Difficult start after Milano has been sitting - Alfa Romeo Bulletin Board & Forums

 
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post #1 of 13 (permalink) Old 03-17-2017, 05:15 PM Thread Starter
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Difficult start after Milano has been sitting

Hi guys,

Not long ago I started a thread about a cold start issue I was having. That thread is here: Milano AAV and TTS spec questions

Turns out it's not so much of a 'cold' start issue, as I found out after several consecutive days of driving the car. When driven days in succession, the car starts right up on the first crank from cold even in 40-degree temps (cold for California!). But when the car sits for a week or so, I'm back to many tries before the car finally fires.

I think what's happening is that the car's fuel supply is draining back to the tank when the car sits. When I go to start it after it's been sitting a week, the fuel pump has to get build pressure all the way back up to the intake plenum before it finally starts.

So, my question is, what component would cause this to happen? Is there some kind of valve that holds pressure in the fuel system when the car is not running?
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post #2 of 13 (permalink) Old 03-17-2017, 05:47 PM
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The pressure regulator is supposed to do that, but in my experience even after fitting new ones it doesn't work brilliantly, especially, as you have experienced, after a few days. The only thing I haven't done with our current 3 litre 75 is to take out the gauze filter in the tank. It has a new pressure regulator, hoses, filter, a good pump, reconditioned injectors and all of the ignition system overhauled and will still sometimes take a few turns to start. The pressure regulators have a diaphragm in them that eventually develops holes and causes raw fuel to be sucked into the plenum which is what happened to ours.

Current Alfas
2004 GT 3.2 V6 (Stromboli Grey).
2008 159 TI Sportwagon 2.4 JTDM (Stromboli Grey).
1987 75 3 litre (red). My first 75 and now my son's.
!989 75 3 litre (black). Shared project with my son.
2000 156 2 litre Twin Spark, ( Cosmos Blu metallic), my daughter's car.

Past Alfas
1990 75 3 litre Potenziata (black), now sold & living in Newcastle NSW.
1990 75 3 litre Potenziata (grey, sadly deceased due to fire).
1982 GTV 2 litre, red, (daughter's first Alfa)
2 x 1992 164s, (1 red, 1 grey).
2 x 1988 33s, (both red).
1985 GTV 2 litre, (white).
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post #3 of 13 (permalink) Old 03-17-2017, 07:11 PM
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Fuel pump check valve or pressure regulator

Hi Rory

You said

"So, my question is, what component would cause this to happen? Is there some kind of valve that holds pressure in the fuel system when the car is not running?"

Well on the fue-in, side it's the electric fuel pump at the back of the car. Although it's not mentioned in the Alfa manuals, an EFI pump should have a backward flow check valve.
Otherwise when the car was turned off, the fuel would drain out of the fuel rail (because the rail is a high point) and the pump would have to run for some time to fill the fuel rail and purge the air.

On the fuel-out side, it's the pressure regulator at the end of the fuel rail. The factory manual tells you how to test the regulator.

Since it takes a week for this condition to develop one or both of these items aren't doing their job 100%.

You said

"I think what's happening is that the car's fuel supply is draining back to the tank when the car sits. When I go to start it after it's been sitting a week, the fuel pump has to get build pressure all the way back up to the intake plenum before it finally starts. "

I think you are right. I had this problem in my Milano too. I solved the problem by not trying to start the car right away. I would get in the car turn the key to accessory and let the fuel pump run for a while.Then I would start the car.

Since a PO wired my car such that when the key is on, the pump is on, this didn't take very long.

Amazingly after about a year of steady driving ( the car had sit for years prior to this) the problem went away.

My guess was that some debris or residue was jamming the reverse flow check valve in the pump and eventually the combination of name brand gasoline, injector cleaner and regular driving broke it free.

Hope this helps
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post #4 of 13 (permalink) Old 03-17-2017, 09:32 PM
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Are there any downsides to wiring the pump so that it comes on immediately Del? Alfa must have wired it the way they did for a reason. How do you do it.

Current Alfas
2004 GT 3.2 V6 (Stromboli Grey).
2008 159 TI Sportwagon 2.4 JTDM (Stromboli Grey).
1987 75 3 litre (red). My first 75 and now my son's.
!989 75 3 litre (black). Shared project with my son.
2000 156 2 litre Twin Spark, ( Cosmos Blu metallic), my daughter's car.

Past Alfas
1990 75 3 litre Potenziata (black), now sold & living in Newcastle NSW.
1990 75 3 litre Potenziata (grey, sadly deceased due to fire).
1982 GTV 2 litre, red, (daughter's first Alfa)
2 x 1992 164s, (1 red, 1 grey).
2 x 1988 33s, (both red).
1985 GTV 2 litre, (white).
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post #5 of 13 (permalink) Old 03-18-2017, 08:10 AM
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It is more of a safety issue. If the pump is wired so that it runs when they key is in the on position when the engine is not running you could have a problem if you get into an accident and a fuel line breaks as it would continue to pump fuel out.

Kevin

Currently Alfaless. Ex: 87 Verde, 86 GTV6, 67 Super, 86 Spider, 88 LeMons Verde
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post #6 of 13 (permalink) Old 03-18-2017, 11:59 AM Thread Starter
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Originally Posted by kredden View Post
It is more of a safety issue. If the pump is wired so that it runs when they key is in the on position when the engine is not running you could have a problem if you get into an accident and a fuel line breaks as it would continue to pump fuel out.

Kevin
I agree with this, it's a safety issue. That said, on a Porsche I just sold, I had converted the fuel pump relay to an aftermarket unit which primes the system when ignition is on.

Perhaps I'll take a look at the pressure regulator and possibly replace and also just try leaving the key in the intermediate position for a while longer before attempting to start when the car has been sitting. If anyone has any other ideas, I'd love to hear them.
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post #7 of 13 (permalink) Old 03-18-2017, 02:52 PM
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Priming the system makes sense, but I doubt that left the pump running for more than a few seconds right?

Currently Alfaless. Ex: 87 Verde, 86 GTV6, 67 Super, 86 Spider, 88 LeMons Verde
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post #8 of 13 (permalink) Old 03-18-2017, 06:19 PM
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Try an inline fuel check valve.

Hi

Just found two items while doing a different search for other EFI fuel issues.


1. You can buy a separate in-line fuel check valve from a number of manufacturers & retailers. It is exactly for this purpose.

Here's the text for one valve.


"Arrow marked on valve, showing fluid flow direction, Prevents fuel from returning back to the tank and keeps it in the line.
3) Also great for water pressure pumps & galley pumps which are not self-priming
4) Professional grade non-return valve - Ideal for marine, automotive, caravans/RV, and agriculture"


INHDBOX 8mm 5/16" Fuel Non-Return One Way Check Valve Petrol Diesel Marine Aluminum Alloy - Auto supplies depotAuto supplies depot



From a Porsche site in a discussion about adjustable fuel pressure regulators. There is a Bosch spec about how long the fuel pressure regulator should hold pressure after shutdown.


"Porsche specs for that series (87MY and up M28.41/42/47/49/50) are as follows:

Pressure at engine standstill (relay bypassed): 3.8 +/- .2BAR

Check value at idle : 3.3BAR

Minimum pressure after 20 min shut down : 3.0 BAR

Porsche P/N : 928.110.198.02
Bosch P/N : 028.160.262"

Bosch# for 3bar L-Jet type FPR? - Rennlist Discussion Forums


So the inline check valve thingy sound good to me, as I strongly suspect it's the check valve in your existing fuel pump that isn't doing it's job.


As to the gas pump wiring, well my car is different than most. First up I don't use a key to start the car. Furthermore the lock cylinder in the steering column is entirely removed and the wiring that goes into it has being moved into the dash. This was done by me, not the PO.

There's a home made plastic plate where the radio normally sits (I don't have a radio) in the plate sit two switches. A small toggle type switch and a larger spring loaded starter type switch. To start the car you flip the toggle switch to on, and press the starter switch till the car starts. To turn the car off, flip the toggle switch to off.

Since I hate keys, this suits me fine.

Hope this helps
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post #9 of 13 (permalink) Old 03-19-2017, 01:42 PM
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Quote:
Originally Posted by RoryJ View Post
Hi guys,

I think what's happening is that the car's fuel supply is draining back to the tank when the car sits. When I go to start it after it's been sitting a week, the fuel pump has to get build pressure all the way back up to the intake plenum before it finally starts.

So, my question is, what component would cause this to happen? Is there some kind of valve that holds pressure in the fuel system when the car is not running?
If it's fuel pressure, than just energize the pink black/wire under the back seat with 12 volt +. You will hear the pump whine. If it starts instantly after a week, than you have confirmed fuel pressure loss.

Louis
2011 M3 e90 ZCP no sunroof, 2004 M3 e46 no sunroof , 1987 Milano 24v, 1987 Milano Verde

Last edited by Potenziato; 03-19-2017 at 01:44 PM.
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post #10 of 13 (permalink) Old 03-20-2017, 11:28 AM Thread Starter
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Originally Posted by Potenziato View Post
If it's fuel pressure, than just energize the pink black/wire under the back seat with 12 volt +. You will hear the pump whine. If it starts instantly after a week, than you have confirmed fuel pressure loss.
But wouldn't this be energized by turning the key to ignition anyway?

Installing a secondary check valve may be a good solution -- will have to look into that. I'll also check the records and see when the fuel pump was last replaced.
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post #11 of 13 (permalink) Old 03-20-2017, 11:34 AM
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No, it's not energized by the key. The fuel pump is turned on by the AFM flapper tripping a micro switch inside when the key is in the run position. You could open the airbox and push the trap door with a long screwdriver to engage the fuel pump.

Louis
2011 M3 e90 ZCP no sunroof, 2004 M3 e46 no sunroof , 1987 Milano 24v, 1987 Milano Verde
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post #12 of 13 (permalink) Old 03-20-2017, 03:18 PM
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Here's what I do. I turn the key on and in the time it takes to buckle my seat belt the system is all primed up to start your Milano. If you hear the pump just wait till it stops, it does when the proper pressure is in the system.
Your chasing ghosts, just let the car obtain the proper fuel flow and it will start fine.
I start mine in -20 below weather.

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post #13 of 13 (permalink) Old 03-20-2017, 03:36 PM
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You can leave the key in all day but it doesn't change the fact that the pump doesn't turn until the AFM door moves.

The fuel system should retain pressure unless there is a leak, but leaving the key in doesn't prime the pressure.

Louis
2011 M3 e90 ZCP no sunroof, 2004 M3 e46 no sunroof , 1987 Milano 24v, 1987 Milano Verde

Last edited by Potenziato; 03-20-2017 at 03:39 PM.
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