Engine stops for no apparent reason

[charlielucky]

Hi, just a short update on my incredibly annoying problem. So my local mechanic removed the catalyser and now the car will not start at all. He thinks that the catalyser is clear and the problem is elsewhere and as he can't find the problem he is throwing in the towel. I am renting a trailer to pick up the car this afternoon and will no doubt be bothering you all again to try and find what's going on.

I mentioned before that I have replaced the fuel tank, filter and pump along with the injectors. Do you think I might have a problem of fuel pressure or blocked fuel return line? Could low fuel pressure explain why the car will not run over 3500 rpm?

Charles

[Nut124]

If the engine does not start at all, that would be the first thing to diagnose. Try to find a mechanic who works on old cars.

To run, you need spark and fuel. Spark is easy to check.

[charlielucky]

Hi. I followed your advice and went back to basics. The spark looks fine so I checked the fuel pressure.

The pressure on the cold start valve was 2.8 Bars on turning the key, but dropped back to 2.1 once the car ran on idle. I decided to check the pressure coming through the fuel pump and filter and it was over 4 Bars. My assumption is that there is something partially blocking the fuel line. Tomorrow I plan to replace the metal line with an 8mm rubber line all the way from the fuel filter to the injector bar. Hopefully this will solve my ongoing problem. Charles

[ORFORD2004]

You should blow air in the line or replace it. Metal is safer and it pass inside the car. I use 5/16 brake line from advance auto parts on mine.

[charlielucky]

Hi and thanks for the tip.

Please assume I haven't a clue what I'm doing. I have the fuel injection notice and think I understand how the system works. So if the fuel pump and filter are both good and I'm getting a free flow of fuel through the fuel line to the injector ramp, the culprit for low pressure could be a faulty fuel pressure valve or a blocked fuel return line. Is this correct? Should I be able to disconnect the return fuel line from the fuel pressure valve, and be able to blow are freely through the line into the fuel tank? What is the function of the connector between the three lines leaving the top of the fuel tank and the fuel return line?

Thank you for your patience!

Charles

[charlielucky]

Hi again, just a quick update.

I used the compressor to blow air through the return hose and there was no obstruction at all. I started the car again and it runs very sweetly to 3500 revs but then jus splutters and dies. In the Fiat shop manual the pressure rating is 2.3 to 2.7 bar which corresponds to the pressure I have in my fuel rail. The pressure when connected to the fuel pump should be 2.7 to 3.2. When I checked mine it was closer to 4 Bar. Can't think of what to check next!

[wizard124]

I'm working from memory regarding the Bosch FI system. So, the car starts and runs well until 3000 to 3500 rpm.

There is a engine block mounted thermo switch which controls the cold start valve. Once warm, it directs the CSV to close to reduce the fuel entering the fuel rail ie. No more choke for cold starts. Let the engine warm up to temp then pinch off the fuel line into the CSV. If this solves your issue then either or both the CSV or the thermo switch is failed.

The other culprit could be the air flow meter. These can be rebuilt. As more air enters the engine, the flap opens wider and wider. If the resistor strip is bad, it may be giving a bad reading to the ECM and shutting off the engine.

[charlielucky]

Hi, I sent my ECU and Air flow meter to Arnold classic in Germany to have them tested. Today I got the results and my AFM is working OK but the ECU is faulty and apparently can't be repaired. Just wondering what my best options are to get a replacement part. I see that Autoricambi has a remanufactured part that is affordable. The problem is that getting it sent over to France and through customs. Has anybody tried to get their original unit repaired?

[bobplyler]

Doesn't https://shop.spider-point.com in Germany have those parts?

[charlielucky]

Hello, just to let all of you kind people know that my engine problem is now resolved. I sent my AFM and ECU to Arnold classic in Germany and they eventually tested the units on the same model car. Turns out that the AFM is working just fine but the ECU is malfunctioning. I called Middle Barton Garage in the UK and they happened to have an ECU taken out of a wreck and I purchased it without a guarantee for 100 pounds. I installed it this weekend and Bingo! The engine runs smoothly and revs up without any problem. The idle is still too high for my liking but with adjustment it should come back down.

I have two problems left to resolve on the car. My local mechanic installed a new universal joint in the propeller drive shaft and after a few miles the top casing on one of the branches broke. The mechanic assures me he kept the shaft aligned when he changed the unit so I have no idea why it failed.

The other problem is how on earth do I change the starter motor?

Thanks again for all your good advice.

[18Fiatsandcounting]

The other problem is how on earth do I change the starter motor?

Unfortunately, this is one of the harder jobs on a Fiat. You have to find the right combination of sockets, swivel joints, extensions, socket drives, etc. to make it work. Of the 3 bolts, the bottom one isn't too bad. The middle one can be removed but it takes a while. But that top bolt is a real pain, and it just takes practice and patience.

Having small hands helps.

I usually start with the hardest bolt (the top one), so that the starter motor flange doesn't tilt and make it harder to remove the bolt. Then the middle bolt, then the bottom one. Learn to curse in Italian.

After many years of doing this, I can usually remove a starter in under 30 minutes. But again, this is one of the harder jobs on a Fiat and not one that I look forward to....

Good luck.

-Bryan

[charlielucky]

Hello Bryan,

When you changed the starter motor on the 124, did you go at it from above or from underneath the car? I've got a dodgy back and crawling around under the car is beyond me!

Charles

[18Fiatsandcounting]

Hi Charlie,
Removing the bolts from the starter motor happens from underneath the car. Once the bolts are removed, the starter can be wiggled toward the front of the engine and then it comes out through the top. But, removing the bolts requires working underneath the car.

But, before you remove the starter, what was the reason for wanting to do this? Some starter motor problems are simply poor electrical connections to the starter motor solenoid, which doesn't require removing the starter to fix them.

-Bryan

[charlielucky]

Hi Bryan,

My local mechanic told me the starter motor is on the way out because it refuses to engage a lot of the time. I'll take your advice and use the Dremel tool to clean up the connections to see if this solves the problem.

regards

Charles

[DustyDave]

Just a data point, on my ‘78 carb spider I had same issue a while back. Tore my hair out to diagnose. Turned out to be bad ignition caps on the rotor. I bought them brand new to replace aged ones, and they would get a spark from the plugs in atmospheric pressure, but they were the problem in the end. I replaced them with ones from another vendor (more expensive), and it fixed it without doubt. They would work cold, but once they got hot my car would stall instantly with minimal amount of sputter. The fuel smell is likely when you stop igniting all that fuel and it has nowhere to go. Not sure what FI ignition setup looks like and if similar to my ‘78, so take my experience for what it is worth. Good luck!
David