Technical Panda 1992 - Electrical - Main fuse

[AAlko]

The car has trouble starting when the engine is warm.
I've had the transmission and injection rebuilt, replaced half the fuel system and sparkplugs.
On italian forums I discovered that a person had the same problem. After replacing the entire engine, it turned out that the main fuse lost conductivity when it overheated.
I'd like to measure the conductivity at it, at 2 different temperatures, to confirm the problem.
I however can't locate it. Haven't found anything online, and Haynes is no help either.
Could anyone assist? Thanks

 

[The Panda Nut]

Main fuse is not a lot to go on. I think this is likely a red herring but would suggest for a few pounds you could change the lot. You can now get fuses that light up when they are duff! Worth their weight in gold. The problem of difficult starting when hot is not uncommon with all small cars of this era and its annoying but to some extent seems to go with the territory. I understand that residual fuel condenses on the cyclinder walls and causes empty float chambers. Sometimes its best to crank without touching the accelerator and after 4 or 5 seconds floor the pedal. Any main fuse will be a higher value one. I cannot remember any others than in the fuse box on previous cars of a simialr age. I think trying a wide variety of starting techniques is your best bet around this. Other than this I would look at the mechanical fuel lift pump. If this is allowing backflow to the tank it could be the issue. Also check the fuel cap is venting as it should be.

 

[Dragon Man]

going on other Fiats, the main fuse is located on the red battery + cable. fiats like the cinquecento and mk1 punto have 2 cables a thick red one going to the starter and a smaller one that powers the ECU. the fuse is on the smaller one if you trace it.

lets not forget about the earth cable also. my advice is to attach a cable to a bolt on the engine, then to the car shell. it is common the original earth cable fails at the body connection. this can cause issues with the ECU. (it did on my cinqucento.)

hope this helps!

 

[AAlko]

Thank you both. I'll check these things once I'm back at the car.
Other issues that happened were it not running on a completely cold start. It cranked and ran with the starter, but lost power once the key was in the ON position. I only succeeded on the 4th try.
The engine completely lost power on the road. It was still running, but the gas pedal was unresponsive. The gas came back after about 300-400m. In the meantime, the injection light was on. Weird.
Sometimes it starts fine with the injection light on, which disappears after a few kilometers.
The one time it started when warm, the entire engine was moving ~5cm in about 0.5s intervals. Like it was gasping for air? I can send a video.
Sometimes the idle is uneven too.

My belt is a bit squeaky but still tight. I don't think that should be causing any major problems.

 

[Dragon Man]

that is sounding a lot like an ignition switch fault...

 

[AAlko]

All of that from ignition switch alone? Or everything but the temperature problem?

 

[Dragon Man]

it could be part of the problem. it could also be a faulty temperature sensor. on fuel injected FIRE engines theres 2x temp sensors. one near the dip stick and one on the intake manifold gearbox side if i remember right. that one can go faulty and cause all kinds of issues.

 

[AAlko]

I will continue the thread here, despite it not being an electrical problem anymore.
The car simply turned off after 20km of driving. It wouldn't restart unless I slammed the gas pedal. Without it, the starter was trying, but the engine wouldn't turn.
When the engine did run, it was pulsating and hopping.
At a red light it almost bogged down too, unless I slammed on the gas. Driving uphill, it screamed in high revs, but the power delivery was minimal.

Attached are the only problems which looked unusual to me.


Thanks

 

[Dragon Man]

hmm with the code light on i would still suspect an earthing fault. have you tried attaching a jumper cable onto a bolt on the engine then onto the car body somewhere? attaching a cable to the battery and engine wont work. the connection usually fails at the car body.


on an off chance. it sounds a lot like when i had water in my fuel tank, if you have one of those universal fuel filler caps get rid of it and get an original from a scrap car as the universal caps let water pour into the fuel tank when it rains.
it may be worth pulling the fuel pipe off the throttle body, putting it into a jug or container turning the ignition on for a few seconds then seeing what is coming out of the fuel line in the container. if you are getting water come out with your fuel keep cycling the ignition on and off to drain the fuel tank then go into the fuel tank from under the back seats to get the rest of the water out.
it may not be water, but its not a hard fix if it is.

i cant remember if the 899cc OHV engine has a MAP sensor (vacuum sensor). if it has they come out of the throttle body on a very thin black pipe. the pipe its self is subject to chaffing on things and getting a hole in it, also it uses rubber L connectors at each end that can split. if this sensor does not read the manifold pressure correctly due to a split in the pipe that will cause the engine to run like this, sometimes not start at all!

the oil coming out of the rubber seal is normal, the crank case breather goes into that pipe between the air filter box and the throttle body. this is where the oil will be coming from. you may want to check to see if the pipe is clear and free from blockages. in the pipe you will find a thing that looks like a wire bottle brush. this is a flame arrestor. it can sometimes get blocked up if the car is used for short journeys.

also check to see if anything is stuck to the crank position sensor. its below the alternator on the crank shaft pully. just make sure its clean and free from iron filings. i had a nightmare once where a magnet broke up and stuck to one. the car never ran but after cleaning all of the magnet fragments from the pully and sensor the car ran perfect.

just some things to try

 

[AAlko]

Right. I finally had the time to try all of these things out.
I wanted to heat up the engine, to get to the same problematic conditions as before, but it simply died on me after 1km on the road, the moment I slowed just a bit down. It had trouble starting, unless, like before, giving it a bunch of gas.
Managed to get back home, where it died sitting stationary. Still jumping/pulsating. Attached a jumper cable to the body and a larger screw on the engine block(restarting it the same way as before). Didn't have an effect.
The only red light that was consistently on, was the injection.

Pulled the thin black pipe/hose with the L connectors off last weekend. Looked just like new.
Took the entire pipe complex between the air intake and mono-injection off too. Looked just like new. It was recently replaced anyways. No brush in any of them though.
Found a tiny sensor by the side of the the pully. Yellow one? At least that one looked fine. Couldn't see much more without removing some parts of the car.
It hasn't properly rained in ages, and the cap is original so I highly doubt that it'd be a water in the fuel tank problem. Also, last time it ran fine for those first 20km.

With the headaches today, with the relatively cold engine, the only reoccuring problem was the squeaky belt in low rpm. Could that cause any of these problems?
Another thing I've noticed is rapid clicking in the injection. But that should be normal, no?

I'm completely inexperienced in such stuff, but wouldn't some of those problems fit a bad fuel:air mix?


Thank you a bunch for any replies at all )