924Board.org

[dpw928]

Ian,

Guess the Haynes manual didn't tell you that there could be multiple shims. On my 924, I had one large shim (didn't measure) and on my 928 I had 6 of varying sizes. I would not recommend changing the shim setup unless you have the gauges to measure system and control fuel pressure and everything else checks out.

You mentioned that you were getting fuel to the warm up regulator (system pressure) but did you check to see if you were getting fuel from the WUR to the center of the fuel distributor (control pressure)?

Dennis

[badenkb]

Hi

Thanks no - I did not check return fuel supply. I had changed the WUR for a spare I have, but with no effect so did not look beyond that. I do recall that when swapping the WUR - fuel leaked from both connections, but as you say, it must be at the correct pressure to allow for the movement of the piston in the fuel distributor to send fuel to the injectors.I'll check it out - presumably by measuring the resistance across the electrodes ?

Thanks

Ian

[badenkb]

Hi All

Many thanks for the advice you have been offering. I think I am making progress:

I bypassed the fuel pump as was suggested and realised that fuel was NOT getting to the engine when I was cranking (but it was with the ignition on (i.e. pumping to system pressure). The engine still did not start however. If I gently lift the sensor arm with the fuel pump bypassed, I do get fuel from the injectors though. So apart from having a dodgy relay, it still seems I have a fuel pressure problem???? WUR ???

Thanks

Ian

[ricomartinez]

It sounds like you have everything you need. You said it would start somewhat with starting fluid, indicating the ignition system should be okay. You got fuel to the fuel distributor by jumpering/bypassing the fuel pump relay. You then can get fuel to the injectors by lifting the the air sensor plate.

It sounds like maybe there isn't enough air going through. With the older 924's, the fuel pump relay works with the air sensor moving off its normal resting area. This might have made the fuel pump relay not seem to work by not providing the proper signal to the relay. But you've defeated that problem and again the ignition system should be working.

The only thing that seems logical is that there is too much resistance in the air sensor plate for air flow while cranking/starting to lift the plate and allow fuel to the injectors and engine. Or, maybe there is a restriction elsewhere which is not allowing enough air to lift the air sensor plate providing fuel to engine.

Have you tried starting it with the throttle open? Or maybe try opening up the idle speed screw quite a bit. There might be other things that are compounding the situation. As always, if I'm out in left field on this, someone please lend their knowledge.

[badenkb]

Thanks - I feel more confident that I will solve the problem, but I am being hampered by previous owners who modified parts of the engine. So for example, I don;t have the sensor on the fuel distributor housing that should activate the pump as on early models and the fuel pump relay is from a 79 model (according to Haynes) not the 77 wiring thats in my car!!

Ian

[TonyMechanic]

Ian, it definately looks like your making progress, sorry for not replying earlier. Try checking the boots from the intake to the fuel distributor, a slight crack in one of thes could mean that air is being sucked in there, not past the sensor plate, meaning no start. If you hold the sensor plate open a little will it start? try pulling off the boot and wedging a toothpick in there. Good luck to you.

[JvGinPDX]

I agree with TonyMechanic. mine did the same thing. Drove me nuts. Turned out to be the connecton from the manifold boot to the aux air sensor. Bad plug wires would cause normal starts on dry days, and no start/poor running on foggy days. Good luck. You seem close to sloving your problem.

[badenkb]

Thanks all - I have noticed some tearnig around the boots and have temporarily used an epoxy resin to fill the cracks (although I know this is at best a temp repair). I'll try the toothpick idea, but I'm also thinking of simplyfing the wiring for the relay - according to Haynes one feed off the relay activates the seat belt warning system (which is not fitted to my car).

Ian

[badenkb]

Hi All,

This is getting like a saga now and I hope no-ones gettign fed up ,...but my 924 na still will not start!

Part of my problem had been that the fuel pump was no running when the engnie was turning over and that seems fnid now. If I lift the sensor plate with a small wedge and turn the engine over, I get fuel from the injectors. I also have a good spark - but the engine will not kick over. I can't even get it to kick over by injecting fuel injection cleaner into the manifold directly .... I am confused.

Thnigs I have checked include :

fuel pump delivery - is within specs
Aux air valve - 48 ohms resistance, getting 12v with ignition on.
Cold start valve - 5 ohms resistance, gettign 12 v for about 5 seconds with ignition on (cranking) - but this is not firing.
WUR - filter is not blocked - (don;t have equipment to check for cold and warm system pressures).
Sensor plate centred and a good 0.1mm gap all round. Even resistance on the up and down movement of the arm.
Air intake boots in OK condition - no air leaks obvious
New fuel filter
New fuel lines throughout.


Car *was* running previously - so I know engine is serviceable and has been running OK.

The only life it has alomst had was when I adjusted the timing as the engine was cranking over - then it stuttered a few times trying to catch - but it is different to replicate this.

Questions and help please!!

For there to be spark and fuel - but no ignition - then the mixture is presumably wrong ? (but then again I was holding the air sensor plate higher than normal for the engine speed...)

I am at a loss as the to what to replace next or where to look...please help!!

Ian

77 924 - 20 months and counting...

[dpw928]

Notice that the auxillary air valve checked out with the ohm meter. Did you check to make sure the plate was open then closing when heated? The ohm's test just checks the heater. The valve plate should be open when cold. When 12 volts is applied you should be able to see the plate slowly close up. BTW the plate is steel and the valve housing is aluminum so corrosion could have gotten to it.

Dennis

[badenkb]

Dennis

Thanks for the advice - I'll check the operation out - should I at least get the car to fire if I simply replace the aux air valve with a straight through piece of tubing??

Ian

[marky522]

i know this will sound stupid but what cond. are the plugs in??? I know that when i floded my 924 the plugs had to sit for 3 days out of the car before they could be used again, i got new ones, maybe you have already fixed the prob and now you just need to replace the plugs...

Just my .02

Mark

[badenkb]

Thanks Mark

I'll try that too.

Ian

[kevrl]

This reminds me of a problem I had many years ago in an old Alfa-Romeo, I had fuel and spark, but it wouldn't run. The car had been sitting for a while and it turned out that the reason it had been left idle was because the head gasket had failed badly and the head was corroded. Lack of compression was not allowing the engine to fire - its a long shot but surely worth checking the compressions.

Also, you have mentioned that you have a good spark, but is it timed right ?, is the contact gap correct and are the earths around the condensor good ? Remember that although a plug may give a good spark when its out of the engine and just resting on the block, the conditions inside the engine at high pressure are differant and may reduce spark quality.

Also what about Cam timing, could it be a few teeth out of alignment ?

Sorry if these are all a bit obvious, but it can be easy to overlook the simple things and look for something complicated. Hope this helps, keep us posted if you identify the problem.

Kevin
(Mine's a 931)

[badenkb]

Thanks for the advice - I'm hoping its not for a lack of compression that the engine's not firing - although I agree it could be a cause. I'm hoping that it is something else, guiven the engine was running ok before christmas.

1) Check compressions

Timing - yes - another point to check - I changed the belt whilst I had the engnie out but maybe didn't tighten it correctly or something similar..

2) Check belt and timing

Other things to do:

3) Feel for pressure at the aux air valve (runnign a long tube to me in the car!)

Will report back..
sigh.

Ian