1971 FI notch won’t run

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packers1712
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1971 FI notch won’t run

Post by packers1712 » 1st February 2020 - 5:43pm

Hi everyone, the reason it won’t run is because the fuel pump won’t prime, I’ve checked the relay and it has no power on the pump feed terminal. The relay has its 12v permanent supply as per wiring diagram and the switching side has an ignition feed it it just doesn’t ground.
I think the ground is controlled through the ECU so that it primes then stops until the engine is cranked and then running, I’ve continuity checked all the harness back to the ECU and it’s all good , I’m thinking the ECU is at fault any ideas?

Thanks Doug.

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Rob 400e
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Re: 1971 FI notch won’t run

Post by Rob 400e » 2nd February 2020 - 11:01am

Wow, no idea. What I suggest however get yourself a copy of Volkswagen fuel injection technical manual, by Henry Elfrink. It’s very comprehensive, plenty of copies available on eBay.
Type 411 Le four door auto .
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purplepeter
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Re: 1971 FI notch won’t run

Post by purplepeter » 2nd February 2020 - 12:17pm

Beyond suggesting a temporary earth to confirm diagnosis, My best suggestion would be that you drop an email to Dave Hall directly- He's always been the FI guru
Would a nos relay help?
Beyond that, I think Jim Bourne has a nos ECU

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 2nd February 2020 - 4:09pm

I’ve tried the temporary earth and it works - problem with that is all the time the ignition is on the fuel pump is running as opposed to the initial prime, then off and starts running again during cranking/engine running as per vw’s intention!

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937carrera
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Re: 1971 FI notch won’t run

Post by 937carrera » 4th February 2020 - 10:56pm

Do you have a D-Jetronic manual ?

If not, have one here : http://w107.pbworks.com/f/DJetronic.pdf

Fuel pump not running was a classic failure on K-Jet Porsches and VW's, using a jump wire across the relay high current terminals was a get you home fix, this sounds similar.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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purplepeter
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Re: 1971 FI notch won’t run

Post by purplepeter » 5th February 2020 - 7:00pm

You have a PM Doug!

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 24th March 2020 - 2:48pm

Good afternoon everyone,

So as I've been told to stay at home by my employer I've decided to work on the Notch some more. Since the last time I posted I've managed to torque check the right hand bank cylinder head fixings and get the engine all back together. However it runs worse than ever, huge misfire, black smoke (probably due to misfire and unburnt fuel) so I went back to basics, checking compression, cyl 3 a little lower than the other 3, so reset valve clearances, all between 135 - 145 psi.
Fired her back up, still the same so I began checking HT leads, they're quite different in resistances depending on length but none open circuit and after wards checked that I've got a spark at all 4, all ok there too.
So broke out the FI diagnostics and after carrying out some testing at the ECU plug discovered that one of the MAP sensor coil windings is showing having gone open circuit!
Just to confirm that the harness was ok did the same test at the component and it is definitely open circuit on one pair of the terminals.
Has anyone ever repaired one of these or is it dead? I've taken it apart and I can only go so deep before it all looks like it can't be broken down any further without causing irreversible damage!
Also has anyone got a good one of these for sale?

Thanks in advance, Doug.

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 24th March 2020 - 3:06pm

Sorry guys,

Forgot to mention that in order to get the fuel pump to run I've supplied the relay with a permanent ground so it runs all the time the ignition is on, not ideal but it works for now until I either fit a "watchdog relay" or find the cause of the grounding issue through the ECU.

Regarding the earlier post I'm beginning to lean towards scrapping the FI in favour of good old carbs any thoughts?

Has anyone ever successfully fitted a single side draught twin-choke in the centre of the engine?

Or are stock twin carbs the answer and what do I need to buy for a stock 1600 DP?

So many questions!

Thanks Doug.

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purplepeter
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Re: 1971 FI notch won’t run

Post by purplepeter » 24th March 2020 - 6:30pm

You know Mike Dempster makes good HT leads?
To convert to carbs You'll need: Manifolds, carbs, 2 linkage rods, central "tree", air filter, fuel pump?- check if you've got the drilling for it, dissy, balance pipe- all fairly easily available

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 24th March 2020 - 7:03pm

Hi Peter,

Sorry my question was a bit ambiguous, I meant more along the lines of what type and size carbs work the best?

What's a dizzy balance pipe is it something that allows a vacuum to be taken from both carbs for the advance mechanism and can I not just keep using my electric fuel pump with a pressure regulator (filter king style)?

Thanks Doug.

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purplepeter
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Re: 1971 FI notch won’t run

Post by purplepeter » 24th March 2020 - 10:17pm

Carbs require a much lower fuel pressure, so as long as yours is adjustable you'll be ok
I was assuming you'd go for stock carbs
The balance pipe goes between the 2 carbs to even things out on idle

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purplepeter
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Re: 1971 FI notch won’t run

Post by purplepeter » 24th March 2020 - 10:39pm

I can sort you out the full kit if needed Doug for a fraction of those carbs

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jmarkha1
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Re: 1971 FI notch won’t run

Post by jmarkha1 » 24th March 2020 - 11:23pm

I swapped from FI to carbs (40mm dellortos) because of engine size being too much for stock FI system. But if I had left it 1600 I would definitely get that FI system sorted - nothing better when running as intended...good luck sorting
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937carrera
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Re: 1971 FI notch won’t run

Post by 937carrera » 25th March 2020 - 7:49am

jmarkha1 wrote:
24th March 2020 - 11:23pm
But if I had left it 1600 I would definitely get that FI system sorted - nothing better when running as intended...good luck sorting
+1 on that

What's the current problem Doug ?

Is the fuel pump earth sorted.

Have you got the test measurements for the MAP sensor to check against, or got one to drop in as a swap to test

These links should be useful:

https://oldtimer.tips/index.php/en/d-je ... -mapsensor

https://members.rennlist.com/pbanders/m ... sensor.htm
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 25th March 2020 - 8:27am

Good morning all,

Yes I have I pretty comprehensive list of tests for all components and the harness and the test between terminals 8 and 10 on the pressure sensor should read 350ohms but its open circuit on mine, weather I test at the harness plug or at the sensor.
I don't have another one to try and yes I've temporarily sorted the fuel pump relay earth issue.

Doug.

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 25th March 2020 - 11:03am

Wow! Just had a look at those two links and there is some pretty in depth stuff in there!

I'm certainly not about to invest in some of the diagnostic kit mentioned in the links, I just need to get to a point where I've got a reasonably reliable classic car that I'm not afraid to drive for fear of 50 year old electronic components failing leaving me stranded hence the lean towards carburettors!

Doug.

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 25th March 2020 - 12:55pm

Peter I've sent you a PM.

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937carrera
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Re: 1971 FI notch won’t run

Post by 937carrera » 25th March 2020 - 3:49pm

Sounds like a replacement / borrowed MAP sensor for the moment, followed by some experimentation for an electrical repair of the failed sensor. It might only be a failed solder joint
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 25th March 2020 - 4:52pm

Yes that's what I thought and why I've asked if anyone on here has one for sale. I have taken it apart as far as I can even de-soldered the coil wires from the back of the multiplug and tested the pair of coils on their own, the fault is definitely inside the coil pack!

Doug.

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937carrera
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Re: 1971 FI notch won’t run

Post by 937carrera » 25th March 2020 - 5:03pm

You haven't drilled the rivets out and separated the two pneumatic halves though have you ?

You know, the bit that those linked pages advise you not to do. But, if it's completely u/s you are not going to make it worse are you
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 25th March 2020 - 6:02pm

Mine wasn’t riveted together it was held together with screws, it pretty much looks like the one in the second link now!
Last edited by packers1712 on 6th April 2020 - 12:37pm, edited 1 time in total.

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937carrera
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Re: 1971 FI notch won’t run

Post by 937carrera » 6th April 2020 - 11:35am

Just seen your other post.

How did you get on, what has made you give up, it seemed you were close to sorting this
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 6th April 2020 - 12:32pm

I haven't been able to source a known good pressure/map sensor!

Doug.

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937carrera
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Re: 1971 FI notch won’t run

Post by 937carrera » 6th April 2020 - 12:54pm

Ah, I thought you were going to repair yours using those instructions.

I assume you have asked Purplepeter / Editor directly ?
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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packers1712
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Re: 1971 FI notch won’t run

Post by packers1712 » 6th April 2020 - 1:00pm

I don't think it can be repaired if the secondary coil is open circuit, Peter has offered me a "carb set up" but I have to admit to not actually asking if he had a sensor!
I also haven't asked Dave perhaps I should!

Doug.

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