504 ignition/starting issue

Tom_95

Tom_95

Member
Fellow Frogger
Joined
Jul 4, 2011
Messages
293
Location
Sunshine Coast, Queensland
Hi all,

Am currently working through a bit of a strange issue with my 504 with regards to starting/running. I believe it to be electrical...

Symptom: Car occasionally stumbles at idle for a second or two and often is difficult to start when hot. However, I feel the issue is electrical as the engine fires as soon as you release the key from the 'Start' position - so it's as if it's giving no spark when cranking. This doesn't occur on a cold start.

I've removed the ignition barrel and had it tested by an auto electrician - is working normally. I've also replaced the battery earth cable as the original was a bit tired.

Car has had a new coil, points and cap in the past 5,000kms. All appear as new.
Plugs, insulators etc are in good condition.

On the road the car runs well - no stumbling/missing and pulls strongly.

What else should I be looking at here?
 
Assuming the ignition is OK (you mentioned coil, points etc... and assuming timing is right) , check the float in the carb
 
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I was having ignition problems with my 504 cab which even after replacing everything. I solved everything by electronic points replacement in the existing distributor . From performance ignition services in Melb. It gives a much stronger spark as i saw demonstrated in "wheeler dealers" tv show. I had to reset the timing but now it works perfectly
 
No mention of CONDENSER replacement?
98% of suspected fuel related issues turn out to be ignition.
 
Hi Tom, it is worth investigating the upgrade to electronic points conversion. I converted my 504's to this a few years ago - solved all the starting issues! I went to Accuspark"Stealth" sold out of Victoria. Available on ebay: Peugeot 504 1975-1979 Electronic Ignition Conversion for Ducellier Distributors. There are also other brands out there.

Cheers,

Neil
 
Tom_95 said:
Hi all,

Am currently working through a bit of a strange issue with my 504 with regards to starting/running. I believe it to be electrical...

Symptom: Car occasionally stumbles at idle for a second or two and often is difficult to start when hot. However, I feel the issue is electrical as the engine fires as soon as you release the key from the 'Start' position - so it's as if it's giving no spark when cranking. This doesn't occur on a cold start.

I've removed the ignition barrel and had it tested by an auto electrician - is working normally. I've also replaced the battery earth cable as the original was a bit tired.

Car has had a new coil, points and cap in the past 5,000kms. All appear as new.
Plugs, insulators etc are in good condition.

On the road the car runs well - no stumbling/missing and pulls strongly.

What else should I be looking at here?
Click to expand...
Battery earth strap at block tight?
Centre carbon brush in distributer cap free to slide?

Easy checks.
 
Tom_95 said:
Symptom: Car occasionally stumbles at idle for a second or two and often is difficult to start when hot. However, I feel the issue is electrical as the engine fires as soon as you release the key from the 'Start' position - so it's as if it's giving no spark when cranking. This doesn't occur on a cold start.

I've removed the ignition barrel and had it tested by an auto electrician - is working normally. I've also replaced the battery earth cable as the original was a bit tired.
Click to expand...

Hi Tom, If that is what you think, then as you are there at "ground zero", the ignition switch may still in fact be what the problem is, despite what the auto elec said. Those older-style ignition switches are known for bad contacts when they get old. I have had that same problem a few times with older 504s. Can you try hot-wiring it ?

If it was the condensor which is faulty, that would show up as the points getting black fairly quickly.
 
Hi Tom. A suggestion. If you use a jumper wire from the battery positive to the coil positive terminal, would the engine then start while the ignition key is in the crank position? This could then rule in or out the suspicion with the ignition switch.

You need to be aware that while the ignition coil is hot wired you wont be able to turn off your engine with the ignition key. You could wire it into the cabin with a switch.
 
Thanks for the tips - I'll try running a lead straight from the battery to the coil +ve to at least eliminate the switch.

Is there anything else inbetween the key and the coil (relays etc) that are worth checking?
 
If this makes a difference to starting you could run it thru a relay. I did this on my car and it always started .[it turns off when the ignition is switched off]. Just run a wire from the dizzy to the relay to connect the batt pos to coil pos
 
Apologies for dragging up an old thread, but I'm still no closer to working out what on earth is happening with this car... (It's stored about 1.5hrs from where I live, so I have somewhat limited time with it)

I've had a bit of a poke around with a multimeter and inline spark tester today and the findings are somewhat interesting. With the inline tester, the spark appears to be perfectly fine (it doesn't cut when cranking etc). The multimeter reveals that when the car is running the voltage at battery is about 14v, however the voltage at the coil posts is less than 2 volts... Which seems far too low for the car to even run on. Would the electronic ignition kit have any bearing on this?

I'll attempt to add a few videos below to try and explain what I'm going on about.


 
Listening to the engine running, it sounds as though the timing is way out.
 
Coils and condensers can be crap when brand new as many have found and reported in quite a few threads around here. I have had my own share of that so I don't trust new parts anymore. I am saying this because your coil sounds like the insulation is breaking down when hot. This is very typical of how coils fail.

To check what is happening with the engine cold I would disconnect everything from the coil and measure the positive feed form the whatever electronic device you have. You can do this with the engine idling immediately after starting it cold (everything is of course connected in this scenario). If the feed has 12V go to the next step.

Now disconnect everything from the coil and with the coil cold measure and record the resistance across the coil windings.

Next, measure the same (everything disconnected now) when coil is hot. If you see a difference between measurements, you found your culprit.
 
You're a genius, Peter C. Thank you for the suggestion re: Timing.

I had a bit of a fiddle with the distributor and ended up turning it a few degrees counter-clockwise. The car now starts, idles and pulls like it should. I even had to drop the idle down a little as with the timing in its "happy place" it was sitting at about 1100rpm. It's not pinging under load, either.

As to how/why it ended up so far out, I have no idea. It's not something I've ever touched before.
 
Tom_95 said:
You're a genius, Peter C. Thank you for the suggestion re: Timing.

I had a bit of a fiddle with the distributor and ended up turning it a few degrees counter-clockwise. The car now starts, idles and pulls like it should. I even had to drop the idle down a little as with the timing in its "happy place" it was sitting at about 1100rpm. It's not pinging under load, either.

As to how/why it ended up so far out, I have no idea. It's not something I've ever touched before.
Click to expand...
The timing can moved by simply adjusting the points. This is one of the negatives of the contact point system.
 
Just realised, with the engine running you measured the voltage on the coil with your meter set to DC volts, that is why you got 1-2V. You need to set it to AC (even then it's not going to be accurate, but closer to 12V; depending on your meter the value read might be RMS or peak to peak). An analogue meter would still give you some information even if set to DC but it may burn out. A VTVM would be ideal.
 
PS. If you want to measure the DC coil voltage you need to measure to chassis ground not the negative on the coil. That one is controlled by the points and you should get nothing if the points happen to be open when the engine is off (ignition on). If you get any voltage under these conditions (ignition on, engine off, points open) your condenser is leaking DC or there is a short somewhere (the points themselves might short through some bad insulation, who knows what). Change the condenser first and check again.
 
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