bureau13

That's a good idea... It would save me from constantly removing and replacing that relay, at any rate.

When I was measuring voltage at the pump, I did have a jumper in that spot however.

soontobered84

Okay. Good. Just trying to help.

WallyP

Serious suggestion...

Go to auto parts store, Home Depot, Lowes, local hardware store, etc. and buy:
- Three feet of lamp cord or zip cord. This is the two-conductor, fine-stranded electrical wire used between a wall outlet and a lamp.
- Two male 1/4" flat spade electrical connectors, crimp-on or solder-on.
- One SPST (Single Pole Single Throw) toggle switch, clearly marked with OFF and ON, with screw terminals or solder terminals.

Strip both connectors on one end of the zip cord and attach a spade connector to each conductor.
Strip both connectors on the other end of the zip cord and attach to the switch terminals.

Installed between Terminals 30 and 87 in the fuel pump relay socket, this gives you a manual fuel pump switch. Remember that the pump will get power anytime that the jumper is installed and the switch is ON, whether the ignition switch is on or off. This makes troubleshooting easier, and gives you an emergency replacement for the fuel pump relay. Store it in the glove box, not the tool box at home!

Note that on the later cars, you can just swap the horn relay or blower relay into the fuel pump socket in an on-road emergency if you prefer.

If the fuel pump doesn't run with the jumper installed, the first suspects are the fuse and its connectors.

bureau13

That's a good idea. I can certainly see that being a pretty easy and useful thing! Question: If the fuse or fuse contacts were bad, would I be getting +12V at the relay socket (30 or 87, whichever is the right one, I forgot)? I did check the fuse, but I haven't checked those contacts yet on the CE. I did just test for +12V at the fuel pump the way MrMerlin suggested, and I am NOT getting it. This seems to suggest I have a problem in the circuit between the relay and the pump. I'm guessing the CE panel (ie fuse contacts, which everyone has been saying to go over with Deoxit, etc) would be the primary suspect there?

Mrmerlin

I will repost the important things you should be checking for, as they happen quite often when the pump does not get power



NOTE if the pump isnt running then drop the CE panel and then check that you have power coming out both of the wires that connect to the fuel pump fuse.

NOTE its possible for the slide on connectors on the back of the CE panel to corrode and the fuse will show good but the corrosion prevents the power from going into the wire that goes to the fuel pump .

NOTE its also possible that the fuse slots have become spread and dont make solid contact on the fuse

NOTE the power comes into the fuse along the top row,
and exits to the device along the lower edge of the connectors

NOTE deoxit should make these connections return to full function, it could take up to 24 hours for the stuff to work
__________________

dr bob

The power at the 30 contact in the socket is battery voltage via a dedicated feeder from the battery positive. There is no fuse. The 87 contact feeds the oxy sensor heater and the injectors, no fuse, plus feeds the fuel pumps and aux air valve through the fuel pump fuse.

bureau13

OK that makes sense. A CE panel issue seems pretty reasonable at this point.

MrMerlin, that is the first thing I will do on Sat. After pancakes of course.

dr bob

Check the feeder red wire from battery direct to 30 in the FP relay socket. If no 12V there, problem is the feeder connection. Most likely at the battery end. The CE panel connectors sometimes get pushed back, so look there too.

bureau13

OK, started chasing down my alleged fuel pump issue in between rain showers today. Good voltage at pin 30 of the relay socket. Good voltage* at the fuse socket. Put fuse back in, put jumper in for FP relay, replaced that "x-bus" relay (I got another 53B and it was on MrMerlin's list) and went back to once again check out where I did or didn't have voltage and/or ground at the fuel pump, when I noticed that the fuel pump was on. Huh? So, it's working now. And I have a suspicion the entire fuel pump thing MAY have been a red herring, because my fused jumper was really a bit dodgy with the fuse popping out. Attempted to start the car, no luck, so I thought I'd check for spark. Pulled a plug wire, tried to stick my spark tester thing in it, but it really didn't want to fit down in there very well. Thought I'd try anyway, and it cranked a bit, didn't really see a spark in the tester (no surprise given it probably wasn't making a good connection) when damned if the car didn't start. I shut it off, replaced the plug wire, and started it up again. It seemed a bit rough and was smoking a bit, but after it ran a while it smoothed out and seems fine. Of course, we know it's NOT fine, because unless that x-bus relay actually fixed something, nothing has really changed. I'm a little afraid to drive anywhere, so I guess I run it in my driveway for a bit more, and if I can't get it to die, I should probably attack some of those grounds and the CE panel, at least. It's gonna drive me crazy if I can't point to something as a definite fix though.

*I measure about 11.7V at pin 30 with ignition off. At the fuse, I measured 9.8V. I wasn't expecting a voltage drop like that. Is that normal?

**Technically, I have no replaced all four of the critical 53Bs...EZ, LH, Fuel Pump and the X-bus thing, which I'm not totally clear on being in the critical category, but it's replaced. Since I think my testing-in-the-dark-with-shaky-tools test methodology is a bit suspect, I suppose it's possible that the fuel pump relay actually fixed the problem. All of the times it failed with the jumper were either the bridge from the reverse lights or the jumper that may or may not have had the fuse loose. So that's a possibility that I can't prove, one way or the other.

dr bob

Measure the battery voltage at the battery terminals. and from battery positive to chassis ground those should be the same number exactly. More importantly, the fuel pump relay 30 pin is connected directly to battery positive, so should read exactly the same to ground as the battery post to ground that you measured at the battery itself. With the jumper in place, you should be able to read that voltage with the jumper in place and the pump running.


Just to make darn sure there's no Stupid Stuff involved, unplug the oxy sensor connector at the bottom of the CE panel area. It's a round barrel connector that lays across the bottom of the panel. Passes from the LH brain, and through a grommet in the side of center tunnel to get to the oxy sensor. If the cable or the sensor itself fault the heater circuit to ground, it pulls the voltage to the pump to ground. It's a collateral load on the fuel pump relay, and is unfused. The other unfused load is the injectors themselves, but no good way to disconnect those and still run the car.

bureau13

Interesting info...I will double-check those measurements.

dr bob

I'm not sure what the original engineers were thinking, leaving the oxy sensor heater unfused. The cable runs across the passenger-side floor right at the bottom of the CE panel, passes through the metal car shell with a rubber grommet as protection, above the heat shield forward of the catalysts, to the oxy sensor that's screwed into a bung on top of the crossover pipe that gets red-hot under high load. What cauld possibly cause a fault to ground in that circuit?

bureau13

It's BBAAACCKKK...my trusty electrical gremlin. Died about a half mile from my house, got it restarted and made it back to a little playground parking lot about a quarter mile from my house, where it died and remains dead. I just checked pin 30 of the fuel pump relay, and there are 3V on it. Eh? Going back over this whole thread, I believe that should be a direct-to-battery connection, yes? So I need to play with that...is it a dedicated feed just for the fuel pump and O2 sensor or are there other things that will be similarly affected?

I had forgotten about the O2 sensor part of the previous discussion, I'm going to disconnect that connector by the CE panel and see if that affects it..as well as checking the batter connections of course.

bureau13

Aaaaand...got it. I think. Maybe. Actually, it makes sense. Checked that battery cable, the main cable was tight, but that secondary cable was loose. Kicking myself for not checking it previously, based on this thread. I was trying too many things and not being rigorous enough, need to keep these diagnostic steps organized. I took it off, hosed it down with some Deoxit, reattached tightly...seems to have corrected the problem. I know this is the third time I've "fixed" it, but I'm guardedly optimistic about this one.

dr bob

As much as I like Deoxit for taking care of casual corrosion in places you can't easily clean, the battery terminals big and small are so easy to access that mechanical cleaning is still my preferred method. Note that this cleaning is on the Annual Electrical Maintenance Schedule, along with ground points cleaning (also a mechanical cleaning process).

For the main battery terminals, I use a battery terminal brush. This is a handy inexpensive single-purpose tool. There's a female end with a steel-bristle brush that wraps around the battery posts with the connections lifted. A few twists with the brush, and the posts are once again shiny and new looking. Inside a cover on the other end of the tool, there's a male brush. That gets used to clean the insides of the battery terminal cable clamps. A few twists and the clamps are similarly shiny and new again.

The smaller connections are tinned-copper ring lugs. The tin coating is there to protect the copper from reaction with the acid fumes from the battery. When cleaning the little ring terminals, I use a small brass detailers brush that looks like a toothbrush. The goal is to remove any oxidation and reacted tin, without getting all the way to the copper. This is the same technique used to clean the ground points, by the way. Because you want to maintain the integrity of the tin plating, avoid using sandpapre or emery for this task, as it's way too easy to blow through the plating.

Once all connections have been cleaned, they are reassembled and snugged securely. The big terminals are generally soft metal, so overtightening them to the point where the bolt wings are deformed really does nothing to improve the connections. In fact, that can distort the clamps and actually reduce the contact area. So use the "just enough" method on the clamp bolts. For the smaller bolts, the connections are 6mm stud(s) with 10mm heads. Torque on these is on the order of something like 6 lbs/ft, same as what you used on the water pump bolts into the alloy block. It isn't much!

Once all the connections are cleaned and assembled, I add a film of Vaseline over the whole thing for protection. Some advocate the use of dielectric gresae for this duty, but I recommend against that. Dielectric grease, by its very nature, has a high dielectric strength. ie, It is an insulator. Great for moisture-proofing spark plug and coil wire boots, but a bad choice for where you actually want current to flow. Vaseline is inexpensive, provides the protection needed, and is easy to remove. It washes out of clothing with plain old laundry detergent too, so your good work coveralls won't get any stains on them from Vaseline.


Again, same cleaning and preservation process for the ground points as you do your Annual Electrical Maintenance.