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Sat Jul 22, 2023 6:05 am

Actually they’re aerobatic compatible so with the right manifolding one could have one on its side. Meaning one can do it with just one afterall

Mon Sep 11, 2023 8:14 pm

Been a while. If I unplug the temp sensor at the AAR, the car seems (haven't driven it, only vroomvroom noises in the driveway) to run well. Connected, the car doesn't respond well to idle adjustments, and doesn't rev. Fuel pressure is set to 28psi and timing is at 5BTDC. Of course I haven't ohmed it. Time to source one? '68 manual

Fri Sep 29, 2023 1:19 pm

Wondering if anyone knows the color of the wire 19 to connection 85 on the pump relay? I'm currently missing this wire. Have a few wires under the dash disconnected. Looks like a ground from ECU

Fri Sep 29, 2023 2:13 pm

It is a white wire, and that T1 connector is in the engine bay, left side, forward of the left intake tubes.

This is an aftermarket crimp on connector, but the clear plastic VW connector goes here also.

Fri Sep 29, 2023 2:18 pm

KTPhil wrote: It is a white wire, and that T1 connector is in the engine bay, left side, forward of the left intake tubes.

Thx. Found it. Someone spliced in a blue wire. That fixed the fuel pump not coming on. Starts, runs fairly well with 2 caveats.

Lopes like cammed when cold
Super rich. Black soot on bumper and black smoke.

Fri Sep 29, 2023 2:21 pm

KTPhil wrote: It is a white wire, and that T1 connector is in the engine bay, left side, forward of the left intake tubes.

Thx. Found it. Someone spliced in a blue wire. That fixed the fuel pump not coming on. Starts, runs fairly well with 2 caveats.

Lopes like cammed when cold
Super rich. Black soot on bumper and black smoke.

Fri Sep 29, 2023 2:27 pm

jasle wrote: KTPhil wrote: It is a white wire, and that T1 connector is in the engine bay, left side, forward of the left intake tubes.

Thx. Found it. Someone spliced in a blue wire. That fixed the fuel pump not coming on. Starts, runs fairly well with 2 caveats.

Lopes like cammed when cold
Super rich. Black soot on bumper and black smoke.

Vacuum leaks often cause these symptoms.

Check hose from plenum (IAD) to pressure sensor (MPS, under left side of engine bay floor).

Then a systematic check of all hoses for vacuum leaks.

Fri Sep 29, 2023 3:15 pm

KTPhil wrote: jasle wrote: KTPhil wrote: It is a white wire, and that T1 connector is in the engine bay, left side, forward of the left intake tubes.

Thx. Found it. Someone spliced in a blue wire. That fixed the fuel pump not coming on. Starts, runs fairly well with 2 caveats.

Lopes like cammed when cold
Super rich. Black soot on bumper and black smoke.

Vacuum leaks often cause these symptoms.

Check hose from plenum (IAD) to pressure sensor (MPS, under left side of engine bay floor).

Then a systematic check of all hoses for vacuum leaks.
Yup, that was it. Many Thanks!

Sun Feb 11, 2024 3:39 pm

Hello Members
I own a 1972 Fastback TLE with the original fuel injection system.
The MPS fitted on my car has an additional wire connected to a single male terminal at the rear of this part and it then goes into the fuel injection wiring harness.
Is this an earth or ground wire ?
I have a better condition spare FI wiring harness i would like to install , however it is not fitted with this wire mentioned above
Thanks for any help provided

Sun Feb 11, 2024 6:49 pm

A photo would help a lot. MPS part number as well.
VW did add some ground wires in later FI cars.

Sun Feb 11, 2024 9:24 pm

That single wire on your mps is a ground. The other end is either all by itself at the engine case center line or with the other grounds at the base of the oil breather (I can't remember which off of the top of my head).

Jon

Tue Feb 13, 2024 2:30 pm

Thanks to the members for the info provided

Wed Mar 20, 2024 4:40 pm

I'm trying to get a 1970 Squareback running, and I've determined that the ECU is not sending ground to the fuel pump relay when the key is turned on. I tested the #19 wire directly at the ECU. It is sending 8v positive instead. The original owners had bypassed the fuel pump relay with a wire directly from the fuseblock to the pump.

Should I:

1) buy a replacement ECU
2) open it up and test the components and solder on replacements
3) just leave the fuel pump relay bypass in place and see if the rest of the ECU still works

Wed Mar 20, 2024 7:23 pm

jessehattabaugh wrote: I'm trying to get a 1970 Squareback running, and I've determined that the ECU is not sending ground to the fuel pump relay when the key is turned on. I tested the #19 wire directly at the ECU. It is sending 8v positive instead. The original owners had bypassed the fuel pump relay with a wire directly from the fuseblock to the pump.

Should I:

1) buy a replacement ECU
2) open it up and test the components and solder on replacements
3) just leave the fuel pump relay bypass in place and see if the rest of the ECU still works

That's more and more of a common issue these days. Ground the pump relay wire to the body and see if she fires up.

Thu Mar 21, 2024 9:02 pm

Tram wrote: That's more and more of a common issue these days.

I've seen a few other mentions of it. I wonder if there's any information about which transistors I need to check, and what kind to replace with.

Thu Mar 21, 2024 9:28 pm

jessehattabaugh wrote: Tram wrote: That's more and more of a common issue these days.

I've seen a few other mentions of it. I wonder if there's any information about which transistors I need to check, and what kind to replace with.

You could always just gently open the box and see what fried. Sometimes it's as simple as re-flowing a solder joint. Sent you a PM back.

Wed Aug 07, 2024 9:46 am

So this is technically not T3 related, but it is a D-Jet system on a Porsche VW 914. Hopefully the guru's on here could give some tips.

A few months ago it died at a stoplight coming home from work. Moved it off the road and was able to barely get it started after some time and pumping the gas pedal, and then it died again trying to pull out of the parking lot. Had it towed home with a free tow through Hagerty.

It started right up the next morning and idled okay for a few minutes before I shut it off to got to work.

A few days later I took it around the corner to a buddy's place and it was idling while we BS'd out front. After a while it sputtered out and died. Wouldn't re-start and smelled strongly of gas. Started right up the next morning and drove home.

What I have done so far: all FI components are correct for the year, no mismatched MPS, TPS etc etc.
CHT sensor tested in boiling water and ambient and lines up with spec.
It has been a while since an oil change and valve adjustment but there was nothing out of whack the last time that would make me think I have an issue there. I'll do that again once it's not so dadgum hot here in CA though just to be sure.

I am thinking it may not be EFI related possibly and I may have a return line blockage that is causing the fuel pressure to climb when it is idling. It has not died on me while actually driving around.

I am hoping it's not the MPS, I have some extra but none are the right PN and would need tuning. If they are even good. Tangering racing does not have diaphragm kits and doesn't know when they are getting more.

Wed Aug 07, 2024 9:54 am

Could be an intermittent on that head temp sensor. High resistance or an open will make it run dead rich and stall it quickly.

Connectors can change with temperature and open up.

Check your MPS for vacuum leaks, too.

Do you have a fuel pressure gauge you can link in to watch it as it dies?

Wed Aug 07, 2024 10:07 am

Agree with Phil- get a gauge on it. It almost sounds to me like a fuel pump that is trying to die. Low pressure can mimic pig rich because the fuel squirts without atomizing. The way these pumps tend to fail when they get older is by heating up under use till they slowly wind down and lock up. Once they're cooled down, they'll work again... for awhile. Need to carefully pinpoint the fault with this and you need a solid diagnosis.

Wed Aug 07, 2024 10:08 am

Appreciate the quick response!

KTPhil wrote: Could be an intermittent on that head temp sensor. High resistance or an open will make it run dead rich and stall it quickly.

Connectors can change with temperature and open up.

That should be fairly easy to test through the harness with my DMM and wiggle and jiggle the wires and see if that connection is intermittent. What pin number is that on the main ECU connector?
All my manuals are packed up in a box somewhere right now or I'd look it up myself. :oops:

KTPhil wrote:
Check your MPS for vacuum leaks, too.

Do you have a fuel pressure gauge you can link in to watch it as it dies?

Tram wrote: Agree with Phil- get a gauge on it. It almost sounds to me like a fuel pump that is trying to die. Low pressure can mimic pig rich because the fuel squirts without atomizing. The way these pumps tend to fail when they get older is by heating up under use till they slowly wind down and lock up. Once they're cooled down, they'll work again... for awhile. Need to carefully pinpoint the fault with this and you need a solid diagnosis.

I can check both of those, we have a small vacuum pump at work I can borrow to test the MPS. What KPA should I check to?

I've also got a pressure gauge I can check the fuel pressure and see if it is steady or changes. The original pump has been replaced already with the inline pump everyone uses. I don't remember the PN and it is probably about 5 or 6 years old. Will verify pressure one way or the other.

I did also "recently" (last year sometime) clean up and re-grease the distributor and reset points and timing afterwards. The issue did not happen immediately after that job so I don't think it is related.

Hopefully I can get some time this week/weekend to check those three things. MPS holding vacuum, Fuel Pressure, and CHT wiring.