No Start. Need help please!

[FL944]

Please help me!

1984 944

Driving to work 3 days ago and as I slow down for a red light, the engine just shuts down completely as if someone turned the key off. I coast and try to restart.. no go.. So I exit the road into a nearby restaurant parking lot and get out my tools.
I pull the distributor and clean copper. Try and start- No Go.
I replug a few sensor wires and look for corrosion. Try to start-No go
I sit in the car wondering what the hell just happened.. and turn the key in spite- Yes Go.

????? Weird.. So I rev it slowly for a moment then decide to continue on to work. Runs fine for the 4 mile duration and gets me to work only 20 min late.

My shift ends. Ready to go home. No Start!

So my troubleshooting begins.
Here is what I have done.
--

1) I rechecked my ignition wireset and then decided to replace them. - No start.

2) I disconnect the battery and reach under the dash and unplug then replug the Motronic unit and check for bent pins or anything obvious. -No go..

3) I decided to see if it was getting fuel. So I opened up the nut/ball bearing seal at the end of the fuel rail feeding the injectors. Expecting to see some pressure bleed out of the system when I cracked it open. There was only a small dribble of fuel. So.. that leads to #3

4) I sprayed some starting fluid into the intake and attempted a start. -She sputtered for a moment as the ether was quickly consumed.. Leading me to understand she was getting fire, but no fuel apparently. Fuel pump problem??Perhaps??

5) I take my voltmeter and have a friend try to start the car as I tested voltage to the fuel pump. The voltage was good. I leaned in close and placed my hand against the pump as he tried to start again.- I heard no humm and felt no vibration or any hint that the pump had actually turned on. So I opened up the fuel rail nut again to see the same dribble as before.

I concluded that the fuel pump was faulty and decided to replace it.

-So I order a new bosch fuel pump and install it today and try to start.- No go.. I crack the fuel rail nut again to see the same dribble of gas as before.

I notice as I am trying to start today that there was no tach bounce..

So my brain (for some reason) has led me to the Motronic dme unit under the dash.
I have it now removed from the car and in my hand.. And with a blatant, blank, confused stare I look deeply into its metal housing.. Searching for wisdom.. Searching for the answer to WHY!!...???

PLEASE HELP ME!

[minho78]

Speed and reference sensor. Also it could be the dime relay.

[Majin325]

If your getting no tachometer bounce it could be the speed or reference sensor. Also check the wires that connect to the positive battey cable are getting a good connection.

[89-944NA]

+1 on the DME relay....it also controls the fuel pump. ALWAYS carry a spare DME relay. Since you know the fuel pump is good, try this:

The DME relay is G5 on the fuse/relay panel.

There are 3 ways to test the DME relay.

Make a jumper wire with three (3) leads, on the end of each lead put a spade (flat) connector.

1) Remove the DME relay, insert jumper wires into terminals 86, 87 and 87b on the relay/fuse panel...turn on the key and this will activate the fuel pump. DO NOT START!!!

2) Insert the jumpers into terminals 30, 87 and 87b on the fuse/relay panel. START the car, if it starts and runs, the DME relay is bad


3) To test the DME Relay itself, do the following:

Measure the resistance across terminals 30 and 87b....should read infinate or "1" on a digital multimeter.
Next measure resistance across terminals 30 and 87...should also be infinate.

Next, connect 12 VDC to terminals 85b and 87 of the relay, and with the multimeter read the resistance between terminals 30 and 87b....the reading should be between 0.1 and 0.3 ohms.

[Ederd]

have you checked the ignition coil? mine has been acting funny for the past few days by stalling me out in the worst possible times on the road.

[944Toon]

Been through a similar process. Intermittent starting problem, getting progressively worse till wouldnt start at all. Ended up changing fuel pressure regulator, pump and filter, coil, dme, plugs and wires with no luck. Finally went back to distributor which by chance had tested okay when problem was at first intermittent and found no juice at on the inside of the distributor cap king lead point (but okay from king lead itself). Replaced cap and rotor (had tried cleaning the rotor at some point) and fired up straight away.

[thekidd]

I have had problems like this, intermittent start. One was my ignition wire was making a poor connection at the battery. Its the wite wire on the positive connection at the battery. The other solution was my speed and reference sensors. Both had a no tach bounce.

[pfarah]

FL944,

While you have the DME out, just take a few moments and remove the two side covers (held by 4 screws each) to determine whether there is any corrosion/damage within the unit. My original DME had extensive rust on one of the printed circuit boards which caused a number of starting and running issues.

[Gawernator]

Pfarah, were you able to repair the damage to your DME or did you have to replace it?

[pfarah]

Gawernator,

I actually replaced the entire unit. I was given a great deal from a local guy who happened to have a "few" in a drawer so I jumped at the opportunity. She starts like a dream now. Unfortunately, I have her in several pieces right now... In the process of replacing a rear axle, replaced driver's side vent hose with a shop vac hose purchased at Lowes. In order to do that, I had to take the dash apart, one more time. While I'm in there, I found and replaced one dash light, took apart the speedo to adjust the odometer worm gear and sand/paint the speedo bezel as there was visible rust. I'm also attempting to troubleshoot a non-operating low fan speed on the driver's side. I also removed the battery and, luckily, only found surface rust on the tray. If the weather holds up tomorrow, I plan on removing the rust and applying POR 15 to stabilize the area. With no garage and the threat of snow looming, I am under a little time crunch. Thankfully, she's not my daily driver however; I want to put her back together before I forget where all the parts go! Have a great holiday!

Patrick

[Gawernator]

I have heard that the fan not running at low speed but higher speed can be a bad or corroded HVAC resistor pack. In the front on the driver side (LHD). Merry Christmas

[89-944NA]

DME relay is only $27.25 (from Pelican), not really worth the trouble to attempt a repair, unless you like tinkering....But I'd have a known good one on hand in case the repair doesn't work. And don't forget to keep a good spare relay in the glove box.

[FL944]

Thanks so much guys!! It was the freakin dme relay all along!!

Phew!

[FL944]

P.S pfarah.. I did crack open the DME itself and have a look. There was very light surface corrosion, so I cleaned it with alcohol and a cotton swab for drill. There didn't appear to be any cold solder joints or burnt out diodes / capacitors / resistors or any of the like. I wiped the rubber seal clean with a wet rag- let it dry and resealed the unit.

P.P.S I am new to this car and had no clue about the DME relay. So.. seriously guys, thank you so much for helping me out. You brought my car home TODAY!

[pfarah]

Congrats!
It was the first thing I did after purchasing my car. I read so many threads on the DME relay so I just tossed the old one.

I'll start a new thread regarding the fan (the resistor tested fine).

[89-944NA]

Originally Posted by FL944

P.S pfarah.. I did crack open the DME itself and have a look. There was very light surface corrosion, so I cleaned it with alcohol and a cotton swab for drill. There didn't appear to be any cold solder joints or burnt out diodes / capacitors / resistors or any of the like. I wiped the rubber seal clean with a wet rag- let it dry and resealed the unit.

P.P.S I am new to this car and had no clue about the DME relay. So.. seriously guys, thank you so much for helping me out. You brought my car home TODAY!

So, now you have learned one of the cardinal rules of 944 ownership, keep a spare DME relay in the car, a failed one is the cause of a lot of starting problems. And if you have purchased a good DME, wrap it up and put it away, you never know when your going to need it...they are getting old.

Good Job, glad we could all help

Don't know if you have checked this site or not, but here is a good resource:

Clark's Garage Home Page