TheSamba.com :: View topic - 1972 square

Tue Nov 11, 2008 2:41 pm

Update on page 3

It starts and runs now, but is missing - see this post on page 2:
http://www.thesamba.com/vw/forum/viewtopic.php?p=3428692#3428692

previous post:
Quote: Hi all -

Just picked up a 1972 t3 squareback; cranks but no spark.
My question - is there something else I should know about these, like maybe the ECU grounds the coil when [x] happens? It behaves like there's no current through the points.

Tue Nov 11, 2008 2:50 pm

Could pull an injector loose to see if they're spraying fuel? Could spray some Starter Fluid in the throttle body? Watch for pinhole leaks in the old braided fuel lines!

Tue Nov 11, 2008 2:56 pm

Hi Mike -

I haven't gotten that far :lol: since I don't have spark, first things first.

I'm pretty experienced with cars in general, though new to veedubs and a total novice at Djet.

Mostly, I'm just checking in to see if there's anything special about the ignition system on these cars before I go to my normal playbook.

Tue Nov 11, 2008 3:07 pm

piercedvw is gonna have her Bentley Manual tommorow! She's gonna be ahead of you! :wink:

Tue Nov 11, 2008 4:18 pm

You are not getting 2 clicks when you turn the key on. One under the rear seat, and one under the dash. That means, you are not getting power to the ECU. Check the wire that comes from the battery to the relay under the back seat. If the car has been sitting, that wire could be corroded at the battery connection.

Tue Nov 11, 2008 4:24 pm

Hi Russ - Do I need ECU power to get spark? Looking at the wiring diagrams and the Clymer EFI manual, it looks like the ignition is standalone.

How many relays are there supposed to be? I have two on the fuse panel, one at each end.

Tue Nov 11, 2008 4:31 pm

Sorry to chime in with this stupid question, but if an ECU is indeed damaged, is it at all possible for the engine to still start and run?

Tue Nov 11, 2008 4:48 pm

I'm thinking dead coil or poor connections not letting the coil energize between cycles of the points. Buy that, anyone?

Tue Nov 11, 2008 4:49 pm

kyle242gt wrote: Hi Russ - Do I need ECU power to get spark? Looking at the wiring diagrams and the Clymer EFI manual, it looks like the ignition is standalone.

How many relays are there supposed to be? I have two on the fuse panel, one at each end.

Under the rear seat, if you have a rear window defogger, there will be 2 relays, beside the voltage regulator.
One is the defogger, and the other is the fuel injection power relay.
Under the dash, the fuel pump power relay is mounted on the firewall, not plugged into the fuse box. above the fuse box.

Quote: Sorry to chime in with this stupid question, but if an ECU is indeed damaged, is it at all possible the engine will still start and run?

Yes, you need the ECU working to get any fuel through the injectors. But you do not need the ECU to get spark.

Tue Nov 11, 2008 4:53 pm

Righteous, that's exactly the info I needed. I'll have at it tomorrow and report back.

Wed Nov 12, 2008 5:20 pm

Not sure exactly what I did, but it has spark now, at least at the coil.

I think there was a faulty connection at the battery - when I cleaned them up and torqued em down, I got the fuel pump relay to click, and had spark at the coil.

Up next, fuel pump:

Took the fuel pump out, took it apart, and found it pretty well clogged with rust, scale, and gum.

Cleaned everything up, put it back together, not a big deal.

But when I went to test it, it won't turn. If I back the cover screws off a bit, it spins great.

1st Question - are those screws supposed to be tightened "all the way" or left a little loose? They were threadlocked in place, so I have no sense of the original torque on them (other than "break out the visegrips" tight).

2nd Question - is it necessary to use new O-rings, and if so, do I need anything special? The existing ones are in good shape, flat on one side, but still pliable.

Wed Nov 12, 2008 5:43 pm

It is NOT cool to start a bunch of threads! Just change the SUBJECT above on Your Build Thread as it progresses. I'm not really sure about your fuel pump deal? We better wait for Russ!

Wed Nov 12, 2008 6:28 pm

You may have something in the pump. It doesnt take much to jamb it up. On cars that have been sitting, I usually pull the pump, and try and run it in diesel fuel, or kerosene. Run it forwards and backwards. This will free everthing up.

Wed Nov 12, 2008 7:07 pm

Thanks Russ -

the fuel pump is clean, as clean as a shade tree is gonna get it....

A couple of the fuel pump rollers have degraded plating, but IMHO they're servicable.

I'm curious: are the cover screws are supposed to be full-on he-man tight, or if there's a little give in there. I did NOT pull the pump star as KTPhil did (hope I got the handle right), but I cleaned scale, rust, and an odd spongy funk off of all the parts.

Think of it this way - if it were a valve, I would know to not tighten it all the way, leave .013 or whatever of clearance. If I crank the fuel pump cover all the way down (remember, I have compressed OEM orings in there), I'm thinking the pump star is too tight to turn freely.

But - is that because there's a layer of funk between the star and the pump chassis (KTP's name for it) or because the Orings are toast or because I overtightened it?

Wed Nov 12, 2008 7:20 pm

You may be overtightening it.

Wed Nov 12, 2008 7:53 pm

kyle, even though you cleaned the fuel pump it would be a good idea to run it forwards and back in a diesel bath. it is a good way to see (visually) how much pressure you have.
Cheers

Wed Nov 12, 2008 7:55 pm

Russ Wolfe wrote: You may be overtightening it. Is there a torque spec you know of, or do I need new unobtainium O-rings, or just back 'er off a hair(1/2 turn?) and threadlock?
Annie - attempting to test pump output per manual revealed a jammed pump, trying to figure out how to get it unstuck.

Wed Nov 12, 2008 8:32 pm

Contact Jim Adney,he can rebuild your pump,did mine in about one weeks time.

jadney@vwtype3.org;

Good luck :)

Wed Nov 12, 2008 9:29 pm

The cover screws can be tight and shouldn't bind. The o-rings will compress and won't add to the tolerances. You didn't sand or plane any surfaces to clean them, did you? Maybe there is gunk in the bearings that prevents the armature form seating fully, so it bi8nds when the cover is tightened?

I'd leav eit loose, do the diesel dunk, then take it apart and spray cleaner and air to remove any grit particles that remain inside.

Ot just send it to Jim and he'll take care of it and it will work for years.

Thu Nov 13, 2008 9:00 am

Do you realize that the fuel goes through the electric motor of the pump to cool it. One of mine was seizing in the motor bearings, and no the pump. The o-rings that seal the motor are not that easy to get. I would suggest either sending the motor to Jim Adney so he can rebuild it, or you can switch to another style of pump. My 71 fastback has an 85 Ford Ranger pickup pump on it. Cost me $20 when I was broke down.