I have no fuel pressure.

Relay swapped back & forth with horn relay same part#, no change, horn worked either way.

I cannot, even on all fours on top of the engine, or from driver's fender find the Prime Connector. If I could feed 12V there, I could find ot if the pump works, then see about the "fuel pump relay control", of the ign. sw.

Instead of the firewall location as I found in another post, could it be under the relay box?

Speaking of that relay/fuse box under the hood, I still haven't even found the actual fuel pump fuse.

Back at the tank, everything still intact, the only connector I can reach is just fwd of what seems to be three, (?), fuel lines; a 0-60-120 degree layout in a mostly round connector with one side clip. it seems light duty for a pump, is it the fuel level gauge instead?

I have the schematic drawing of the fuel pump circuitry, and the F/Pump relay shows five points, but the relay only has four. Wassup wit dat? Do I have the wrong drawing? I thought I found it in 2nd Gen S.

Edited to add: When I short the relay's source voltage and output pin, A2 > C1, which should mimic the "Prime Connector" path to the pump Motor, there is not even a voltage drop, totally open, so it looks like an open in the pump or wiring to it. I will start the procedure to drain tank, and let it down soon.

Is there any recently outed pdf's or something that were smuggled out of GM?

Should I just have myself committed and stop worrying about this stuff?

Bruce Hinton

 

*MOVING TO 2ND GEN TECH*
Please note the description of the DIY section:

Do-It-Yourself
This section is specifically for informational articles to assist other members in working on or modifying their own vehicles.

 

You will not be able to locate the fuel prime connector. It simply is not there. This reference on the later 2nd gen models is only on the diagrams due to the use of these same diagrams across the S-series vehicles. The prime connector is only used on the pickups with the 2.2L I4 engine.

As you have found out, the relay is only a 4 pin relay. To power the fuel pump just as it is when the relay is triggered, you will need to make a fused jumper wire that fits into the cavities where the relay plugs in. The jumper wire should go between pins 30 and 87 if the relay has these numbers listed. If the relay output is numbered 1-5, then it will go between 3 and 5. Use a fuse of 20A.

The fuse that supplies the fuel pump with power once the relay is energized is the ECM B fuse (20A) which should be located just to the left of the fuel pump relay in the underhood fuse block.

 

Yes my relays use pin #s 30 & 87, -the A2,C1 was from the schematic. Had an old fuse holder from driving lights, but with an open at the pump end I won't know much until it is tested at that end. I will admit to a disappointment when I heard no pump...

That little three conductor plug will be tested for voltage and ground, then I guess I'll be on eBay for a pump, Delco, of course.

Is that the one i need to check or is it only tank level? I just assumed the level gauge wring would be two cond., but this your grandfather's Oldsmobile.

Bruce

 

So if I am reading your reply properly, you have jumpered the connection where the relay normally resides, correct?

Have you tested the other pins in that location for proper power/ground? The connection that accepts pin 85 should have +12V (battery) with the key on for the first 5 seconds or so, then the PCM will shut it down. Pin 30 should have +12V at all times. Pin 86 should be grounded at all times.

As far as where at the pump to test, here is the fuel pump connector view:


There are two connectors, the 3 pin connector is for the fuel tank pressure sensor used in the monitoring of the EVAP system. The 4 pin connector is used for the fuel pump and the fuel level sending unit.

And here is the schematic of the fuel pump power/ground:

 

OK, wiring feels pliable and shows no signs of heat damage, connectors showing clean white metal. Pin B to chasis or C read identical, full voltage with the jumper in the relay socket base. C to chasis was a dead short.

I will just replace the pump! Not the harness, at least for now.

Dropping the tank is partially done, but I hung up on getting that @$#!%&* filler hose off the tank neck. Fortunately no kids were around to listen in on my analysis. If I cannot get the hose's top end loose, (it's clamp screw is rotated to an impossible angle), i will cut it off and splice a new one in.

Unless there is an obstruction near the tank I don't know about, I hope to get a siphon hose in the filler neck.

I try, I learn,
Bruce

 

Once the filler hose is off of the tank, you should be able to put the siphon hose right in.

And yeah, sometimes those clamps can be a real pain just due to location. Shows just how these trucks are assembled. Must be nice to put the tank assembly in without the body on!

Sounds like the wiring checks out perfectly fine and the pump is the problem. Would have sucked to find out otherwise if this test was not performed!!

 

Ever heard of Global Automotive of Miami? They sent what was supposed to be an AC Delco fuel pump and it may be, -but I thought a brand new one would be in some package besides bubble wrap with its part number, and maybe a moulded in brand ID. Totally nothing, though I have not pulled the actual motor out of its housing.

The fuel level pot. has no hinge-pin for the float lever and I didn't want to mis fit one and put it in a bind.

Can't get them to answer the phone Went on-line and immediately found many reports of them on a site called ripoffreports.com

I don't like what I am thinking right now...

Bruce

 

Global Automotive is A-OK by me, I regret that I forgot and left this issue in limbo. I eventually got in touch with them to replace my pump for the wrong one I ordered by moving too fast, (who knew the number of doors affected the fuel pump design? ) I do now!!!

They even shipped it while I was still waiting for the freight amount so I could pre-pay.

Now I am back to this project after an extended hiatus.

Pump replaced, now runs up to about 60-ish psi., but only when I bypass the relay the way I first did to determine power to the pump and pump dead. The new pump had upgraded connector on top of housing. I think that is a good thing.

Back to that schematic! I'll report back if I discover anything useful to others.

Still grateful for the help from those of you that responded, back when this all began.

Bruce

 

I have searched a bunch, had about 20 tabs going before I read them, but cannot find a checklist procedure that I remember seeing. Not the factory dealer one for folks having the electronic diagnostic equipment... "Search fu" is apparently weak in this one.

If I put a 20A fused jumper in place of the relay, the pump instantly hits 61 psi, engine starts and runs, but will not stay running if I remove the jumper, (relay #30 to #87). The two second duration hit of 12V occurs with the turning on of the key, as measured grounded to a ground strap from #85, (current from the ECM), but with a tested relay in place, the fuel pressure never moves from zip-point-zero.

The downstream side of the relay's coil seems to be a problem, it shows about 6 ohms to ground strap with the key in any position, but 26 ohms with the headlights on, (?). Seems it should be as close to 0 as practical, so the coil can activate, unless something is preventing it.

Has anyone access to a grounding schematic? I see a couple of mentions of it on the schematics I have now.

Steadily going crazy, quietly so far,
Bruce Hinton