81 928S cranks, rumbles but won't start...

[ajmarton]

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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

[Danglerb]

Check for spark, I found an inexpensive timing light with an inductive pickup works very well. If you have a spark on all the wires, then I would pull the plugs and examine them. No spark, then work up the food chain, wire to coil, check coil resistance.

Old buried alarm systems can be a REAL pest too. Disconnect the battery ground and make sure it has a full charge.

I'd say resist any kind of starting fluid, but opinions may vary.

[785sp]

As nobody else is answering:

Simple order of things: Yes, try starting fluid, just one or two squirts behind the air filter. If it starts, then you probably have a fuel pump, fuel filter or fuel relay problem. If no start, then it's probably either a spark or timing problem. Neither is a big deal in an 81, as the engine is non-interference.

If no start after spraying ether, and you want to spend 30 minutes, check the timing belt for signs of slippage. Remove the top timing belt cover and inspect underside of belt with a flashlight, turning the engine by hand using a big wrench on the crank bolt. You might have to remove some spark plugs to lessen the pressure, unless your wrench is long and you're strong. If you come across any "torn" looking sections of the underside of the belt, it probably slipped and you have to replace it. Should take a mechanic a couple of hours, plus a cheap part or two.

If a spark problem, that's a longer conversation.

[Danglerb]

Make those really small squirts of starting fluid, too much and it can get dramatic.

Before starting fluid, I would smell the exhaust for any fuel smell, and pull a spark plug checking for same. If someone cranks the car for you, you should be able to hear the pump run from the back "I think" maybe mine is just noisy.

Very often its a relay or fuse, so many will start with those given how easy it is to check.

[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

[Danglerb]

Could be the injectors, they click pretty loud.

One of mine made some lifter noise after sitting for a few months, but once the motor warmed about halfway up it was gone.

Timing light with an inductive pickup can check all the spark wires and distributor in about 5 minutes, thats where I would start.

[SeanR]

It could also be the warm up regulator (WUR) When they go bad, it could cause the same type of issues. As the part is rather expensive, trouble shoot everything else first.

[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?

[DanielDudley]

Check the green wire to the distributor, and have a good look at the plug wires. If it is a dampness problem, it is probably one of those two things. PS. the green wire corrodes from the inside, so it could look OK

[ajmarton]

The gas smell is from pumping the gas pedal to try to turn over the engine. Fuel pressure and electrical have been ruled out by my mechanic. I will pass everyone's comments along to my mechanic and see what happens.

[Danglerb]

When its started using starting fluid, does it continue to run?

How well does it run?

Will it restart?

[EuroShark]

I 2nd the green wire. I had one go bad on me and the car was doing the same thing. I replaced the plugs and wires at the same time because they needed to be changed. My green wire was no longer green from being 28 years old at the time, but the 928 was still green

[ajmarton]

I will restart if you try immediately. But may not if you want 5 minutes. The engine will run smooth and powerful like nothing is wrong.

[Danglerb]

Originally Posted by arclight53

Where are you having the work done? Does your mechanic have in-depth 928 experience?

From another post, "Classy Cars in Culver City"

If starting fluid gets it started, and it runs fine once started, that kind of narrows the things that might be wrong.

Spark was stated to be "Strong", and it starts with starting fluid, so I would think that rules out any spark issues except maybe something like gross timing error (not likely to me).

Makes me think fuel amount is "wrong" either too much or too little. Maybe verify the idle switch on the throttle, and I would check the spark plugs immediately after trying and failing to start it.

[ajmarton]

Ok. The answer was the fuel injector relay. My mechanic assumed I replaced it when I said I replaced the fuel pump relay. He did not realize that there was a separate relay for the fuel injectors (at least on the 1981). Go figure.

[Danglerb]

As JimB says, relay, relay, relay.

[MPDano]

I am having the same issue with mine, but mine is CIS, so I shouldn't have a FI Relay. I got fuel and spark, but it doesn't even sound like it wants to catch. I'm going to verify my plug wires are in the right spot and check TDC again.

[785sp]

Hey Dano,

The bonehead who had mine before me somehow got the distributor turned one 'gear' off, and also had the timing 180 deg off, both of which had me scratching my head for some time. Also, confessing, I couldn't really hear the difference between the sound of the engine cranking with the right timing vs. the 180 deg off timing, although the mechanic who listened heard it right away. You might want to pay for an hour of someone's expert ear. If you have both spark and fuel pressure coming out of the fuel distributor, and especially if starter fluid won't start it for a few seconds, then it almost has to be a timing issue.

[MPDano]

I do have starter fluid which I may try, but I think I will verify my timing first. I was real careful when I put my TB on and putting the distributor on correctly as well as the plug wires, but anything is possible. My engine was out of the car too, so I had plenty of time and room to do it. Thanks 785sp!