Help - ? - 84 C4 No Start - No fuel issue

[speedingaj]

Hi,
I read a post Frizlefrak wrote here regarding a No-Start, no fuel issue... I have been troubleshooting for weeks now. I am NOT getting power at the Fuel Pump Fuse. The Fuse is good; I am not getting power there. I have bypassed the fuel pump relay, and I have tried your 12 volt from the battery to terminal G on the ALDL connector. Even with that 12-volt power, directly to the G terminal I did NOT have power to the fuel pump fuse. I am begging to think My ECM may be the problem. I WOULD love to have a better way to test the ECU. I am having no luck finding one. I seem to be getting only the "12" code when I jump terminal A and B on the ALDL connector.
- Another note... My daughter was driving it when she said it seemed to "go on its own" - she said it sputtered then sped up to about 40mph on its own, then went back to normal. She drove it home. I was able to start the vehicle after that - however she had pinned the seat too close to the steering wheel for me to get inside, so I had to replace the power seat switch - while doing that (like a bonehead) I had a screwdriver near the switch while removing it, and had a nasty spark with a little smoke appear. I figured it was just the switch; however, after that event the car would no longer start. - Also all other fuses are good, none had blown. I have a new 85 version Fuel Pump, and the fuel pump relay is new. I hope that you can shed some light on how to test the ECM and or any other issues I should test.
Thanks!
-AJ

[SQUIRMIN VERMIN 84]

The ECM has a self check feature. The 1-2 code is a 'all ok' status which covers the car and the ECM. I don't remember the code it will throw if it detects an ECM issue.

The 'go on it's own' with your daughter sounds like a cruise control issue(maybe operator error?).

Do you have an FSM for the '84? The Electrical Troubleshooting supplement is really handy. The CD version is nice as you can print all the pertinent topic diagrams/schematics to study without flipping through the pages.

Page 8a-21 shows the fuel pump circuit. It shows when the f/p relay is operated, the Battery path goes thru the relay from the orange wire on the relay (E) terminal, thru the contacts and out the relay at (A) and on to the f/p fuse.

When the relay is not operated, the path from the ADL (G) goes thru the relay at the (D) terminal and out on the (A) terminal to the pump fuse. If you supply 12v to the (G) terminal, you're still going thru the relay in it's unoperated condition. It looks like no 12v is getting thru the relay by either the (G) path or the operated (E) path. It sounds like you may have an open relay. Can you put 12v on the red wire that conects to the relay (A) terminal and check the fuse for 12v?

I don't know if the relay has the letters on the relay terminals.

At this stage I'd try a new relay. If you don't have a FSM, let me know if you want the CD.

[speedingaj]

Thank s for the info. I sort of have it running now. For some reason It won't start with a little shot of started fluid. I am not sure which circuit is open, but once it fires it runs great. I'll re-trouble-shoot it again this weekend.

I do not have an FSM, and I would love to get a hold of the CD.

[email protected] is my regular e-mail.

Thanks again!

[SQUIRMIN VERMIN 84]

E-mail sent.

[speedingaj]

OK, so AFTER a TON of troubleshooting this is what I have... I have a cold no start condition.Here was the original problem: The wires were shorting out on the connector before the relay - http://www.thevettebarn.com/forums/members/speedingaj-albums-fuel+pump+relay+electrical+connection+1984+corvette-picture1580-img-0311.html

So I re-wired the wires. The problem still exists...except now it is not intermittent. Thank goodness. http://www.thevettebarn.com/forums/members/speedingaj-albums-fuel+pump+relay+electrical+connection+1984+corvette-picture1581-img-0507.html

and the relay - http://www.thevettebarn.com/forums/members/speedingaj-albums-fuel+pump+relay+electrical+connection+1984+corvette-picture1579-img-0512.html

So...what I think I have now as a problem is there are three red wires. I am not 100% sure I have them in the correct location.

When looking at the newly connected connection they are numbered A through E. E is near the notch in the connector (at the bottom of the picture)

When I plug in the relay the car will not start unless I use Starter fluid. There is no initial fuel pressure.
When I put a jumper between E and A, the car starts perfectly
When I put a jumper between D and ! the car starts and runs perfectly.

I can remove the jumper or the relay after the car is running with no affect

When I performed the re-wire, there are two red wires to A and one to D. I think I have the wrong wire wired to D. D is supposed to go to the ALCL I believe... so I think I have one of those connected to A instead. How to I figure out which is which? Can I do am Ohms test or something?

Thanks a BILLION for the answer.

-AJ

[SQUIRMIN VERMIN 84]

Just saw this tonight. Your posted picture isn't accessable, can you email it? Yes, you can trace out the 'D' wire with an ohmeter set on ohms. All 3 red wires should be unplugged at the relay and separated from one another. Clip one of your meter leads(either one), to the ALCL pin(G) under the dash, and the other to each red wire in turn to get a contact reading. I sometimes have to use a jumper wire if the distance exceeds the meter lead distance. If your meter has an audible tone with the ohms reading, that's also helpful if you can't quite see the meter when you're making the connections..
Once you identify the red wire from the ALCL plug, put it on the 'D' terminal. The other 2 red wires go to the 'A' terminal. At least according to the diagram on page 8A-21. I'll try to grab a look at my heap tomorrow afternoon to scope out what you're looking at. I'll know more hopefully tomorrow. BTW, You mentioned you replaced the relay-have you tried the old one again now that your wires are repaired? more later...

(Hey is this Allen to whom I gave the FSM CD? My memory sucks...)

[speedingaj]

I will have to double check everything. I went out today and the battery (new) was dead after a full charge... so something is certainly wrong somewhere.

Also I think...C is supposed to have power when the key is on, and it didn't...I think. I'll reset it again Saturday after charging the battery.

And yes I have tried the old relay again...still didn't work.

Yes i can e-mail them.

[SQUIRMIN VERMIN 84]

I will have to double check everything. I went out today and the battery (new) was dead after a full charge... so something is certainly wrong somewhere.

Also I think...C is supposed to have power when the key is on, and it didn't...I think. I'll reset it again Saturday after charging the battery.

And yes I have tried the old relay again...still didn't work.

Yes i can e-mail them.

"C" will be powered by the ECM only after the ECM sees distributor pulses. Initial power to the fuel pump comes through the oil pressure switch with cranking speed oil pressure(about 5 lbs) as per the FSM.

[speedingaj]

Well....does that mean my ECU is fried? I do have continuity from D at the relay terminal to the ALCL pin G, and from the relay terminal A to the ALCL pin A. I do have like 5 volts at C with the ignition on, but I never get 12 when cranking. I have No codes, and the car runs great if I jump A and E at startup. Would the car still run if I fried the ECU? Would/could that be what is causing my battery to drain (A fried ECU)? Why does it run perfect? It doesn't even seem to be in limp along mode...it runs great. (With no relay - after I pull the jumper - I figure I can't just leave it there...it will run my fuel pump 24/7 right?) ....and I have never left the jumper there...in case you think that might be what is killing my battery.

Thanks.

[SQUIRMIN VERMIN 84]

Well....does that mean my ECU is fried? I do have continuity from D at the relay terminal to the ALCL pin G, and from the relay terminal A to the ALCL pin A. I do have like 5 volts at C with the ignition on, but I never get 12 when cranking. I have No codes, and the car runs great if I jump A and E at startup. Would the car still run if I fried the ECU? Would/could that be what is causing my battery to drain (A fried ECU)? Why does it run perfect? It doesn't even seem to be in limp along mode...it runs great. (With no relay - after I pull the jumper - I figure I can't just leave it there...it will run my fuel pump 24/7 right?) ....and I have never left the jumper there...in case you think that might be what is killing my battery.

Thanks.

Hi Allen. Bear with me. Buggered up my ankle on stairs last Wed. and am house-bound and unable to check my car to compare conditions.

Looking at page 8A-21, the fuel pump has 2 paths to receive operating battery current. Through the fuel pump relay and also through the oil pressure switch. When your car starts ONLY when you jumper FPR-E to FPR-A, you're bypassing the FP Relay contacts. That means your relay isn't being operated. Those relay contacts are normally operated when the energized coil inside the relay closes the contacts between FPR-E and FPR-A. That coil is energized when the ECM sees distributor pulses and the ECM puts voltage on ECM-18 to FPR-C which goes through the coil winding and the ground waiting on FPR-B. If the ground is not there on FPR-B, or if it isn't a good ground (lots of resistance in the connection), the coil isn't operated and the relay never makes the FPR-E to FPR-A path.

When you jumper around the relay and the car starts, the running engine's oil pressure closes or operates the oil pressure switch's contacts and you are running the 2d current path to the fuel pump. That's why the engine contues to run with the fuel pump relay and the jumper removed.

From this, (no hands or eyes-on feedback), I suspect a missing or very poor ground to FPR-B. See if you have a good (zero or near-zero ohms path from the opened ground lead at FPR-B to the ground at G-160/G161 (back of driver's cylinder head, Fig 8A-16)

As far as the 5v you mentioned at FPR-C, I can't find out what voltage should be there. The ECM may very well supply just 5v as all it does is operate a low-impedance relay coil. Did you disconnect the ECM lead from FPR-C and test that at the lead end or was it still connected to FPR-C?

The draining battery may not be related. Believe me, the CF has had a lot of posts with this complaint. Lots of places for that current to be drawn to. Do a search for that problem after this one is fixed. Always one at a time.

[SQUIRMIN VERMIN 84]

Anybody else reading this, please, feel free to chime in with anything you have to help...:yesnod:

[speedingaj]

Thanks for the post! ....I've been in hell here myself. I have not had a chance to perform the checks you mentioned...however I have a different problem at the moment. After the battery dies, and I charged it.... I discovered the Fuel Pump is now running 24/7. My oil pressure is reading incorrectly. It does not fluxuate at all anymore. ....however the oil temp seems to be very accurate. The pressure reads was low (12 to 18 - changes every time I start the car) and stays steady no matter the rpm of the engine...so I certainly have something wrong with the circuit somewhere. .....however right now...the car fires right up....I just have to pull the Fuel Pump fuse when I shut her down.

If anyone else is reading this...Why..OMG why... can' I just re-wire the Fuel Pump so it turns on with the key? ..Or even put manual switch inside the car on the dash? Has anyone done that? - And if you are an electrician living in So Cal.... lets talk...I can buy beer!

Is this a poor job of creating a crash safety? Why the hell did Chevy make this so complicated?

[SQUIRMIN VERMIN 84]

At your last post, you had the wires apart for tacing. Apparently they're back together now . Clarify for me:

1. Do you still have to jumper the relay to start it?

2. Since your pump is running 24/7 as you say, instead of pulling the fuse which kills both the relay path and the oil pressure switch path, this time just pull the relay and see if it kills it.

[speedingaj]

I no longer have to jumper the relay to start it. I don't even need the relay connected anymore. The Fuel Pump just runs....and runs. Only way to stop it is to pull the fuse. Strange... because I have not changed any of the wiring configuration.
It is raining cats and dogs out here....so I haven't been able to trace back where the power is coming from yet. Maybe this weekend. If not, I am on a 2 week break over Christmas. I'l be trying to get that fixed before the end of that break.

Also - where would you go to get new seals? Like Window and door seals? ...Also the lexan top cracked.... do you know of a good place to get it replaced? The sunroof is where I got this one from....and yeah it gets to 115 out here...but still its barely a year old and it cracked... :-(

[SQUIRMIN VERMIN 84]

I no longer have to jumper the relay to start it. I don't even need the relay connected anymore. The Fuel Pump just runs....and runs. Only way to stop it is to pull the fuse. Strange... because I have not changed any of the wiring configuration.

OK, looking at page 8A-21, the only place it's getting battery with the fuel pump relay out is through the oil pressure switch. With the fuel pump relay out and the car off, locate the oil pressure switch (diagram 8A-20), and disconnect the harness. Now try to start the car. OR..
start the car with the fuel pump relay out and then pull the harness off the oil pressure switch and see if it kills the engine.

I think the oil pressure switch is hosed. As it also is your sender for the oil pressure gauge, that might explain the weird oil pressure readings.

[speedingaj]

I haven't tried pulling the relay and the plug for the oil pressure sending unit. At this point...I am looking at putting in a switch directly to the fuel pump. Solve all my problems with one swoop.

[SQUIRMIN VERMIN 84]

I haven't tried pulling the relay and the plug for the oil pressure sending unit. At this point...I am looking at putting in a switch directly to the fuel pump. Solve all my problems with one swoop.

Without repairing the problem, it may leave you with bad readings as well as no fuel pump kill switch in the event of a crash that ruptures your fuel line while you are incapacitated and unable to turn off your manual switch....

[Frizlefrak]

I no longer have to jumper the relay to start it. I don't even need the relay connected anymore. The Fuel Pump just runs....and runs. Only way to stop it is to pull the fuse. :-(

Oil pressure switch is stuck. Energizing circuit full time. Disconnect, problem should go away. Replace oil pressure sender.

[SQUIRMIN VERMIN 84]

Well, that's 2 votes for the switch. Will this finally be over?

[Frizlefrak]

Yes Bunky....I will ship a new one to Rancho Cucamonga, and we can put it to rest. :lol:

[speedingaj]

This is a new oil pressure sending unit.

You are in Rancho? That's really close. :-)

I hope this is over soon. Ill pull the plug tomorrow and see if the fuel pump dies.

Thank you.

[speedingaj]

Yep... Once the oil Pressure Switch is disconnected there is no more power to my Fuel Pump. Damn...this was a new switch. Grrrr.

Thanks A lot Bunky and Frizzlfrak. I guess I'll have to actually get a Chevy Switch this time. Hopefully this will all be over after this.

-AJ

[SQUIRMIN VERMIN 84]

So Allen, can we get a picture of this shop-queen?:D