Refuses to idle 83 sc

[hughc]

I dropped the engine last fall, mainly for cleaning but I also replaced the front crank seal, replaced intermediate shaft cover plate gasket and adjusted valves. I had valve covers, cooling fan and housing cerekoted.
So as I can see, I did nothing that would adversely affect the running of the engine.
Today I finally got to try and start it and it fires up but refuses to idle.
I checked the fuel pressures and they were good. I should point out that the car was running very nice before I dropped the engine. and I can't imagine what might have done (accidently) that would cause the current problem.

Are there any suggestions as to what I might look at before I go any further.
Thanks
hughc, 83 sc

[ahh911]

Since no one else answered, I'll give it a first go.

1. The cold start valve and sensor plate connectors are in their correct position?
2. The multi-pin connector on the left of the engine is seated?
3. The FV connector hooked up and functioning?
4. Brake booster line connected?
5. Oil cap on, breather line connected?
6. Vaccum advance/retard (blue/red hooked up in the right place)?

I'll stop, it sounds like pretty much anything that might have been removed or possibly played around with should be double checked, but I guess that's obvious...

Phil

[moparrob]

Vacuum leak immediately come to mind

[boomvang1]

I would check all hoses, sounds like a vacuum leak. A smoke machine would come in handy.

[LIRS6]

Pop up valve, if you have one, not seated?

Jason

[marty911sc]

There is a vac hose off somewhere in the front of the engine. I have not read "check fuel evap hose" yet.
Get a cigar and have someone blow smoke blow in the brake booster or evap hose. have the inspection mirror and light ready. I have used a collapsable camping water jug and filled it with cigar smoke and had my son sqeeze it. he didnt start smoking cigars until he was 10.
go through the parts break down and physically I.D. every AL Y tube, rubber hose and control valve. The Aux Air valve circuit hoses anD tubes are huge for some reason. it is acts like a Idle control vave. i had 4 in vacuum brake booster hose fail inside the tunnel next to the gas pedal.

[targa80]

Check each of the connections in below diagram. I would guess that you either have a vacuum line off or swapped line or electrical connector.

[Matt at Pelican Parts]

Since you dropped the engine, logically you'll want to inspect anything that you disturbed in the process.

As others have mentioned, a vacuum test might be a good start to investigate. We have a good DIY article on using a Smoke Pro to look for vacuum leaks on the 911.

Also make sure all the connections are tight on important components like the fuel regulator, distributor, and fuse box.

-Matt

[proporsche]

Phil..so when you start the engine.., it would start...after if you step on the throttle, the car runs but if you let got the engine dies? is that correct?

Ivan

[hughc]

When I start the engine, it runs, but for less than 5 sec. If I try coaxing it by pressing on the accelerator it might run for an extra sec or 2, then immediately quits.

I borrowed a Evap tester (smoke machine) and plugged it into the right hand side of airbox. (as you might know, there's a removable rubber plug there). I wrapped the air box cover with a plastic bag to prevent smoke from escaping.
Once the smoke pressure had built up the only smoke to be seen was coming from around the cover. I did not see any other signs of smoke.
From that test I am suspecting no air leaks, but my friend the mechanic will come over to verify the work I did.
If there are no air leaks then obviously something else is amiss, but at this point I can't imagine what.
I'll update as I can.

[boyt911sc]

Originally Posted by hughc

When I start the engine, it runs, but for less than 5 sec. If I try coaxing it by pressing on the accelerator it might run for an extra sec or 2, then immediately quits.

I borrowed a Evap tester (smoke machine) and plugged it into the right hand side of airbox. (as you might know, there's a removable rubber plug there). I wrapped the air box cover with a plastic bag to prevent smoke from escaping.
Once the smoke pressure had built up the only smoke to be seen was coming from around the cover. I did not see any other signs of smoke.
From that test I am suspecting no air leaks, but my friend the mechanic will come over to verify the work I did.
If there are no air leaks then obviously something else is amiss, but at this point I can't imagine what.
I'll update as I can.

Hugh,

You need to isolate the SYSTEM (airbox and surrounding areas) from atmospheric condition and perform a pressure test. I don’t understand how wrapping the CIS airbox with the motor installed could help you locate the culprit. Hope your friend mechanic could help you identify the culprit. Wish you luck.

Tony

[hughc]

Originally Posted by boyt911sc

Hugh,

You need to isolate the SYSTEM (airbox and surrounding areas) from atmospheric condition and perform a pressure test. I don’t understand how wrapping the CIS airbox with the motor installed could help you locate the culprit. Hope your friend mechanic could help you identify the culprit. Wish you luck.

Tony

Tony, I may not have explained myself clearly.
I introduced smoke thru the bottom of the airbox (thru the pluggable hole on the side) and to prevent the smoke from escaping thru the air intake I tightly wrapped the cover of the airbox with a plastic bag so that any smoke introduced would have nowhere to go except up thru the metering system. Does that not make sense?
I suppose I could have accomplished the same thing by just plugging the air inlet hole.

I guess I'll understand better after my mechanic looks at it.

[TibetanT]

I am NO expert....but:

1) Can you smell gas ?
2) Sticky injectors maybe...since car was offline for a few months.

My other thought was that Cold Start valve connector is swapped ( in other words connected to the wrong plug-in ) As was said in the first post reply #1
1. The cold start valve and sensor plate connectors are in their correct position?

Good luck

[proporsche]

Originally Posted by TibetanT

I am NO expert....but:

1) Can you smell gas ?
2) Sticky injectors maybe...since car was offline for a few months.

My other thought was that Cold Start valve connector is swapped ( in other words connected to the wrong plug-in ) As was said in the first post reply #1
1. The cold start valve and sensor plate connectors are in their correct position?

Good luck

this is a good guess ..but he has mentioned post #2 that he has it right

Ivan

[boyt911sc]

Originally Posted by hughc

Tony, I may not have explained myself clearly.
I introduced smoke thru the bottom of the airbox (thru the pluggable hole on the side) and to prevent the smoke from escaping thru the air intake I tightly wrapped the cover of the airbox with a plastic bag so that any smoke introduced would have nowhere to go except up thru the metering system. Does that not make sense?
I suppose I could have accomplished the same thing by just plugging the air inlet hole.

I guess I'll understand better after my mechanic looks at it.

Hugh,

Let’s wait until your mechanic had done his investigation and identify the culprit/s. But I doubt you would be successful using the “plastic bag wrap” method(?). Keep us posted.

Tony

[hughc]

Well guys, some good news.
My mechanic came over and before looking at the possibility of vacuum leaks I started the engine to show how it was behaving.
He suggested that maybe the FP wasn't continuously running so I removed the relay and replaced it with my jumper wire. The car started and continued to run, like it should. So, suspecting a bad FP relay I switched in my spare relay and ended with the same results, ie, the car started then died.
So, at this point the FP relay is not staying engaged once the engine starts.
I'll have a look at the wiring diagram to see if I can figure out the circuitry that keeps the relay engaged.
One other problem is that the alternator is not charging so I'll have to remove it to check the wiring hook up.
At least now the car is running so that's a big plus.

[T77911S]

if i remember correctly, been thinking 930 too much

the FP relay works in the DE-energized condition. the AFM sensor plate grounds the FP RLY to turn off the FP.
remove the connector on the back of the AFM. the FP should run all the time with key on.
if it does not run you have grounded that wire somewhere,
oh, did you get the CSV and the AFM connectors mixed up.

[Walt Fricke]

Start but won't run seems like fuel only being introduced via the cold start valve, which is just a fuel injector. When that squirt runs out, the engine can't keep running because you aren't getting fuel through the regular running fuel system.

At least you know the fuel pump works, so the somewhat complicated relay system you are checking is a good place to investigate.

If you really get frustrated, you can install a switch on your dash easily enough so you can manually control the fuel pump. But you shouldn't have to.

Swapping the CSV and fuel pump safety circuit plugs is a common mistake - the plugs are the same configuration, fairly close together, and as I recall the same color plastic? Their wires have enough length to spare for either easily to fit in the other socket.

[hughc]

Thanks guys.
The alternator problem somehow got solved. I removed it and took it to a local shop only to be told it is working fine. I re-installed it.

Latest update on engine is I removed both connectors (CSV and AFM). The engine started up and idled as it should. At this point I should mention the alternator light went out so I don't know why except maybe the wire connections were not tight enough.
I tried swapping the connectors and I was back to the same problem, ie, engine will not idle.

So, as it currently stands the engine runs fine with both connectors off.
Tomorrow I'll try again with only one connector at a time to see if it makes any difference.
I'll up-date then.

[boyt911sc]

Originally Posted by hughc

Thanks guys.
The alternator problem somehow got solved. I removed it and took it to a local shop only to be told it is working fine. I re-installed it.

Latest update on engine is I removed both connectors (CSV and AFM). The engine started up and idled as it should. At this point I should mention the alternator light went out so I don't know why except maybe the wire connections were not tight enough.
I tried swapping the connectors and I was back to the same problem, ie, engine will not idle.

So, as it currently stands the engine runs fine with both connectors off.
Tomorrow I'll try again with only one connector at a time to see if it makes any difference.
I'll up-date then.

Hugh,

Make sure that the plug (green) for the AFM has two (2) brown wires (1 solid brown and the other has brown with red stripe). If you inadvertently switched these plugs, and continue to start the motor, the harness could be burnt.

Tony