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Discussion Starter · #1 ·
Has anyone else experienced poor starting in hot weather on a 155?

I need to crank the engine for upto 30 seconds before the motor (1.8 16v) fires. When it does fire, it starts cleanly and runs quite happily.

My feeling is that it is fuel starvation, possibly vapour locking in the fuel pump(it seems worse when the tank is low).

Any ideas appreciated.

Simon
 

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I get the exact same problem (1.8 16v) on hot days, but starts first time after 5-10 minutes. Alfa garage could find nothing wrong and suggested vapour lock also. I just try park in the shade now!
 
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Discussion Starter · #3 ·
Sounds as though it could be vapour lock or possibley a fault return valve in the pump. One easy way to check if it is fuel is to pulse the pump when you have the problem. Ie if she wont start, don't crank the engine, just switch on the ignition, wait 5 seconds then switch off, repeat 4 or 5 times then crank the engine. Each time you switch on the ignition the fuel pump is pulsed for a few seconds and so if done in sequence it will prime the fuel system and build the pressure up. If it works, next time reduce the times you pulse the pump, until you find the minimum number of times required. Dont bother cranking as all you do is waste the battery. To check for vapour lock/valve fault you need to have a fuel pressure guage fitted and recreate the conditions which cause the problem.
 
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Discussion Starter · #4 ·
There is a lengthy thread on this subject the on alfa155.com technical forum (called "poor starting").

Chris posted the following message there...
"Some earlier versions of the ECU had a fault when cold starting after the car had been sitting in the sun. This can be corrected by a PROM upgrade but its probably not worth it if the problem goes away after a minute or so. No matter if this is the reason or if its just vapourisation of fuel, either way you know its not terminal"

Does anyone else know about this ECU fault?

My car also suffers from this problem (2.0 16V 1997) so I have to park it under a tree when it's sunny where it ususlly gets covered in bird s**t and sap. A more paintwork-friendly solution would be nice.

David.
 

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HI SIMON, HOW ARE YOU, IT´S ME JORGE DELGADO FROM URUGUAY, SOUTH AMERICA AND WE USUALLY TALK BEFORE AT ALFA155.COM, DO YOU REMEMBER?
I MUST SAY THAT NUMAN AND DAVID ARE IN THE RIGHT WAY, IT IS NO OTHER THING TO DO WITH THIS PROBLEM
CHEERS
 
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Discussion Starter · #6 ·
Thanks for the replies. I've ordered a cheap(ish) pressure tester as the fault is intermittant and that way I can leave the tester in the fuel circuit. BTW does anyone know if the fuel filter has a non return valve in it? I know that it is direction specific.

Simon
 
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Discussion Starter · #7 ·
I think I may have finally solved the problem! (with Mangoletsi's help).

Whilst on holiday in France, I noticed that when I had the starting problem, the cooling fan would run, even though the engine was cold. Picking peoples brains revealed that on the last 155's, the fan was controlled by the ECU. In the end I put it in to Mangos as I didn't have time to look at it myself and they found that the coolant temp sensor had corroded connections under the rubber boot. This was causing the ECU to run rich as it thought the coolant temp was a lot lower than it really was- this also explains perhaps the fact that it's on the 4th (!) lambda probe.

Now I've got to wait until the hot weather again!

Simon
 

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I had a similar hot starting problem with my old 8v 155. Engine would turn over and over but not start properly, then when you release the key it would pop back. One time it did this it literally blew the 4 rubber connecting hoses off of the plenum chamber. And of course this all happened when I was on my way out and in a hurry.
30 mins later with the rubber tubes back on and things were back to normal.

Never managed to fix the problem properly, kinda went away when I sold the car.

Steve
 
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