72 Tii Sputtering- After Warmed Up

[torquewrench80]

4 hours ago, ray_ said:

Well, the alt is putting out voltage. But it seems the regulator is not regulating. 

 

You may have a bad diode in the alt; that can cause the light to glow.

 

I'm wondering if excess voltage is causing the ignition to act wonky. But I don't think so.

 

I'm pretty sure you can pull the plug from the VR and take the alternator out the the circuit.

 

I suggest pulling that plug, checking with your meter to confirm the voltage when running is just battery voltage (12-ish), and seeing if the stumbling continues.

Yes, if you disconnect the plug from the VR you should only read battery voltage. If you jump the blue and black wires at the plug when it is disconnected you will see max voltage, just as you are now, IIRC. Been so long so I've run that test. It's called full fielding the alternator. So, like Ray says you've got good output, but no regulation and that could/maybe/might be a short or bad diode in the alternator. Does the alt warning light come on with engine off, key on?

[Ncbimma]

18 hours ago, torquewrench80 said:

 Does the alt warning light come on with engine off, key on?

No. It only begins to light up after the sputtering begins..

 

Car fires up after 3-4 tries and cranks up solid. Finds steady idle fast and is ready to rock.no lights, no weird smoke or smells..

 

It's only after that warm up period/ sloshing of the tank that the sputter comes on.

 

So I feel the light is due to the engine straining...

 

Will be picking up a fuel pressure gauge this week to verify.

 

I've already been browsing/ shopping for ATL fuel cells just in case...

[torquewrench80]

20 hours ago, torquewrench80 said:

......Does the alt warning light come on with engine off, key on?

2 hours ago, Ncbimma said:

No. It only begins to light up after the sputtering begins.......

 

Okay, there is a troubleshooting chart in the factory workshop manual. I uploaded the entire page. According to that it sounds like you have a defective alternator. The first 5 items on the list you can eliminate through process of elimination, leaving an internal problem with the alternator. If this was an E21 I could say for certain, 100%, that the alternator is defective. As far as I know the only difference between the two is that the E21 has an internal regulator. So, you can open the alternator up and try to fix it yourself or get a factory replacement. Personally, I would not bother with an aftermarket rebuilder. It has been my unfortunate experience that they are often a waste of time and money. 

 

A straining engine is not going to cause that light to come on, no way, no how. Aint gonna happen!

 

 

 

Trouble Shooting - Alternator.pdf

Edited July 31, 2017 by torquewrench80
additional notation

[Ncbimma]

Disconnected VR...ran car at 2k rpm and got 12.6.

 

Idle and any throttle input range held 12.6 give or take a tenth.

 

Also hooked up the meter and got  20psi at idle and up at 2k rpm. Location was bt cold start and Kfish.

Should pressure be at 24? 

 

L light came on faintly after stabbing the throttle abruptly after 10mins of idling..I ruled out the sloshing of the gas in tank stirring up sediment by not driving and letting the car idle in driveway to warm-up. I'm not sure if the interior suction would be strong enough in the tank that would cause a  collection of sediment at the filter or not...

 

Sure do want to drive you:

[Son of Marty]

Fuel pressure at the K-fish needs to by 29 PSI when its operating,  check and clean all filters if not that your fuel pump or pressure regulator are failing.

[torquewrench80]

1 hour ago, Ncbimma said:

Disconnected VR...ran car at 2k rpm and got 12.6.

 

Idle and any throttle input range held 12.6 give or take a tenth.

 

Also hooked up the meter and got  20psi at idle and up at 2k rpm. Location was bt cold start and Kfish.

Should pressure be at 24? 

 

L light came on faintly after stabbing the throttle abruptly after 10mins of idling..I ruled out the sloshing of the gas in tank stirring up sediment by not driving and letting the car idle in driveway to warm-up. I'm not sure if the interior suction would be strong enough in the tank that would cause a  collection of sediment at the filter or not...

 

Sure do want to drive you:

"Disconnected VR...ran car at 2k rpm and got 12.6"

 

Of course! It's supposed to do that. Here is the way it works: when you switch on the key the warning light gets battery voltage on one side it it's two terminals. The other side grounds through the alternator, causing the light to glow. When the engine starts and the alternator spins the warning light on the dash now has equal voltage on either side of it's terminals and the bulb extinguishes. If the voltages vary, the bulb glows dimly. If the bulb fails to light when you turn on the key, the alternator is defective. There is a way to confirm it by testing. There Is a three wire plug in the back of the alternator. Remove it and measure the voltage at the blue wire with the key on by using a DVOM.  Let me know what voltage you get. Measure it with the VR connected and with it disconnected.

 

As someone else has already pointed out the fuel pressure should remain at 29 psi constantly. You do not have to run the engine, just switch the key on. Running the engine should makes no difference.

[Ncbimma]

7 minutes ago, torquewrench80 said:

 

As someone else has already pointed out the fuel pressure should remain at 29 psi constantly. You do not have to run the engine, just switch the key on. Running the engine should makes no difference.

 

Will try out the alt testing a bit later.

 

I found that fussing with all the fuel hoses that they are pretty brittle and now I can't get a proper seal on the csv without it spewing. I cut off a piece of hose and it's all has cracked/ veined fissures on the interior.

 

I need to replace all the hoses first as it seems 40+ yrs took it's toll on them.

 

Just received an afr, volt, water temp, and oil pressure gauges in the mail too. Will be fabbing the console up as a side project.

[Ncbimma]

13 hours ago, Son of Marty said:

Fuel pressure at the K-fish needs to by 29 PSI when its operating,  check and clean all filters if not that your fuel pump or pressure regulator are failing.

I've replaced the filter already by the radiator. I'm not sure of any other filtering devices on the car besides the in-tank screen. A new one should arrive here in the next day or so- the existing wasn't too gunked up. 

 

I've no idea on a pressure regulator...thought that if the pump was correct, you shouldn't need one? Regardless, I have a Bosch 69418 I was going to throw on to replace the existing. 

 

But as I said above, it looks like I need to work on the fuel hoses first.

[Son of Marty]

There are small cone screens in the pump inlet and the K-fish inlet the pressure regulator for the system is located in the fuel return nipple at the back of the K-fish pump and this controls pressure on the whole system.  

[ray_]

Read all this, too...

 

 

[Ncbimma]

Quick update.

I got the tank out to flush and reseal it. There was a bunch of fine sediment in it.

 

Pulled the pump and the inlet screen was caked full of this sediment- the cone was packed to the brim.

 

I'm working my way back from tank to engine, replacing hoses and updating items as needed.

 

I will try to blow clean the hard line with a compressor.

 

I have a feeling all that sediment has stricken everything leading to the engine.

 

[jgerock]

 Never underestimate the effects of old gas and crap inside the tank of any car. There is a reason why BMW installed all the screens and large filter. Your clogged cone shaped screen will cause the electric pump to work harder. Hopefully it doesn't fail. 

[Ncbimma]

Tank cleaned... Yay!

Going to seal it and spray the exterior.

I cleaned up the OE pump and expansion tank. All seems to be okay...but should I use the old pump or swap to the new 5er pump?

 

 

[Simeon]

1 hour ago, Ncbimma said:

Tank cleaned... Yay!

Going to seal it and spray the exterior.

I cleaned up the OE pump and expansion tank. All seems to be okay...but should I use the old pump or swap to the new 5er pump?

 

 

If you have the pump out already, you may as well put the 5 pump back in. You can keep the tii pump on the shelf as a talking point. 

[Ncbimma]

Sputtering gone!

 

Thanks to all who pointed things out- this was a result to a literal fuel starvation issue due to dirty gas, mucked up hoses and an overworked fuel pump.

 

New pump is so quiet in comparison to OE. 

 

Now onto the next issue: shaky ride over 50. Bassett wheels most likely are not balanced/ wheels aren't road forced properly.