Have replaced in-tank fuel pump, external fuel pump, check valve, accumulator. Still have hot start problem. Occurs if I leave the car off for 15 minutes or more. Starts but stumbles, coughs, etc until I give it the gas and get it going. Mechanics, IPD all don't have a clue. Checked vacuum lines etc. New plugs, wires, rotor, cap. No problem with cold start, but when really cold, starts but doesn't seem to want to idle very well.

Hi,

What year is the car?

I imagine that the fuel is flowing back into the tank, or leaking onto the ground.

The fuel pressure regulator seals the fuel return line
The fuel pump check valve holds the fuel feed from vapor locking only if
The fuel injectors are not leaking


Goatman

It's a 1982 240 with K-jet. Sounds like I should check the fuel pressure regulator. All the other stuff has been replaced and there's no visible leak and I've replaced the injector seals. Any other thoughts? Thanks
Jim

Howdy Jim,

Any other thoughts?

Why, yes, I have a few. ;-)

You have pretty much exhausted the free advice resources and thrown some pretty expensive parts at the problem. All the information sources you mentioned that "don't have a clue" probably do have a clue, but no data.

It is well nigh impossible to isolate a problem without test data. Sure, there are common failure items that cause this symptom or another. But, if the problem is not common, throwing common failure parts at it will be frustrating and expensive. Without test data no one at IPD or the Brickboard or over at Turbobricks or at the local Burger Barn can tell you what is wrong with your K-Jet.

You could take the car to a diagnostic shop and help them pay for all the tools and test equipment it takes to run a multi-marque diagnostic facility.

Or, you can acquire the specifications, tools, and methodology necessary to gather the data yourself.

I like the second option. But I have no way of knowing your background or ability to work on your car. So, the call is up to you. Here is the best advice I can offer:

Visit K-jet.org to get the Green Books for your car. Then, ease over to this Saab owner's web site to get the Bosch manuals for K-jet. Read each of them like a novel. Then go back and read them again, reference back and forth, and make notes. Once you have a pretty fair idea of how the system works you can do the checks necessary to isolate the problem.

Do you have a fuel pressure gauge setup for the CI system? If you need a gauge, this one that Lucid has posted links for several times is the best deal available.

Most of the other tools necessary to work on K-Jet are usually in a DIY mechanic's tool chest. There are a few exceptions. One is the injector test rig. If you find it necessary to test the injector opening pressure, I think a viable work around can be devised using a garden sprayer or shop air to pressurize a container. I haven't tried it yet. I think I will, just to see if I can make it work.

Another tool you are not likely to have is a CO meter. That it a tuning tool, not a troubleshooting aid. It is certainly nice to have. But you can get the car running at least 95% efficient without it. I am chasing down a CO meter now. If I can get one for a reasonable price, I will report it to the Brickboard.

If you are looking for an easy or quick fix, I don't have the magic bullet. The only way I know to isolate the problem is to analyse the test results.

Good luck. And, let us know how it goes.

--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 52 year old fat man ;-) -- KD5QBL

Hi,


Go after the fuel pump check valve first and observe the fuel accumulator closely for any leak, and while running.

I've seen some CIS Injectors on eBay. It would be good to replace the set at the proper price.

Since your car is CIS, it is the LINE PRESSURE REGULATOR that seals the return line, and it consists of a spring and small plunger inside of the control unit. Remove the plunger and either polish it or replace the entire assembly.

Again, make sure to check for ANY external leak while the car is operating, including the tank bung and hoses.

Goatman

Sure enough, we put a pressure gage on the fuel distributor and it is losing pressure. Problem is, on the '82 K-Jet, the fuel distributer is tucked under the intake manifold in an inaccessible place. You literally have to take the manifold off to get at it. A new distributor was priced at $420 and labor at $280. Does anyone think that installing the impulse relay that Volvo suggested for the turbo models would work for the non-turbo models? It's only $100 and easy to install.

HUMBO,

Sure enough, we put a pressure gage on the fuel distributor and it is losing pressure.

What is the pressure while the pumps are running? It should be above 65psi. How far does it drop when the pumps are turned off? The spec given in the Green Book is no less than 24psi after 20 minutes at rest. Does the pressure drop lower than that?

The reason I ask is that the fuel distributor, as you pointed out, is expensive and difficult to get to. It is best to eliminate all possibilities before replacing that component.

Have you checked to see if there is fuel flow from the return line port after the pumps have stopped? Fuel flow from the return port should stop when the pressure falls below 65psi. If it does, the pressure is dropping because of outflow or backflow, not return, which, unless I misunderstand the fuel distributor, is the only place that fuel can leave the distributor and the fuel distributor be at fault. An outflow problem will be either the injectors or the frequency valve. Backflow will be a an external leak, accumulator, or check valve.

--
Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 52 year old fat man.

I have a k-jet and am experiencing a similar hot start issue as yours. See

http://www.brickboard.com/RWD/index.htm?id=1269589&show_all=1


I found my accumulator to be leaking at the vent side. I replaced that and the hot start became better but not resolved. I don't have access to a pressure gauge nor does my mechanic.

I read with great interest that you have no pressure at the fuel distributor. I'm not well versed with using a pressure gauge and am still learning about my k-jet, but could the loss of pressure measured at the fuel distributor be due to other causes eg, leaking fuel injectors or leaking cold start injectors? A fuel distributor is darn expensive and I may be wrong but going through brickboard and other k-jet related forums, I get the feeling that a fuel distributor failure is not common.

Hello,


Remove the fuel distributor and clean that plunger Humbo, That is the next step. You can do that for free if you are careful.


Goatman