Hey guys

Please watch this space for update on today's events, could use some perspective before going any further...

Thanks for standing by, and again for all your help

PS It's a 1990 740 GL

 

ok, a 1990 740 Regina uses 'combined tank unit' 3547206

thatst the fuel level sender, the in tank pump, AND the lid with the plumbing and wiring.

this is held in place with lock ring 1325236 and seal 1367623 ... later cars put a steel band clamp around that lock ring because it has a tendancy to warp and not hold tight... mine wouldn't go back on after replacing the tank pump, so I had to get a new one.

 

So I returned to the car this morning in the hopes of maybe budging the banjo bolt on the fuel outlet. Or the clamp on hose on the fuel return. Or the clamp on the end of the filler hose (as in the clamp that can't hardly be gotten to, but must be, for verily the whole damn hose must come out or pump won't make it out the hole). Or the locking ring. Nothing would budge. Which got me thinking "I wonder if I can just repair the electrical connection, since that may be the only problem here, like with my IAC," which led me to examine the connector again, and immediately upon handling it the wiring popped right out of its "potting."

Which started my gears turning.

I ended up going full Frankenstein, pirating then modifying (for snug contact) the pigtail connectors to my cooling fan relay in order to devise a new set of connections to the "four pin connector" which I exposed yesterday and today cleaned up (they're not actually pins, as can be see in the macro-focus pic). The two 16 and two 22 gauge wires from the fan relay were right on time (16s for earth and "computer" contacts, 22 for power and ground to chassis). I here submit my jerry-rig for your evaluation, because while all connections are tight and are separated from each other by a small central piece of plastic partitioning which "divides the pie" into four quarters, and while the "pie" is itself housed in a plastic cylinder (whose white edge you can see encircling the "pie"), there be fumes coming up that cylinder, seeping past the circumference of the pie and wafting past my custom-built connections...and though I don't see how sparks would ever fly from this set-up, my pride is not worth risking self-immolation. (Nor is my desire to execute pierce's tank-hank, as fierce as that desire may be.)

 

um, the 4 wires are fuel pump +, -, and fuel level sender +/-

later cars didn't have that banjo fitting for the fuel line, and only had 3 wires, with both - signals in common.

 

OK. I appreciate the education.

So red and brown are fuel pump + and - ? While black and gray are fuel sender + and - ? I was certain that the black wire goes to the chassis; when I run a continuity test now from "brown male" on connector to chassis ground I get 0.00 ohms? Or is black the - here? Do the sender and pump have a common ground (e.g., the chassis)?

There are indeed only three wires at the connector in the trunk/going into the pump. I must admit I have not known how to interpret the portion of Fig. 2 here as pertains to the fuel pump... or where the gray wire (which connects to a gray-white wire at trunk connector) finally ends up (though I think I'm clear on the path of the pink wire, to which the red wire connects at trunk connector)...

I have in fact triple-checked that all wires are going to the places they did when the original connector was in place...

 

According to that diagram, the in tank fuel pump is pink (+), and black (gnd)
The fuel sensor is grey-white (+, signal) and brown (ground). The fuel sensor is grounded at the instrument panel.

These are the wire colors in the engine harness. They usually don't bother to specify the colors used inside a part, like the pigtail from the tank assembly to the harness connector

 

Ah, so the brown wire is the ground for the grey-white wire, while black is ground for the red wire? Should I be seeing continuity between red male pin at connector and ground to chassis? (I was mistaken about 0.00 from brown male to black at chassis, am now finding 0.00 between brown male and grey-white male, which would be the fuel level sensor circuit.)

Where is the fuel level sensor grounded in the actual car (trying to learn where all the grounds are)? Geeking out hard on this, sorry. I'm here for the education, especially the electrical education, as I feel like automotive wiring is one of the blackest of boxes. Thank you again. (UPDATE: I see there are other wiring diagrams in this pdf; found fuel sensor wiring on Fig. 10.)

I take it I might go ahead and try the jumper from 1 to 11 without serious risk of grave bodily harm? Or is everyone looking forward to an end to this interminable thread?...

 

Did you ever figure out if the pump itself is OK? I'm not clear if the connection was bad or it broke when you were trying to disconnect it?

 

Hey Lev:

I myself am not clear whether I broke that connection in my early ignorant explorations (or when I went back to handling it lately), or whether it fell apart on its own due to all the rust (opened the trunk this morning, condensation was beading on all the fittings; are there some plugged vents I should be looking for?), or whether the fatal breakage is inside the pump after all (I am not seeing the continuity between red male pin at connector and chassis ground that I think I should be?)...

I am hoping to find out about the functionality of the pump by trying pierce's tank-hack again with my new rig in place, but I'd prefer to get a word from you guys on the soundness of the rig first...? Though I would understand if no one wants that on their conscience (or if the rules of the forum forbid such assurances)...

 

the grey-white wire goes to connector B1 on the instrument panel, while the brown goes to C6 on the instrument panel. the panel itself is grounded at C11 . this is all on page 12 of your PDF link

 

I'd test the pump going by applying power to the connections. You may need to get the pump out, siphon the bad gas, etc. Pump contamination? You may have to do this anyway.
How's this car other than that? I hope it's worth doing all that work!
Just repairing the connections may be pointless (I don't like rust... )
As far as condensation, the trunks of the sedans are known to let in water, usually through the lights, it collects in the side pockets under the lights.

 

Hey

So that was a non-starter heh.

The sad thing is that I only launched into that rig because I thought I was reading continuity, though inconsistently, between red and black wire "pins" on the "pie," and thought I just needed to create some solid contacts to restore the circuit. But after getting no action at the pump and then pulling my contacts I wasn't able to find that continuity after many tries. So either I was mistaken or whatever was dying inside the pump just died all the way.

(I still have continuity between gray and brown "pins," and yet no reading on gas gauge... is fuel level sender powered by red wire too? Last wiring question for a while, I promise.)

Back to waiting on B'Laster.

Thanks again guys.

Re: is it all worth it... though this car has been, well, a brick, there is in fact much rust afflicting it. Perhaps my aesthetics will have to give way to more practical considerations. Especially if I can't bust any of the rust holding the pump fast.

 

Post some pix of the car, let's see how it looks, get some idea of its overall condition; it's a personal decision for you, of course, but how much rust is there and where?
Are you having trouble removing the bung nut?
Do you have any wrecking yards near you, with 740/940 laying around? That's my first place to go for parts though I realize the Regina is rarer.

 

Busted through the rust. Required busting through my fear of making sparks with my hacksaw. Chuckled when I noticed how beaten-up the locking ring was even before I started in on it. Looks like maybe someone else gave up; I highly doubt this pump is a replacement. Anxious to order my replacement from my man in Atlanta.

Re: Is it all worth it. I’ve attached a couple pics of the rusty innards, one straight down the hole, one looking toward the left rear wheel. Recalling now that I bought this car from a guy who lived in the woods. I don’t care. I’m here for this.

 

What I meant was some pictures of overall looks, to see if it's a "nice" car worthy of all the effort. The under carriage shots are not very encouraging, but I do respect your stick-to-it ness-- I have saved many a Volvo from the wrecking yard and passed on to new owners. I do love the challenge of making something out of nothing so I understand what you are doing. That said, I wouldn't blame you if you walked away...

 

Hey

So the pump came out.



Putting it on the workbench gave me a chance to give the wiring, including the external contacts, a new inspection and conditioning. Re-acquired continuity between pump power and pump ground contacts.



Re-inserted and re-connected pump (probably checked and triple-checked that I hadn’t broken continuity about thirty times while doing so).



Was a little frustrated that I apparently couldn’t seat the pump all the way into its porthole; the pump mechanism itself dropped in all the way free and clear (a 90 degree rotation of the filter sock helped; it had apparently been smashing up against the right-hand wall of that receptacle at bottom of tank), but I couldn’t push the pump’s gasket all the way in the hole, and when the locking ring was on as snugly as I could get it on I could still feel exposed threads at the back.



“F*CK IT” I said after an hour of that fruitlessness. I hopped out of the trunk, reconnected the red wire from the pump to the pink wire from fuse #11, reconnected the battery, got in and turned the key to ON.



Was stunned and elated to hear a WHIRRRR from the boot (also felt a little stupid; shouldn’t I have noted its long absence long before this?). Lept out and onto the ground to look under the car. That’s a drop of the gas that ACTUALLY GOT PUMPED OUT hanging there on the end of the fuel outlet line.



I’m thrilled. Looking forward to finally purging the tank tomorrow (using pierce’s 1-to-11-jumper hack) on the way to a thorough clean-out of the tank on the way to a proper Italian tune-up.

Please let me know, however, if pushing the pump all the way in the hole is mission-critical and if so please advise me on HOW THE F*CK to get it all the way in there when I put the pump back in following the alcohol rinse of the bottom of the tank and before refilling with fresh gas.

Thanks again for being there.

 

The pump assembly MUST be seated all the way in or it will leak after a fill-up. The bung ring shrinks when out, it must be reinstalled when the pump is out, may be you can heated up some...
Use petroleum jelly on the ring to get it to go on, the rubber seal goes on first on the opening, then you put the pump in...
I'd have siphoned the gas out when the pump was out, it's easier than to do it electrically...

 

Hey Lev. Glad I called. WOW was it easier to seat the pump by first setting the pump’s gasket in place before inserting the pump assembly. Before that I was completely unable to push the gasket in past its inside lip (even with the jelly). Who knew the gasket came off?! (You did of course; again, thanks.) VERY satisfying to feel that locking ring easily sliding/dropping all the way into place.

Re: tank drain... perhaps siphoning would have gotten out every last drop, but I ended up going with the electrical hack right to hand (I stopped tasking the pump when the fuel line started spurting rather than streaming fuel). Overall I think it went well; also felt good about my guess that my spare cooler was approximately the same capacity as the tank, which saved me having to buy multiple 5-gallon gas cans. (That's rainwater at the bottom of that catch tray, btw, not water from the tank.)

FYI, in case it’s something you're not already acquainted with, attached is a view of the silt-sifting receptacle in which the pump assembly sits, with indicators of how fuel flows to pump from the tank-at-large; yellow arrows point to fuel entries, red arrows indicate fuel flow to pump. (To be candid, I'm beginning to wonder how practical/effective the alcohol rinse would be, as the pump apparently can't eject that final 1/2" of liquid; again, would siphoning do better here?)

PS. I found these two little rubber sleeves (pictured below) at the bottom of the receptacle... any idea what they might be?

 

Good job, making progress! You are right about the siphoning, personal preference... The two sleeves look like electrical insulators that may be detached sometime in the past... Who knows?

 

Was quite exercised tonight jumping from back to front to underneath the car chasing and shutting down leaks in gradually-increasing fuel pressure like an automotive Hans Brinker. Had to redo a couple of connections more than once, replacing copper washers and otherwise refurbishing/renewing facing surfaces in order to make for the snuggest possible connections (which process comprised purchasing a new fuel filter, or should I say repurchasing it, because I had already returned it once before, because the answer is never the fuel filter lol). I finally got to a place where cranking didn’t cause any dripping, at which point I held the key in the START/III position until the ECU figured it out (?) and VRRRRROOOM there it went. And kept going. A steadier and cleaner idle than it has ever maintained. It has now been taken for its first (short) drive in 5 1/2 months. I’d say it’s like nothing ever happened except now it runs better.













My only lingering concern is that I’m wondering why the temp gauge isn’t ticking up at all. More bad wiring? Power/ground to the cooling fan is good, 0.00 ohms from "black female" at cooling fan connector to fender ground, and fan comes on when red and grey-red wires touch... but then the hot air blowing from the heater never got that hot either...? Might relay be bad? (Yes that’s my (literal) pressing of some Dorman female bullet connectors from AutoZone into service, since I pirated the original pigtails to fabricate the new connector at the pump assembly; everything feels quite tight though). Bad thermoswitch? Just didn’t get hot enough?










Open to perspective as usual. Extremely grateful for all your help here.