Car stalls without warning

Hi, thanks for sticking with me on this 👍

Yes, I blocked off the open end of the vac pipe at the carb :)
Water in fuel is an interesting idea - hadn't thought of that. Presumably the car would be hard to restart though?

I would love to swap back to my points dizzy, but the cap broke and the only UK supplier says they are on back order from Russia (?). I might buy another new old stock SE100CX and try swapping the amplifier module over, see if that works

Despite all the progress made with timing and fueling, it really does feel like an electrical gremlin. I might even run fresh copper to the coil and fuel pump to rule this out. Failing that, she is booked in for a rolling road session on 29th April.
 
Hi mate
What pump do you have had a issue once where pump was not powerful enough and would die when driven hard but you could hear it working harder at this point. Don't think this is your issue but do you still have mechanical one might be worth trying. I bought electronic dizzy for mine and was having trouble with the advance so put old set up back on for now till i sort it. To be honest though performs great with points and i have a few mods was it a marelli s135 originally i know you can get caps but they aint cheap. Im in the Midlands if you were closer you could try mine hope you get it sorted sure you will with help from the forum
 
The pump is a Hardi 14412. The manufacturer website says it is good for 100bhp and suitable for Fiat 128. It was recommended by another forum member who had fitted the same pump.

Yes the original dizzy is an S135 and I had to pay £75 for the cap 2 months ago, only for the graphite centre contact to snap on me. The seller has agreed to refund me, but doesnt have another in stock.
 
jimrat said:
The pump is a Hardi 14412. The manufacturer website says it is good for 100bhp and suitable for Fiat 128. It was recommended by another forum member who had fitted the same pump.

Yes the original dizzy is an S135 and I had to pay £75 for the cap 2 months ago, only for the graphite centre contact to snap on me. The seller has agreed to refund me, but doesnt have another in stock.
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You can just replace the spring and carbon centre think you just wind them in
 
Just a thought, have you got a fuel pressure regulator in your fuel system? Also if you have a spot to fit a fuel pressure gauge?


I am far from an expert but even with a return line in the carb, but 10 bar (from a search I did on the pump) seems a bit high.

Might not be it but just a thought
 
Spec for the pump is 0.18-0.26 bar. According to their literature, a regulator is not needed, and this was the main reason I chose the pump, to keep things simple in the engine bay

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This appears to be an electrical intermittent more than a fuel system problem. Given this exxe has a carb which has a fuel bowl that will hold fuel for some time before running out of fuel regardless of fuel pump operation.

The problem could be an intermittent electrical connection in the ignition system or some iffy electrical part in the ignition system. Common today are absolutely bottom scraper aftermarket parts that are absolutely inferior to decades old oem parts. New does not mean good or high quality, it simply means made not too long ago of questionable quality in every way.

That broken off center contact in the rotor is an example of how parts are made today... or where there is smoke, there is or will be fire...

Given you're in the UK there has got to be plenty of known good used oem Fiat ignition systems available. It is worth a try to source one of these systems, do an extensive bench test to verity operation then install the entire system into your exxe... with a direct wire to battery power bypassing the current ignition system wiring as a check.

Alternatively, do the direct from battery power wiring bypass with the current ignition system as another test..


Bernice
 
The strangest part of this whole story is the fact that the car starts right back up again.

I'm leaning toward the problem being loss of 12v supply and blaming it on the ignition switch.

I'd be quite interested in troubleshooting this car, but Alabama...
 
Ernie said:
The strangest part of this whole story is the fact that the car starts right back up again.

I'm leaning toward the problem being loss of 12v supply and blaming it on the ignition switch.

I'd be quite interested in troubleshooting this car, but Alabama...
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Yes, or why direct power to the ignition system would be a valid test..

All power (up to and more than 50A) for the electrical system in the exxe goes in-out of the ignition switch, that switch will wear out, die or become intermittent at some point. Second to this, the entire electrical system power goes in-out the large gauge (sized) brown wires with push on spade connectors that will also die or become intermittent. Those push on spade connectors heat cycle and eventually lose their ability to make a reasonable electrical connection. Once the quality of that connection goes down from heat cycling, the increased resistance causes more heating and further degrades that connection until that connection roast or causes a fire or similar...

While push on spade connectors were and to some degree popular with production motos, they are iffy for long term low resistance electrical connections.. These push on spade connectors and similar are not limited to Fiat, they were and are common on nearly every moto made during that era of moto production.


Bernice
 
Direct wiring sounds a good shot :)
chumley said:
You can just replace the spring and carbon centre think you just wind them in
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Yes, that's correct - can't be sure of the specific russian cap, but the chances are it uses the common 6mm centre core that's in the current "good" cap. Try (if you dare) to fit the good one into the broken one: pick out any remains of the broken one with long nose pliers; grab the good centre by hand and pull it upwards, twisting as you go. This is what you're looking at on a good day, note the conical spring - it may need some persuasion to get it re-fitted though - perhaps the centres will just interchange and it'll be an easier route?
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Ernie said:
The strangest part of this whole story is the fact that the car starts right back up again.

I'm leaning toward the problem being loss of 12v supply and blaming it on the ignition switch.

I'd be quite interested in troubleshooting this car, but Alabama...
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I fitted a new Marelli ignition switch a couple of weeks ago
 
jimrat said:
I fitted a new Marelli ignition switch a couple of weeks ago
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Which brings us back to Bernice’s point of one or another connector failing/intermittent. This could include the grounds at the transmission, body or battery.

I had an issue where my positive battery clamp wasn’t making good connection due to being brutalized by the past owner. Sometimes it is the most inane things.
 
jimrat said:
I fitted a new Marelli ignition switch a couple of weeks ago
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"New"means zilch. that "New" Marelli ignition switch could be Dead Out Of Box...

The reasons for doing a direct connect is to assure the ignition system is getting a known and proven source of power disconnected from the normal power system... which could have an intermittent in the wiring anywhere between the battery to power mains to power switch or all other possible places the in-car wiring can fail.

Really, this test is not that difficult, run a heavy gauge wire with GOOD connections direct from the battery to the power input of the electronic ignition system... start up the motor and test if the ignition system continues to run or stops as before..

Much about doing the work and test methodology or knowing how to design a test that has a possibility to verify what might be happening,
Bernice
 
Ok. Not the ignition switch, then. But, the problem still seems to be electrical.

If fuel related, the car either wouldn't start back up or it would take some cranking to get it going.

The reason I thought it could be the ignition switch is there is a mechanical intervention (you turning the switch) on the side of the road.

Now I'm thinking it's the distributor you've been referring to. If that's the one that has the electronic module fastened to it, there have been posts on this forum about it. I seem to recall the reviews were somewhat negative.

I can't help but have doubts about that being the problem, though, because electronic circuits don't generally behave in the fashion you've described.

So, it's drive the car a short while. It shuts off. Pull over to get out of any traffic. Hit the key and car starts. Then repeat this process til back home? Wild story, for sure.
 
jimrat said:
Water in fuel is an interesting idea - hadn't thought of that. Presumably the car would be hard to restart though?
Click to expand...
Perhaps. But the pick up is not right at the bottom of the tank - which is where any water will settle. So can start well and run well but as you drive, the water gets shaken [never stirred Mr Bond] back in. Doesn't take much to knock combustion over. Rinse and repeat.
 
So, it's drive the car a short while. It shuts off. Pull over to get out of any traffic. Hit the key and car starts. Then repeat this process til back home? Wild story, for sure.
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Yes, exactly this behaviour

But the pick up is not right at the bottom of the tank - which is where any water will settle. So can start well and run well but as you drive, the water gets shaken [never stirred Mr Bond] back in. Doesn't take much to knock combustion over. Rinse and repeat.
Click to expand...

I'll try and siphon from the bottom of the tank where any water might be 👍
 
If you think that it is water in the gas, you could try putting some dry gas (alcohol) in. The water will mix with the alcohol and combust in the engine. I haven't seen dry gas around here but when I lived in fridgid climates it was popular since condensation was an issue. It used to come in small metal cans with a screw top.
 
Water injection was used in WW-II aircraft to control detonation, increase power output of turbo vintage Dino juice consuming motors..

If there is suspected water in the fuel tank, drain the fuel tank completely, refill with known good fuel.
Or rig up a small fuel tank with a gravity feed into the carburetor or other using the fuel pump, fill with known old fuel as a test.

Water in fuel usually does not produce sudden running of the motor followed by a easy re-start.


Bernice
 
Figuring out what is the root cause of intermittent run/on/restart demands methodical reduction of possible problem areas that could be a cause with precise testing and observation of test results.

There will be no "instant" answer/solution to this problem,
Bernice
 
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