CIS Spitting Gas

DSPTurtle · 03-16-2018, 08:39 AM

Hi Guys,
Just installed a rebuilt fuel head on a '79SC. Raw gas now comes out from the exhaust pipe. With the engine idling it is spraying gas. Can't believe it still runs with that much fuel pumping out the exhaust.
Changed the plugs, cap and rotor, and did a leak down thinking it was missing a few holes. Everything on that side seems good. New fuel pressure regulator and the cold and warm pressures on the WUR are right where they should be. And I have 4.5-5bar on the system pressure. Pulled the cold start valve and it wasn't leaking at all. What the heck am I missing here?

Mark Salvetti · 03-16-2018, 10:20 AM

Were any of the plugs wet with fuel? Almost sounds like you have one or more cylinders that are not firing, although I would think that would be obvious at idle?

Mark

sixbanger · 03-16-2018, 10:31 AM

Are you sure it's gas and not water?

RarlyL8 · RarlyL8's Garage

If the system pressure and control pressure are in spec you may have a damaged diaphragm. I'd pull the injectors, measure the flow and see which cylinder is flooding.

DSPTurtle · 03-17-2018, 04:58 PM

Hi Brian,
I am now at the point where the injectors are flowing with the fuel pump hot-wired. It's like the plunger is stuck or something. Never seen this problem before.

psychoideas · 03-17-2018, 05:04 PM

Quote:

Originally Posted by DSPTurtle

Hi Brian,
I am now at the point where the injectors are flowing with the fuel pump hot-wired. It's like the plunger is stuck or something. Never seen this problem before.

With the injectors in separate jars, and the fuel pump running, do the injectors squirt?

If they do, with the air cleaner off and you lift the sensor plate, is there resistance or is there free play to a certain point?

timmy2 · timmy2's Garage

Did you adjust the rich/lean screw when you installed the rebuilt fuel distributor?
Turn mixture screw counterclockwise (lean) slowly until all stop spraying then clockwise (richer) until they just start to dribble.
Then put the injectors back, try and start the car and adjust your mixture CO from there.

boyt911sc · boyt911sc's Garage

JB,

Test run your FP and check the fuel flow of the individual fuel lines or injectors (engine off):
a). If all six (6) fuel injectors are prematurely deliverying fuel, the problem could be the FD plunger not fully going down or mixture set too RICH.
b). If only one or more fuel lines are prematurely delivering fuel with the FD plunger at rest, there is fuel leak that is caused by defective o-ring/s or defective steel diaphragm.

Keep us posted.

Tony

T77911S · 03:16 AM

tony meant RICH, not reach.

most likely as tony said, but, how old are the injectors

one note of caution, if you are dumping fuel with the engine off and pump running, you run the risk of hydro lock.

DSPTurtle · 03-19-2018, 05:26 AM

With the fuel pump jumpered and no pressure on the flapper plate, the injectors are blowing a lot of gas through all of them. That's the current update. I have a feeling that the sensor plate roller had a big flat spot on it. When I rebuilt it, I had to really work that roller to get it to spin. So, next step to see if I can back out the adjuster far enough to stop the flow.

DSPTurtle · 03-19-2018, 06:02 AM

Does anyone know if the airflow meters are interchangeable between a '79 and an '82? Of course the bosch part numbers are different. Jim's site only shows a photo of the airflow meter and no cross reference data except by year.

T77911S · 03-19-2018, 06:22 AM

that would not do it. go back to what tony said and look at "A"

setting the mixture would "compensate" for any wear on the sensor plate roller.

I kind if hate to tell you to do this as it will dump fuel into the cylinders, just do it quickly and start it ASAP to burn the fuel,. caution hydro lock.

with the FP on, check the sensor plate for any "free play". if you can freely move it up and down then the plunger IS stuck in the up position. you should feel resistance as SOON as you touch the plate.

DSPTurtle · 03-19-2018, 06:42 AM

T77, Haha... yes, I have had fuel leaking through the exhaust joints. I've pulled the cat and poured it out and had cups of fuel in it. There is zero free play in the sensor arm. I'm gonna pull the FD and the plate and shoot some photos. I've never seen this issue before and I've rebuilt more than I few of these. But it would explain some of the other issues the car had before Changing the injector seals, holders and booties.

T77911S · 03-19-2018, 08:40 AM

pull the injectors and put in jars to how much is coming out, or remove the line and out in jars.

if you have the flexible lines its easy to pull injectors with lines on.

you have checked the sensor plate with the pump on.

its goes back to what tony said.

some FD's have a tab that keeps the plunger from falling out, the plunger should be all the way down. you should be able to push it up and it come back down. slowly but it will come down.
you can remove just the plunger. be careful not to scratch or drop it.

DSPTurtle · 03-19-2018, 08:47 AM

So this little bugger is sitting proud of the control pressure line hookup. None of the other fuel heads in the shop have that in common. He doesn't seem to want to move down easily. Anyone have any ideas? Or a '79 fuel head for sale

Vereeken · 03-19-2018, 11:03 AM

That is not good.

Let it sit overnight in a tub of white spirit. That worked for me.
Next blow some compressed air at low bar into the control pressure connection.
It should come down. Make sure you blow it in a soft towel.
Post a picture of the plunger once out. Lets see if you have scarring.

I think I have a good FD that is valid for a 79 SC.

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by T77911S

tony meant RICH, not reach.

most likely as tony said, but, how old are the injectors

one note of caution, if you are dumping fuel with the engine off and pump running, you run the risk of hydro lock.

Ty,

Thanks for catching it.

Tony