ajmarton

I checked prior posts but could not find anything on point. I have an 81 928s that has been sitting around for around 6 weeks. No prior problems. Fuel relay was changed (just to get a new one in) in 2005. I tired starting it with no luck. It cranks and tries to start but never seems to catch. I can smell fuel at the exhaust tips and it seems like it wants to start but just can't. The engine will actually rumble like its going to start but then won't start. OXS light with parking brake light stay on after I try. I have a half tank of fairly new gas (2 months old at the most.) It is also somewhat cold (for Los Angeles) - in the 40s - 50s so I am wondering if it is due to the cold weather effecting a sensor. Any help appreciated. Andrew

Mongo

This could be related to the air flow meter if it is a Bosch L-Jetronic car. There may also be a very large vacuum leak coming from somewhere.

Mrmerlin

You might try installing a new set of plugs if your smelling fuel at the pipes then its a good bet that your plugs are fouled. Try using the least expansive Bosch plugs IE either the copper tips or silver tips, You may also have other problems but a new set of plugs will probably let the engine start. Also make sure your battery is fulley charged before attempting any more starts

marton

Green wire, if you have one? Runs across the front of the motor from the distributor to a device just behind the "jump start terminal" that provides timing pulses.
If that is toast & is shorting on the motor it will never start

marton

Landseer

I'm new, and clearly nowhere as experienced as these gentlemen who have already answered, but here's something I ran into, building on the first reply.

If its a huge vaccum leak, which was my problem on the 84, it might not be pulling enough air through the air filter/air gate to run. You might try taking off the air cleaner and using a clean rubber hose to hold open the air flow valve somewhat (use one too long to get sucked-up).

The gate spring is pretty tight, so in my case the vaccum leak prevented the gate from opening far enough to allow enough airflow do anything but barely chug, if run at all. (I also had ignition and timing issues, but once they were solved I still needed to use this approach to get it going and satisfy that it wasn't other further injection or green wire issues).

I then found leaks were througout the emission/carbon filter system, including under right front fender, plus at brake booster connection to intake. All places where my flailing arms contacted stuff while working on other stuff. Hope this helps a little. (If you mess with the woven-surfaced hoses, if they are fragmenting like mine were, you might want to be careful not to breath the dust, I wet mine down a little --- I am not sure what they are made of.) Good luck with it!

PorKen

The Temp II/coolant sensor is a prime suspect. It's the sensor on top of the coolant bridge, with a fuel injector type connector (the one with two spades is for the temp gauge/idiot light).

Vacuum leaks are likely, as is a bad thermotime switch for the cold start injector, or a sluggish cold start air bypass valve.

Have you tried holding the pedal down part way as you crank?

ajmarton

Ok, here's a quick update for hopefully someone's future reference. The mechanic changed out the coil and the thermal switch. 928 started fine for him for several days. I drive it home (5 miles) and she behaves great. The spark is strong and engine seems lively. Get home and turn her off. Next morning - same problem. She rumbles, wants to start but just no ignition. I can smell gas so it is not the pump. It's like that the next morning. Finally she starts on the 3rd day. I let her run, shut her down and then she won't start. Mechanic thinks it has to do with something expanding upon heating up and loosing contact. He is going to check the distributor. I will keep everyone advised. Also, the lifters seem a little loud when the engine is running cold and the quiet up. Is that normal or a telltale sign of upcoming issues? Andrew

Mrmerlin

The lifters being loud is usually OK if after the car warms up they quiet down, the lifters seem to make more noise if the car isnt driven and only started a few times,
I think your cold start system needs further diagnosing I wonder if the mechanic checked fuel pressure leakdown and the cold start injector for leaks, Try the easy way add a can of techron to half a tank of fuel lots of short drives are better than one long one also there is a possibility of a vacuum leak. this may also be an indication of not driving the car enough

PorKen

If the wire from the distributor, which goes over the engine to a connector on the passenger side fender wall, is not green, then it's likely old and bad. Also, the connector at the end falls apart when old.

ajmarton

The car does sit around as I only get to drive it every few weeks as it is one of several so perhaps that does have something to do with it. And the lifter noise does tend to disappear if I use the 928 on a regular basis. BTW mileage is approx 54k (manual).

ajmarton

My 81 928 still has starting issues. Same symptoms - electrical works - plugs are ok. Replaced the Bosh coil. I can smell gas so I assume pump is okay. If the mechanic squirts some starting fluid the car starts. He said the leak down test was a little faster than what he expected but he thought it was oky and fuel pump presure was fine. Any suggestions?

John V

YES,

check the AFC relay-

read this thread.

https://rennlist.com/forums/showthre...ight=afc+relay

ajmarton

Ok, it turned out to be a bad fuel injector relay (there is a separate one for the injectors). It was one of the first items my mechanic replaced so he crossed it off the list of things to check on the follow up. But it looks like the new relay went bad as he ultimately determined that power was cutting out to the injectors. Hopefully this information will be of use to others in the future. NOTE: There is a separate fuel pump relay for my 1981.