D-Jet wiring diagram

Bobnotch · Post by **Bobnotch** » Wed Feb 22, 2006 8:00 pm

Does anybody have a type4 Bentley they could scan a page and p-mail me with? What I need is the FI wiring diagram. I've been working with a type3 one, but some of the numbers are different, and I want to make sure I'm hooking everything up right.

I've got most of it in place, but I've got a couple of wires that I'm not sure about. Thanks for any help.

raygreenwood · Post by **raygreenwood** » Thu Feb 23, 2006 7:42 am

Which car is the D-jet on and what year is it from. There are about three diagrams.
This will help:
Does yoour system use an MPS with the diaphram in the back...or does it use the early one with th eseperate full load switch? What is the part number on the TPS? Is this type 3 or 4. I will try and scan one tonight at home and can drop it into a pm to you tommorrow. Ray

Bobnotch · Post by **Bobnotch** » Thu Feb 23, 2006 5:53 pm

Both the car and the wiring harness are from 71. It has a 5 termnial TPS, and the MPS is an "E" version. I know it'll need some magic adjustments (that I'll get from you later) due to it running on a "B" brain. This engine and FI combo was supposed to go in my 69 T-3 Square, but the PO offered and gave me a nice chunk of cash to buy it back.

I finally got the balance of the pieces to finish the swap, and I'm putting it into my 71 Square.
Like I said prior, I've just got a couple of wires that the numbers don't quite match up with in the T-3 Bentley, and I'd like to verify that they are wired up correctly before I plug in the ECU. I figure it's easier to test the full legth of each wire before I get to far, in case I need to repair any. I appreciate any help you can and already have given me Ray. THANKS.

raygreenwood · Post by **raygreenwood** » Fri Feb 24, 2006 7:12 am

The "B" brain pretty much interchanges. There was also a "B" MPS, which I have swapped in and out with E brain and B brain. The B MPS, generally has the "long nose" main spring. It takes just a slight adjustment or two of teh center screw to work like the E. The E brain main difference.....from my experience only.....seems to be the Co adjusting knob. It generally performs bout the same and ther wire terminal order is still the same.
In general, if your TPS had a 4 wire and your harness is five wire...or if you have a five wire TPS and a 4 wire harness...either will work. I think the four wire harness plugging into five wire TPS...simply skips teh terminal that was for teh overrun fuel cut-off (terminal 17?). Thats better anyway...because depending on the adjustment of the TPS, rate of tune of your system...and the level of built in slop on teh whisker switches of teh five wire fuel cut-off model...that over-run cut-off feature was a major source of "the bucking" syndrome. On all of mine with five wire, I disconnect that one terminal anyway.
Yes...having it hooked up "could"make for slightly better emmissions on over-run.....but since I have a decel valve.....it makes teh fuel cut-off kind of redundent....as the decel valve leans the mixture at part throttlke over-run and keeps you from detonating at throttle closed overrun by giving vacuum bleed to the MPS.
I find better throttle response and drivability by disconnecting that extra wire. Ray

vwbill · Post by **vwbill** » Fri Feb 24, 2006 5:55 pm

Hey Guys, I thought someones site has the wiring diagrams available. Maybe in one of the sticky notes or post? http://www.type4.org/technology/wiring

hoodsy · Post by **hoodsy** » Sat Feb 25, 2006 5:46 pm

there is a beautiful full color wiring diagram for the type 4 as well as other vw's at vintagebus.com only thing is the key is in german but it's not to hard to figure out.

Bobnotch · Post by **Bobnotch** » Sat Feb 25, 2006 8:09 pm

Thanks for the help VWBill, I had the one I really neeeded. I got it from Russ Wolfe's site; http://classicvw.org/gallery/main.php?g ... age=3along with this http://classicvw.org/gallery/main.php?g ... &g2_page=8 , as I've got what's shown in the pics, and for the most part follows a type 3 (which I have the t-4 in). Right now, I can't get the front relay to energize, so I've got no fuel pump, unless I ground the wire in the engine compartment (#19). I think either I'm missing something, or I've got a bad ECU (using the "B" brain). THANKS for any help.

vwbill · Post by **vwbill** » Sat Feb 25, 2006 8:55 pm

Hey, is that the deal with T3 Djet where the fuel pump doesnt run if the throttle switch isnt all the way closed or something? Isnt there a thermo time switch type thing in the ECU also that can be burnt? I'll have to think about who talked about that! I though maybe Longbeach had a post like this symtom? Also someone's site had a ecu decription and functions? Sorry not much help!
I thought on some FI setups the pump pressurizes and others it doesnt?
Did you look at Paul's sites? And his other ref? http://members.rennlist.com/pbanders/FP ... _frame.htm

http://www.914fan.net/fuelpump.html

So when you ground wire #19 does the pump pressurizes or just run?

Bobnotch · Post by **Bobnotch** » Sat Feb 25, 2006 11:03 pm

vwbill wrote:So when you ground wire #19 does the pump pressurizes or just run?

It's supposed to do both, and does.

Bobnotch · Post by **Bobnotch** » Thu Mar 09, 2006 7:30 pm

raygreenwood wrote:The "B" brain pretty much interchanges. There was also a "B" MPS, which I have swapped in and out with E brain and B brain. The B MPS, generally has the "long nose" main spring. It takes just a slight adjustment or two of teh center screw to work like the E. The E brain main difference.....from my experience only.....seems to be the Co adjusting knob. It generally performs bout the same and ther wire terminal order is still the same.
In general, if your TPS had a 4 wire and your harness is five wire...or if you have a five wire TPS and a 4 wire harness...either will work. I think the four wire harness plugging into five wire TPS...simply skips teh terminal that was for teh overrun fuel cut-off (terminal 17?). Thats better anyway...because depending on the adjustment of the TPS, rate of tune of your system...and the level of built in slop on teh whisker switches of teh five wire fuel cut-off model...that over-run cut-off feature was a major source of "the bucking" syndrome. On all of mine with five wire, I disconnect that one terminal anyway.
Yes...having it hooked up "could"make for slightly better emmissions on over-run.....but since I have a decel valve.....it makes teh fuel cut-off kind of redundent....as the decel valve leans the mixture at part throttlke over-run and keeps you from detonating at throttle closed overrun by giving vacuum bleed to the MPS.
I find better throttle response and drivability by disconnecting that extra wire. Ray

Ok, found out my "B" brain is bad (looks like it got wet internally or something), so that was the cause of no pump action, unless I gounded #19 wire (pump control wire). I temporarily used a t-3 brain to verify this (everythings working like it should). As I was mainly checking the fuel pump circuits anyway at this time (gotta have fuel, spark and air for it to run

). You know checking for leaks and pressure testing).
I do have the opportunity to pick up an "E" brain, should I use it, or find another "B" brain? .

What I've found out, is that the system has a 4 wire TPS harness, hooked up to a 5 terminal TPS switch, it has one wire already deleted? it was supposed to be out of a 71 T-4 wagon. Thanks for ALL your help.

raygreenwood · Post by **raygreenwood** » Fri Mar 10, 2006 6:42 am

Yep the four wire harness is the five wire plug is fine . You can use either 4 or 5 wire TPS with that....just find a spare four wire plug housing to keep around. If you can get an E-brain...get it. It has the CO adjustment knob. Its a nice feature. It gives you something like a 5-10% +/- on CO across the board.

Its worth it to keep most D-jet brains in my opinion...wether type 3 or 4. I have about a dozen or so. As you have found...one of the two main reasons they may ever go bad is moisture and corrosion. Its extremely rare.

In general...almost any D-jet brain can go into almost any system with any MPS. The only things that limit you arewether its an early non- diaphram type or a late diaphram type. Those should be kept seprate. But even then...in a pinch....if you want to do a little wiring...you can work around that.

the brain letter codes were mainly top designated signifigantly differnt calibration of one brain with one MPS. Most MPS can generally be adjusted enough to run with an out of sequence letter code brain. Ray

Bobnotch · Post by **Bobnotch** » Sat Mar 11, 2006 7:24 am

Thanks Ray, I've got a couple located, and will try to get them. Will the "E" MPS need much tweaking to work with the "E" brain? I know it'll need some, just to fine tune it to the engine. Thanks for all the help.

raygreenwood · Post by **raygreenwood** » Mon Mar 13, 2006 10:19 am

Did you really mean the "B" MPS to work with the "E" brain or vica versa?

. The B will not take too much. If memory serves, the inner stop settings for the diaphram are the same. It will take a tweek of teh center screw...and possibly a tweek of the outer plug setting. The main thing to also look at is the part number of the CHT and the ambient air temp sensor. It may or may not be different. Look in the interchange info section in Muirs book. He did a good job covering what brainb series needed the eraly or late letter prefix CHT and ambient air sensors. I will look in mine tonight. Ray

Bobnotch · Post by **Bobnotch** » Sat Mar 18, 2006 9:44 pm

OK, that sounds good to know. I've got both a good "B" brain, and a couple of "E" brains here to use. Which would you use? I'm not sure if I have a decel valve or not, as I don't recall seeing one.

I've found that I do need to swap the fuel pressure regulator, as it'll hold 32#, but starts bleeding off quickly after the pump is shut off (well past 15# heading to 0 ), and I've already got one here. It's either that, or the check valve in the pump needs rebuilding.

raygreenwood · Post by **raygreenwood** » Mon Mar 20, 2006 5:53 am

For sheer adjustability I would use the E brain. It has the CO knob. Look for prior posts about back-stopping the regulator...with another regulator. It works quite well.
Iwould not mess too much with the D-jet pump. Technically it does not have a check valve,. The valve that comes off the side that is gping to teh return pipe is technically not a check valve per se. It is a relief valve. It keeps the pump from over pressureizing if there is a crimp in the line. But yes...if it is leaking.....it can drain pressure. But if you take it loose it will never re-seal properly as it is under that little aluminum crimped cap.
If the pump is tight but that valve is leaking.....put a new valve...like even D-jet a fuel pressure regulator downstream of that valve in the "R" line coming off the pump. It sounds micky mouse but is an excellent way to extend teh life of an otherwise perfect D-jet pump. Ray