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Discussion Starter #1
Dear Friends,

I bought a non running '93 33 1.5 IE about 1.5 years ago and fixed gearbox synchros, changed T-belts, changed fuel filter, replaced all fuel hoses from the tank, replaced HT leads and installed a new clutch kit. It was running well and passed the emission test as well.

Later it spent a 2-3 months not running at the mechanic for some suspension repairs.

When it came back, this problem appeared.

When I start it in the morning, it starts and then stalls. Then when I crank again, it starts and then stalls. This happens 3-4 times and then only it starts and goes to idle. But when I press accelerator when it's idling, it tries to stall/stalls.

I have to leave it idling for about 1 min and then there is no problem at all. It pulls well, revs well, idles well and starts without any problem too.

But this stalling problem re-appear when I keep the car non running, say 8-10 hours? This is not a cold weather problem since it is there when I start it after work too.

I used Motul fuel system cleaner suspecting varnish buildup in injectors but it did not improve.

What could be the issue?


Appreciate your advise.
 

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Hi,
it could be a problem with the bypass air valve for cold start,
or with the temperature sensor, I mean the one used by the
iniection system, not the other one used by the temperature
gauge fot the pilot.

There are two different version of the
inection system for the 33 1.5 i.e./1.7 i.e.,
I think is "before" and "after" the year 1992 (or the year 1993)

I'm not not sure, the first version ("before" year XXXX)
could have a strange (old but simple) type of bypass air valve,
it has a 12v resistor that in few minutes warms
the valve, so a bi-metal part inside will bend to act
as a valve varying the opening section for the air;
you can see the valve as number 2 in this picture:

FIAT ePER

You could verify if it is alimented by the 12v, if it is working,
and if connected rubber pipes are not craked.

If necessary you can do some tests also out of the car
by heating up ther valve with a phon or connecting it at 12v.

Also another try, to verify is temperature sensor is connected
(I think it is an electric faston near one of the two
blocks with the fuel iniectors)

Bob
 

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Discussion Starter #3
Hi Bob,

I've attached a picture of the engine bay. This has Bosch MP3.1 system where there is no air flow sensor. It has only a MAP sensor which is inside the ECU and a vacuum line goes from the manifold to the ECU.

I don't think I have the item 2 of the ePER link you sent. Other picture is the idle control valve I have. I am confused on how the idle works well after 1 minute if it is bad?

I will check the engine temp sensor connected to the engine block.

Thanks for the input Bob :)
 

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Hi,

I think it could be low fuel pressure as well.
The fuel pump might gets stuck after a few hours of inactivity.

The MP3.1 injection system doesn't primes the fuel rail
when turning the ignition on, instead the pump relay is triggered
by the first valid signal from the crank sensor during cranking.

You can try to check the voltage directly on the pump terminals at running engine.
If there's a voltage drop somewhere in the power car's power supply route, it affects
badly the delivery of the pump.

If possible try to energize the fuel pump after a certain time of inactivity
from an external 12VDC power supply (capable to 10Ampers),
while checking the noise and the current drainage of the pump.
(without starting up the engine)

If the pump doesn't starts instantly when the power is applied to it's terminals
and/or the running current exceeds 4.5A for sustained period,
that suggests a dying pump.
 

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Discussion Starter #5
Hi,

I think it could be low fuel pressure as well.
The fuel pump might gets stuck after a few hours of inactivity.

The MP3.1 injection system doesn't primes the fuel rail
when turning the ignition on, instead the pump relay is triggered
by the first valid signal from the crank sensor during cranking.

You can try to check the voltage directly on the pump terminals at running engine.
If there's a voltage drop somewhere in the power car's power supply route, it affects
badly the delivery of the pump.

If possible try to energize the fuel pump after a certain time of inactivity
from an external 12VDC power supply (capable to 10Ampers),
while checking the noise and the current drainage of the pump.
(without starting up the engine)

If the pump doesn't starts instantly when the power is applied to it's terminals
and/or the running current exceeds 4.5A for sustained period,
that suggests a dying pump.
Interesting point. :thinking: I will definitely check that during the weekend and report the results.
 

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Discussion Starter #6
Dear friends,

It took a while to find time for this actually.

I noticed mine had NGK BKR5EGP (heat range = 5!!) so I put BKR7EIX (iridium plugs, pricey but very good)

Then I found some cracked fuel hose at the pump and upon replacing those, I noticed some rust at the pump. So I removed it and shook it. Loads of rust fell through as you can see in the photo. Then I noticed some idiot has put the filter before the pump in the wrong direction! :curse:

I had a new fuel pump (el cheapo) in hand so I replaced the fuel filter and the pump altogether. The fuel filter at the front was new already.

Still no good with the hesitation problem.

I replaced the Idle Air Control Valve (IACV) to another new one (el-cheapo once again) and that made a very big difference. Earlier the car stalled when A/C is on and at the junctions when slowing down. Now that is no longer a problem!! :bow:

Ignition leads were installed last year and no more than 1000km on those.

Then I removed and cleaned the injectors too (some varnish dripped on to paper).

Checked the air intake temperature sensor according to workshop manual and the resistance was in par with the outdoor temperatures.

However, after all this, the stalling at the starting is still there only briefly though and few small dabs on throttle cures it for the day.

Out of ideas too now :ermm:
 

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Discussion Starter #7
You can try to check the voltage directly on the pump terminals at running engine.
If there's a voltage drop somewhere in the power car's power supply route, it affects
badly the delivery of the pump.
This I just noticed. Will check and post the results soon
 

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Hi,

From the pictures I think the injector valves are not the original ones,
they seem to be "brown-top" Weber IW052 instead of "light blue top"
Bosch 0280150703.

The brown-top ones are suited for the 1.4 engine (with lower flow rate),
which would explain the A/C related and cold stalls.

Anyway the pump supply voltage could be a factor as well.
 

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Discussion Starter #9
Solved!

Finally took the car to an electrical specialist. Found out the reason to be the coolant temperature sensor wiring. :tired: The ECU wasn't getting the signal from the unit. Most probably a loose connection because the only thing I saw later was heaps of sealant at the sensor connector. Hope this solution will help someone in future. Thank you all for your suggestions!
 

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Discussion Starter #10
Hi,

From the pictures I think the injector valves are not the original ones,
they seem to be "brown-top" Weber IW052 instead of "light blue top"
Bosch 0280150703.

The brown-top ones are suited for the 1.4 engine (with lower flow rate),
which would explain the A/C related and cold stalls.

Anyway the pump supply voltage could be a factor as well.
Hi George,

I think the injectors are correct for MP3.1 system with distributor less ignition system.

Just posting for information purposes for any forum searching people.


Sent from my SM-J730F using Tapatalk
 

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Hello,

There were four different injector valves were used on the Alfa Boxer engines:
  • Weber (for the 1.3/1.4 IE engines for both 33 and 145/146) having the lowest rated flow rate of the four
  • Bosch Blue top (used on 1.5 IE regardless of ignition arrangement, 1.7 IE, and the very early 145/146 1.6 IE)
  • Bosch Yellow top (1.7 16V only) having the highest flow rate
  • and the GM for the for the 145/146 1.6 IE
Earlier the brown-top Weber was mentioned and due to the flow rate figures it is not ideal
for the engines other than the 1.3/1.4

Regarding the GM injectors as I recall they have a different length,
and they're not drop-in compatible when using with the 33's fuel rail.
Also the valve solenoid resistance / impedance is higher than the Bosch and IAW ones,
so it is suitable only for the GM ECU.

But this is only my personal experience / opinion, the reality could be different :)
 
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