Alternator not powering battery

[Dave WM]

The best thing is to just read that EFI section a few times, keep in handy read several times, it will begin to sink in. On mine the temp sensor was reading low on the ohm for the given temp, this will make it run lean since the EFI unit thinks the engine is warm when its not (it works temp/resistance inverse relationship).

there is a table in the EFI that will give you approx. resistance reading for given temps. check at the 36 pin connector, if not ok, check at the sensor, if still not ok then prob the sensor, if ok at the sensor then prob corrosion in the wire harness plug.

[siteunseen]

I'm glad you posted that.  I need to permanently set my potentiometer with meter. It's a volume knob that I've adjusted by the seat of my pants and the TEMP gauge. It's been laying in the passenger's floorboard for a couple of years now.

[jlenownnab]

Possible good news here in Cincy. Since the number 2 spark plug was not changing the idle like the others did we focused on the number 2 cylinder. Compression was good 150+. so after checking connections we found the fuel injector was not clipped in all the way. That made the car run much better at operating temp, we checked the distributer and advanced it a little further which also helped. So tonight things are good, tomorrow we will check the timing when the car is cold and hopefully we have a smooth running car when first started. We never checked numbers on ecu because we felt it was an isolated issue to the 2 cyl. 

[jlenownnab]

Not as good of day in Cincy, Cold car still running badly. We have learned that the distributer only goes in one way, we were hoping it was one tooth off. The timing is where it needs to be so we started doing some testing.

Here are the numbers per your request.

Test 1 in troubleshooting section idle resisted .3 ohms

Test 2 full throttle test, open.4 ohms/partial .4 ohms    failed, partial should have been zero

Test 3 full throttle/closed throttle 26.2 mega ohms

Test 4 air flow meter resistance #1 184.

Test 5 air flow resistance #2 238.5

Test 6 air flow meter resistance #3 103.9

Test 7 air temp sensor 1.5 k ohms

Since test 2 failed, it led us to the throttle position sensor, I guess we will start there.

I hope these numbers help someone in the future.

[siteunseen]

The TPS may need adjusting. One screws locks it down the other has some movement for adjusting. Pop the cover off and see what rpms it moves off the right side contact.

[jlenownnab]

My guy said it was adjustable but didn't bother adjusting it???

[Zed Head]

32 minutes ago, jlenownnab said:

Cold car still running badly.

The timing is where it needs to be so we started doing some testing.

Test 2 full throttle test, open.4 ohms/partial .4 ohms    failed, partial should have been zero

Actually partial should have been many many ohms, like kohms (kilo-ohms, thousands) or infinite, and full should have been low, as shown.  For Test 1 (2). But you're only saying open, not fully open.  So not clear if you had the throttle wide open or only partially open.  Either way, that measurement would show full throttle to the ECU, adding extra fuel.  When there's continuity (very low ohms) on 3-18, the ECU adds a lot of extra fuel.

Not clear what "running badly" means either.  Is this driving, or idling, or revving?  At least you know the timing is correct,  Although you didn't report the number,or if it advances like it should when revving.

Sorry, we've asked you step in to a messy world.  But you know some things for sure now.  

I copied the test I think that you mean by Test 2.  The TPS has three states - idle, not idle (partial), and full throttle.

[Zed Head]

Considering that the car had some questionable work done to it and probably sat for a while, have you changed the fuel in the tank?  If it sat for over a year, it could have bad fuel.  Also, fuel pressure is critical to proper operation of these systems.  The tanks are known to generate rust and cause fuel pressure problems.  Worthwhile to measure it.

Good that you've already solved some problems and know more about the state of the engine.  Might be worthwhile to tell as much as you can about how long you think that car sat, what, in detail, you've done to it since you got it, and how, exactly, it's running and driving.

 

[jlenownnab]

Wide open and partially open test. I think the timing numbers are 23?? The car is out of Texas, no corrosion anywhere as far as I can see, its super clean. Oil change last April per sticker in window, Its clocked 1,200 miles since then. I put a full tank of gas in the car 2 months ago. The car runs strong warm but when you first start it and try to rev it it cuts out and will even backfire in the manifold. If you keep revving it you can get it to rev. It will run and drive cold but I wouldn't pull out in front of anybody. We have thoroughly looked for vacuum leaks, new plugs, wires, cap and button. We hit quite a few things on daves list but when the test failed we thought we found the problem.

[Zed Head]

You might have overlapping wrongness then.  Because the test results would be showing the ECU that you have the throttle wide open.  That adds 27% extra fuel to whatever the base calculation is, which should cause it to run better when cold and bad when warm.  Gassy smelling and rough running when warm.  But the fact that it runs better warm would indicate a lean mixture.  Which could be a shorted coolant temperature sensor circuit (page 56 in the 1975 EFI Guide), indicating a very warm engine to the ECU, and removing fuel.  That might be the popping when cold, but runs okay when warm.  The ECU thinks it's very hot and removes fuel, but the WOT (3-18 continuity) indication adds fuel.  Or you might just have low fuel pressure (lean), or clogged injectors, being compensated for by the WOT 3-18 results.  

23 degrees is way advanced timing for the EFI engines.  Spec. is probably 7 or 10.  Many people run a little extra, like 12-15 to add some throttle response and a bit more power.

You have an engine that runs which is more than many.  But you have to get all of those small details right.  Once you start knocking some down it's not a bad process.  Set your timing to 7 degrees when warm for starters.  That's where it should be. Picture from the Engine Tuneup chapter. 

[jlenownnab]

Thankyou for response, should I replace tps to wipe that off the list? I have mentioned the coolant temp sensor to my mechanic but he seems to keep avoiding it. Will set timimg back and go from there.

[Zed Head]

Like site said, it's adjustable.  Engine Fuel chapter.  Really can't emphasize enough how one of the main things that make these cars so easy to own, fix, and maintain, is the availability of the free Factory Service Manuals.  

The TPS can get dirty also.  Note that we call it the TPS but it should really be TVS.