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  #1  
Old 22nd November 2008
Esteid Esteid is offline
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Default Loss of power

Hello all, I'm a new owner.
Had the car a few months and everything has been fine.

A few days ago I noticed that under full throttle I had trouble getting full power.

It has progressed and now I can barely drive the car. Here is a typical drive with me and my C900.

Car is very hard to start. when I finally get it running it idles ok, occasionally dropping too low and the car stumbles.

I have to rev the car up to about 2K rpm to get it to move off in 1st gear. I rev over 3K and it stumbles again.
Put it into second and keep it between 2K and 3K and repeat all through the gears.


Why would I have bogging trouble in lower RPM and higher RPM? Higher RPM I would check for a clogged exhaust..

I've done plugs wires cap and rotor. I pulled and cleaned the coil.

Next I got the car running and pulled the vaccum hose off of the fuel regulator and the car died out immediatly. Is this normal or does this mean I have a fuel problem? I've never been able to hear the fuel pump, so I cant tell if its running poorly. The tank is 1/4 full right now.

Thanks in advance all.
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  #2  
Old 23rd November 2008
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JKlaveness JKlaveness is offline
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What did your spark plugs look like? White / light brown / black? Wet or damp? Did they smell of petrol?
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  #3  
Old 23rd November 2008
16saabs 16saabs is offline
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could be petrol pump/and or filter, either pump is not doing enough,(worn out )or filter is stopping fuel going through it,(clogged) or even both especially if the filter has been bunged up for a while
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  #4  
Old 23rd November 2008
Esteid Esteid is offline
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The plugs were white.

guess I'll do a fuel filter next.
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  #5  
Old 1st December 2008
Esteid Esteid is offline
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So does anyone know what is expected when you pull the vaccum line from the regulator? Should the motor shut off?

Anyone have a tutorial or guide for replacing the fuel pump? Maybe even an exploded view of that area?

Best place to get a pump?

Can anyone tell me a bit more about the Hall Effect in the distributor?

Does the distributor go in only 1 way? If I were to remove it, could I get it back in without an amazing hassle?

Rebuild parts for the distributor?


Thanks in advance all.
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  #6  
Old 1st December 2008
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JKlaveness JKlaveness is offline
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White plugs rhyme with lean mixture.

Pulling the vacuum line from the fuel pressure regulator does two things. Firstly, it makes the mixture leaner by letting air into the intake manifold without having it measured by the AMM (Air Mass Meter).

Secondly, it should have an effect on the fuel pressure regulator as well, but I can't say which way. I suspect that the effect, whatever it is, is slight.

The two things I would do first, in your case, is

a) Check the compression, and
b) Check all vacuum lines.

:-J
Jorgen
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  #7  
Old 1st December 2008
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>> Anyone have a tutorial or guide for replacing the fuel pump? Maybe even an exploded view of that area? <<

The "Bentley Bible" should tell you all you need to know about this. If you take the pump out, be very careful when you pull out the plugs with the fuel lines. Pull them straight. Don't bend. Don't break them!!!

>> Best place to get a pump? <<

I'll leave that to members in your area.

>> Can anyone tell me a bit more about the Hall Effect in the distributor? <<

Some models have this sensor in the distributor. Mine all have it attached to the rear end of the engine, under the pulley wheels for the V-belts.

>> Does the distributor go in only 1 way?<<

Yes. The question indicates that you should try to find someone who knows a little more about engines to help you with this project.

>> If I were to remove it, could I get it back in without an amazing hassle?<<

Generally speaking, yes. But it depends on your proficiency level.

>> Rebuild parts for the distributor? <<

Rotor and lid are dead easy to change (but make a note of where the cables go before you take any of them off).

:-J
Jorgen
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  #8  
Old 1st December 2008
Esteid Esteid is offline
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Thank you.

I realize you all do not know me well enough. I have plenty (too much?) experiance with older american motors. With a distributor with a gear and no IDing process. I've since read that the dizzy on this motor is index'ed to only go in one way.

My 1990 non-turbo 16v have the hall in the dizzy? Is there a dizzy rebuild kit that includes this sensor?

Regarding some of my questions, I find it easier to just ask than to dive in without any idea. Which is why I was hoping for an exploded view or guide on the fuel pump.

Quote:
Originally Posted by JKlaveness
>> Anyone have a tutorial or guide for replacing the fuel pump? Maybe even an exploded view of that area? <<

The "Bentley Bible" should tell you all you need to know about this. If you take the pump out, be very careful when you pull out the plugs with the fuel lines. Pull them straight. Don't bend. Don't break them!!!

>> Best place to get a pump? <<

I'll leave that to members in your area.

>> Can anyone tell me a bit more about the Hall Effect in the distributor? <<

Some models have this sensor in the distributor. Mine all have it attached to the rear end of the engine, under the pulley wheels for the V-belts.

>> Does the distributor go in only 1 way?<<

Yes. The question indicates that you should try to find someone who knows a little more about engines to help you with this project.

>> If I were to remove it, could I get it back in without an amazing hassle?<<

Generally speaking, yes. But it depends on your proficiency level.

>> Rebuild parts for the distributor? <<

Rotor and lid are dead easy to change (but make a note of where the cables go before you take any of them off).

:-J
Jorgen
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  #9  
Old 1st December 2008
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JKlaveness JKlaveness is offline
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The fuel pump is inside the fuel tank. Taking it out is simple. Just unscrew 2 screws holding the floor in the trunk, take the plywood sheet out, and pry away the larger of the two lids. Improvise a wrench to grip the ring that holds the pump down. NO KNOCKING. I use the handles of a pair of polygrip pliers, usually, and a piece of wood. Be kind to the large O-ring.

However, before you try taking it out, I suggest that you check the fuel pressure. Low pressure can be due to pump failure or to a faulty Fuel Pressure Regulator. You can check the pressure on the rail by loosening a connection on the forward end of the rail while running the starter motor. The pressure should be around 3 bar, which is a LOT. Behind the Fuel Pressure Regulator, there should be a good flow, but no pressure to speak of. You can open a connection either under the Reglator or take out the return lead at the pump.

Search the archives here for info on the Hall Sensor. There are some excellent pictures.


:-J
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  #10  
Old 1st December 2008
Esteid Esteid is offline
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Very helpful.

I thought the floor access was only in "Early" 900's is my 1990 considered early?

I am used to checking fuel pressure with a gauge pressed onto the Schrader valve. (Fords)

is there an easy way to hook up a gauge to this motor?

I see your suggestion on how to check pressure. I'll use that, but I fear that where my problem doesnt present itself so much until under load it may not help me.

Quote:
Originally Posted by JKlaveness
The fuel pump is inside the fuel tank. Taking it out is simple. Just unscrew 2 screws holding the floor in the trunk, take the plywood sheet out, and pry away the larger of the two lids. Improvise a wrench to grip the ring that holds the pump down. NO KNOCKING. I use the handles of a pair of polygrip pliers, usually, and a piece of wood. Be kind to the large O-ring.

However, before you try taking it out, I suggest that you check the fuel pressure. Low pressure can be due to pump failure or to a faulty Fuel Pressure Regulator. You can check the pressure on the rail by loosening a connection on the forward end of the rail while running the starter motor. The pressure should be around 3 bar, which is a LOT. Behind the Fuel Pressure Regulator, there should be a good flow, but no pressure to speak of. You can open a connection either under the Reglator or take out the return lead at the pump.

Search the archives here for info on the Hall Sensor. There are some excellent pictures.


:-J
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  #11  
Old 1st December 2008
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My tip would be to forget the fuel pressure for the time being, and focus on simple things like compression and vacuum hoses.

:-J
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  #12  
Old 1st December 2008
Esteid Esteid is offline
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Understandable, I'll give it a run over with the starter fluid tonight.
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  #13  
Old 2nd December 2008
Esteid Esteid is offline
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So I removed the floor as suggested and the pitch of the fuel pump does not change when the car struggles. So I'll spend more time on vacuum lines first, and maybe the fuel regulator.

It was lightly raining last night so not much work could be done.
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  #14  
Old 2nd December 2008
Esteid Esteid is offline
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Anyone know the size of some of the fuel fittings if I wanted to install a fuel pressure gauge temporarily?
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  #15  
Old 7th December 2008
Esteid Esteid is offline
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So I did the compression test.

1. 150
2. 155
3. 160
4. 140


Is number 4 out of range?

I also put some suction on the regulator. The RPM rose, but then feel and almost stalled quickly after.

Later there was a surprising change. I pulled the MAF off the air box to see if there was any change and there was. The car idles much better, starts much easier. Driving it there is still a signifigant loss of power. At least I dont have to worry about it not starting which was getting worse, taking 10 minutes and multiple tries to get it to run more than a few hundreths of a second.

So, anyone have any new idea's?

My local autoparts place had no fuel pressure tester to rent, and nothing for the saab to buy. Any suggestions what I could do to test the pressure?
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  #16  
Old 7th December 2008
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900t 900t is offline
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It's okay... general thumbrule is 10% within max to min, but it is just outside... if you had 14 instead then you would KNOW you need to teardown
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  #17  
Old 7th December 2008
16saabs 16saabs is offline
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compression ranges are ok, as you will always vary a little, as the unit you use is'nt always screwed dead home into plug hole or the seal on the item loses a bit etc etc, but if your car runs better with the AMM off, its possibly the problem as they can fail and if connection removed the car goes into limp home mode which it is designed to do, it also could be the lambda sensor on the downpipe which senses the exhaust gases, if that's faulty problems again, but normally if one of those 2 the CEL light comes on as a warning.
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  #18  
Old 7th December 2008
Esteid Esteid is offline
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Thank you both for your comments.
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