The SAAB has a possible vacuum leak.

The car... 1996 SAASB 900 SE. It has a turbo and a manual transmission.

An auto supply store employee smelled gas under the hood and suggested that I may have a vacuum leak. I need help finding a diagram to tell me where the vacuum lines are.

I searched vacuum line issues, and it appears this can cause stuttering. I do have stuttering and stalling as I go from a full stop to 10 MPH, first gear only. So likely I have vacuum line problems. I need help finding them.

Are there several systems that have vacuum hoses? I'm lost.

Elsewhere on the WWW I found several forum threads specific to SAAB 900 list that I need a 4mm silicone hose. The old hoses are rubber. Would 5/32 rubber hose work? I have found this as well as the 4mm silicone hoses. Those forums do not have diagrams currently displayed in these threads.

Is either of these vacuum lines for my Saab?
https://www.esaabparts.com/viewparts.php?searchpart=1§ion=112217785
https://www.esaabparts.com/viewparts.php?searchpart=1§ion=112217928

Here is a 40-second video showing vacuum lines on a C900. His car needed about 6 to 8 feet of hose. This is not my model. My car has the engine oriented sideways.

A vacuum leak sometimes is detectable when the car idles. With the car just idling does there appear to be a steady up and down increase in rpm's? I wouldn't immediately suspect a vacuum leak because of smell of gasoline. I'd be a bit concerned but look at fuel delivery hoses first.

I googled this "1996 SAASB 900 SE vacuum tubes diagram" and found plenty of references for you.
4mm usually means 4mm, but you may find alternative imperial sized hoses are actually metric sizes, just check.

Petrol smells usually come from petrol leaks not vacuum hose leaks, so you may have 2 problems.

from a SAAB site '....... Also, the vacuum line attached to it [ mass air flow meter ] . But I'll give you this, they are a site for leaking, so it's a good bet it MAY have came through there... ."

Just spray carb cleaner all over everything that would have a vacuum under the hood. When you hear the car rev up, that's where it's leaking.

If it is a hose, just cut it out and bring it to the auto parts store. They will getcha the right size.

Thanks, guys.

Robert, I'll drive it tomorrow, and find out for you.

John, did you click through the links, finding a diagram? What came up for me were a bunch of old posts with defunct links to images, or comments to get the diagram from the dealer. SAAB went out of business. Could you post a link to where you quoted from?

And Dan, where are vacuum lines attached so I know where to spray the carb cleaner?

I suppose I could spray every 4mm hose...

One thing to mention is its generally really easy to replace vacuum lines. Take one line off and than measure the line and replace the line you took off. 5/32 would be fine. I just bought silicone line from rock auto for my truck. I have been replacing lines, its super easy.

Does your saab have a vacuum diagram under the hood? Most have some diagram showing how the lines are routed. or possibly a shop manual. With the little bit of searching online i didn't come up with a vacuum diagram.

Another thing is some vehicles have vacuum canisters which can leak as well.

Just so you know the vacuum diagram's only show you where the lines plug in, they don't show how its routed or even where the part is located. So my suggestion is to take it one line at a time. Spend some time figuring out where the lines go.

This is generally what a vacuum diagram looks like.

Thanks Jordan. Maybe. Is this it?

And this diagram? For part of it maybe. #4 is called a check valve.

From here.

Jordan wrote: Another thing is some vehicles have vacuum canisters which can leak as well.

Hmmm... Evap Canister Purge Valve #8 shown here maybe? AND listed on the diagram under the hood.

Edit: No, more likely Evaporative Emission Canister #1 diagram here.

Additional components shown in that diagram under the hood.

Idle control valve #1 as shown here.

PCV check valve #8. Diagram.
Fuel pressure regulator #6 diagram here.
Charge Air Bypass Valve #23 diagram here.
Charge air bsolute pressure sensor #25 in this diagram.

Is your concern the smell of fuel?, or a performance issue? When you start the car in the morning just let it idle and watch the tach. It should idle steadily at about 700 or there abouts. If you notice the tach going up and down that is a classic vacuum leak tell. Most likely a hose but possibly a leaking gasket. Since you had to remove so much to replace the radiator, something might have been bumped.

Well... that might explain the new steering fluid leek I have to track down. Sigh. But this problem existed beforehand.

Performance is my concern.

Joylynn here is the link https://www.saabcentral.com/threads/petrol-smell.78132/
I googled  petrol leak in....

So what I was trying to say is that you don't need to know what you are looking at to test it for a leak. Or even to fix it. You just have to locate a leak in the "whatever hose" and remove it and replace it. Or, if it is horribly hard to get off, cut the bad piece out and take to the store to get an appropriate barbed connectors and length of hose to reconnect.

Spray EVERYWHERE if you need to, it won't hurt anything.  Just quick squirts of something flammable, like carb cleaner or brake cleaner, and just listen for a change in RPM. Spray any hose that you think is vacuum and any you aren't sure about. Vacuum hoses are generally the ones that go to the top of the engine and from where you fill the brake fluid, the brake booster.

This is how it's done under the shady trees of Dan's Redneck America. I am not a real mechanic, just poor.

And here is my best advice for a fuel leak, hahaha...

The fuel only travels out side the engine in a few spots. From the tank, along the frame of the car and then up to the throttle body and associated  junk on top of the engine. Put 'er up on jack stands and follow the hose. Then try to see if you can either clean it up then run it and then look for wet spots, or smell around for fuel. Best would be to have somebody else rev the car up to get a lot of fuel pressure going and maybe increase the chance of locating a leak. Don't put your hands somewhere dumb while the car is on, by the way.

Also, an exhaust leak might smell like fuel. If it sounds loud or "buzzy" up front this might be the case.

And a car with a vacuum leak might run so poor (rich) that the exhaust just might smell a lot like gas.

another way to check for vacuum leaks is with a propane torch, barb-que lighter (unlit), even a normal lighter( unlit).

Pay attention to fans/belts.

Keep fire suppression at hand.

Listen for a change in RPM.

who stops and goes 10 mph anymore anyway,this sounds like a low end stutter,tps mafs,sparkplugs and coil packs will cause this,obviously check for fuel and vacuum leaks,but you might need to get it scanned to check ohms in your sensors as well,just to see if they are "in range"

When the gas smell was first brought to my attention, I did smell it too. I had not noticed it until it was mentioned. But the good news is, there is no gas smell today.

I forgot to watch the tachometer today. Will try for that tomorrow. But look at this lovely hose. It is slightly larger than 3/4" diameter whith was thelargest hose O'rielly's had. Auto Zone didn't have it either. Off to wander the interwebs in serch of what the hose is called.

It is #24 in this diagram. It is called a hose. Isn't that helpful?


Here is a picture of it.

Do those markings tell anyone what size the hose is? I'm trying to get one locally.

Joylynn Hardesty wrote:An auto supply store employee smelled gas under the hood and suggested that I may have a vacuum leak.

That parts guy did you a disservice. You have a computer controlled vehicle that measures Manifold Absolute Pressure (MAP) with a MAP sensor. The vacuum diagram there calls it absolute manifold pressure, but most parts guys will know it as a MAP sensor. The easiest way to see if you have a vacuum leak is to connect a trouble code reader and see if any MAP sensor codes pop up, which the parts guy probably could have done for you, most likely for free.

The only way you would smell gas from a vacuum leak on a multiport fuel injected system is from the vacuum controlled fuel pressure regulator or an internal leak on one or more fuel injectors, on top of an existing vacuum leak, if one even exists. Those same parts could also cause a gas smell without a vacuum leak. If this person didn't check your car for trouble codes from the computer then he didn't properly try to diagnose your issue. Trying to diagnose a fuel injected car with carbureted engine diagnosis procedures is going to have you wasting a bunch of time and not fixing the problem.

With the turbocharger having vacuum controlled actuators, I would imagine you would have issues with surging and/or delayed boost onset. I see the charge air bypass valve in the diagram. I don't see the wastegate labeled, yet a quick search suggests you have a vacuum controlled wastegate actuator so I'm not certain about that one. This is more of an FYI. I don't believe the fuel smell is caused by a vacuum leak, however that doesn't exclude the possibility that one exists or that the lines smell of gas.

Given the gas smell, I would follow the diagram and pull the hose off of the fuel pressure regulator and see if it smells of gas. If not, then you would need to inspect the fuel injectors and the connections where the fuel supply and return lines connect. It is very possible that the fuel leak may not be substantial enough to set off any trouble codes.

EDIT - Given the issues you will face with having metric hoses on the car and SAE hose sizes available locally, this trick might help out a lot. I usually will find an old cheap deep socket or punch or something of an appropriate size with some sort of small step or taper, heat it up, and press the hose on to swage it out to the larger diameter I need. If the difference in size is just enough that you just barely can't make it work, then this trick is easy to do. If the difference is a bit more significant then it can take a bit of time to do it without ruining the hose. I use either a torch or heat gun, and you would want appropriate safety equipment to avoid burns.

That number on the hose is the part number:

https://www.esaabparts.com/saab/parts/4444261

You might want to call O'reilleys and give them that number I bet they could have it in their store by 3pm. No shipping that way. Or for example in my town, we have an "import parts store" that does a lot of business in harder to find car parts. Maybe you do too?