Pelican Parts Forums - weird starting problem

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I have the exact same issue with my CIS. It's probably not flooding, it just feels like it. It is most likely loosing pressure as everyone says. Most likely accumulator. (my theory) When the pressure drops the heat makes air bubbles in the fuel lines that purge out and make it stumble (like it's flooded) That's why no smoke or rich smell is noticed, it's not flooded. Also I noticed that the type of gas I use has an effect. I used to use Mobil and it always happened. I switched to Shell and it never happens any more. The only time I will have issue's is that first tank in the spring that is old and stabilized. Once I go through that tank it's perfect.

Well, I guess that I will start from the accumulator. Although in my case, I do have a strong smell of fuel after I start it with the gas pedal pressed to the floor :\

Quote:

Originally Posted by JK McDonald (Post 5751246)

Hey Yoni - Don't forget that during the initial start your engine is cold and the cold start thermistor switch (in the front water jacket) is probably energizing your cold start injector as the starter turns. This solenoid style injector throws any remaining residual fuel pressure left in your system into the intake manifold (like a bucket with a hole in the bottom) and helps to start any engine as long as there is at least some residual pressure remaining. If your car does not start after the 1st cold engine attempt - all of the residual pressure may have been used up. Any additional attempt has no residual fuel available. Once the engine has warmed up - the cold start injector is no longer in the start mix.

After driving around a while - everything will be fine until you park the car. Then if you start it back up within a relatively short period of time, your residual pressure may not have bled down very much. But if you have shut down the car for too long, the residual pressure may now be too low for an easy start.

At this point the engine is probably too warm for the cold start circuit to activate and since the 8 primary intake injectors only open by pressure, they wont even begin firing until about 30 Psi is in the lines. The fuel pump has an air flow safety switch in the mixture control unit which doesn’t allow the fuel pump to run until air is being drawn into the intake from piston movement. Naturally - if the residual fuel pressure is too low - it takes 10 - 15 seconds of starter operation to bring the fuel pressure up high enough to begin opening the main 8 intake injectors.

All the above information is assuming that you have tested for a residual pressure issue. Please realize that we are all troubleshooting by guess and by golly using the information provided and there may very well be a different problem you need to chase down ... check Mrmerlin's input.

Hey Landseer - the thermo-switch (cold start thermister switch) may be good call if the cold start injector is trying to over fuel every start process. Yoni - check to see if 12 volts is being applied to the cold start injector at every attempt to start your car.

Good Luck, Michael

Thanks Michael! ;)

Troubleshooting Steps -

Hey Yoni, Even under the best of circumstances most experienced owners will readily confirm that it can be expensive to maintain a 928 - but to just start swapping out parts without taking steps to troubleshoot a problem can get real pricey very fast.

It is not that your planned attempt to change out the accumulator might solve your problem - it is just that this part can be easily tested. The accumulator is simply a sealed canister containing a spring on top of a flexible rubber bladder. As the bottom inlet is exposed to your operating fuel pressure the spring is compressed. It holds this position until the engine is shut off. With the fuel pump now stopped - the fuel pump check valve on the back end of the main fuel line and the injectors at the front end of the main fuel line are supposed to now seal the system. The accumulator spring (basically plumbed between the fuel pump and the injectors) now expands to hold a minimum of 14 Psi within the fuel lines - waiting for the next engine restart.

Once the accumulator is removed - it is simple to test. Apply about 25 psi to the bottom inlet port using an air nozzle. This will compress the spring. No air should pass out of the top connection. When the air nozzle is removed, the spring will extend and push the air out.

You should not have to step on the accelerator to restart a cold or warm engine.

Good Luck, Michael :)

Jk's right. Test as much as you can first. Since you do have the gas smell I assume you are getting plenty of gas , maybe too much. A failed accumulator would most likely not create that. I would look towards a leaky cold start valve and/or the components that control it.

hmm.. seems like my car problem.. Will read it later..

Well, found the problem...
amazingly it was a battery problem!!! it seems that it has some sort of internal malfunction.
So thats why from time to time it didnt have enough power! it did have enough power to turn the starter but not enough for all other electrical systems...
I just replaced the battery and the car starts immediately at any time :)

I am sooo happy!

Excellent!
Sorry to lead you all over the place.
Michael had the voltage thing pegged, though, didn't he?

Congrats!

Quote:

Originally Posted by JK McDonald (Post 5750200)

One other comment - If the static pressure is bleeding off at the fuel pump - some of the early pumps integrated the check valve into the output port of the fuel pump. You may have to replace the fuel pump with a later year model that has a replaceable check valve. (I have seen where some owners with the early style fuel pump have added a new Bosch check valve (stacked in series) onto the built in check valve output port)

Good Luck, Michael :)

Keep in mind that your CIS fuel pump has a higher flow rate and produces more pressure than the ones used later in the electronic injection systems.

More-Better Capacity

Naturally, it is important to only install a fuel pump that is capable of producing the correct operating pressure and flow rate - this is especially true for a high performance vehicle. During the troubleshooting phase of this post, I had only mentioned to Yoni that he may have to update his fuel pump if he had the earlier design (with the internal snout check valve) and the check valve was defective. Some 928 owners install a newer style pump not only for the replaceable check valve but for the ability to install a larger pump with more-better operating capacity.

Michael :)