I have an '87 Firebird Trans AM with a 305 TPI engine code "F" Standard Transmission.

i have been having some problems with the wiring on the 3 relays under the hood(Fuel pump, MAF pwr, and Burn off) well FINALLY i have got them wired up correctly as in the diagram Vader posted in this thread:

https://www.thirdgen.org/techbb2/sho...ight=fuel+pump

The thing is now there is a constant draw on my battery and it is draining it. The draw stops when i disconnect the MAF power relay.

Could it be the relay is fried and it is stuck closed?

any help would be GREATLY apperciated,

Thanks,

Skunkmang

 

Are you using the stock wiring colors? I could look at my 88 and tell you how the wires are run on it. This is the burn off relay right? Should energize for just a moment after engine shut down.

 

yes i am still using the stock wires, if i disconnect the relays (the MAF pwr and/or the burn off) there is a brief draw that sounds like it is coming from the headlight relay... and then nothing.

Plug them back in and power draw. i am testing this with a test light to i should add, i disconnect the positive teminal and complete the circuit with the test light.

 

Skunk,

Put the test lamp back in your toolbox and save it for diagnosing trailer harness connections. Go get at least a cheapo voltmeter (about $8 at Harbor Freight) and get actual voltage readings from the harness. Fro $9, you might even get one with a resistance scale or two, which could be even more useful. Go ahead, you're not going to hurt anything.

You should be able to use this to diagnose the wiring colors and connections:

 

i have a multi-meter, i just didn't have it with me at the time. I have it all wired up the way it show in that diagram, it actually seems to be running worse (VERY rough idle, and i can smell raw fuel very strongly). Can anyone tell me how to test the relays?

 

Use that same diagram, and test the wires on the relay connectors and the MAF connector to make sure the power is at the correct points.

What you are describing sounds like a sticking MAF burn off relay or very corroded MAF power relay or relay socket. If you read much more than a volt at the 'C' terminal of the MAF with the engine idling, you may have voltage at the 'D' terminal of the MAF when it shouldn't be there (it should never be there while the engine is running).

 

Ok, so i tested the points at the relays and the MAF, the relays have the correct power at the correct places. i tested the MAF sensor as well i am reading 5.05v at the 'C' terminal, at the 'D' terminal i am getting the same full voltage i am getting at 'E'.

I pulled the 3 relays off and started testing them for continuity between 'A' - 'D' and 'A' - 'E', all three checked out. So then i tested for resistance between 'B' - 'C' (this is where it gets interesting) one of them gave me between 62 - 64 ohms, another gave me 56 - 58 ohms, and the last one was 683 ohms.... yes it is right i tested it with my voltmeter set to the 2K setting and it read 683.05...

Well i figured this was the problematic relay and when i set it down, water came pooring out

I have to get a new relay to see if it fixes it/do more testing, but my problem now is that i do not know which relay is which... i thought they were all the same untill i tested for resistance and they are a little mixed up from 2 months of playing with them.

So here is what i know about them:

Relay 1:
62-64ohms resistance from 'B' - 'C'
Printed number on it - 10094701
Stamped number on it - 6211

Relay 2:
56-58ohms resistance from 'B' - 'C'
No printed number on it
Stamped number on it - 7112

Relay 3:
testing at 683ohms resistance from 'B' - 'C'
Printed number on it - 14078907
Stamped number on it - 7005

Any help or point in the right direction with this would be MOST appreciated, and i want to thank you for your time helping me in this as well Vader.

Thanks,

Skunk

 

can anyone tell me? or am i going to have to go talk with the *******s they've got over at my local dealership?

 

The resistances you measured for the relay coils appears correct (except for the "683 ohm" unit). The relays should all be interchangable. They are all 12VDC operating coils and have the same contact arrangement, even if all the contacts are not used in a aparticular application or circuit.

I am also curious about the resistances between the A, D, and E terminals, or the relay contacts themselves. Pitting, corrosion, and carbon from arcing can become conductive and create a current path on N.O. even if the relay coils are not energized, or allow a current path when N.C. contacts are supposed to be open. The "water-cooled" relay is certainly a prime example.

The relay sockets and wiring can also suffer from corrosion and allow the same phenomena. Get a new FP relay and pop it in wherever necessary. More parts stores are likely to list an FP relay than a MAF power or burnoff relay, even though they should be the same P.N. An FP relay will have an adequate current rating for any of the circuits.

You might want to open the other two relays and check their internal condition.

 

From what i can remember, the contiuities were correct (being A - D had connection and A - E did not)

The resistance between A - D on all 3 relays was low (i think it was .3 - .5 on the 200 setting) and there was no data displayed from A - E when tested.

All pins look clean and non-damaged Relay-side, and i replaced the 10 of them on the connector side of the MAF and FP recently (i guess i should do the burn off as well).

I will double check this on Wednsday when i return to work (where my car is) but right now i have to go get 2 root canals done, YAY!!!

I will let you know wednsday.


Thanks, Skunk

 

WELL!... i tested them... and i was right, one was .5ohms and one was .3ohms i did not test the third one that water was in... neither had any reading between A and E.

Just for the hell of it i decided to shake the other two to see what i would hear... can you imagine what i heard???

Yep one was full of water and the other had stuff rattling in it. i popped the one with water in it open and it was in worse condition than the first one... rusted all over on the inside and quite in operable.

The third was even WORSE!! it was not only rusted but the rust had turned black and the little switch that moves inside of it was rusted solid to the D terminal.

I guess this is what happens when a car sits for quite some time (and the relays are not bolted to the fire wall). so a little note to any one out there that doesn't have the screwed to the fire wall... PUT THEM ON THERE ASAP!

Needless to say i am going to replace all 3 relays and then see how it goes from there.

report back soon and let you know how it goes...

 

Well that was it, i replaced the three relays today and it is running fine, no SES light no stalling no jumping idle... it is still running a little rough but i imagine that is from sitting so long.

Thanks again Vader for the help, it is much appreciated. now i am just have to get it through e-test...

 

found this online hope it helps

10094701 is the maf sensor burn off relay, this should power up for a few seconds after you turn your engine off.

14078907 is your fuel pump relay

The third one is the maf power relay the oem number is 10067925, sounds like somebody replaced it at some time.

 

Hey I got a 87 Trans Am 5.7L V8 TPI and when I disconnect my MAF Sensor my car runs great. if I have it plugged in the car bogs/misfires during acceleration. I replaced the MAF sensor itself, and checked/replaced the 3 relays ( MAF power, burnoff, and fuel pump). checked connectors and get 12V on oranges, 5V signal on C of MAF sensor, 12V on red while engine running, and my black/whites read good to ground with ignition off, but with ign on or running they read 350 ohms. is this wierd or normal? my pump 2 sec primes no matter what relay I put it in. I do have a fuel pressue issue it reads 31 PSI always but I flow tested the pump and it put out 3/4 a quart in 15 sec. also my burn off circuit works. just a bad ground? or could tripping the MAF code by disc it make the car run good with bad fuel psi?!??

 

I bought a 1988 with a 305 TBI at auction, and the previous owner bypassed the relay closest to the driver's side fender on the firewall with a toggle on the dash. The relay is a 8120 over 14089936, five pin, but I have no idea what it controls. There are two relays beside each other, and this one is unplugged, with a jumper shoved into the plug, and a ground wire spliced into the harness through the toggle. Engine runs whether the toglle is on or off, so I guess it is not a fuel pump relay. Also there are two burned wires hanging loose behind the TBI, not sure if they are related.

 

That used to be the cooling fan relay, the switch on the dash probably turns the fan on and off manually.

Not sure on the other 2 wires, but I'm guessing it is the intake air temp (iat)sensor. It's located under the air cleaner.

Is the check engine light on at all?

 

Sorry for slowresponse, working night shifts. I have only driven it twice, and check engine light came on after a while, but reset when engine was restarted. Noticed pressure on gas cap, and replaced that thinking that could be a problem. Temperature gauge has been replaced with a manual dial mounted on dash, and there is a plug laying loose near the t-stat housing (no sensor on current housing) so there may have been a problem with the sender, so you are probably right about the fan switch. Would it cause a problem to put a relay so that the fans runs whenever the ignition is on?
As to the other two wires, what does the IAT look like?

 

The 2 wires by the tstat housing have nothing to do with the temp guage, or the fan, those are for the coolant temp sensor, without it your ecm has no way of knowing the coolant temp, you should think about replacing that.


The temp guage is controlled by a sender in the drivers side head between the first to spark plugs.


The cooling fan is called on by a switch in the passenger side head between the last two spark plugs, it is not controlled by the ecm. If the toggle switch on the dash was wired right you should be able to turn the fan on and off with that, assuming thats why it's there.


The iat sensor is located on the bottom of the air cleaner housing.


All this is how my '89 shipped from the factory, the '88 may have been different, but I don't think so.

 

The previous owner replaced the air filter with a chrome one. Just got an original off Ebay. The car had been wrecked on the front, and that may have damaged the fans, and they just jury-rigged the switch. I would like to put everything back original, but need the diagrams/schematics, since parts are missing. It's worth fixing right, because the engine sounds great, and the trans. seems in good shape.

 

http://austinthirdgen.org/mkportal/m...ine_wiring.gif

go here.