Car stalls without warning

Finally, a breakthrough! But it's weird......

My fuel pump uses much of the old carb fan wiring and relay in the spare wheel well. I decided to bypass all this, and run a wire direct from the fusebox to the pump, with a switch in the cabin to control the pump, and an indicator bulb on the pump so I could see if it lost power.

I took the car for a long test drive and it is still stalls / goes into limp-mode. When this happens the indicator bulb is still lit.

But instead of pulling over to a stop and turning the ignition key, I just coasted along and flicked the pump switch in the cabin a couple of times, and the engine picked up again. Happened 4 or 5 times.

So the act of turning the pump off and on again clears the fault.
 
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jimrat said:
Finally, a breakthrough! But it's weird......

My fuel pump uses much of the old carb fan wiring and relay in the spare wheel well. I decided to bypass all this, and run a wire direct from the fusebox to the pump, with a switch in the cabin to control the pump, and an indicator bulb on the pump so I could see if it lost power.

I took the car for a long test drive and it is still stalling. When it stalls the indicator bulb is still lit.

But instead of pulling over to a stop and turning the ignition key, I just coasted along and flicked the pump switch in the cabin a couple of times, and the engine fired straight back up again. Happened 4 or 5 times.

So the act of turning the pump off and on again clears the fault.
Click to expand...

Procure another known good fuel pump, remove the current fuel pump, install the known good pump. Repeat this road test identical to see if the results are the same or different.


Bernice
 
jimrat said:
Finally, a breakthrough! But it's weird......

My fuel pump uses much of the old carb fan wiring and relay in the spare wheel well. I decided to bypass all this, and run a wire direct from the fusebox to the pump, with a switch in the cabin to control the pump, and an indicator bulb on the pump so I could see if it lost power.

I took the car for a long test drive and it is still stalling. When it stalls the indicator bulb is still lit.

But instead of pulling over to a stop and turning the ignition key, I just coasted along and flicked the pump switch in the cabin a couple of times, and the engine fired straight back up again. Happened 4 or 5 times.

So the act of turning the pump off and on again clears the fault.
Click to expand...
Does it? If you were talking in terms of off once and the on again and it is immediately good, perhaps. If you "flicked the pump switch in the cabin a couple of times" then there is scope for a bunch of other things to be happening in that window. The pump is new, looks like a good brand and assuming it is installed per Hardi guidance, seems unlikely to be the problem.

What is the state of the flexible fuel lines? And even if they are new, are they good :). That pump can handle 1.5m of suction head so is pulling pretty hard on the supply line
 
jimrat said:
The fuel pump is a new Hardi 14412. Listed as suitable for fiat 128
Click to expand...
"All HARDI-Pumps have a special control system that enables the adaption of the pumping capacity to the consumption of the engine. This means, it will pump fast at high consumption, slow or not at all at low consumption and therefore a great deal of energy is saved (flexible stroke frequency)."

quickparts.mobi

Fuel Universal Pump 12V | Max 108 l/h | Hardi 14412

For vehicles with carburettor as conveyor pump from tank to carburettor, Fuel Universal Pump, Easy to install, Hardi 14412, Mitsuba- fuel pump.
quickparts.mobi quickparts.mobi


Appears this pump has a self shut off when some predetermined off point is reached. This could be the reason why the sudden fuel off, followed by pump switch cycled on/off several times, then the pump runs again. Without knowing the absolute specifics about how this pump functions (which does not appear on their data sheet).. the lump might be listed as ok for Fiat 128, in reality no.

Try a different fuel pump.
Bernice
 
Hi

Agreed, there is quite a lot of electrickery going on inside this pump, so I can see how a power cycle might 'reset' the flow.

I've just ordered the Pierburg 7.21440.51.0 recommended by lots of folks on here. I'll report back once fitted.

Thanks again for your help - great forum :cool:

1712946569712.png
 
jimrat said:
It feels electrical because it stops suddenly, but after its stalled, the dash battery light is on, I can hear the electric fuel pump whirring and there is still +12V to the coil. The ignition switch and battery are new, and the alternator is kicking out 14.4V.
Click to expand...
From the first post on this thread. If you can hear the "the electric fuel pump whirring" then its pumping. In other words, I don't think replacing the pump will fix the issue.
 
Please post some photographs of the engine bay showing the carb, fuel pump and lines, emission piping, tank sender area etc. A picture = a thousand words etc :)
 
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