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tj924 · Posted: Tue Nov 09, 2004 2:30 pm Post subject: Startign problem

And just for something different, my car has developed a different problem.

I got it off the stands last night & took it for a short drive. Started OK but I had to give it a little gas for 20 or 30 seconds to get it to idle by itself, then it idles a little rough but came good after a couple more minutes.

Put the battery on the charger (alternator not working, thats in another thread) overnight & started OK again this morning. Warmed it up (but didn't drive it), turned it off, left it for 15 minutes & started it again OK.

Thinking all was good, my wife drove the kids to school in it & found it wouldn't start again for her. The motor would just crank & crank (so battery still OK) but not kick in. Got the local car club guy to have a look & it is sparking OK, but he reckons it was flooded. He removed the fuel line near the air filter box just above the fuel filter & confirmed the fuel pump is pumping OK. Started the motor with the fuel line still off & it started OK. Reconnected the fuel line again & it started right up & ran fine.

Got it home again (< 5 minutes running) & it wouldn't start again, same symptoms. The first crank sounded just like a flat battery (not enough juice to turn it over), but then it would just crank & crank.

The car club guy reckons it might be a problem with the cold start injector. Does that sound feasible, even through it was only about 25 to 30 minutes from when my wife stopped it at school to when she tried starting it again & it was < 1 minute when I tried starting it again at home? Where do I start to troubleshoot this one?
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TJ
Silver '82 924 NA 5-Speed Manual

leadfoot · Posted: Tue Nov 09, 2004 7:22 pm Post subject:

Cold start injector would just cause a rough idle during a cold start as it doesn't supply the extra fuel which i might add only really goes for about 20 seconds.
Suggest you check your timing...
You may have bad injectors causing the flooding but this is just a guess, how did the car run whilst going?? was it rough idle and smoothed out after warming up?? or did it stay rough.
If it stayed rough then I would suspect timing, pull a spark plug to see what condition it's in and that will give you the best indication of any problems with oil, fuel rich/lean, too hot, pre ignition etc.
Have you changed the fuel filter recently?? is it clean/not blocked as this could reduce your fuel pressure...
try these first and see what you find out...
Leadfoot

924RACR · Posted: Tue Nov 09, 2004 11:06 pm Post subject:

If the cold start injector is stuck on it could produce the starting problem described, I'm thinking - either a problem with the valve or the thermo time switch is stuck on (controls the CS valve). The poor idle immediately after starting could be caused by an aux air valve not working properly (essentially a throttle bypass for cold starts, allows additional air into the engine). Note that these are more likely to have wiring issues (except maybe the thermo-time switch, since it's a switch) than be broken. Time to put your multimeter to work!

Cold start valve function is more to get the motor to initially fire; only operates for about 8sec max (or should, anyway). Idle quality after that is controlled by the aux air valve.
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tj924 · Posted: Tue Nov 09, 2004 11:11 pm Post subject:

The car idled & ran smooth after a couple of minutes. The plugs are new & the car has only been started 5 or 6 times with them in. Fuel filter hasn't been changed but I have a new one waiting to go in. Fuel pressure appeared fine when the guy held the fuel hose just above the filter into a jar (ie heaps of fuel poured out when I turned it to start & the fuel pump came on (the familiar buzzing in back). As I said, once he disconnected the fuel line, I cranked it & it started immediately. He then reconnected the fuel line & it started immediately again & ran fine 'til I got it home & turned it off. Didn't want to start again.

I expected a problem with the cold start injector to be too little fuel to start, not too much (ie enough to flood it). I also didn't expect it to be the cold start injector as the engine would have been warm on both occassions it has failed to start. Again, once it is running it idles & drives fine.
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TJ
Silver '82 924 NA 5-Speed Manual

924RACR · Posted: Tue Nov 09, 2004 11:14 pm Post subject:

Too much fuel = flooding.

Or don't believe me. But next time it doesn't want to start, like that... try holding the accelerator to the floor, see if you get a nibble.
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Vaughan Scott
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'79 924 #77 SCCA H Prod racecar
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tj924 · Posted: Tue Nov 09, 2004 11:27 pm Post subject:

Vaughan, my response was in answer to Leadfoot's questions. Only just read your response now.

So, where do I start to look/test for an aux air valve/thermo time switch (I'm an absolute newbie)?

If the cold start injector were stuck open, would you have expected that disconnecting the fuel line, starting (ie to burn the fule currently in the motor), then reconnecting the fuel line would cause it to start properly?

Are you indicating that if the aux air value &/or thermo time switch were playing up they may effectively believe it is always cold & give too much fuel to start (ie flood it)? What would holding the accelerator to the floor do?

Could the initial 1/2 crank (sounded like a flat battery) be another symptom or probably just a flat battery, even though it continue to crank strongly.
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TJ
Silver '82 924 NA 5-Speed Manual

924guy · Posted: Tue Nov 09, 2004 11:59 pm Post subject:

Just a thought, but it is possible these symptoms can arise from a bad positive battery cable.. i went nuts at one point trying to cure a similiar ailement in my 78.. finally took it to a pro who told me something to effect that the cable was old and building resisance due to internal corrosion , the hotter it got, the less voltage flowed, yet not enough to kill the battery while driving, just to much to allow it to start once warm , the kicker was that the engine seemed to be turning over fine, just slightly below "fast enough" to induce combustion.. very weird, and i dont quite get the increasing restistance principle, but anyhow, he made me up a new cable (no longer available and not a standard cable) and i never had another problem with it...) the old one was quite crispy...
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tj924 · Posted: Wed Nov 10, 2004 12:11 am Post subject:

Where does the big +ve battery wire go to?
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TJ
Silver '82 924 NA 5-Speed Manual

5150 · Posted: Wed Nov 10, 2004 12:42 am Post subject:

the heaviest wires on the positive side connect to the starter and alternator mate...
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924RACR · Posted: Wed Nov 10, 2004 1:19 am Post subject:

That's what I'm thinking, the thermo-time switch may be leaving the CS valve on (or the valve's stuck open) flooding the engine. Holding the accelerator down (WOT) might help counteract the excessive fuel by allowing more air in. Works on carbed cars when they're flooded. Likewise, disconnecting the fuel line allows the fuel that's in there to be burned and/or pumped out without replacing it, leaning the motor back out to a reasonable point.

To replace the parts, I'd wait for your Aussie buds to chime in on best sources down your way.

For electrical diagnosis, you need to get a multimeter and a wiring diagram (from the manual) and start checking - first check grounds, of course.

Does sound like your car might like a new battery cable, yes. New grounds cables too, while you're at it.
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'79 924 #77 SCCA H Prod racecar
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#25 Hidari Firefly P2 sports prototype

Johno · Joined: 14 Oct 2003 Posts: 53 Location: Greendale, WI

I have what I think is the same problem, I believe that the car is flooding.

I had checked my CS injector and it was working, isn't this the same injector that you are to hook the switch up for the hot start problem? I just don't recall if it shut off after a few seconds - I think it did.

Anyway, I have tried the WOT and it typically starts the car, the other thing that I have done is to pull 2 of the injectors and crank the engine over, it will usually try to start, I then put the 2 injectors back in and she fires right up.
If the CS injector is stuck open wouldn't the car run poorly? I did check and my injectors are not leaking - as I thought that might be causing the flooding.

One side note - how do you attach a photo - I redid my car seats and would like to show everyone.

thanks
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79 924 NA

tj924 · Posted: Wed Nov 10, 2004 7:58 am Post subject:

Smoothie · Posted: Wed Nov 10, 2004 8:41 am Post subject:

WOT = wide open throttle - the idea being to let more air in to mix with the overabundance of fuel.
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tj924 · Posted: Wed Nov 10, 2004 1:08 pm Post subject:

Well, WOT worked!

Started her this morning after it sat all day yesterday & overnight. She started up first hit just like yesterday morning. Ran her for a few minutes & stopped her again. Waited 15 minutes & restarted OK. All without touching the accelerator.

Left her a further 30 to 45-odd minutes & experienced the starting problem again. WOT & enough cranking & away she went. Little rough at first but smoothed out fine. Idled for a few minutes & stopped her again. Started her again about 10 minutes later & needed WOT again.

Drove her to work this morning (first real run since I drove it home but still has a wobbly wheel so can't go over about 60kph) & she ran fine. Temp down in the 1st quarter for most of the journey.
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TJ
Silver '82 924 NA 5-Speed Manual

tj924 · Posted: Sun Nov 14, 2004 2:52 pm Post subject:

Looks like I may have found the problem, but not haven't tested enough to say for sure yet.

The 1st owner had a "choke" switch installed which the PO (the 2nd owner, so I'm the 3rd) told me about but had never personally needed to use (lives on the Gold Coast so it doesn't get cold enough). The switch is on the drivers side (RH drive) on the left about 1/3 of the way between the seat & the pedals (so it sits next to & just lower than the CD player).

I'd never touched it & didn't know it had been played with (3 year old son, 'nuf said

), but found it in the UP (ie ON) position when I had a look under there the other night to check the clutch cable at the pedal. If the "choke" has been on the whole time that may explain why the engine is flooding when it is already warm!

I'll keep ya posted!
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TJ
Silver '82 924 NA 5-Speed Manual