Saturday morning I drove my trusty Series III about 40 miles away. When I started out, it was cold, so I ran the heat. By the time I reached my destination, it was over 70 degrees Fahrenheit and I'd turned off the climate controls. The engine read warm on the gauge but not overly so.

I stopped the car for about 10 minutes, then tried to start it to move to a better parking space but while it started to catch, it stumbled and died. I tried again, pumping the gas and it caught but the moment I took my foot off the throttle, it died again. I finally got it to catch by pumping the gas while turning the key and kept it revving at about 1200 RPM for maybe a minute, at which point it idled normally (at about 750 RPM). Thinking it might be vapor lock, I moved the car, popped the hood and left it like that for the next few hours while I went about my task.

At the end of the afternoon, I tried again and, after a few attempts, got it to run/stay running and drove it home. Sunday morning, it started strong like it usually does and has continued to start strong and run fine since but I haven't had the chance to get the engine really hot.

This car has a history of "previewing" issues before things outright fail (which is a kindness, I suppose), so I'm taking it seriously. It's not unusual for the idle to run "lumpy" for a minute or so after a starting hot but out and out failing is atypical. In case it matters, I run the car every day as my daily driver.

Any ideas?

Thanks in advance,
Rhett

 

Hi Rhett,

My 85 VDP did that to me.

I suspected a suspect coil so I swapped it out for a new dlb198.

Started perfectly when hot a couple of times before the problem came back.

Turned out the AFM was playing up.

The film strip arc in the little black box on top of the unit (in the sealed bit) had become really dirty with carbon and was messing with warm starts.

I dabbed cotton wool buds in pure alcohol and carefully wiped the film clean.

Problem seems to have been wiped away.

Cheers,

Nigel

 

The 'could be' list includes just about anything in the fuel injection or ignition systems. An outright failure would be a blessing as far as diagnostics go. Or, bring some basic test equipment with you and be ready to swing into action whenever the problem strikes. Spark tester, fuel pressure gauge, ohm-volt meter. Naturally, all the testing in the world is unlikely to reveal the fault unless while the problem is occurring.

Checking/cleaning/tightening all pertinent connections and grounds might be the cure.

A skewed/failing coolant temp sensor is a possibility. The beauty here is that it's only about $25 and takes 5 minutes to change....not hateful as guesses go. Oh, and the wiring to the CTS is critical as well. Check carefully

Try switching fuel tanks as soon as the problem occurs. Any change?

The ducting downstream of the AFM might be coming loose.

The "main" and "fuel pump" relays can fail. Cheap to replace as guesses go.

Fuel pressure regulator might be failing...a pressure test would confirm.

Both the ignition coil and ignition module often show signs of weakness when engine heat builds....but that isn't carved in stone. Check for spark and quality of spark next time the problem occurs...or replace both if you feel like guessing.

Rig-up jumper wires to bypass the fuel pump circuit and ignition switch...I can help with this if needed....and drive the car for a few days. if the problem goes away then at least you have a clue.

Pick a couple possibilities as a jumping-off point and run 'em down. If no joy, move on to a couple more.

Or wait for an outright failure.

Cheers
DD

 

All I can add is that on FI cars, pumping the throttle does nothing! Opening it and cranking might help in clearing a flooded engine.


Carl