HELP - E21 doesn't start at all after renovation

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SFerrari
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My E21(s): 1978 E21 318 carb

HELP - E21 doesn't start at all after renovation

Post by SFerrari »

Hello :-)

Here, I quickly summarize the situation: I completely renovated a BMW E21 318 from 1978.
After 8 months of work, I tried to restart the car yesterday for the first time without success.
Initially the car ran perfectly.
The top engine has been redone.
The carburettor completely dismantled, passed to the ultrasound, and ALL reassembled with new seals/membranes etc...
I installed also a manual starter kit.
I switched the ignition to electronic ignition.

So when I turn the starter key, the engine shows NO sign of starting, not coughing even a little.
I do have a spark at the plugs (ignition seems OK, but you never know whether to shift to 180° or other?)
I do have gasoline coming into the carburettor inlet (if I disconnect the inlet duration, beautiful jets of gasoline come out under the action of the starter).
When I activate the accelerator manually I have a nice strong jet in the primary body of the carburettor coming from the curved brass nozzle which is under the butterfly of starter (so the gasoline arrives correctly no??)
I think (without certain) that I don't have an air leak in the circuit between the carb and the cylinders: all new seals, correctly tightened (but hey, you never know....)
Despite all this, the car gives NO signs of micro start wanting to show any sign of starting.

What I think is the major issue I noticed: the spark plugs stay dry!!!!

My question 1: in view of a whole day of tests / start-up attempts: they should be wet, even drowned?? Can you confirm this point for me, in order to already know if the fact that the spark plugs remain dry is a major point? They don't even smell gasoline...

My question 2: according to your experience and your knowledge, what could I do as a test in order to target the problem: do you put a little gasoline directly into the cylinders with a pipette and try to start (to rule out the pb of arrival of gasoline or air intake)? If yes, how much? Or else gasoline directly in the body of the carb (but how much)? I do my tests without the air box above the carb: is this a big pb? I tried with it but it didn't change anything by the way...

My question 3: what is the test on the carb side, without having to disassemble it, would allow me to know that the main jet sends enough gasoline for starting? That the carb's tank is full enough? Is having the brass nozzle which sends fuel under pressure from the accelerator a sufficient factor to say that the fuel supply to the carb is good and that this quantity of fuel alone would be sufficient to at least make the car cough at startup??

Thanks for your help if any abvious idea came up, and just some additional testing track...
Regards


SFerrari
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Posts: 18
Joined: Tue Mar 01, 2022 3:21 pm
My E21(s): 1978 E21 318 carb

Re: HELP - E21 doesn't start at all after renovation

Post by SFerrari »

Two more additional test I have just done :

1) I have put the all 4 plugs out and starting the engine : I can see 4 alternate plugs flashing. But I cannot tell if the flash is good/strong enough !
2) I have inserted some gasoline directly into the 4 cylinders through the spark plug entrance, and even also directly inside the primary body of carburator : nothing happen ! Maybe just one very very tiny cough once !!

What to conclude at this stage ???? Bad ignition (becasue I istalled new electronic ignition with new ignition coil etc...) despite the good spark plug flash or bad carburation ????

I am fully lost at this stage !!
Putting gasoline directly in cylinders should have help in the engine caughing no ????

I have 2 ideas at this stage :
1)putting back all the old ignition system, cables, ignition coil, etc... and test it.
2) Also I may need to take engine compressions to make sure I have no leak (I have renewed the engine head, valve seals, timing chain...) or bad timing. What do you think ?
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Jeroen
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My E21(s): '81 323i Baur
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Re: HELP - E21 doesn't start at all after renovation

Post by Jeroen »

Oh man I can only imagine how you feel, not being able to get the car to run after so much work done!

Since you already did some experiments with fuel and spark, I'd definitely do a compression test first, just to be sure.

Usually with these carb models, it can be a pain to get the fuel pump to get started after a long time of no use, and usually a little carburant in the carburettor chambers should suffice to get things back to life again, and as you wrote, should at least give you a cough. With the spark plugs staying dry, I'd definitely test measure fuel pressure as well.

Even though you have a spark, your new ignition may be playing up as well. Not enough current from the battery, bad ground connection, bad coil or timing incorrect... could all be the case, and perhaps you are so unlucky that for example you have both an ignition leak and a fuel pressure problem at the same time. Small chance, but not impossible after a big project. Make sure both engine timing and ignition timing is spot on, it may be worth to try the old ignition indeed. Note that you need a different coil now you've changed the ignition set up.

These are the first things I'd check... fingers crossed mate!
Regards/groeten, Jeroen
SFerrari
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Posts: 18
Joined: Tue Mar 01, 2022 3:21 pm
My E21(s): 1978 E21 318 carb

Re: HELP - E21 doesn't start at all after renovation

Post by SFerrari »

IT IS ALL GOOD NOW !!!! IT WORKS :-)

I have finally discrovered that (for unknown reason !!!!) have reversed by 180° the camshaft, so cylinder 4 instead of cylinder 1 was used, and so for cylinders 2 and 3.
I just have reversed the spark cables and now it fires up at first crank !!!!!!!!!!!!!!!!!!
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Jeroen
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My E21(s): '81 323i Baur
Location: The Netherlands
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Re: HELP - E21 doesn't start at all after renovation

Post by Jeroen »

That is great news! Enjoy now!
Regards/groeten, Jeroen
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uwbuurman
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My E21(s): 1978 type 1 323i 5speed dogleg Polaris
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Re: HELP - E21 doesn't start at all after renovation

Post by uwbuurman »

So you'll have an later type ignition and earlier engine of the other way around. Since those run in opposite ways.

But you'll figured it out, congrats! Beware of oil degredation, since it would not fire up, after numerous attempts, you'll bound to have gasoline in your oil, which may harm your engine, hence the oil is to thin. (I would change it....)
It's the man next door!

1978 BMW 323i
1980 BMW 528i maior restitutio
1987 BMW 325iA cabriolet
2006 BMW 320d touring High Executive
2015 BMW 320dA touring xDrive High Executive ///Msport
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