My CIS Problems in my SC

[LM3929]

My CIS Problem so far is hard starting, back firing, stalling and no residual fuel pressure after 10 seconds, plus a noise or two in the motor that I can’t identify

My car is an 83 SC US/Can model and my WUR is a stock 090.

I finally started my engine last Feb after 10 years of sitting, (I turned the motor over every 6 months and re-fogged the cylinders each time and then sealed the spark plug holes with desiccant plugs.
The engine started and ran but it didn’t show oil pressure or any temp, so I shut it down quickly.

I had wires on the 14 pin connector wired up wrong (I had lots of oil pressure). When I thought that I had repaired the wiring problem the engine wouldn't start or run, so I hooked up a remote switch to the starter and turned the engine over that way and found after checking the green wire and harness that I had screwed up the pins on the 14 pin connector again.

Now it starts and runs but it take 10 seconds of turning the motor over to get it to start

I finally got my fuel pressure gauge back from a friend and hooked it up at the WUR.

1st pressure test
Engine cold - WUR plug removed - valve open, key on 30 psi
Engine cold - WUR plug removed - valve closed, key on 48 psi
Engine cold - WUR plug removed - valve open key off, the pressure dropped to 0 psi within 8 seconds

I replaced the fuel pump check valve with a new one and the max pressure is now 68 psi but the residual pressure still drops to 0 within 10 seconds

I replaced the Fuel Distributor primary pressure regulator with new parts from Pelican but the first section of the valve that I have looks like one out of an 78 not the one showing for an 83 (In one of Boyt911SC posts), now the residual pressure drops to 22 psi for about 6 seconds and then drops to 0 psi

I pulled the WUR and made it adjustable, cleaned the screens and re tested it; the WUR Ohms was measured at 9.4 Ohms

I first adjusted the WUR down to O psi cold (Hit it too far down) and then reset the WUR to 23 psi

I removed the return line off or the WUR (and plugged it) and when I turned the power on to the fuel pump, I had a small amount of fuel coming out of the unplugged WUR port., I tested the cold control pressure with the valve closed it was 68 psi and when I opened the valve for one second it dropped to 41 psi, I did that twice and the results were the same.

Then I tested the WUR with the power connected
Engine cold - WUR plug on - valve open, key on 23 psi
Engine cold - WUR plug on - valve open, key on, after 10 seconds 38 psi
Engine cold - WUR plug on - valve open, key on, after 20 seconds 51 psi
Engine cold - WUR plug on - valve open, key on, after 60 seconds 51 psi


I have pulled off the Fuel accumulator, checked it and it is good
I pulled off the CSV and checked to see if it leaks (what a pain) no leaks
I pulled all the injectors to see if they leaked (nope) and then changed them to new ones that I had and retested them for leaks and spray pattern all were good

The residual pressure still drops to about 15 psi within 8 seconds pauses the drops to 0

I think that the only thing left to check is the fuel distributor

I have also done Tony’s vacuum leak test and everything is good

What Have I missed?

Thanks Lorne M.

[timmy2]

How did you check your fuel accumulator?
Run the fuel pump up to normal pressure for a few minutes without starting the car, turn it off and then remove the lower fitting of the FA. Any fuel coming out? If so, the internal diaphram has failed and you need a new one.

[LM3929]

No I pulled ithe accumulator off and put a small amount of air presure in the inlet wwith the outlet pluged and checked the bottom for leaks and then I inverted it filled the bottom side with fuel and repressurized the inlet to check for bubbles

Lorne M.

[timmy2]

Perhaps not enough pressure to breach a minor diaphram leak? Try what I described, takes about 10 minutes to do.

Or, just wait for Tony to find this thread...

[boyt911sc]

Originally Posted by timmy2

How did you check your fuel accumulator?
Run the fuel pump up to normal pressure for a few minutes without starting the car, turn it off and then remove the lower fitting of the FA. Any fuel coming out? If so, the internal diaphram has failed and you need a new one.

Dennis,

The fuel coming out from the bottom port of the FA is not a sure indicator of a bad or defective FA. We had a lengthy discussion of this topic some years ago with our buddy (Gunter) from north of the border. It took a lot of effort and work to convince him. A leaking FA is a sure sign of a bad unit. No question about it. Once the FP starts to run, the fuel delivery system is pressurized with fuel including the return line. Small amount of fuel gets into the bottom chamber of the fuel accumulator. This small amount of fuel that gets into the bottom chamber will leak down when you open or break the bottom fuel return line.

To test a fuel accumulator for a ruptured diaphragm, apply pressure (gas or liquid) to the top chamber and the bottom port left open. Or by blowing air using your mouth (like blowing a balloon) to pressurized the upper chamber. I have a post that has a show & tell demonstrations if anyone would like a technical discussion.

I apologize for openly disagreeing with your post. This is a technical forum and some myths have to be explained or contradicted to establish which is fact or myth.

Tony

[timmy2]

No problem Tony, My thought was there may have not been enough pressure applied in the bench test to detect a leak. I have read the other discussions you mentioned and have seen a a few drips of fuel come out of my own FA that works perfectly.
I guess I'll need to get more detailed in my descriptions.
(Sometimes I just want to spur the poster to research by testing as well as provide troubleshooting ideas)

[timmy2]

My other thought was with the car sitting for 10 years, the residue inside the FA could be so gummy that it is sealing intermittently over a small leak in the diaphram and perhaps system pressures were enough to make it fail as opposed to low air pressure.
Lorne did not mention if or how he cleaned the fuel system afer sitting for so long.
Maybe all he needs is a good dose of techron and some running time...

[timmy2]

Due to a concurrent CIS quiz by Tony, I have to ask, Is your Fuel Distributor plungr sticking at all and if not sticking, is it seating fully closed?

[LM3929]

There is no fuel coming from the injectors with the fuel pump running and engine off .

lifting the air flow arm with the pump running, I feel slight resistance when I push the arm up and down, so the plunger is free.

I have just pulled the FD and it is as clean as a new one inside and the plunger is free.

My concern here is that the first valve of my Primary pressure regulator is different that the one that Tony showed in one of his posting and may be that is why my residual pressure is disappearing

[LM3929]

The fuel originally had Stabil in it when I took the car off the road.

the tank has been cleaned and sealed, the main lines replaced, the filter replaced

[timmy2]

Perhaps post a picture of your primary valve and the one you are referring to so that comparisons can be made. Did you add or subtract any shims to your valve?

[boyt911sc]

Lorne,

If I were to troubleshoot your problem I would do the following:
Test I: Determine where the residual pressure loss is occurring. Connect your pressure gauge at these locations:
a). Between FP and FA.
b). Between FD and main return line.

Run the FP and record the fuel pressures @ valve open, and @closed position (very briefly just to read the pressure, then open the valve).

Test II:
Turn ignition switch to ON position (not start) and lift the AFS (air flow sensor) plate for 1 sec. (max) and immediately start the engine. Start the engine immediately after lifting the sensor plate is lifted. Have a second person on stand-by to turn the ignition switch because this is critical for this test.

I've read your data. Something caught my attention and need to verify. So if you could kindly perform the above tests would be much appreciated. Keep us posted. PM me if you have any question.

Tony

[boyt911sc]

Originally Posted by boyt911sc

Lorne,

If I were to troubleshoot your problem I would do the following:
Test I: Determine where the residual pressure loss is occurring. Connect your pressure gauge at these locations:
a). Between FP and FA.
b). Between FD and main return line.

Run the FP and record the fuel pressures @ valve open, and @closed position (very briefly just to read the pressure, then open the valve).

Test II:
Turn ignition switch to ON position (not start) and lift the AFS (air flow sensor) plate for 1 sec. (max) and immediately start the engine..... (edited)..... Have a second person on stand-by to turn the ignition switch because this is critical for this test.

I've read your data. Something caught my attention and need to verify. So if you could kindly perform the above tests would be much appreciated. Keep us posted. PM me if you have any question.

Tony

Lorne,

After re-reading my previous post (attached above), I noticed something to be corrected. Take note of the instruction that's underlined (above). That won't be able to check the residual fuel pressure, instead:

Test Ia & Ib:
Run the FP and record the fuel pressures @ valve open, and @ closed position (close the shut-off valve and immediately read gauge and switch off the FP. Observe and record the fuel pressure drop (if any) for several minutes after the FP and valve have been switched off.

Disconnect gauge from test Ib and install it the conventional way between WUR and FD.

Test II:
With the gauge installed, do test II as explained earlier. Try this a couple of times. Keep us posted.

Tony

[LM3929]

I have the Fuel Distributor off and apart right now and just leaving to get new O rings so I can reassemble as soon as I do that I will run thoses tests

Thanks again Lorne M.



Lorne M.

[boyt911sc]

Lorne,

If the FP check valve is good according to your test, the FD return/primary valve is suspect. Another thing that caught my attention was your WUR's ability to build-up cold control fuel pressure that quick!!!!!

You have two major issues:
1). Sudden loss of residual fuel pressure.
2). Control fuel pressure increasing too rapidly.

Could you make the engine start and idle it for even a short time? I'll be away for the weekend so most likely I won't be able to follow this thread. Keep us posted.

Tony

[LM3929]

I picked up the new O rings for the fuel distributor and replaced them

Future info

the O rings that I used in the FD were 6 of 7 X 2 mm for the injector delivery ports, 2 of 19 X 2 MM to seal the main control valve and 2 of the 11 X 2 mm to seal the pivot shaft ends on the air flow meter

I will put the unit back on tomorrow and retest the pressures

Tony
can I put regulated air pressure to the inlet port of the FD, cap off the cold start valve port and see if the primary regulator is sealing properly?

Lorne M.

[LM3929]

I put the newly re O ringed Fuel Distributor back on and with the exception of holding pressure for 4 more seconds nothing has changed.

I hooked up the pressure gauge after the accumulator, turned on the fuel pump, the pressure went to 120psi before I shut off the pump, and then the pressure went down to 0 again.

the check valve is a new one from Pelican so I will have to pull it off again and see if there is dirt in it and try it again

Lorne M.

[timmy2]

There's no way to put the check valve in backwards is there?

[LM3929]

Nope

[timmy2]

Didn't think so.
It would suck if it was a faulty new one you installed.
Should be able to bench test it before putting it back in.