ok, after fixing the short from when i grounded the positive battery cable on my header(caused a fire)( turned out it was the oil pressure switch)
anyway, the car ran with the new oil pressure switch installed. all i did after that was bolt the FP relay back to the firewall and put the cover back on the ECM. when i was connecting the negative battery cable back up, i accidently touched the positive andd negative cables with my wrench. I didn't think think anything about it. then after lowering my car off jackstands, i went to start it, nothing.
so, i checked ALL fuses, got a new FP relay, and got a new oil pressure switch. nothing works. But the FP runs and the car starts if i hook a jumper wire from the battery to the FP power wire. also, i blew that fuse beside the battery twice, but can't figure out why. also, when it runs, the battery voltage is very low, like 8V and doesn't charge, but it still starts. my oil pressure gauge stays in the red, but when you rev it, it goes up to 20.

Help me!!!!!! I can't think of anything else that could be wrong. like i said i have checked and double-checked all fuses and replaced several, to no avail.

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89 RS (supposed 350) TBI auto

It sounds like you may have a couple/few problems. But first, I'd like to confirm that the fuel pump circuitry is working. I know you replaced the fuel pump relay.

Will the fuel pump operate when you first turn on the ignition (but without starting/running the engine)?

The ECM should turn "on" the fuel pump relay for only 2-3 seconds initially to get the fuel pressure up to start it, and then the ECM should turn (keep) the fuel pump "on" when receiving igntion pulses (so the ECM will believe that the engine is running).

By having to apply +12 to the fuel pump positive, it sounds like the ECM is not switching "on" the fuel pump relay (initially to build up pressure to start the car, and later, once the car is running, to keep it "on" as detailed above) since you stated that you can start it if you bypass the ECM and short the positive wire at the fuel pump directly to battery positive.

I'd like to know the answer to that before trying to guess further.

EDIT:

Because you had to replace the fuel pump fuse twice, I wonder if there is a short to ground from the fuel pump oil pressure switch (you did say you replaced it, didn't you?). According to my schematic, this switch has three terminals for connecting to four internal contacts - two of which are N.C. and two which are N.O. . Actually, there are two schematics in my manual - the fuel delivery section shows three terminals, the schematic section shows two (because I believe one terminal [A] is used only for idiot lights).

1. One (A) goes to the indicator (I believe this is not used for me since I have no idiot lights), which is Normally Closed (N.C.) to ground (via the base).

2. Another (C) goes directly to the fuel pump positive. This is a N.O. contact to the battery (via the 20 ampere fuse). It is a grey wire which is also connected to the common of the fuel pump relay terminal "E").

3. Lastly, (D) goes to the positive battery terminal through the fuse that you keep having to replace. As stated in #2 above, it is N.O. (Normally Open), but will close upon detecting enough oil pressure (this is why you sometimes hear the fuel pump operating after turning off the engine, because there is still enough oil pressure to keep these N.O. contacts closed).

My guess is that when you replaced this switch, you did not connect the wires properly, and connected "A" (N.C. to ground) to the wire that goes to the battery positive (via the fuse). I think that this wire is orange. So, without enough oil pressure to open this N.C. contact, you will be shorting this terminal/circuit (fuel pump fuse) to ground.

I don't recall how many terminals this switch actually has on my car. If this switch does indeed have three terminals, the terminal you connected to the battery is switched to ground, (or perhaps you have a two-terminal switch that is not electrically equivalent to what you replaced/need) then this would be my guess.

[This message has been edited by Stuart Moss (edited June 10, 2001).]

No, the fuel pump does not prime at all.
also, when i tried the last time to start it once with the new relay and once with the old relay. the fuse did not blow. also even when i started it with the jumper wire, with the new oil pressure switch on it did not blow. i don't know why it blew before. yes, i have replaced the oil pressure switch twice. it does have three prongs. there is no way that it can be connected wrong.
i went out and disconnected it and reconnected it and still nothing.

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89 RS (supposed 350) TBI auto

Okay, the problem (or "one of the problems") seems to be no power to the fuel pump.

See my post (just made minutes ago) in the electronics section titled NEED HELP REAL BAD GUYS!!!! https://www.thirdgen.org/messgboard/...ML/001664.html for my suggestion on how to test the fuel pump.

It may be easiest to just jumper a long wire to the grey wire at the relay socket to the positive terminal of the battery. This will essentially put +12 directly to the fuel pump motor positive input (via the wiring and connectors along this leg of the circuit).

If that works, try jumpering the grey and orange wires (see my post at the site listed above for specifics) together with a paperclip/needle nose plyers, etc.

If that works, then I'd say that the ECM is not providing power to operate this relay to turn the fuel pump "on".

If that's the case, I suppose that you could just wire the positive side of the fuel pump relay coil to the +12 accessory position so that the pump will be "on" when the igniton is "on". Plus, if you turn the key to "run", you'll be able to operate the pump to get pressure, then start it. This should at least get you moving. This wire is dark-green/white (according to my 1991 service manual) and is terminal "D" on the relay socket. (Terminal "F", black/white, grounds the coil permanently.)

You should be able to at least get the pump working without having to start the car. Because your oil pressure gauge is reading low (or no) pressure, I would be very concerned about running the engine without enough oil pressure.

Let me know what happens.

//Stuart

[This message has been edited by Stuart Moss (edited June 10, 2001).]

ok, i have already jumpered the grey wire to the positive battery terminal. that works fine fuel pump comes on soon as you connect the wires.
i tried jumpering the orange and grey terminals--nothing happens

what causes low oil pressure?--the car runs fine- no visible oil leaks. i think the gauge must be wrong. what could cause this?

I don't really want to rig anything up i want it to work as it should.

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89 RS (supposed 350) TBI auto

When you shorted the battery it may have effected the alternator. I would check this as well. It might not be all of your problem but it could be part of it. You might also check the positive wire that comes off the starter, I think this wire has a lot to do with the rest of you electrical system.

Steve

You probably blew a fusable link. They are in the wires coming from the starter. They look like a small bulge in the wire just before the starter, usually at the end of the #10 wire going to the hot post on the starter this also effects the Alt.

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Chronologically challenged. But still kicking!
'92 CAMARO RS
305 TBI 5/spd (now TPI)
B4C Alt.
'69 camaro-BB/Lenco,1050 dominators, /Pump Gas/no drugs 8.97-150+/3200lbs.
SoCal Thirdgen F-Bodies

Sounds like a blown fusible link to me as well. I'd check them. A visual inspection isn't always the best as they can look like they are fine even if they are blown. When they do blow, they will pull apart very easily when tugged on or they will completely burn into two pieces so you should be able to check them easily with a minimal time investment.

An idea.......

Good luck.

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, Home-made cold air system w/ K+N cone and AFPR, TB bypass, AirFoil, !AIR, !A/C, !EVAP, 2300 stall.

"Stop Lights timed for 35Mph are also timed for 140Mph"

I went out and checked all those little bulges I pulled on them and they didn't pull apart and they looked fine visually.
I have not only checked all the fuses in the fuse box, but have switched in fuses that I know are good. I have changed the fuse by the battery two or three times.

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89 RS (supposed 350) TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k

I haven't looked at the post that Stuart refrred you to, but I'm guessing he has listed the pinouts for the FP relay, if so, use a test light and probe the coil side of the relay socket that goes to the ECM (relay removed).

Have someone turn the key on, while you're watching the test light, the light should come on for two seconds as mentioned before, if not, the QD inside the ECM is dead, or the wiring leading back to the ECM has a problem (open or shorted to ground), or you have no ECM ground.

ok, i'll get a test light and check that out, and, just for curiousity, where is the ground for the ECM and the other grounds located?

Thanx for all the help

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89 RS (supposed 350) TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k

ECM grounds are on the back of the cyl. heads, you'll see a few wires all ring lugged together.

Ryan,

As mentioned in my above post, the orange wire that you jumpered to the grey (going to the fuel pump) should have turned on the fuel pump. This wire (at least on my 1991 Camaro) is connected to the battery positive terminal through a 20 ampere fuse located next to the battery and not a fusible link. I believe that this is the fuse that you've had to replace several times. The $80 question is what caused it to blow?

Ensure the fuse is good. Check for +12 at the orange wire on the relay socket. If, jumpering this wire to the grey (pump motor) does not operate the pump, then I'd say you do not have +12 here. If the fuse is good, check it with a light and/or voltmeter and physically trace it back to the battery to ensure that this is indeed the same wire to the fuse by the battery.

Is it possible that this wire is shorted to ground somewhere between the fuse and the relay socket? (I'm stretching my imagination at this point.....)

I've just got off a 13 hour shift, so my brain is not at its peak - sorry.

<8 volts indicates to me that there are more problems (battery, alternator, wiring, Lord only knows what). Lets get the fuel pump working correctly then we can tackle the other problem(s). I've made several lengthy posts regarding this very problem (low battery voltage) in the last three days. Do a search using my name in the "electronics" and possibly the "general engine tech" section to see them.

Thanx guys, I'll keep ya posted.

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89 RS (supposed 350) TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k

Ok, I got it running. I hooked up the new FP relay and it started up fine! so I drove it. anytime I hit a bump or pushed the brake hard, the check engine light came on and it would try to die. the rest of the time it was fine. The only thing I can figure is there are some loose wires somewhere that hit just right at certain times and that is the problem.
My oil pressure gauge still doesn't work right. it still says i have almost no oil pressure. What could cause this? The sender is new.
And I'm pretty sure my alternator is bad, It won't charge the battery at all, and I know the battery is good because I've had it in my 91RS and it works fine.

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89 RS (supposed 350) TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k

Anybody have any ideas where i could have those loose wires?

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89 RS (supposed 350) TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k

Ryan,

ECM terminals D1, D3, D6, D10, and A12 all should have a solid ground path to the chassis and engine. The outer case of the ECM does not necessarily have a dedicated ground connection.

Given all of the electrical gremlins you are experiencing, and the odd problem of the brake pedal travel causing the symptoms, I would advise you look very closely at the wiring in the driver side footwell and the bulkhead connector there. The connections through the firewall are very important. You should also disconnect the battery and disassemble and clean the positive power node connection and ground node connection blocks near the battery. Don't just look at them, but disassemble and clean them. You have an intermittent problem and need to positively eliminate some potential problems, not just assume they are O.K. Check the grounding strap at the right rear of the engine, and the negative batter cable connecions at both the battery and at the engine. Don't just tighten the connection, but disassemble, inspect, and clean it. I've had good luck coating these connections with anti seize compound to prevent corrosion and provide a good conductive path (since the compound contains metal particles). Don't overlook the positive connection at the starter as well. There are several wires on the positive battery stud of the starter and if you recall, that is where the problem all started....

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

Well thanx for the advice, Vader, but I found the ground problem. It is where I had stripped away the wiring protector where it goes behind the AC compressor. I wiggle it and the engine sputters. I'm going to remove my AC, so this will be fixed shortly.Any helpful hints about removing AC?
I'm going to check all my connections again and make sure the alternator connection at the starter is good and if it is I guess I'll replace the alternator. Any other ideas about why the alternator does not work or do I have the idea?

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89 RS (supposed 350) TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k

Ryan,

Do you have a voltmeter at your disposal?

Nope. Can't say that I do. I will probably get one pretty soon after this ordeal.

And I forgot to mention that my oil pressure gauge still doesn't work. it says my oil pressure is like less than 10. That couldn't be right could it? It runs fine. The sender is new, what else could cause it to malfunction?

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89 RS (supposed 350) TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k

up

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89 RS 350 TBI auto Hooker SC/LT headers Open element 3in K&N CVT protorque mini-starter

Daily driver 91 RS auto LO3 63k