DME Relay, No Start, Battery...Some Tests

[exitwound]

Did some more testing on the no-start situation on my car. Few precise questions this time. Might actually be two completely different problems creeping into each other.

The DME Relay

• Took the DME Relay out today and tested the resistance in the circuit. Both tests (as done from Clarks Garage) shows infinite resistance across 30+87b and 30+87.
• Opened the relay and inspected for anything 'obviously' wrong, such as broken solder points, blown diodes. Nothing appeared out of the ordinary.
• Created a jumper bypass between 30+87+87b on the relay port as shown at Clarks Garage.

THE CAR STARTS and runs. Rough idle when cold.

The Battery

• Car has been sitting for 4+ days no-starting, presumably due to the lack of fuel as stated in the above scenario.
• Attempted to start, very little starter action. Solenoid clicks in, starter doesn't turn.
• Charge of the battery takes 30-40 minutes, indicating the battery is quite low.
• Starter now starts the car.

After Turnoff...

• Turned the car off and pulled the DME jumper to stop the fuel pump from operating.
• For the next 40-60 seconds, a loud hissing sound can be heard from somewhere under the fuel rail. It's hard to pinpoint, but it sounds like it's one of the two fuel lines going back into the body of the car. After a minute or two, the hissing subsides and stops slowly.

Questions...

• Does this indicate the DME relay is likely somehow nonfunctional? There's no obvious damage to it. Have not yet done the 12v test to the relay outside the car. Will do that soon.
• Why is the battery seemingly so low after sitting, not even attempted to be started in days? There's no extra load on the battery while off. Drain was measured at 69mA (..if I remember correctly)...a little higher than the 60mA recommended maximum, but not much.
• I've never noticed the hissing before out of the fuel rain after stopping the engine. Is this the pressure inside the fuel rail somehow dispersing? There are no fuel leaks anywhere in the system. Note: I have a fuel pressure gauge but cannot find an adapter to mount it to the rail as of yet. Will do that soon, hopefully.
• Are these two problems somehow related? Does a failing DME Relay link in any way to battery drain? I dont' see how, but you know more than I do.

[zedsn]

Hi, my 83 944 has a battery drain and the easiest thing for me to do was narrow it done to the 3 factory power wires going to my positive battery terminal under the hood and interrupting it by putting a switch inside the car with a correct gauge wire below the ignition switch and turning it off or on when I have to start or stop the engine. Basically put a switch and am cutting out the circut and completing the loop so to speak. I have heard of factory 944 alarms doing the battery drain thing but like I said this was easiest for me to do and still does the trick years later. Alos, a diode can go bad in the alternator and drain a battery as well. Maybe you jumped your battery and messed the alternator up? You may also want to do some relay tracing. Can' help on your fuel issue though.

[hpservertech]

That hissing sound isn't good. focus on that for now. Battery issue is easier to fix...replace it.

For the hissing, have you checked the FPR/dampers yet? If not do that. If I had some extra's I would send them to you. Also, you might want to get a noid tester to check to see if power is getting to the injectors.

It's sounding more and more like your having a fuel issue. Injectors could also be bad/going bad. Check each one when it's cold by putting 12+ & - to the terminals. you should hear them click on/off. If not it's definatly bad. Remember the fpr/damber are vacuum feed as well, so check your vacuum connections.

[hpservertech]

Also, why not take the alternator off and have Autozone/Parts America test them for you? They do it for free. Same with starter & battery if your adventerous enough. All those test good, then you could simply have bad battery cables. After 20+ years they usually are bad.

[exitwound]

How would I go about checking the FPR and FPD without the fuel gauge being hooked up? What test can I do to see if they're working properly?

Battery is 4-6 months old. Alternator was tested and new regulators put into place. Negative cable was replaced as well. New starter solenoid, two starters, cleaned all contacts in the starter circuit. Haven't replaced the positive cable since it's big and embedded into the wiring harness.

As for vacuum, there might be a small leak. We've noted some peculiar problems occasionally that all lead to vacuum. I want to replace the entire vacuum system in the engine bay, all those hoses and elbows and junk with new ones. Can I purchase the hose anywhere in a roll or something? The elbows and y-joints Advance Auto didn't have, nor the correct hose diameter.

[hpservertech]

Lindsey racing has a complete kit for the vacuum lines. Everything you will need.

Basically put the car back together. try to start the car. If no start, go to the fpr & damper. Disconnect the vaccum hoses and see if there is any gas in them. That's the one way I know how to test them.

Otherwise see if there is anything on Clarks-garage.com about them.

[exitwound]

Update: First day I could work on it was today.

• Inspected all injectors for any leakage. Found none.
• Refitted all the vacuum lines properly. All are tightly sealed (will clamp them all down with new clamps soon) except one. The line which connects to the intake near the throttle position sensor is loose and doesn't seal very well. The rubber elbow there is quite hard and needs to be replaced. No gasoline in the vacuum lines.
• 12.0V on the battery measured across the terminals. Shouldn't it be higher? It was fully charged a few days ago and the car hasn't been touched. How do I measure on a multimeter the drain the battery sees while the car is off?
• Installed DME jumper (30,87,87b) and looked around and listened for any anomalies in the fuel rail. No leaks, no unexpected sounds. Fuel can be heard flowing through the rail and back into the tank.
• Attempted to start the car with the DME jumper enabled and it starts! First try. No hesitation. It's 28F out and extremely windy and brisk. Car turned over very quickly. Idles rough until warm, 2-3 minutes later. Idles at 800rpm cold, 1200 warm.
• Drove around the block a few times. No anomalies.
• Turned off the car. Pulled DME jumper.
• Listened for that hiss that I heard the other day. Nothing. No sounds present after the engine turned off.
• Put in the DME Relay. Car started. Car runs fine.
• Turned car off. No signs of hissing or leakage.

Hmmm. DME intermittant? Still can't test fuel pressure at the rail. Can't find a local supplier for the fuel pressure gauge converter. RAWR.

I think I'm dealing with two issues: no/low fuel pressure, battery drainage.

[Razorback1980]

Here is how I do it. I take the battery cable off the battery. I get a meter with a 10 amp reading and clip the negative lead on the battery post and the positive lead on the battery cable you just took off. This will tell you the amperage traveling through the meter. Should be less than 100 mA. Actually ideal is around 60 I think. Car should not be running and all doors should be shut and all lights off. Anything that should be shut off normally over night should be off. That will give you an indication of how much electricity is being pulled while it's sitting overnight in the driveway.

You may want to check your engine temp sending unit to make sure it's working properly. It tells the DME whether the engine is cold or not and may not be informing the DME correctly. 1200 for a warm idle is a bit high I think.

[zedsn]

Hi, with my battery drain problem I could have a volt meter to my + and - on the battery posts for awhile and I could actually see the battery being drained slowly but surely. I have a VDO gauge that mounts to the end of the fuel rail and you can borrow it if you pay postage both ways and promise to get it back to me. Ed from Ohio.

[exitwound]

Well a parasitic drain test on the battery isnt possible tonight as my Multimeter has a blown fuse in it. Only local shop who has them closes at 4:30. Who closes at 4:30??? RAWR.

I'll test tomorrow.

Zedsn, thanks for the offer. I will keep it in mind.