the PCM is very specific to each engine. I would not be suprised if you end up spending $1000.00 and several months installing and tunning it. You will probably need to reprogram the chip several times before you get it right.
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81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 11-13-2003, 05:04 PM
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The fuel distributor was actualy rather clean inside (with the exception of the air flow meter part of it). The pressure valve is in working order, although I could not remove it as the bolt is siezed with rust (in other words, inside=clean outside=not). I recently aquired an oldsmobile 350 that may end up in the car (no, I don't mind welding), but I have been working too many hours lately to even bother with the CIS. One thing is clear: that motor & it's fuel system are coming out to be replaced with something more reliable and more powerfull than that 2 litre with ever be (even if it were to start running today, I just couldn't trust it ever again).

So with that, I close this post. Thanks for the help everyone, and if anyone knows where I can get a 944 S2 motor for cheap, send me an email or post it here

Old 11-13-2003, 06:06 PM
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