E30 Zone

Non Starting S 14 engine, car has been stored but has been started frequently and has never been a problem before

I remove the airflow meter to clean the engine bay below, I've put it all back together and now she won't start whether this is coincidental I don't know. I have checked the two relays behind the header tank they seem to be okay and fuse 11 is okay . There is fuel in the injector rail but I need to check if the fuel pump is working and the injector system is working correctly how do I do this?

The engine turns over and nearly wants to fire up, if I spray starting fluid into the plenum chamber it fires up for a few seconds but will not continue to fire up and idle, it feels like fuel starvation.

Any help would be much appreciated

M

Pull off the fuel supply hose at the injector rail and give the engine a short crank. Fuel should pour out of the hose. Note that the supply hose is the one that goes straight to the rail, not the pressure regulator.
If this works, check for sparks at a spark plug when you crank the engine. Make sure any spilt fuel from the first test is gone first.

As above, get yourself a closed container and pull the fuel line to the rail. Just turning the ignition on should I think prime it enough to give you an idea of fuel flow.
If nothing much happens, check the pumps. You should be able to hear them prime or running. If the in-tank pump is bad/blocked, I don't think the other pump by the drivers rear wheel arch is enough to make it run alone.

If the only thing you've done is remove the AFM ,Check the wiring to the and the contacts on this and the plug to make sure they weren't damaged in any way. If the cars been sitting, pull the dizzy cap and just make sure the cap and rotor contacts are fine.

If you are leaving the car for a long period of time unused , what is the fuel like ? Has it sat for years with the same fuel ?
You could pull the in-tank pump and check the tank for rust and test the pump. The M3 in-tank pump is a complete unit and something stupid like £350 from BMW. The cheap eBay pumps are nearly always with the wrong electrical plug for an M3 . If you have problems with this, check on s14.net, I think some people remove this and use a higher flow main pump alone. If the pump by the wheel arch sounds like its not working, a gentle tap might wake it up.

It's only two bolts to remove the fuel rail and then unclip the injectors. Look on YouTube how to test them simply with a battery. They don't have to be producing a perfect stream, but you can verify if they are working/blocked.

I take it you just unplugged the AFM and removed the whole airfilter/AFM assembly as one to clean that area of the car ? Apart from the wiring plug, I can't think what else could really go wrong unless you did something really daft like left a rag in there and blocked the airflow. I guess if it's been sitting ages, especially outside, it is possible to have had something nibble on the wiring.

Thanks for your advice guys .
Is ther a noticeable noise from the wheel arch pump when working, l have given it th the usual tap or two but still no joy so will have to try in tank pump next. When taking off hose on injector rail does the fuel flow on cranking of engine all the time ?

Will the fuel flow out of rail hose with just ignition on at key position two ?

Not totally sure, but think they many only run when the engine is running or your cranking the motor. If you crank it over you should get decent fuel flow. Just try the ignition and see what happens first if not crank it quickly. You may need an assistant to crank it over while you listen for the pumps. Remove the rear seat base ( just pulls out ) and remove the access cover plate ( 4 screws ) and you should be able to hear the in-tank pump do something. I guess you could always try running a live feed direct to the pumps to quickly try them.
Did you pull the plugs last time you tried, were they wet with fuel or bone dry ? Might be obvious, but please remember to disconnect the battery when doing anything on the fuel system and don't need it live.

M3888 wrote: ↑

Sat Jun 20, 2020 5:02 pm

Will the fuel flow out of rail hose with just ignition on at key position two ?

No. Engine must be cranked.

Engine will start and idle almost normally with the AFM unplugged.

The pumps are providing fuel immediately into a container when first cranking so would it be the pressure regulator or an electric feed / signal issue to fuel injection ?
Thx M

Did you check for a spark, did you check if the plugs get wet when you cranked it over ?

l have a spark ,plugs are not wet ,fuel is being pumped on cranking,
Is there a way of testing pressure regulator ,does it come off the injection rail ?

The regulator is a push fit on sealed with an o-ring and two little bolts holding it in place. It's only two bolts to remove the whole rail and injectors. Might be worth removing, draining, cleaning and testing the injectors. How long has it sat for since last running ? Not sure how to test the regulator or pressure, there is no valve to easily hook up a pressure tester.
Try asking on s14.net, you have many more M3/S14 owners and a whole section in the forum on no start issues.

20160517_124446 by E30M3powered M3, on Flickr

If your car has an in tank 'lift' pump feeding the main pump, then the fuel flowing could be from this. Fit the hose back onto the fuel rail, and disconnect the hose from the pressure regulator, then crank the engine. If fuel flows from the regulator, then you can be fairly sure that the main pump is working and that the fuel rail is up to pressure. It's almost unheard of for pressure regulator to fail in such a way as to give no pressure.
If you still want to confirm the fuel pressure then ebay offers gauge kits for less than £20. You need the type that includes a tee piece and a short piece of spare hose.
The M3 engine management is fairly primitive when compared to its M40 and M20 compatriots, and, according to the wiring diagrams, still used two flywheel sensors throughout its life, using one for engine speed, and the other for cylinder identification, instead of using a single sensor and a missing tooth for cylinder ID. If one of these sensors fails, the pulses from the working one will still operate the fuel pump, but the injectors won't operate, because they have no information as when to fire.
The system above was also used on early M20 engines, and as well as the sensor failing, there was also the possibility of the trigger magnet for it, which is attached to the flywheel, deciding to unattach itself, although I'm not sure if this happens to M3 flywheels as well.

Morning Brian
I pulled off the hose by the pressure regulator and cracked her over and a decent amount of fuel flowed so I'm happy at the moment but the fuel pumps are working.

I changed over the airflow meter just to check to see if it was a bad connection but the airflow meter seems to work okay on another car so I have discounted that
Thenext thing I was looking at maybe is the crank sensors that you mention I have located both on the gearbox which is which I can see there is a top one and a lower one?

I will now change over the injector rail completely I will also pull out the injectors to see if they are blocked .

Starting to run out of ideas now maybe rust in the tank but it is flowing from the rail at a decent rate I assume not
Any more ideas would be much appreciated thanks

Lack of signal from one of the sensors on the gearbox would give the symptoms you describe. I would expect it to be the position sensor (the straight one) rather than the pulse sensor, although I'm not familiar at all with M3 engine electrics in detail. The system is similar to the early M20 engines, which I'm still only slightly familiar with, but these used two identical sensors that could be swapped over to see if the symptoms changed.
The pulse sensor tells he ECU that the crankshaft is rotating, so it's happy to switch on the fuel pump, but without the position sensor it won't know when to fire the injectors.
Ideally, you want to get an oscilloscope connected to both sensors.

Hi Brian
I have found three sensors on the gearbox I removed the top one and changed it over from another car and tested it and no difference so I am assuming this is the speed sensor which is the top one

Assume the bottom two ,are the ones you are talking about so I will remove these and change them over from the other car as I don't have an oscilloscope
Thx for your help and advice Mike

I started to change over the injector rail ,I removed the two bolts and the feed and return pipes at the rear of the injector rail , I have also removed the four clips that hold the injectors on but I'm not too sure how the injector rail pulls off ,is it just a bit of brute force to remove it ?
Thx Mike

If you have another working engine to borrow bits from, then yes, change the sensors over, starting with the straight one. You could also compare resistance readings at the plugs before removing them from the car, to see if that gives a clue.

M3888 wrote: ↑

Sun Jun 28, 2020 10:40 pm

I started to change over the injector rail ,I removed the two bolts and the feed and return pipes at the rear of the injector rail , I have also removed the four clips that hold the injectors on but I'm not too sure how the injector rail pulls off ,is it just a bit of brute force to remove it ?
Thx Mike

Stuck O rings probably. These should really be replaced if you remove the rail, so I'd just put it all back together. All four injectors are unlikely to fail all at the same time.

What readings should I be expecting?

Identical ones between the same sensors on both cars. I've no idea what the figures are for S14 sensoors, sine I've never measured one.

Hi Brian
, l have managed to get the engine going although it is misfiring, I changed all three sensors from the other car and found that one of the pulse sensors was faulty.
Got the engine going although it has a misfire,
I changed all three sensors from the other car and found that one of the pulse sensors was faulty, from the top of the gearbox there is the position sensor the smaller one and then to pulse sensors ,it was the middle one that was faulty ,part number on it is1708610,( The one below has a part number 1730772.9) it is connected to the left connector of the three behind the plastic casing at the bulkhead I'm not too sure which pulse sensor this is activating . I called Cotswold parts and they identified the pulse sensor as both the same with the part number of 1730 773 for that car . I have found a non-OEM post sensor on the net with a part number of 170 8610 for less than half price of the genuine one ,do you think this iwould be okay? Oem is £120.
The misfire seems to be on cylinder one and two as I can remove the plug lead from the distributor cap with no difference in engine tickover or rev which is obviously lumpy , so it seems that the injectors on one and two are blocked , l do have a spark from one and two
I have ordered a set of four O-rings for the injectors so I can remove the injector rail and see if I can clean and service the injectors , what's the best way to clean the injectors and to test them do you know a method?
New injectors are not available anywhere at the moment so will have to persevere with trying to clean them and hope this will rectify the misfire, the plugs on one and two don't seem to be wet either after I have run the engine with a misfire, so I assume it is not getting any fuel or if it is very very little .
Any advice on above would be much appreciated
Mike

M3888 wrote: ↑

Fri Jul 03, 2020 8:26 pm

what's the best way to clean the injectors and to test them do you know a method?

Send them to James at Injectortune, he is a trader on here or make contact through the web site and tell him you come via the Zone.

http://www.injectortune.co.uk

He has done injectors for a few on the Zone (including me) and does a good service

Before you remove them you can listen to them with a stethoscope or a large screwdriver touching the body of the injector and fat end against your ear, a working injector ticks. If they are not ticking they could be stuck which can be fixed by a tap with a decent sized spanner, I find a 19mm works well
I find the best way to see if injectors are working as they should is to remove the rail with the injectors attached, sit it on top of the engine with hoses/injectors secured and crank the engine over so you can see the spray patterns from each injector

The lower sensors in the bell housing are the ones the ECU uses, the upper one is for diagnostics and is not connected to the ECU, only to the diagnostic port.

Thx will try that tap
I've had a reply from james at injecturetune too
Referring back to the two lower pulse sensors it's the upper one that was faulty and would not let the car start what does this do? ,as this was not allowing it to start,

Thanks Mike

Eureka!!!

Thanks Dan ! I should've hit it like I do with most things when they don't work and that's always the last resort is to hit it with a hammer should've thought of that but every day is a school day you could definitely hear the tapping of the working injectors and then I listen to the nonworking ones no sound did have a good time and boom they were working thanks really appreciate it now just got to sort out the faulty pulse lead mike

....good tap and boom .....

I can't remember which way round they are but one is closer to the engine which lines up with the ring gear, the other is further back to line up with the reference pin