Another SC that won’t start

[whiteSC]

Seems to be a number of recent threads on CIS car start/run problems, so I thought I’d add to the fray with my tale of woe in the quest for fire.

My car (83 SC) quit for good after stalling out twice on its last drive of about 20 miles. It was running normally for the first 10 mi when it started to stumble as if it was fuel starved and quickly died out. It started back up in about 10 min but quit again in a few miles and took a little longer to restart. A few miles later it died and hasn’t started since. The stalling out was undramatic - no bucking, backfiring etc.

Due to a combination of life stuff and a procrastinating owner, the car has been parked for a couple of years. Hopefully my failure to take swift action hasn’t made my job too much more difficult.

Thus far:
-Didn’t have spark, so I put in the MSD I had & verified spark using a spare plug as a tester
-Battery kept charged, checked OK with Harbor Fright tester
-Put in spare cap, rotor and plug wires; plugs were clean
-Checked fuel pump circuit per Bentley, electrons seem to be where they need to
-Drained tank (which had Sta-bil), pumped fresh gas thru line from tank out thru filter inlet hose
-Replaced filter, checked fuel flow > 2l/min, injectors spray cone-like pattern when inlet plate is lifted

When cranking the starter, the engine turns over at a steady cadence and doesn’t spit or cough, as if no gas is being lit in any cylinder. I don’t have a fuel pressure gauge, but wouldn’t the decent flow rate imply that the FP is putting out in the ballpark? I‘ve read through Jim William’s excellent site to get a CIS overview. Thanks for looking through my post.

Jeff

[millarg]

Hi Jeff, I feel your pain, replying so that I can eves drop on any replies

[fred cook]

A couple of things that you might try:

1) Check the grounds to the engine. When I put the MSD in my SC, I ran a ground to the chassis and then to the engine "just in case".
2) Run a +12v jumper to the coil to make certain that it is getting juice while cranking the engine.
3) Check the fuel pump relay fuse. It is the one that is #16 from the front of the car on the fuse block. This fuse tends to get lots of corrosion build up and thus creates lots of heat. Could be causing the fuel pump to not provide enough pressure to the injectors.
4) Double check the distributor timing. Pull the cap, turn the crankshaft pulley until the rotor is pointing at #1. Check to see if the pulley is at or close to the timing mark.
5) Make certain that you have the correct rotor for the cap. Don't laugh, it happened to a friend of mine once.
6) Make certain that the plug wires are completely seated in the dist. cap.
7) Pull the air box top and filter and check for cracks in the airbox. If you have
a popoff valve, make sure that it has not come loose.

If you have good fuel, spark and correct timing, there is no reason that the engine should not start or at least try to start.

Good luck!

[whiteSC]

Fred,
Thanks for the checklist. I'll get to work.

Glen - the guys here have solved tougher problems than ours, so hang in there!

[boyt911sc]

Jeff,

You have been given very good advises and suggestions. I'm no CIS expert by any means but making these engines come to life is easy and enjoyable. I just finished a few days ago an engine start-up for a fellow Pelican member who did a top-end rebuild for his motor.



It started after the second crank of the starter. You need to verify or confirm the following:

1). Sufficient ignition spark and correct timing.
2). Not only good fuel but the correct fuel pressures during start (ignition).
3). No significant air/vacuum leak.
4). Battery fully charged and starter cranking fast.

Avoid guess-work and you'll be able to make a meaningful diagnosis of the problem/s. BTW, the above engine is a late SC model too. Keep us posted.

Tony

[Bob Kontak]

Hi Jeff,

Pull an injector up and have someone else turn the car over to see if fuel is coming out. It is not easy to see so I just let it spray onto a finger to see if it gets wet.

Double check the spark again on two separate plug wires with an extra spark plug (need your friend again)

I like step #4 from Fred Cook.

Double check connections at the cold start valve's thermo-time switch on the driver's side chain box cover.

[Joe Bob]

If you have spark....squirt some ether/quick start into the intake. If it coughs or actually starts.....it's fuel.

Fuel filter or pressure is the bane of CIS. Got test gauges? If not...beg, borrow, steal or buy....someone will likely buy them from you when done....someone is always looking.

[jeffs9146]

Originally Posted by Joe Bob

If you have spark....squirt some ether/quick start into the intake. If it coughs or actually starts.....it's fuel.

Fuel filter or pressure is the bane of CIS. Got test gauges? If not...beg, borrow, steal or buy....someone will likely buy them from you when done....someone is always looking.

I agree and if it does cough check for vacume leaks in between the CIS and the throttle intake!

The draw from the vacume decides how much fuel is sent to the injectors so if there is a leak it wont give you any fuel to the injectors!

[whiteSC]

Thanks to all for input. My latest efforts:

-Verified that rotor pointed to cyl 1 cap wire when TDC marks were lined up
-Sanded fuel pump fuse and holder
-No cracks observed in air box, pop off is secure
-Thermo sw connectors on securely, no break or short obvious
-Plug wires are seated & in the correct order
-Swapped in battery from DD family car, cranks well
-Verified spark at each plug wire, one at a time with a spare plug
-Pulled injector and verified atomized spray in clear bottle, no drip when off; recall that pump flow rate was found within spec (more than 2 liters per minute). Does this indicate that the fuel pressure is at least close to what it should be?
-Verified FP was getting voltage during cranking using a test light with long leads

Sprayed ether at sensor plate & under pop off valve and tried to start, but no joy. Not even any sputter or cough to indicate combustion. Even if there’s a vacuum leak and it wasn’t getting any gas, the ether should have lit.
Seems like I covered the basics, but I'm not there yet. I'll try to locate a pressure test set up suitable for CIS, but I'm thinking the checks thus far should have been more enlightening.

Thanks, Jeff

[Staylo]

Have you checked the condition of the green wire at the distributor?

[boyt911sc]

Jeff,

You did pretty good in your investigation but troubleshooting any fuel injection system requires (mandatory) the use of a fuel gauge kit. Without this tool, you are at the mercy of too many variables. You maybe lucky sometime working without one. But you cannot rely on luck all the time. The pump maybe good but that does not tell you anything about the fuel pressures (control, system and residual). You are in the right track. A defective or out of spec WUR could cause you this problem too.

(1). Try to start the engine with ignition (CDI) disconnected:
Observe if the all the (7) injectors are spraying fuel. The 7th injector is the CSV. Omit the 7th if you are not equipped for such test. It would require that you pull out the injectors and place them in suitable transparent containers. Gerber's baby food bottles are what I prefer to use. Crank the starter several times and check the amount of fuel delivered.

(2). Try to start the engine CDI connected but the FP relay removed. Replace the injectors back and pull out the spark plugs. Crank starter several times and observe the ignition sparks on each plug.

If both tests above are good, then you could focus your investigation to other possible culprit/s.
fuel injectors..........good (???).
ignition sparks........good (???).
vacuum leak...........?????
fuel pressures.........?????

The flow rate test you did for the fuel pump is correct for determining if the FP is good. But you need info about the fuel delivery to/after the FD. So having no fuel gauge kit put you in a disadvantage. HTH.

Tony

[whiteSC]

Tony,
I’ve checked the spark plugs as you suggested in item 2. Sparking at all 6 tells me that the infamous green wire is triggering.

I spot checked the injectors on the “easy” side, now I’ll do the rest. I cranked long enough to see a spray (that soon condensed), but not long enough to get a measurable amount to determine the flow rate.

The CSV test in Bentley looks simple enough, so I’ll check that too.

Next up is to buy or borrow gauge kit. I see your point about the pump – it may operate at the correct pressure, but there could be a problem downline, say with the FD’s output or at several other components.

Vacuum leaks, ugh, to be done by visual inspection since it doesn’t run.

Jeff

[boyt911sc]

Originally Posted by whiteSC

Tony,
I’ve checked the spark plugs as you suggested in item 2. Sparking at all 6 tells me that the infamous green wire is triggering.

I spot checked the injectors on the “easy” side, now I’ll do the rest. I cranked long enough to see a spray (that soon condensed), but not long enough to get a measurable amount to determine the flow rate.

The CSV test in Bentley looks simple enough, so I’ll check that too.

Next up is to buy or borrow gauge kit. I see your point about the pump – it may operate at the correct pressure, but there could be a problem downline, say with the FD’s output or at several other components.

Vacuum leaks, ugh, to be done by visual inspection since it doesn’t run.

Jeff

Jeff,

As long as you get a decent spray pattern from each injector, that will be good for the start up. No need to measure the individual flow rate at the moment. What is critical is that you get the ignition sparks, fuel in mist form, no significant vacuum leak at the time you crank the engine and that engine should come to life. It might sputter depending on the control pressure.

I did a start-up run for an '81SC this morning with a replacement WUR with lower cold control pressure. The old WUR has a rather high cold control pressure and would take multiple attempts to get the motor running smoothly from cold start. Plus the vacuum test showed 2 of the 6 injectors were leaking.

The actual test for locating vacuum leak/s takes less than a minute after you pressurized the system. This is the picture of Ed Decker's engine (scheduled for pick-up tomorrow) during the vacuum test this morning. Note the latex glove under pressure.



The injection of low pressure air (1-2 psi) is sufficient to find those illusive vacuum leaks we all dreaded to have. Some people prefer to use starting fluid or the like to find this vacuum leak and what are their chances in locating them? With some luck they might locate it but most of the time not. Which ever process you decide to implement is all your choice. Good luck.

Tony

[Bob Kontak]

General question - On the ether test, does one spray some, run around and start the car or should you have a two person team spraying and cranking at the same time??? I am struggling why there is no coughing or attempt to fire.

Supplementing the distributor and timing mark test, you may want to get a timing light and see where #1 is firing. Something fundamental is amiss.

Has anybody bought this pressure set? Does it work with CIS?

Master Fuel Injection Pressure Test Kit

Pelican Parts tester is actually cheaper than the HFT kit when not on sale and it is made for the CIS. If you have a few days to wait, I would spring for the PP product.

Pelican Parts - Product Information: TOL-TA33865

[whiteSC]

Tony,

I think the starting fluid trick is just one of those things ingrained in everyone's mind and is probably useful in some circumstances. Visual inspection is limited to spotting obvious stuff since you can't always tell if something is OK by looking. Neither is very systematic. Are you able to elaborate on the low pressure leak test in your photo? Specifically - -

1. Can it be done with the engine in the car & airbox on?
2. Were the injector leaks you mentioned at the intake o-rings?
3. What has to be blocked off in prep and where does the test air get introduced?
4. Does the glove serve as the leakdown indicator or just a handy test plug?
5. Does it require a specialized rig or is it doable with common tools & soapy water?

A definitive test for vacuum leaks that takes only minute or two after set up would be invaluable to people tending to CIS cars.

I'm still a bit mystified why I don't get at least a hiccup or cough with spark at the plugs, spraying injectors and starting fluid. I'll press on with leak detection. BTW I'm buying a gauge kit from our host today to deal with the pressure end of things.

Thanks, Jeff

[fred cook]

have you checked compression in each cylinder? If you have fuel being delivered, spark at each plug and the distributor timing is ok, the only thing left that is required for running is compression. The fact that you get no starting effort when ether is sprayed into the intake suggests that the cams might not be turning! You could pull one of the top rocker covers and bump the engine over to see if the cam on that side is turning (watch the rockers for movement). If it is not, then you have found the problem. If it is, go to the other side and check it. If the cams have stopped turning then you probably will have bent valves and thus no compression. Might be time for a top end job!

[boyt911sc]

Originally Posted by whiteSC

Tony,

I think the starting fluid trick is just one of those things ingrained in everyone's mind and is probably useful in some circumstances. Visual inspection is limited to spotting obvious stuff since you can't always tell if something is OK by looking. Neither is very systematic. Are you able to elaborate on the low pressure leak test in your photo? Specifically - -

1. Can it be done with the engine in the car & airbox on?
2. Were the injector leaks you mentioned at the intake o-rings?
3. What has to be blocked off in prep and where does the test air get introduced?
4. Does the glove serve as the leakdown indicator or just a handy test plug?
5. Does it require a specialized rig or is it doable with common tools & soapy water?

A definitive test for vacuum leaks that takes only minute or two after set up would be invaluable to people tending to CIS cars.

I'm still a bit mystified why I don't get at least a hiccup or cough with spark at the plugs, spraying injectors and starting fluid. I'll press on with leak detection. BTW I'm buying a gauge kit from our host today to deal with the pressure end of things.

Thanks, Jeff

Jeff,

Don't get me wrong. I like to have starting fluid in my garage but I never used it for fuel injected system troubleshooting. And never for air leak detection. I use it for my VW bettles ('63 & '73) and lawn mower when they failed to start.

Answer to your questions:
1. Yes.
2. Yes.
3. Plug all open or unattached breather hoses including tail pipe (optional). Injection could be done at numerous points. But for convenience, I use the brake vacuum line at the side of the air box. With the engine install use a different injection point of your choice. It does not matter.
4. The latex glove is used to seal the throttle body. Too much air would inflate the latex glove too much. Just enough air pressure to inflate the glove.
5. An air pump, foot pump, bicycle pump would work. I actually tried one time to blow air by mouth and it was doable. All you need is a small amount of continuous supply of air to inflate a balloon (latex glove). I like to use my granddaughter's 'Miracle Bubble' solution which is available in most kid's stores.

This is not a novel procedure. This is a common and old technique for finding air leaks. I've been doing this start-up test for several years now for free to fellow members. But starting this year, I began to charge $10 an hour after a fellow Pelican reneged to buy me lunch after an engine drop and clutch installation. This is true and this guy could be reading this post.

PM me and I'll be more than happy to assist fellow 911 enthusiasts. Keep us posted.

Tony

[whiteSC]

I sprayed a nice cloud of ether in the open filter box and a healthy blast under the pop off, with assistant at the ready with the key. Remember, the injectors are putting out a spray as well.

Don't know about the Master HFT kit, but the cheap one says right on the box: not for Bosch K-jetronic. I sprang for the PP unit.

I dug out my Sun compr gauge but don't know if I like how there's only about 3 threads on the section of the fitting where it necks up to the 18mm diameter. Maybe I'll pull a plug from each bank & feel for air while bumping the remote starter.

I'm hoping the failure mode - a couple of stall outs & restarts before it quit for good - indicate that a big mechanical fubar isn't the cause.

[whiteSC]

Tony,

Thanks a ton for all the info. I think I was still typing when your last post went up.

[Bob Kontak]

Originally Posted by boyt911sc

I like to use my granddaughter's 'Miracle Bubble' solution which is available in most kid's stores.

Accept no substitutes.



Good job on getting the pressure tester.