medipedicman

The car starts perfectly fine when cold. After a short drive she wants to stall out at stop lights. If I am paying attention to it I can work around that by adding throttle.

Last night I ran downtown to get some good pics before the small town that I live in removed the flags from memorial day. Got some good pics but started and stopped one too many times. She would crank but not catch and the lovely wife said she smelled strong gas. We thought we would take a walk and let her settle down (both the wife and the car). After 20 minutes still no start. I secured her and we walked the approx 4 miles home. No big deal, but it was after 10 pm with rain clouds on the horizon.

This morning I drove down to check on the 79 and she cranked right up. No issues at all. I drove her back home with little fan fair.

I have searched the topic and have found issues with WUR, issues with rubber intake boots. Texting with a friend last night, spark came up and sticky plungers at fuel distributor.

This engine is about to be pulled and replaced so I don't want to put any new parts on it, but I am planning on driving her over to SITM.

A little recent history: Issue has been present for a while. Idle was turned way up and issue disappeared enough for a trip to Atlanta, but idle was at 2000 rpm. I mentioned it to my body man who is also a mechanic. Since he ran about 3 weeks over on the body work I asked him to look at idle. He turned it back down but the original issue remains.

I guess I am looking for a magic bullet for an owner with limited skills and no gauges. I can turn the A/F mixture down a little (more lean) but at this point am somewhat afraid of making it worse to the point of not making the trip.

Any new eyeballs with ideas and/or shared experience?

upstate bob

gauges will give you the answer. Now it's running off the cold start injector until warm. The old CIS system is quite dependable until it gets a chunk of crud in it. Although mine still runs well I know I had better start doing some PM on it. Old accumulators rot out, check valves stick on the main pump, WUR gets tired, injectors get senile.

s54venture

Mine has a similar stall symptom that I can avoid by keeping on the throttle.
When it stalls out I pull the fuel pump fuse and crank with the throttle down, it'll start and run for a little.
One time mine ran for a couple minutes and I could not figure out why
When the car finally dies off if I put the pump fuse back in I can usually get it to start again.
If it stalls out and I try to start it with the fuel pump fuse in it won't even try to start, with it out it'll start every time.

It really only happens when I'm babying the car, if I'm taking it up through the revs it doesn't happen.

medipedicman

Thanks for that helpful info. The 79 does not have a fuel pump relay, it has a jumper instead. But it stands to reason that in an emergency when I'm far from home that will be an option.
Thank you for your help.

medipedicman

Last night I allowed the 79 to warm up in the garage. I made a slight adjustment to the front screw. Moved it barely an 8th of a turn (ccw)to get it horizontal. Then moved to the plunger between the spider and the air box. slight ccw adjustment.

THEN I cranked her up and she started fine and idled well. I am sorry that I didn't time this step but she warmed up and then started to bog out, sputter and die. Approx 6-7 minutes.

The engine had a slight waft of smoke coming up after I removed the keys and after further investigation I realized the smoke was coming from under the car. I had some old cardboard under the car and the section that was under the cat was smoldering like it was going to ignite. So the smoke was from a combustible material under the car and not the car................ kind of freaked me out a little. While I was under the car retrieving the cardboard from the driver side I noticed a small puddle under the passenger rear wheel well. I do not have the sense of smell (short boring story) but I suspect it is fuel. No one else was home at the time to verify but it was coming from the front of that wheel well.

I will take the fender liner off tonight before turning over and see how bad it is. I have plenty of extra soft fuel line but if it is the accumulator or a hard line that is leaking I will have to take the wifes DD to SITM. I will also turn the front screw 1/4 turn ccw and give the plunger a 1/2 turn ccw before turning her over. By the time she stalled out last night my eyes were burning so I suspect she is WAY to rich.


Personal safety aside, I just have too much time and money tied up in this thing to watch it burn up on the side of a mountain rd.

Kiln_Red

Whoa! You're running intermittently rich. You really need to get this figured out before taking it on long travels. The cardboard isn't the only thing that may ignite. The interior might catch a blaze if the exhaust temps get too extremely hot.

Why are you replacing the engine? How old are your ignition parts approximately? Can you hear abnormal air turbulence in the spider at idle with the hood up?

medipedicman

Thanks Austin. I'm only replacing the engine to upgrade to a 4.7 Euro S. I don't hear any strange noises until the very end, right before it cuts off.
I will be removing the airbox tonight to gain better access to the adjustment screw. It sounds like I need to do a couple full counter clockwise turns before it is close to correct.
The fuel leak near the accumulator is troublesome. I have a feeling that will determine whether this car makes the trip or not.

Kiln_Red

It's likely unrelated but you should have a look at your ignition coil ballast resistors. The connectors, hardware, etc. are probably corroded big time. I feel like this is a largely overlooked area in diagnostics among 928 owners. I cured intermittent running issues in an l-jet car by cleaning there. Just food for thought.

medipedicman

During the last six months I have been doing a lot of troubleshooting various issues.
Part of that included swapping out the ignition coil with one I had had on the shelf for a very long time. The coil had a different connectors than the stock. It had wings that would accommodate a blade fitting. Should I swap back in the original ignition coil?

Kiln_Red

Absolutely. Put up a picture of the one you installed. May not be an ideal replacement for the 928. What do your ballast resistors look like?

medipedicman

I will take pictures tonight when I get home from work.

SharkSkin

Actually, no. The third relay from the right on the bottom row(XVII) is the fuel pump relay, and it has an extra sense wire that senses the tach signal so that the fuel pump won't stay running with the engine off, for example in case of an accident. Should be p/n 928.615.113.01 or equivalent, NOT a general-purpose relay.

Early 5-speeds have a jumper in the fourth relay position from the right on the bottom row(XV). Rogerboxes have a relay in that position that locks out the start circuit except in Park and Neutral -- not needed on a 5 speed.

The FPR has what amounts to a frequency counter inside; if the frequency from the tach signal is too low it shuts off. If the freq counter has gone out of spec it's possible that it's fine when you are on cold start/high idle but then when the car comes down to warm idle the FPR cuts off. You can test this by jumpering the FPR and repeating the warmup process, and if it stays running you've found the culprit. Just don't forget to remove the FPR jumper. Given the reported fuel leak I suggest you do this outside. You can get the car back in the garage by cranking in first gear with the clutch out if it's too much of a slope to push it. Just disconnect the coil wire to make sure it doesn't get away from you. And don't make a habit of it, it's a lot of strain on the system.

Also, AFAIK there is no aftermarket coil that will work worth a damn on an otherwise stock OB. You would probably have to change the ballast resistors to make it work right. Better to get the right coil IMHO. You might want to have a look at my ignition troubleshooting page, test #5; probably not relevant to the "dies when warm" issue but you can check your original coil condition.

medipedicman

Thanks Sharkskin. I stand corrected. I was confusing the FP with the starter relay which is a jumper on the 79.

Accumulator leaking. I am downloading pics and video. Totally fubar. On the hunt.

medipedicman

This may be completely unrelated to the thread title but it needs to be overcome in the next three days.

SharkSkin

I saw a drop come from above in the vid. Are you sure it isn't the hose end, top center of the pic below? If it is, you could have the parts by Thursday and job done within a couple of hours by following the relevant steps here. You'll need at least one piece of the right size hose, two clamps and a couple of copper sealing washers. I doubt you have the dual pumps like mine, the other end of that hose is probably a banjo on the fuel pump under the tank.