81 SC - Control pressure way too high - won't take throttle.

[Bob Kontak]

Car has been sitting for a few years. Start occasionally and put a couple gallons of gas in every once in a while. It's been starting and idling fine.

Last week when idling in garage I blipped the gas pedal with a broom handle and the pedal stuck. Revved to 5000 rpm and I freaked out and pulled off the battery terminal which was hand tight - of course it remains running. Finally had the sense to turn key off.

Since this incident the control pressure is way too high - like over 60 psi. It starts on CSV and dies but I can eventually get it to barely spin at 200 rpm but zero throttle response. Extremely lean.

If I cheat I can push the pressure gauge relief button (into a bucket) and drop control pressure to around 30 psi and RPMs jump right up to normal idle and there is robust throttle response. This tells me the path from the WUR to fuel distributor is clean and the plunger is responding.

Assuming crud was dislodged and I don't know where except for it's in the return circuit. The main return line is free to the gas tank. Between that connection under the accumulator and the fuel distributor is hard to access plumbing.

Once I figure out the plumbing and isolate can I simply blow these lines out? Assuming I will have to do a partial engine drop to allow access.

Could there be a blockage inside the fuel distributor? That's what scares me.

I purged the old gas and put in five gallons fresh and a several ounces of Seafoam. I can now get it to make an extremely feeble increase in RPM's to 900 rpm with throttle input. A long way from ok though.

[john walker's workshop]

Maybe blockage in the screen under the larger WUR fitting.

[boyt911sc]

Dear Bob,

If I were in your shoes, I would hook up the CIS pressure gauge and test run the FP. No need to run the motor until you have confirmed that the CCP is low and does not get close to 60 psi. or higher.

A 60 psi. CCP or greater means you have flow restriction in the return line. Get to work and keep us posted.

Tony

[proporsche]

Hi,just a question ..is the sensor plate free?Do you think the distributor pin-plunger is free?How about side relief valve on distributor..i
Ivan

[Bob Kontak]

Originally Posted by proporsche

Hi,just a question ..is the sensor plate free?Do you think the distributor pin-plunger is free?How about side relief valve on distributor..i
Ivan

Sensor plate and plunger appear ok. I have not touched the fuel distributor yet.

I bled down control pressure with the relief valve of the CIS pressure gauge while the car was running. It responded favorably with higher idle and throttle response when I moved the linkage by hand. That is the basis for me saying the sensor plate and plunger are "ok". It also makes the squealing noise when I lift the sensor plate with the key on/engine off. It gets progressively louder the more I lift. That noise is similar to history.

I feel I am going to be learning some things about the distributor. I know there are many posts I can review on the FD and I am just getting into this problem so just a touch overwhelmed - mainly because of all the plumbing.

Originally Posted by john walker's workshop

Maybe blockage in the screen under the larger WUR fitting.

Forgot to mention that. There was some crud in there - a decent amount but I could still see some screen - I cleaned it out but only with spray carb cleaner and the nozzle tip of an airhose angled across the top of the hole - more of a suction vortex than a blow. I was hesitant to blast in there direct with the air hose.

[RarlyL8]

As John stated there is trash in the WUR inlet screen.
Pull the WUR and stick it in the freezer overnight then blow through it backwards, from the outlet. See what that does for you. Most likely problems will continue until the system is fully cleaned.

[Bob Kontak]

Originally Posted by boyt911sc

If I were in your shoes, I would hook up the CIS pressure gauge and test run the FP. No need to run the motor until you have confirmed that the CCP is low and does not get close to 60 psi. or higher.

I have a feeling you are going to get a phone call one of these days. Let me wrestle with it a bit. I read a post where you advised the return line is in sections. That's my fear right now. How to break it apart and isolate.

[Bob Kontak]

Originally Posted by RarlyL8

As John stated there is trash in the WUR inlet screen.
Pull the WUR and stick it in the freezer overnight then blow through it backwards, from the outlet. See what that does for you. Most likely problems will continue until the system is fully cleaned.

I can do that.

[boyt911sc]

Originally Posted by Bob Kontak

I have a feeling you are going to get a phone call one of these days. Let me wrestle with it a bit. I read a post where you advised the return line is in sections. That's my fear right now. How to break it apart and isolate.

Bob,

I am in Monterey, CA for the whole month of November. I know you have my home phone number which is a land line. PM me your phone number and I will return it ASAP.

Tony

[dhanl82]

Good morning Bob,

Earlier this year I had a similar problem where both my cold/warm control pressures were the same as my system pressure - 70 psi. I discovered this issue as a result of various tests to determine why I was not getting any additional fuel enrichment after passing 1/3 throttle as the system is designed to do – my in dash wideband air fuel ratio gauge informed me of this problem plus the car did not run as it had before.

Thanks to a lot of communication and excellent suggestions from Tony Donato I was able to determine and solve the problem. I will attempt to effectively describe what I did below.

It appeared that after checking the screen in the wur and finding no debris that this was not the problem.

I then disconnected the wur return line (at the wur) and connected a rubber hose over it which I ran into a container. I then ran the fuel pump and checked the control pressure and discovered that it had dropped to the correct normal pressure, this confirmed that I had a blockage in the return somewhere in or after the fuel distributor.

I then attempted to blow through the rubber hose connected to the wur return line but was unable to due to the “push valve” in the fuel distributor being closed as it is intended to be when the pump is not running.

I then removed the primary pressure valve assembly from the distributor in order to get the “push valve” out of the fuel return circuit.

I then put my finger over the opening in the in the fuel distributor from which I had removed the primary pressure valve assembly and attempted to blow through the rubber hose connected to the wur return line. At first I was unable to but then something broke loose and I was able to. I could even hear bubbling up front on the fuel tank telling me that everything was open all the way to there.

I reconnected everything and determined that the problem was solved.

In conclusion, There must have been a blockage in a fuel distributor orifice not allowing the fuel to return from the wur through the distributor to the fuel tank, resulting in very high control pressure – this pressure was so high with its resulting pressure on the top of fuel distributor piston resulting in such a lean mixture that the normal action of the “frequency valve” attempting to lower the pressure in the lower distributor chambers could not overcome the very high control pressure resulting from the blocked wur return fuel path, hence no enrichment after 1/3 throttle.

I hope that I have successfully articulated the above so that it my perhaps provide some help.

[Bob Kontak]

Thanks Dave. This is the kind of info I think I need.

Got your PM. Appreciate it.

[proporsche]

Of course Bob, let us know what you`ll find...
Ivan

[Bob Kontak]

Originally Posted by proporsche

Of course Bob, let us know what you`ll find...
Ivan

What's funny is even with all of the posts I have made to help folks with basic CIS stuff, I have never touched the back side of the fuel distributor. It always came off as a unit. So I am going to be entering a new area.

Tony and I have been trading voice messages today trying to hook up and dhanl82 PM'd me his number so that will be a good start.

I suspect something in the distributor but I ain't touching nuttin' until I gain some knowledge.

Thanks again.

[proporsche]

HI,now you are in good hand with Tony...yup, the distributor was my 1st guess...let`s wait and see

Ivan

[patkeefe]

The fuel distributors are ugly to take apart and reseal. They have little screens in there that get really clogged up. There is a great write up on rebuilding them here somewhere, and if I find it I'll post the link. Did you try back flushing the return line yet? Open it at the engine and fuel pump and hit it with some compressed air. You can likely get the line open in the engine compartment.

[patkeefe]

CIS fuel distributer cleanout w/pics

[pmax]

Originally Posted by Bob Kontak

Car has been sitting for a few years. Start occasionally and put a couple gallons of gas in every once in a while. It's been starting and idling fine.
...
I purged the old gas and put in five gallons fresh and a several ounces of Seafoam. I can now get it to make an extremely feeble increase in RPM's to 900 rpm with throttle input. A long way from ok though.

Curious how old was the gas before it went bad ( I assume ) ?

[Bob Kontak]

Originally Posted by pmax

Curious how old was the gas before it went bad ( I assume ) ?

Oh, it was totally moderately bad if that is a choice. There was three year old gas in there but overlayed with a fresh 2 gallons every six months. It was brown colored and smelled like paint thinner. Turpentine comes to mind. Brown. Not deep brown but pretty damned brown.

[Bob Kontak]

Originally Posted by proporsche

HI,now you are in good hand with Tony...yup, the distributor was my 1st guess...let`s wait and see

Ivan

Finally talked to Tony. I misunderstood the plumbing and where control pressure is applied to the plunger. I thought it was downstream of the WUR.

So, start at the WUR which was mentioned as a potential culprit in the beginning of the thread.

[proporsche]

ok thanx ..to be continued;-)