Help. replaced dead battery, now engine starts but won't run.

fuel compression spark

something is not right. Maybe the spark is too weak due to a failing ign. coil. Ignition module is a possibility also or bad ign switch. The systems can be checked easier while the engine is not running or not starting. I like to use a remote starter while checking components. ;-)

THESE ARE THE EXTREMELY BIZARRE ONES! LOL I have seen a few vehicles that had trouble like yours. 2 had timing belts with crushed/missing teeth. Sometimes would start and other times would not. It might have made the 'NO-COMPRESSION" cranking sound sometimes too. The other one that I have seen was a bad oil pump. It would start and then quietly die out. The problem was the oil pressure became so great that the lifters pumped up and kept the valves open killing the engine. Of course when the lifters bled down the compression would return and the engine would start until the lifters pumped up too much.

Thanks Dave and Mister Lull for your suggestions.

Hmm, interesting thoughts about the alternator, seems to fit the scenario. Are there any tests on the alternator or voltage regulator I can do without the engine running? Bentley doesn't give diagnostic tests for the voltage regulator only on the alternator output voltage with the engine running. The alternator is less than 2 years old and the windings are in good condition and the brushes are still longer than the minimum 0.5 cm.

Guess I can try another voltage regulator.

I wonder if I disposed of an otherwise good battery? I suppose at 9 years old it was going to go eventually, probably sooner than later.

thanks,

-Tony

Mister.Lull wrote:

I expect the voltage on a charged battery with the engine running with only a normal accessory road to be greater than 13.5 volts. If the battery is discharged, the voltage could be lower, but would be rising.

With the alternator not working but the engine running, I expect the voltage to be under 12.5 volts. The voltage would be dropping with time.

Hi, An update, I tried a brand new voltage regulator, but no change. Engine will turn over, catch for a fraction of a second then quit. Could an alternator failure be more serious than the voltage regulator? Could I temporarily swap an alternator from a '90 Golf?

Have also replaced the short rubber hose between the valve cover and the intake manifold. Next I'll try replacing the short pieces of cloth covered rubber hose that join the various pieces of solid plastic vacuum lines. I don't have high hopes though.

Other possibilities: failing main fuel pump?

-T> To clarify - Say your alternator goes out while you're driving. You

Hi Dave, Will check the less common causes you mention. The timing belt is past the recommended replacement interval. Will also check the compression.

stumped,

-T> fuel

The alternator, if it is bad, should not stop an engine from running if the battery had a full charge in it. ;-)

The timing belt will create a difference in the sound of the engine as it spins over with the starter. You can usually tell with your ears. ;-)

I guess I would jump the fuel pump relay and keep the fuel pump running to see if that could be the problem.

good luck,

Hi Dave and all, Agreed the battery should be able to run the engine on its own without the alternator. The battery is brand new and has no trouble repeatedly cranking the engine so has lots of capacity.

I checked the timing belt and it is tensioned correctly and is in fair shape. I didn't notice any weird sounds when cranking, such as valves out of synch with compression and exhausting--if that's what I should be listening for. Cranks normally.

I put my hand on the main fuel pump while my wife cranked the engine. By the vibrations, I'd say the main pump is running througout the cranking and not quitting.

Question: from the positive battery post, there are 3 wires/cables. One really large red cable going to the starter, one large cable going to a plastic connector which I presume leads to the fuse box. There is a third small cable with "invisible link" printed on the wire and there is a rubber cylinder encircling the wire part way down the wire before it disappears into the plastic loom. What is this third wire for? It's under some tension when connected to the battory and I'm wondering when I changed the battery I overstretched it and broke the conductor?

Second question, I'm pretty sure there is at least 1/4 tank of gas in the car, but could it be as simple as being out of gas? Quite a coincidence if the gas ran out the instant my wife parked the car. I'll add 5 litres tomorrow and see.

thanks again,

-T> The alternator, if it is bad, should not stop an engine from running if the

The engine will run if the alt isn't even on the car so rule out going there.

Hi Woodchuck, Okay, thanks for eliminating the alternator, won't go there.

Question (I thought I posted this question yesterday, but don't see it in this thread). On the connector to the positive battery post, there are 3 wires. The largest diameter goes to the starter, the next largest seems to go to the fuse box. Then there is a smaller diameter wire that is marked "invisible link" and disappears into the plastic wire loom. Part way down this 3rd wire is a rubber cylinder encircling the wire. This wire is under some tension when connected to the battery post. I wonder when changing the battery if I stretched it too much and broke the connector inside. Not that I recall being rough with anything.

Off to the garage to do some more diagnostics. Wife really wants her car back, in fact she's mowing the grass so I can work on her car.

thanks,

-T> The engine will run if the alt isn't even on the car so rule out going > there.

Is it possible that says 'fusible link'?

Hi Tom, By george, it does say "fusible link". I isolated the wire with the fusible link and checked resistance and continuity between the connector on the end of the wire to where its termination in the relay socket on the driver side inside fender. Resistance was zero, and continuity was present. Is that power for the headlight relay?

Tonight I checked the resistance on the ignition coil and all 5 ignition wires. All within spec. I checked again for spark. White spark present on cranking.

I checked km driven since last fillup--325 km by odometer AND trip meter. Normal safe range on a full tank is over 500 km. But I will put

So we've got fire and I'm pretty sure we've got oxygen, the small and large throttle valves open when the throttle is actuated. Fuel is the unknown. I plan to undo the banjo bolt on the front of the fuel distributer and test flow (the union in the fuel line near the strut tower is seized tight). Any recommendations on testing fuel flow? Other than fuel flow from the main pump, I've never taken an injector out before to test flow and spray pattern.

Maybe a dead batter was symptomatic of another problem?

Blocked exhaust? How long will an engine run if exhaust is blocked?

thanks,

-T> >

If someone claims the problem is the air in your tire...................slap them! lol

I remember some people checking for a running problem, starts but dies right out, and the problem was that they did not reinstall the large intake boot back after testing. ;-) Might just be a large vacuum leak or out of gas! Does your fuel distributor have the rectangular electronic fuel pressure regulator on it's side? Might be a wire ground problem and IIRC the ground wire is by the Cold Start Valve bolt. Not sure on this though but checking power going to the FPR might determine if that is your problem. Or you might be missing a fuse in the fusebox.

Just thinking of the little things! BTW is this the '85 Golf?

intank transfer pump not working? That might cause a "NO-GAS" condition. Since I think you mentioned you were getting spark...........I will assume that youi are not getting gas into the cylinders, or the gas isn't gas! 8^o

I would probably pull out a fuel injector after opening up one of the fuel lines to see if I get gas. PLEASE BE VERY CAREFUL!!

As I recall on your vintage 12V is supplied to the coil and the ignition module provides the path to ground. First determine if this is correct by checking for 12volts on the coil while cranking. Then determine if it's there when it starts and the key is returned to run position. If 12v goes then replace the ignition switch as was mentioned earlier. Also recheck all the wires going to the positive post of the battery.

JoBo

Hi Phred, Dave and Jo, Thanks for the additional suggestions. Have been away, but eager to try your tips.

I've also been thinking the ignition switch. After 21 years, maybe it's worn out? :) Any chance a faulty ignition switch also didn't completely turn off on the last successful drive home and that's what drained the battery?

Reading other posts on the ignition switch, it looks like an easy replacement, no drilling required? I have Bentley and will look more closely.

Dave, affirmative, it is the '85 Golf, my wife's trusty wheels of 21 years (original owner). It's the same car that intermittently stalled earlier this year (2006) while driving--turned out to be a faulty hall sender, darn thing failed after 20 years and a gazillion on-off cycles.

Thanks everyone for your continued support. My wife thanks you too--she's taking the bus to work. cheers all,

-T> As I recall on your vintage 12V is supplied to the coil and the ignition

Hi all, An update, success???. I replaced the ignition switch this weekend. Had a choice between VW or 3rd party, went with the VW switch. Pencilneck's illustrated instructions were great.

The engine wouldn't start though, it exhibited the same symptoms: engine would turn over and seem to catch for a fraction of second, then quit. Then by jove, on the 4th or 5th attempt, it caught and kept running. Seemed the main fuel pump was louder that time(??). I test drove the car, stopping the engine and restarting. Other than one sticky tappet that cured itself after the oil warmed up and the hydraulic lifter worked again, the noise went away. But I'm still leery the engine will quit and leave my wife stranded. So I'm not saying it's solved yet. Will write again in a month if it is.

Re: replacing the ignition switch, I highly recommend wearing safety glasses. There is a spring that is under considerable compression. That cupped washer was the biggest challenge to the job. Pliers worked best for removal, there wasn't much to grab with a puller. I tried multiple ways on re-assembly, but a short length of 1" plastic water pipe worked best to push the washer back on. The original ignition switch was 21 years old and I estimate had been activated some 8,000 to

Thanks everyone for your suggestions, you're GREAT! With your help, I'm hoping the '85 will reach 25 years old. regards,

-T> Tony: