1969 Fuel Injection, problems started during drive. Help!

[squanchy]

Hi, all. 1969 Squareback Fuel Injected Automatic. Was driving really well, nice and smooth, then while on a drive... it wasn't!

Now when I start it the idle is erratic, all over the place. It has no power, it's missing, minor backfiring, some smoke (I think it's black) from tailpipe.

• New vacuum hoses (except trans hose).
• New spark plugs and wires as of today (plugs were fouled).
• Fuel pressure is solid at 28psi, plenty of fuel to lines in back.
• Injectors have been removed and cleaned recently.
• Fuel tank was de-rusted and new in tank screen installed.
• Timed to 0 TDC mark per Bentley manual, idle at 950.
• New points gapped correctly.
• Valves adjusted and still holding gap.
• MAP sensor holds vacuum.

What could cause this out of nowhere, during a drive (barely made it home)?

My list of things to do:
1) Replace vacuum line from trans to intake, it's the only old line.
2) Pull distributor and clean injection trigger points.
3) Pull injectors and test/clean.

Any advice? Am I on the right track with troubleshooting? Thank you for reading!

[KTPhil]

You are smart to give it a tune-up first, as most "FI faults" are not in the FI system. But you've done that, so time to move on.

I'd pull the ECU connector, and get out your VOM, and start measuring per any repair manual's table of readings. You may have a loose or broken wire, broken temp sensor, etc, and this way you can go through all the wires at one time. Wiggle the connectors a little as you are taking readings.

This system is reliable overall, but wiring faults take it down. Fortunately, they can be found without special tools, and if you are handy with a factory-style crimper and pins, you can repair the wiring yourself.

[squanchy]

Thanks, KTPhil. I'll start taking readings. We rewired a bunch of it already, new wires and connectors, so to respond, yes I'm pretty handy with a crimper after building an entire wiring harness from scratch on my last Bug! Not looking forward to this, hope it just a connector, but I will start with testing the head temp sensor. Thanks for the info!

[Ceckert64]

This happened to my Squareback, it had sat for 44 years before I got it and when I got it running it was back-firing, dieing, etc. it was the tabs on the return spring for the counter weights for the centrifugal advance bent, the spring fell off shorted the trigger points and was causing it to advance crazy. If you turn the rotor for the distributor and it doesn’t spring back that could be the issue. I also had a computer that was causing the engine to run horrible and was shaking horribly.

Kinda what KTPhil said, just check all the connections. Check to make sure the one at the starter didn’t come off. Good news is you know it isn’t any backwards wiring because it was running fine

Hopefully that helps a bit, Aiden
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1964 sunroof Beetle Restoration "Herbie"
“Joann” 1970 Elm Green Squareback
1972 Yellow Tin Top Westfalia -Sold
“Fitz” 1971 Westfalia Poptop EJ22 swap
“Rome” 91 Syncro

[VW_Jimbo]

I have read a number of threads recently like yours. Most ended up finding a faulty condenser. Worth a few minutes to check.

Weak spark looks like a rich condition on the spark plugs.
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[airschooled]

Check your TS2. It should read more than a thousand or two thousand ohms (depending on model) at cold ambient, and a few hundred (or less) on a hot engine. A sensor reading too high will run extraordinarily rich, if at all.

Do you have a way to smoke test the intake system? D-Jet usually runs rich when a vacuum leak causes low manifold vacuum, tricking the MAP/ECU combo to think that you're floored since manifold vacuum is low.

Good luck,
Robbie
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[raygreenwood]

A couple of items.

First.....as others have suggested.....ignition first. Check everything. And...want brand/part number of points are you using? If they are Bosch ake sure the contacts are parallel and not burning on one edge. Make sure there is not a burned high peak in the center where the contacts traded metal.

Second......you noted "recently cleaned injectors". To start with....how did you clean them?

Next....this also means a lot of things got moved around. Did you replace the injector tip seals?
If you stay with stock style seals.....which I hate.....then the only brand currently available that you should be using in my experience....are Echlin found at NAPA.

Otherwise use Bosch or Beck Arnley CIS injection donut shaped seals.....preferably the green colored viton seals. Much better fit and seal.....and especially better iniector centering in the intake casting with less movement.

But.......its most likely (after ignition checks out)......to be either a vacuum leak......or a connector.

You had to unplug the injectors to service them. Its very, very common that the,female connectors in the plugs are a loose fit. And.....you cannot tell this simply by the tightness of fit of the plastic plug. Typically the plugs fot tightly....even when there are no connectors inside.

The only way to be sure is to de-pin each female connector one by one and tighten them slightly at the rolled sides with a small pair of "bald"....meaning no teeth...jewelers pliers. You can buy a nice pair for $4 at wall mart in the arts and crafts section where they sell stuff for "beading" and jewelery making.

The other VERY common problem that causes this after injector servicing.....are the ground ground wire bundles on the case center line under the intake.

You will typically NOT....find any of these poor connections by pulling the ECU plug and checking with the volt meter. This is because you have to do that with the engine off when there is no heat expansion or vibration.....which are what cause loose connectors to rear their ugly head.

The best way to 100% check and KNOW they are tight.....is by physically removing and making each one tight. I check each individual female connector on a male pin before re-inserting it back in the plug.

Another OK method is to lightly sand each plastic plug for a light slip fit into its component. That way you CAN feel that the connectors are latching on with good force.....but you cannot be sure that all of them are....without checking each one individually.

Lastly.....stable voltage is critical. As already mentioned.....grounds. you can have perfect 12.0 volts ....coming from the fuse block......but if the grounds are poor....any of them....ECU harness, battery connection....ground cable on the transmission......then your voltage is only as good as what can flow through the ground.

Likewise....perfect grounds....but low input voltage.....causes rich and poor running. Ray

[evanfrucht]

It sounds like a bad condenser to me too. Could be a few things, but that is a good place to start.
_________________
1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder )

[raygreenwood]