Weird starting issue (744 B200F)

[AllHailKingVolvo]

Hi all,
My Mrs hopped in the 740 today to do the school run and to her (and my) surprise it wouldn't start. Tried cranking it for ages and other than an occasional splutter, no sign of it firing up at all.

I checked injector relay, fuel pump relay, main and lift pumps, coil, leads, plugs and allsorts...no dice.

Eventually I called the AA who came extremely quickly (under ten mins!) and explained everything, he checked for spark (all cylinders getting power) and feed to injectors (all power supply plugs lit his noid light), which left us both stumped. Tried to fire it up using Easy Start...still no luck.

Eventually, he took all the plugs out, cleaned and dried them, spun the engine over to clear any flooding, refitted the plugs and it started first time. It seems like it was flooded and couldn't clear itself...the first time that's ever happened to me in a Redblock car.

He suggested a dodgy CTS could be the cause. I know the IAC Valve is slow to respond and needs changing, but I'm not sure that would cause a problem like this.

Any ideas? The car is starting and running fine at present.

[Laird Scooby]

Battery. Sounds ridiculous and totally unconnected, especially as it's spinning over nicely but my money would be on the battery Phil. Very often when they begin to weaken, if left for a little longer than normal between uses the power drops just enough so while it still supplies enough grunt to spin the starter over, there's not quite enough for the ignition - this lets it flood and then there's no chance!

Other than that, Volvos sometimes do this, if it happens again, floor the throttle and hold it there, insert key in the ignition and turn the key to the start position and hold it there until it starts but no more than about 15 seconds.

This is the "flooded engine starting procedure" and usually works fairly quickly. If it needs a second try, remember to keep the throttle floored before turning the key from the zero position.

In either case, once the engine cathces and runs, come off the loud pedal.

[bob12]

As Dave, and followers of this Section will also know ... I have never found the final solution for this problem with the B200F which first manifested itself about 6 years from new (shan't go into the detail of what I haven't done to try to fix it).

I have learn't to live with it, and put in a higher power battery.

It always happens when the engine is either warm by driving and you need to re-start after 20 mins (shorter time and it starts on the button), or hot as a result of standing in the drive in the Summer without use - never, ever when the weather is cold. Has assumed it was a water senor or FPR, but no.

I have a slightly different method to Dave to start in when it wont start ....once the obvious problem happens I keep the starter turning, floor the accelerator and keep spinning the engine until it fires up after a few more turns and then immediately take my foot off the accelerator ... and orf we go without any thought of a problem.

Currently off the road while a new exhaust from the cat back being fitted ... it's never ending story, but I still quite like my 1990 745. Bob

[Laird Scooby]

Your "flooded starting procedure" is the Volvo method Bob, i found mine in a Bosch Technical manual i was reading one lunchtime while scoffing my sarnies.

The subtle difference is with your method, the ECU knows you've opened the throttle wide, with the Bosch/my method, the throttle is already open so the ECU ignores it. Your/Volvos method, the ECU then throws in fuel for WOT (Wide Open Throttle), my/Bosch method, it ignores the WOT switch because it was already there when the ECU was powered up by the ignition.

Both methods work well though.

[bob12]

Originally Posted by Laird Scooby

Your "flooded starting procedure" is the Volvo method Bob, i found mine in a Bosch Technical manual i was reading one lunchtime while scoffing my sarnies.

The subtle difference is with your method, the ECU knows you've opened the throttle wide, with the Bosch/my method, the throttle is already open so the ECU ignores it. Your/Volvos method, the ECU then throws in fuel for WOT (Wide Open Throttle), my/Bosch method, it ignores the WOT switch because it was already there when the ECU was powered up by the ignition.

Both methods work well though.

Dave, are you suggesting that the non-start could be due to lack of fuel being injected? Because, if you don't use 'a starting method' and just keep switching off and trying/cranking again, and again without touching the accelerator (opening the throttle valve) you flood the engine and make it nearly impossible to start even with either of the two 'starting methods'.

Bob

[Laird Scooby]

Originally Posted by bob12

Dave, are you suggesting that the non-start could be due to lack of fuel being injected? Because, if you don't use 'a starting method' and just keep switching off and trying/cranking again, and again without touching the accelerator (opening the throttle valve) you flood the engine and make it nearly impossible to start even with either of the two 'starting methods'.

Bob

Not at all Bob, i'm suggesting that by having the accelerator floored before turning the key, the ECU recognises the situation (flooded starting procedure) and not only does it not fuel for an engine with a Wide Open Throttle (i.e. extra fuel) but it also inhibits the cold start injection pulse helping to eliminate the flooding that occurred in the first place.

You're right, if you do keep switching off and retrying without opening the throttle, it will flood easily and be near impossible to start - hence the AA bloke Phil mentioned removing the plugs, drying them and cranking the engine to expel excess fuel - top marks to the AA for once!

[bob12]

Thanks Dave for clearing that up. The cold start injector is about the only thing I haven't changed - got a spare so might (only might) do it later in the year! Bob

[Laird Scooby]

Originally Posted by bob12

The cold start injector is about the only thing I haven't changed - got a spare so might (only might) do it later in the year! Bob

My point of view is that if Bosch knew about this in the early 90s and published their version of the flooded starting procedure in a TSB then it's not going to be an easy fix Bob - as such, i'd leave well alone and just deal with it if and when it happens.

The big thing as we've both pointed out in our posts is recognising that it may well be flooded and using the flooded procedure ASAP after that, before it has a chance to not just flood but drown!

[bob12]

Originally Posted by Laird Scooby

My point of view is that if Bosch knew about this in the early 90s and published their version of the flooded starting procedure in a TSB then it's not going to be an easy fix Bob - as such, i'd leave well alone and just deal with it if and when it happens.

The big thing as we've both pointed out in our posts is recognising that it may well be flooded and using the flooded procedure ASAP after that, before it has a chance to not just flood but drown!

'That's quite interesting'!! - and may be the answer to the problem in that there was some problem with the original ecu's although it doesn't answer why it took 6 or more years to manifest itself in my case. The original Bosch LH2.4.1 ecu for a very early 1990 B200F was a .... 590, but that was quickly changed to a .....549 in Aug 1990, and then again to a .... 936 (LH2.4.4) a year later when as I understand it the electronics did away with the cold start injector (or as Bosch called it 'valve').

Anyway after all this I think I shall continue to live with it as you know when it's going to happen and just deal with it ... I guess it doesn't help the longevity of the starter motor though, but I have a spare one of those!

Bob

[AllHailKingVolvo]

Thanks gents. The car did it again this afternoon...we went to leave for the school run at 2:30 and it spluttered then died, then wouldn't start at all. A VERY strong smell of fuel and no sign of it firing whatsoever.

Did the school run in the 240, came back and tried both flooded start procedures and it's still dead as a doornail.

The way the AA chap got it going was by disconnecting the injectors and cranking it until the fuel cleared enough to start, then reconnecting them. He thought the CTS was at fault and could be telling the ECU to fire the cold start injector even though the car is warmish/had been previously run that day, causing it to flood...it seems weird to me though.