Northern Auto Tech - ECU and Blue & Me Repairs

Technical Seicento 2002 stuttering

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Technical Seicento 2002 stuttering

I have had a lot of time this w/e but had a short play around yesterday.

I am not convinced about the fuel pump but bow to you Guys greater experience on these.

What does confuse me is that this only happens once the car is, that is once the cooling fan has run a couple of times. I am sure what heat related item might be relevant here. I tried disconnecting the pre exhaust sensor but that had no effect.

With the cover plate off the fuel pump I could hear it ticking regularly at about every second, but as the engine heated up it gradually slowed till the engine stalled. Quickly blipping the throttle could not catch it. Checked the temperate on the top of the pump but was only a couple of degrees warmer than the tank.

I have read somewhere on this forum that not all the sensors are activated when cold so allowing it to run rich until up to temp. Does this have any bearing?

Thoughts please?
 
I could be wrong but my understanding of your fuel pump is it should sound like an electric motor running , not ticking noise.
If I'm wrong or right please someone else help by posting.
 
Maybe it's the time it takes to warm up to fan starting rather than the heat generated.
 
jackwhoo said:
I could be wrong but my understanding of your fuel pump is it should sound like an electric motor running , not ticking noise.
If I'm wrong or right please someone else help by posting.
Click to expand...
A poor description on my part.

It is an electric motor but it was operating every second or so. I assume to maintain the pressure. That's why I described it as ticking.

Are they meant to run continuously or intermittently? You can hear it start when you switch on but then stop and restart intermittently once it starts.
 
All the ones I have seen on fuel injected engines run continuously.
The pressure regulator maintains the fuel pressure. By bleeding off excess fuel flow back to the tank.
They only electric fuel pumps I've come across that tick are ancient technology for carburettors that only need around 3psi fuel pressure.
Surely someone else can add to this.
 
To clarify pump runs briefly on key on to pressurise the fuel supply at injector ready for starting.
The pump then runs again while cranking on starter to maintain fuel pressure for starting.
Then if the ECU detects engine running ECU keeps pump running continuously .
 
You mean the fuel pump?

If you switch the ignition on but not start the engine, you'll hear the pump click a couple of times and then cut out. That's because the pump has supplied pressure - but there's no demand for fuel - so it stops. That's how it's meant to be otherwise if you left the ignition on the fuel pump would run continuously pushing unwanted fuel to the engine and back into the tank via the return.

In normal circumstances the pump will click/tick and whirr or 'hum' when the engine is running, though be aware you probably won't hear it from the driver's seat.

When I had trouble with my Golf estate I removed all the panelling in the rear and drove it with a mechanic friend who had his ear pressed to the top of the tank. Apart from getting a bang on the ear every time I went over a bump, he couldn't hear the pump working. It was working obviously .. but at times it would stall/stop and cause the car to splutter and die.

It's difficult to see how the fuel pump is affected by engine heat.
Too weak - a lean -mixture will cause overheating. Too rich a mixture -like running with the old manual choke pulled out - causes a loss of power and cutting out. If the mixture is too rich your plugs would be blackish.

The image attached shows spark plugs that have had a lean-rich and normal running.
 

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Yes I mean the fuel pump.
I have heard them whirring but not ticking.
 
OP I think it's time to just try a replacement pump or you will get no where.
Did you try monitoring the return flow to the tank as suggested?
 
jackwhoo said:
OP I think it's time to just try a replacement pump or you will get no where.
Did you try monitoring the return flow to the tank as suggested?
Click to expand...

No did not do the return as it does not go back through the top of pump but the hose goes under the back seat somewhere to some other connection. I'll try and get a photo when I take the dog for a walk in a minute or so.
 
Here is the pump. The blue pipe continues under the seat towards the nearside and I assume is the return pipe.
 

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glenn2602 said:
Seamus, I full agree with Jackwhoo. You now need to fit a new fuel pump. You're not going to progress one way or the other until you've fitted one.
Click to expand...

Looks like it. Trying to avoid unnecessary expense but looks like it.

I will get those small nuts off tomorrow and get a better look at it to make sure I get the right type.
 
Get yourself a manual for the car, you will learn a lot and it will give advice and info specific to your car.
 
Where the fuel return to tank pipe connects to the fuel rail . If possible disconnect it there. Connect a spare hose to the fuel rail and measure the return flow there.
Don't cause a fire , if you are not sure don't do it.
But a manual for your car , worth repeating.
 
Another thought is the crank position sensor.
When starting to fail they usual cause problems when hot, no starting when hot a typical sign.

When your car stalls and won't restart , immediately check you are getting spark from HT lead to engine , use a spare spark plug if you have one , so there is as little delay between stall / won't restart and spark check as possible.
If you have no spark try a new crank sensor.
If you have spark then change fuel pump.
 
Ok. Made some progress today.

Got the fuel pump and stripped it down to clean the filter which was not that bad. Then bench ran the pump, yes I know you are not meant to but a few seconds on and off should not hurt it. Did not run well to start with then got to run more steadily.

Put it together and back in the tank. Ran the pump with a spare hose connected into a can so as to purge and remove any much that might have entered. Noticed that it will only run for a few seconds at a time. Presumably ecu detects no pressure and turns off.

Connected pipework and started engine - all ok. Noticed that now the pump runs continuously. Once hot took it for a 6 mile run and no problems. So maybe problem solved. Definitely fuel pump, whether a temp cure or not we'll see. Probably will replace the pump when I see one at a good price. Are the other makes compatible?

Thanks to you both for persisting with the fuel pump. I really did not think that was the cause.
 
jackwhoo said:
To clarify pump runs briefly on key on to pressurise the fuel supply at injector ready for starting.
The pump then runs again while cranking on starter to maintain fuel pressure for starting.

Then if the ECU detects engine running ECU keeps pump running continuously .
Click to expand...

There is no component to detect fuel pressure.
Only if the ECU detects the engine running does the ECU keep the pump running continually
 
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