E30 Zone

Right, since buying the car a few weeks back, i've not been able to solve a problem

3.20i (m20b20) if anyone asks

trying to start the car, it will turn and turn and turn without firing, then it will either start eventually or will drain the battery and it will need a jump where it will turn over a few times and burst into life

once its running, it wont cut out, doesn't pink or misfire, doesn't idle irratically

when i bought it, following a problem with a cracked radiator (and dumping all the coolant over the road on the journey home), i replaced radiator, water pump, cambelt, aux belts, air filter, rotor arm and dizzy cap.

i'm still to do a spark plug change, and oil filter change.

i have also been thinking about doing a fuel filter change

checking the plugs currently in the engine today, they are a light straw colour which indicates the engine running hot/lean (i think)

having tried starting the car multiple times before checking the plugs, they were dry (would expect them to be wet, which may indicate a lack of fuel on start-up?)

checked the coil which produces a decent spark when the engine turns over

a few times when checking the plugs, there didn't seem to be a spark (but if it fired on the other cylinders, then the plug being observed was sparking properly)

what function does the current transformer on the 6th lead serve?

engine doesn't smoke, and there is negative pressure in the rocker cover which indicates no problem with the head or gasket. no mayo on filler cap, or obvious oil in the coolant reservoir


what should i be looking at as the source of this problem? car had been stood for a year, so i expected a few probs, but not as many as i have already

thanks

please help me! this is the biggest concern i have with the car and the reason i'm not happy driving it anywhere

have changed fuel filter now and it seems a bit better, plugs are returning to their normal colour, but there's still a hesitation if you blip the throttle

is it worth getting injectors cleaned?

The Problem remains

still cant fathom it, thinking of taking it to a specialist

am i talking to myself?

Check out the condition of the plug and socket under the inlet manifold where the injector loom joins to the main engine loom. This plug and socket is like a miniature version of the diagnostic plug and its cap, and is fixed to the black metalwork. Especially check under the lower rubber boot, where water can become trapped.
The next thing you need to do ideally is to get a fuel pressure gauge teed into the feed fuel hose just before the fuel rail, to check on the fuel pressure and whether the system is maintaining pressure when the car is parked.
The low rev hesitation you experienced when you thought the fault had been cured is a very common fault occurs if the mixture is too weak at this point. This can be for many and varied reasons, such as a misadjusted throttle position switch, assorted air leaks, worn injectors, etc.

hmm, i shall check that plug, when i bought the car, it was not connected through the metal bracket, so i put it back through, i'll try disconnecting and reconnecting again

and as with most of the plugs, the rubber boot was not on it properly

i'm also liking the idea of a drop in fuel pressure, what should it be when running and when parked?

the fuel hoses do look quite old, i guess i could make a start of renewing them, what else could be the cause if the pressure is dropping?

how can i reset the tps?

oh, anyone know off the top of their head the fuel hose diameter? i'll just go and order a few metres and some new hose clamps whilst i'm at it

When you crank the engine and it does not start,are the plugs wet with fuel?

last time i checked, they weren't

try a can of this,

So your problem could be fuel related.

Lift the back seat cushion and remove the black cover over the fuel pump.
Wire a bulb across the pump connector.The bulb should only light when the engine is cranking.

If the bulb fails to light;
Fuel pump/fuel pump relay/fuel pump fuse and wiring must be suspects.
Or the ECU cannot detect the engine cranking which points to the CPS.

Fuel supply circuit works on the basis that the ECU knows that the engine is cranking,this information is supplied by the CPS,then power passes via fuse 11 to the fuel pump relay,this hides under a plastic cover mounted on the n/s inner wing close to the AFM.From there the feed goes to the fuel pump.
The relay can be proved by removing it and bridging two terminals,the one's you want have red/white wire(feed) and a green/violet(supply)this should make the pump run constantly,regardless of ign switch and CPS.

Have fun...

The fuel pressure should be whatever is marked on the regulator, which varies with model, but referred to the pressure in the inlet plenum, not atmospheric.
At wide open throttle and when the engine is switched off it should be what's marked, but at idle, when there should be a good 1/2 bar of vacuum in the inlet, it should be that much lower, as your gauge will be measuring with reference to atmospheric.
The fuel pressure should be maintained for days at least after the engine is stopped. If it drops, then either the backcheck valve in the pump is leaking, a fuel hose is leaking, or one or more injectors are leaking.

so the problem didn't happen today

but... when i turn the ignition on, i cant hear the pump prime. should it? wondering if the relay is on its way out/sticking? i know the little black box by the afr you're talking about, just need to locate the correct relay (there are two there from what i remember)

i cleaned and re-connected the random stupid twisty connector that goes to the injectors as well

havent had a chance to do the fuel pressure checks, need to know hose diameter, then i'll just order a few metres and start replacing it, and whilst i'm at it, add an inline gauge.

someone else said it could be the little valve in the pump



i'm noticing every so often the car stutters when driving (not a misfire), just loses power for a second then picks up again

does this suggest anything?

ooh, another related question...

can i replace the fuel pump through the rear seat? or does the tank need dropping?

thanks for the help so far, when i eventually find the main culprit of the fault, i'll put it up here for all to see

fuel pump is replaced by removing the rear seat bench and it's just under it, twists out on my 320i.

Check you fuel pressure regulator as mine used to stutter when driving because i needed to replace the O ring on it. Sounds fuel related though, and I also had similar symptoms when my fuel pump went.

cool, shame the pump isn't a cheap item

not sure what to go for/where to get one from

might go and nick the box of o-rings from work for the pressure reg

is there anywhere that sells the regs new? can't find them listed

and is it a possibility that i might be able to thread new hoses around?

i just really cant be bothered to drop the tank if i dont have to

I got a fuel pump from here for about £30 posted so just post in the wanted section. Would think Bmw still sells them but not sure, and perhaps they wouldn't be so cheap. Could also purchase an O ring from them as you can still get the ones for injectors for around 60-80 pence.
Then again you can check it it's leaking by running it for a while and see if it's damp after a drive around the bottom of where it joins onto the fuel rail.

New hoses for what? You don't need to move the tank at all for the pump. Take the bottom part of the seat out and there's a black cover that you undo with a few screws then you use two flat objects like screw drivers around the slits of the circle to turn it around and it just pulls out easy and hassle free.

someone on here suggested the fuel hoses may have perished

Green wrote:I then you use two flat objects like screw drivers around the slits of the circle to turn it around and it just pulls out easy and hassle free.

Not until you have removed the fuel level sender, it doesn't!

D'oh! well nearly remembered it all from back then haha

Also barton if there's a fuel leak, you can usually smell petrol before you can see it

yeah, dont think there's an evident leak, but i know for defo the hoses look old, and the one that joins the fuel rail is crispy

went to bmw for a price on a few bits

fuel pump = £90 ish - screw that , i'll get something off ebay for £30

fuel pressure reg - £180 ish - i'm not sure if he was looking at the right part or not, thats a lot of money

The great thing about BMW is that if you have a dud part, the chances of the same part being dud on a scrapper is generally very low. There's very little need to buy new.
One question that I can't see answered above: What age is this car?

1989

went to both my local scrappers, and all i found was a lowly 318 that had been stripped

i will always try to go for new over old these days, at least that way, you know that it wont be the source of fault

A 1989 car will be Motronic 1.3 - ! was just making sure this wasn't some primitive early M20 with things like cold start injectors grafted on to it.
I could reel off half a dozen faults on cars that have been caused by brand new components!

i have now replaced the fuel pump and fuel pump relay with no joy

Spoke to a guy today who said to check the fuel pressure reg and the timing sensor (on the front of the gearbox)

he apparently used to work on them and this was a common fault

i have a fuel pressure reg and phase sensor on order and will look into this timing sensor thing, i have a feeling its going to be a pain to get to

thats why the reg is on order, well its ready for collection, i've just not had time to get it

There are three other reasons why the car might not maintain pressure, other than the regulator.
Always test before replace!

pump has been replaced to ensure the non return valve is good, no obvious leaks around tank, filter, hoses in bay (although i will slowly replace for new hose for good measure

once the reg is replaced, that would only leave the injectors

the stuttering i get occaisionally would suggest its an actual fuel feed issue or electrical, this is why the sensors will also get done, if they aren't at fault, hopefully being new oe items will ensure they wont go wrong for a while (hopefully)

replaced the fuel pressure reg, the fuel hoses and the crank pulse sensor

THE PROBLEM IS STILL THE SAME!



i've got a mate coming over sometime in the week to check the fuel pressure, and i think we're gonna check the cylinder compressions just incase, but i really dont know what else to try, i've now spent as much as i paid for the car on new parts for it