E34 long cranking. Why?

[bimmerman]

Don't know why but lately I have to crank the car up for a few seconds and apply some throttle to get the car started. Used to happen when I don't drive the car for 1 week or more but these days it happens even when driven daily.What could the problem be? I'm using Splitfire plugs and they're only about 6 months old. Could it be my fuel filter? I'm not experiencing any power loss though.My car is a late model E34 M50B20 with Vanos.Thanks!

 

[flash]

Ahhhh, someone with the same problem as what I am suffering now.

Initially my car started out with erratic idling. Checked all hoses, fuel pump, fuel filter, ICV, etc, etc. Changed some parts. Idling better but still erratic and kena occasional hard starting problems. Traced to faulty MAF. Changed the MAF and now my idling is better, though not perfect yet. Could be due to ICV which needs to be serviced. But I still have that occasional hard starting. Oh, forgot to mention, my crankshaft sensor is ok.

Then I noticed it.... if I were to crank the engine immediately before waiting for the dashboard lights to go out, the engine cranks immediately. If I were to wait that few seconds for the dashboard lights to go out, then I would to crank for a few seconds. The symptom is almost like having flooded the engine with fuel before starting. So its like having to clear the cylinders from the excess fuel before the engine will fire. So it looks like I have leaking injectors and perhaps my fuel regulator is faulty.... something to look at the next round I visit the mech....

 

[ehoe]

I too had a similar problem on my E34 and traced the problem down to a faulthy timing sensor (aka crank position sensor). had it replaced and car starts up with a crank or two.

Have the sensor checked, apparently you can check its resistance level using a meter to see if its working ok or not. Search the forum on this, its been discussed several times before.

Good luck!.

 

[wan520i]

yeah...same here..it happens to me too...,

I Just added extra relay for the starter 2 weeks ago..., now still monitoring that sickness...

But seems it has improved..., but sometimes it also takes 2 - 3 seconds to start...

Before I add relay, worse case happened..., I can't even hear the starter cranking when I start, that happened after I came out from bank, not early morning. For info...my battery is new..about 2 months old.

Can some BMW experts help please... :cry:

 

[bimmerman]

But my car idles well and runs well. Only thing is that I have to occasionally crank a bit longer and sometimes I don't have to as it starts up immediately. I'm thinking maybe fuel filter stuck or injectors dirty and not enough fuel going to the engine during first crank? :dunno:

 

[wan520i]

Can it be spark plugs issue...? :dunno: when is the last time you change them?

I haven't change mine ever since converted....

 

[525iBoy]

mines the same but only when hot / after being driven few kms, starts right up on cold.

my mechanic says its quite normal for the m30, m20 engines and not to worry. I believe him as my e28 was similar and my fathers e23 the same (also from new). sometimes cleaning the injectors with some clean up stuff helps as does keeping the car in top tune.

Also helps to turn off the ACon

Hope this helps

 

[BmwRocks]

is the longer cranking due to not enough fuel or too much fuel? i had the same problem but after i changed the petrol filter it starts ok

 

[pussy]

hehehe.. the famous 34 cranking problem..

 

[wan520i]

hey pussy..., then do you have the famous solution for this..please??

Thanks...

 

[pussy]

sure.. i have wan.. buy me tea tarik and roti sardin..hehehe

 

[flash]

sure.. i have wan.. buy me tea tarik and roti sardin..hehehe

pussy's solution? Upgrade engine.... hee hee.

Ok, ok, I also wanna know because I too once in a while have long cranking issues.

 

[wan520i]

sure pussy.., no problem for teh tarik & roti sardin, i will add on with "gear box soup'....hahah...

so how la..what is the secret recipe to solve long cranking...please....

 

[pussy]

okay, this a step by step dianogsis procedure..cheapest method first.

1. check with a ohmmeter on the current supply for the fuel pump, starter wire from the ignition key, should be 8.3v above.

2. also check the ignition key switch current supply or the condition of the switch, newer ones clik once, engine starts.

3. buy a bottle of redline fuel injector cleaner, prior to that make sure your fuel filter is relatively new,max 3 months - reason is clog injectors with varnish & sulhpur built-up;

4. next is the condntion of your fuel regulator, old ones can't hold the pressure therefore once the pump loads up the fuel line, the petrol returns back hence the long cranking..or check the fuel pump relay or fuse, connection blades gets often dirty or 'burnt', more resistance.

5. purge valve on M50's only, is leaking, hence can't hold the fuel tank in-pressure
if the purge valve is ok, then replace the fuel filler cap. or worse case, check the purge valve hoses, front and back in the boot.

6. Crank sensor, cam sensor and TPS (trottle position sensor) needs to be check for current resistance.

7. if any modifications done to the cooling system, will also cause long cranking.. espiecally the cold start sensor/ valve.

8. As for M20's can be solved easily by getting the CO2 mixture right, ignition timming, new ignition coil, contact point rotor, etc..

hopefully this items help you guys...

 

[bimmerman]

Wow! Puss is a genius. Respect!

I think I will start from step 3 onwards. I think my car will pass step 1 and 2 because the starter motor cranks with such ferocity I feel you could stick the car on 3rd gear and drive it by starter motor and hit 60KPH!! I'll change fuel filter first and buy a bottle of redline injector cleaner and try it out!!

But I've got a real strong feeling that point 4 and 5 is the culprit.

Respect!!!

 

[flash]

Great guide. I will start from step 4.... having another set of injectors and still the same problem. Think my problem is with 4 and 5 because I have no starting issues just after shutting down the engine. The problem usually comes in when engine have rested for a longer period.

 

[bimmerman]

Here's the srangest thing guys! After changing my Aux Fan the long cranking problem went away! It's been 2 days already and no long cranking problem!!!

My guess is that the high underhood temperature was evaporating the balanced petrol in the fuel line or the regulator once I turned the engine off hence no fuel in the fuel line causing the long cranking. Also, there used to be a strong smell of petrol in the passanger compartment and under the hood when the car was hot.

Could this be the cause of the problem guys you think?

 

[bmwky]

Here's the srangest thing guys! After changing my Aux Fan the long cranking problem went away! It's been 2 days already and no long cranking problem!!!

My guess is that the high underhood temperature was evaporating the balanced petrol in the fuel line or the regulator once I turned the engine off hence no fuel in the fuel line causing the long cranking. Also, there used to be a strong smell of petrol in the passanger compartment and under the hood when the car was hot.

Could this be the cause of the problem guys you think?

Highly doubt the petrol inside the fuel line can be evaporated by the surrounding temperature of the engine.

 

[bimmerman]

Highly doubt the petrol inside the fuel line can be evaporated by the surrounding temperature of the engine.

I can't think of any other reason but it does seem like there is a connection. Now the underhood temperature is cooler the petrol smell is gone and the car cranks up immediately. Can anyone solve this mystery?

 

[wan520i]

PUSSY,

T H A N K S for the step by step tips..., so how you want your "gear box sup"? manual or auto? or with short quick shifter...haha...