Possible to disgnose a modern petrol non starter at home ?

[billm]

To be honest I'm more used to fixing petrol engines with traditional electrics, distributors and carbs.

So when it comes to modern petrol engine is it possible to identify why a car won't start with simple tools and logic as a home mechanic even though it's got sensors all over the place or does it need the professional analysers that garages use ?

As a hypothetical example, lets assume I have a '51 plate Astra 1.6 petrol engine car that now refuses to start yet last week it ran fine. Lets assume the battery is fine & fully charged, all electrical connections are sound, there's fuel in the tank and it spins over but just won't fire up & run.

If it's possible, what would be the sequence of tests you would follow if you had this problem at home to try to find the fault - other than tow it to a garage or call the RAC ?

[billm]

Krikkit - You're probably right, but it's a shame the home mechanic can't at least try to find simple faults like sensors going faulty without the need for expensive analysers.

My son did buy one off eBay a year or so ago to try to identify an ABS sensor fault on his Clio. It didn't help. So he asked a local garage to use theirs and nothing showed up on theirs either although of course the ABS light was still on. They said that not all codes can be picked up by and that it was likely it needed a main dealer analyser to find it.

[billm]

Agree, that's the same as any petrol engine, so if there is fuel in the rail and compression but no spark from any plug where would you go from there ?

There are a variety of sensors and lets assume in this hypothetical discussion one of them has decided enough is enough.

Presumably to start an engine, there are some sensors that must be working while others are there to make the engine run better once it's running.

So what I'd like to know is what are the important sensors to check that could stop it from starting.

I assume the Crank Sensor is one of them, and if it's petrol supply related presumably there is a sensor to confirm the fuel pump is running.

Any others that would stop it sparking ?

As a home mechanic admittedly there is a limit to what you can do with a reasonable set of tools and a meter but it would be worth knowing which sensors to check before admitting defeat and asking the local garage to fix it.

Edited by billm on Thursday 12th March 11:20

[billm]

Megaflow- Ah right thanks, I didn't know a failed crank sensor would do that. That's worth remembering.

Andy - With regard to a good manual do you mean a workshop manual from the dealer or a Haynes manual .. or would you recommend another brand ?

[billm]

kambites said:

Mine cost less than five pounds and, coupled with a smart-phone or laptop, will do everything I want it to. Best tool I ever bought.

What make/model is it ? That sounds like a good investment

thanks

[billm]

thanks, that's like the setup my son bought to find the ABS error on his Clio. Unfortunately we think not all Renault codes are publicised so it didn't tell us anything, neither did the local garage analyser who said the same thing, and said we'd have to get a Renault dealer to diagnose it with theirs.

But he has used it on his motorbike and it works on that too