BC

I may just snag you on that offer Neil. Its been frustrating doing it at night, so I may try and make some time in the day.

neilh

Just let me know any time after about 9AM is good.

Landseer

It would be great to know, in a situation where you jumper the fuel pump relay but get no fuel, what voltages are on the 30 and 87 pins, respectively, to ground.

Check also fuel pump ground.
I think its at the rear quarter panel, under the panel ( is for 85/6, don't think it changes for 86.5).

Another thing that can happen is fuse 42 is corroded or blown.

BC

Thanks Land. Its probably the combination you speak of. It idles in the driveway just fine. But then when you drive it (after its warmed up) it will just die flat and not start again. The first night it would start and then die, now it just dies. So heat or resistance related could be an issue.

But as you said, bridging the FP socket should make the pump run, which it does not.

I don't know if you saw, but I wrote about a relay that was spliced into the Rd/grn wire to the fuel pump. It was haphazardly done, but it was obviously someone who knew enough to be dangerous. It was spliced into the rear loom going to a blk/blu wire that may have been for lights or the hatch lock. Maybe it was to fix THIS issue, or it was for some other reason.

BC

Fuse is new, and has been replaced, from evidence in the footwell.

neilh

Brendan, assume you are using the 86 diagram, although the 87 looks the same around the relay and pumps. Anyway, as Chris asks - what voltage do you see at 30 on the FP relay? Should be hot +12.
Jumper 30 to 87, should see same +12 at both ends of fuse 42.
Back to pumps - pull connectors, should have +12 at pin 2, ground ( check with ohms meter, at pin 1.)
BTW, that relay you found was probably a crude attempt at an immobilzer!

soontobered84

Brenden, check your engine grounds. clean the 2 at the back of the V(under the fuel lines), main engine ground on passenger side under the car, and the coil grounds. My '89 exhibited similar symptons (would run all day in the driveway, then strand you alongside the highway in a construction zone when you least expect it. The fue pump would not consistently run without being jumpered. I thought it was the LH, which I had rebuilt. Come to find out that the engine had no ground. The computers were trying to find a ground and when they did, the car ran great, when the didn't the car wouldn't run at all.
Good Luck

svp928

Brendan, since it a new(er) pump, to rule out pump malfunction try jumpering direct from the bat to the pump to see if it runs, then you know if its a wiring prob or not?
Careful, use small wire 16ga or so- if the pump is shorted or jammed, you may get sparks. In fact connect two jumpers together away from the pump and the bat to do this....no expl
osions needed

BC

I think its compound. There is a chance the used fuel pump is quiting occassionally, and there is also a chance the LH relay is heating up and releasing.

BC

Well, today it is running. And what seems to be permanently. Drove it about 7 miles to get gas and see what else shakes out. Seems pretty tight except for no seals in the doors or hatch. Fixed some of that today, and put a door seal on. I must glue another one together for the passenger side.

It shifts well, engine knocking noise seems to be resolved.

There seems to be a sort of stutter or stepped power delivery when accelerating from lower revs. I will start a thread on that.

Some connection issues still linger, and I am going through the steps to clean contacts and grounds. Essentially the fuel pump was stopping when there was a big bump or the hatch was pushed down. Yes, weird, I know. Its not happening, but I would possibly have liked to know the true issue.

Landseer

Interesting. Glad its running. Keep diagnosing though.

Valley grounds are big.

Did you change-out battery ground cable?

14 pin is important, too.

svp928

Strange.....might look for a bad connection down where the patched-in relay was..?
Run a bottle of good fuel treatment through it. Maybe two..

BC

The battery is not stock. So the connection of the positive was sort of moving I think. It seems more stable now, but i'd like to make some more slack on the pos cable. I tightened up the leads on the pump.

You'd be surprised what was going through my head when the hatch shut and the motor cut out - more than once under testing.

Ground cable was greenish, but ohmed at .3, so I cleaned it up and re tightened.

Did clean the grounds at the back of the valley.

I feel as though the car is running very rich. The cats may just be dead as doornails. I should think about getting cleaned 24lb injectors.

Landseer

I think the ohm test doesn't apply to a ground cable, Brendan. When that cable is under load, or car hits a bump, or change in humidity, I think the electrical pathway can still breakdown. I also think .3 is a lot. $7 spent at Advance Auto can take it out of the equation.

BC

You mean LR stan?