fuel pump wiring and other silly electrical questions

[darkstar]

Rewritten for clarity and brevity. The original inane text is at the bottom.

1. What are the red and green/pink wires in the fuel pump harness for? If I'm reading page 47 of my ETM correctly they aren't used, and can be eliminated entirely. Together with a ground wire, they make up the entire small connector (closest to the front of the car) on the fuel pump. Can someone explain this? it doesn't make any sense to me. solved, see reply #13 below.

2. As far as I can determine, the red/gray wire is a switched ground from the ECU for the check engine light (which has ignition power from the instrument cluster harness). When there are no codes set I would expect to see continuity to ground here for a few seconds when the ignition is switched on, and then an open circuit. I get closed circuit (i.e. CEL is illuminated) but there are no stored codes according to my scanner. all the wires to the data link connector are intact with the following exceptions: two ground wires which were grounded to different sources now share a common ground. Black/pink and yellow/pink wires are cut--these came from the ABS ECU and the alarm ECU. Power source switched from constant power to ignition power. Why would this switched ground be on all the time when no codes are stored? Or am I misreading the ETM yet again?



Original diatribe below for your :shaking: pleasure. For amusement purposes only. No information content. I advise you not to read any further, but skip to the next post in the thread.



OK--I am dangerous when it comes to reading a wiring diagram. I'm trying to plan out some dash indicators and gauges, so here goes.

Fuel pump: ETM shows three wires: white/purple (#12 wire, this is power), green/black for fuel level and black for GND).

what do I need to do to wire a fuel gauge into the GB wire? I assume I splice it in, because it goes to the ECU, or should I just cut it? what is the voltage range here? Edit: found it... yes, splice in, and found the ohm range in the ETM.

then, there are two other wires coming from the pump and going into an under hood harness: red and green/pink. what are these for? the ETM doesn't seem to show them.

Then other stuff... red/gray wire coming from ECU appears to be the check engine light. stick an indicator between this and +12 to make a check engine light? Edit: with the key in the run position I have solid continuity between this wire and ground. I would expect that if the CEL was on (as opposed to just for a couple of seconds during the test) but my scanner shows no codes at the moment. ??????

ETM shows a black/orange wire as the lead from the CDL switch. I have two of these coming from a harness on top of the bellhousing... why two? there is no continuity between the two wires. according to the ETM the diff lock indicator has voltage when the key is turned and the diff lock switch supplies the ground. Edit: figured this out... when the diff lock is on these two wires complete a circuit. indeed, wire a lamp between them and you have the CDL indicator.

electrical experts speak up!

[mightymg1]

I was kind of wondering a few things about the stock fuel pump wiring too. I used the white and purple for my hot to my new pump, I kept my green and black just in case, its just heat shrinked and hidden.

Here what im wondering, when i turn my key with out starting it the fuel pump runs for 10 seconds or so then turns off. so does that ecm some how sense pressure and when the line is pressurized, and it turns the pump off till it needs it? This would keep you form having a pump that is running 24 7 when the key is on. maybe its not a bad idea to leave those other wires. dunno :confused:


OK--I am dangerous when it comes to reading a wiring diagram. I'm trying to plan out some dash indicators and gauges, so here goes.

Fuel pump: ETM shows three wires: white/purple (#12 wire, this is power), green/black for fuel level and black for GND).

what do I need to do to wire a fuel gauge into the GB wire? I assume I splice it in, because it goes to the ECU, or should I just cut it? what is the voltage range here?

then, there are two other wires coming from the pump and going into an under hood harness: red and green/pink. what are these for? the ETM doesn't seem to show them.

Then other stuff... red/gray wire coming from ECU appears to be the check engine light. stick an indicator between this and +12 to make a check engine light? Edit: with the key in the run position I have solid continuity between this wire and ground. I would expect that if the CEL was on (as opposed to just for a couple of seconds during the test) but my scanner shows no codes at the moment. ??????

ETM shows a black/orange wire as the lead from the CDL switch. I have two of these coming from a harness on top of the bellhousing... why two? there is no continuity between the two wires. according to the ETM the diff lock indicator has voltage when the key is turned and the diff lock switch supplies the ground. Edit: figured this out... when the diff lock is on these two wires complete a circuit. indeed, wire a lamp between them and you have the CDL indicator.

electrical experts speak up!

[darkstar]

I was kind of wondering a few things about the stock fuel pump wiring too. I used the white and purple for my hot to my new pump, I kept my green and black just in case, its just heat shrinked and hidden.

Here what im wondering, when i turn my key with out starting it the fuel pump runs for 10 seconds or so then turns off. so does that ecm some how sense pressure and when the line is pressurized, and it turns the pump off till it needs it? This would keep you form having a pump that is running 24 7 when the key is on. maybe its not a bad idea to leave those other wires. dunno :confused:

I think its timed... it pressurizes the fuel system, like you said, when the key is turned. the green/black wire is the fuel level sender output. don't know what the other colored wires are for. I spent an hour looking for them in the ETM and can't find them.

[afirover]

alex call me in the moring i'll walk you throu it easy stuff
:flipoff2:if you need my # 's call paulina

[afirover]

ok i'll bite
Fuel Gauge
When the fuel tank level is low, the resistance of the
fuel gauge sender is approximately 245 ohms. As the
fuel level increases, the resistance of the sender
decreases, causing the gauge to register the change.
When the fuel tank is full, the resistance of the sender
is approximately 19 ohms. When the fuel gauge
sender’s resistance falls below approximately 25
ohms (6 liters/1.5 US gallons), the fuel warning light
will illuminate to warn the driver .



ok to run the fuel pump the schem looks like this

power starts at the fuse goes to the mfru then the inertia switch to the pump thou that to ground
so translation
fuse 6 main fuse box inside (pw)
in to the mfru and out as(wp)from their inertia switch color stays the same (wp) to the pump after the pump(b) to ground
you can replace the mfru section with a hella syle relay for this job (still need the mfru for the "heaters" on the o2 sensor but baby steps for now


the (gb) wire is discribed in the txt at the beging of this long ass post
enjoy get stuck call

[darkstar]

Right, I get that. have another look at the OP.

[mightymg1]

Do you think it would be better to switch to a 19 ohm GM sending unit, most gauges are made to run witt them? Your pump is already being shady, maybe now is the time for a external. since your tearing it apart anyways.

[darkstar]

not just yet. I have another pump, and another housing. I'm pretty sure the problem I was having was due to a loose connection, which is now fixed.

also, my cell is set up for an internal pump. I would have a big gaping hole on top, there are no provisions for pickups, no sump, etc....

[PTSchram]

OK, first off to address Lane's comment, the pump runs for seven to ten seconds to pressurize the fuel rail and then shuts off until the ECU receives a signal indicating the truck is running. This is a safety measure to ensure that fuel is not pouring out of the rail, or into the intake with the engine not running.

With respect to the fuel pump wiring, gimme a minute!

First off, knowing for sure that we are all looking at the same page might be very helpful! I'm using a RAVE disc from 2001, the ETM section applicable to this vehicle is, I believe, A3, Sequential Multi-port Fuel Injection. With respect to what those wires do, I suspect they are most likely associated with the advanced evaporative loss control circuit. IIRC, the system is such that at some idle conditions, the valve is open to allow for purging of adsorbed fuel vapors into the intake for eventual combustion. I'm not able to find it in the ETM right now and sadly am WAY too busy to try to do more right now.

[darkstar]

in my ETM it actually says NOT USED through those wires.. yes, SFI. I'm not sure if it applies to my exact vehicle....

I think you are on the right track with it being linked to the EVAPS system.

now, the CEL mystery.. I guess I can omit the light, but it would be nice to have if it is usable (i.e. not on all the time)

[afirover]

try page 39 etm and the green/pink answer is on pg 43 fuel (psi) hope this helps

[darkstar]

unfortunately it doesn't help. my etm must be outdated.. it doesn't show the advaned evaps fuel pump at all. the only wires it shows to the fuel pump (on page 47) are the WP GB and B. it shows the entire component for the fuel pump (solid line) and it only shows one connector, whereas it really has two.

hook me up with the newer ETM dude! I need the 1998 ETM, only have 95 and 96

[darkstar]

OK, I think I figured out the extra wires going to the advanced evaps fuel pump. I don't have the right ETM, but this is what I determined by looking into a spare fuel pump housing. The extra harness goes into a little vent valve or sensor at the top of the pump. there is also a small hose barb with a rubber hose that vents to the atmosphere. if the wires power a valve, it probably opens up and vents through the hose. If that's the case, the hose can go and the vent can be plugged, since I have a 1/2" vent tube in the fuel cell.

can't confirm which it is without an ECM that covers advanced evaps (hint hint) but either way that harness can be deleted and the wires at the ECM trimmed.

[mightymg1]

Your first post is like a set of twinkle lights :eek: .. MERRY CHRISTMAS!!! HO HO HO!!!! Every time look at it, a different part is lit up :flipoff2:

[PTSchram]

What you've discovered is the fuel pressure sensor for the AEL system and the valve that allows fuel vaoprs to flow to the charcoal canister and thence to the intake.

I'm sure that if you search, you can find an FTP site that will allow you to download the ETM for your truck.

[darkstar]

I'm sure you're right, but some hours of searching have not yielded anything newer than what I have.

[rangeyrover]

isohunt.com has a rover manual
There is some interesting stuff here: Green oval (http://green-oval.com/joomla/index.php?option=com_docman&task=cat_view&gid=13&Itemid=29)
I have a 97 ETM if thats any help?

[darkstar]

d'oh.. I realized that I actually have the RAVE that's on Green Oval. I hate using it, because it forces you to use Acrobat 4. do you have an unlocked version of the 97 ETM (one that will open with any version of Acrobat)?

[rangeyrover]

The RAVE cd has a crypto plugin that prevents you opening it any other way. I tried to print to pdfcreator, but it fails if you try in postscript mode.
I have tried in image mode, but that fails at page 22.
You would lose all the useful bookmarks too, I think.
working on it....

[darkstar]

Right, I know... I have a copy that's decrypted, but the ETM is one year older than I need (the WSM is current though).

Whean I run it off the CD, it screws up my acrobat install, and the firefox plugin stops working. I then have to reinstall acrobat (the current version) every time. real pain.

[darkstar]

All I have to say is d'oh! :homer:

the check engine light works fine. Stupid me didn't bother to put a test light on the circuit with the engine running, only with the ignition on... And of course, the check engine light does more than just a bulb check like the rest of the idiot lights. it remains illuminated until the engine starts. stupid.

yeah, it works fine....

I'll be making a separate post outlining which wires and relays need to stay in a GEMS car to run the engine, in case anyone wants to do an engine transplant into something else, or something along the lines of what I'm doing here.

[PTSchram]

I'll be making a separate post outlining which wires and relays need to stay in a GEMS car to run the engine, in case anyone wants to do an engine transplant into something else, or something along the lines of what I'm doing here.

LOL, and they accuse me of renventing the wheel.

The Morgan and MG guys have done this already. Afi and I tried to talk to one of the Morgan guys about the alarm issue, but he was abroad.