No fuel pump prime 89 SHO

[revhardSHO]

EDIT: READ LAST TWO POSTS FOR UPDATES

Strange problem with the new 89. I drove it back from NJ yesterday, about a 500 mile drive. It ran great all the way. I was really close to running it out of gas but I made it home without a problem.
I go to start it this morning and all I get is cranking. So, I figure I must have run it out of gas in my driveway. I put about 5 gallons in and it does the same thing, just cranks.

Fuel pump is not priming
Inertia switch is fine

Where are the fuel pump fuses located on the 89 SHO? They are not under the hood like 90-95 SHOs.

 

[Wht91+]

Strange problem with the new 89. I drove it back from NJ yesterday, about a 500 mile drive. It ran great all the way. I was really close to running it out of gas but I made it home without a problem.
I go to start it this morning and all I get is cranking. So, I figure I must have run it out of gas in my driveway. I put about 5 gallons in and it does the same thing, just cranks.

Fuel pump is not priming
Inertia switch is fine

Where are the fuel pump fuses located on the 89 SHO? They are not under the hood like 90-95 SHOs.

Check on the starter relay. there is 2 or 3 wires that go on the same terminal as the power. check to see if one of those is loose or came off. i had the same problem when i swapped motors.

 

[revhardSHO]

Still no start. The soleniod / relay is good.

Im just going down to run the codes, hopefully that will reveal my problem(s).

Any other thoughts, are there even fuses for the fuel pump system on an 89 SHO? I cant seem to find them. On 90-95 they near the firewall drivers side, big 60amp fuse.

 

[revhardSHO]

KOEO (engine off) test revealed the following codes:

21 - ECT out of self-test range

95 - Fuel pump secondary circuit failure

I would assume my problems are with the later code, but I should problably replace my ECT while im in there. Do you generally need a new fuel pump with code 95? What does it mean exactly, how can I troubleshoot this?

 

[revhardSHO]

Changed the IRCM, DIS, and put a new battery in it. Still no start. Would this be a ground problem, if so, where are the places to look. Could the soleniod be bad inside (hence no fuel pump) even though it cranks the engine over?

Edit: I just reseated the ignition but the problem occured before that, so I doubt its related.

thanks
silas

 

[revhardSHO]

More progress, still no start. I changed the Soleniod to make sure that wasnt the problem, then I grounded the motor to the chassis to make sure, still no start. I dont know where to go from here, but its gotta be something simple. Any help is appreciated.

 

[projectSHO89]

Is the fuel pump priming at all? If not, then the 95 code indicates you likely lost drive power to the pump.

Power FROM the IRCM comes out on pin 5.

Power TO the IRCM for this circuit, IIRC, comes in via a wire that is supplied by a fusible link that is just off the battery's positive terminal. Locate the small wire and find the link. The link is just a short piece of smaller guage wire that is supposed to "blow" when it fails fue to high current. They're supposed to bubble the insulation when blown, but they sometimes just open from age and vibration. The link is within 10-15" of the battery.

I did an extensive writeup for the 89's FP circuit a few years back, but it got lost in the forum software that took place a couple of years ago. I guess I'll need to dig up the EVTM and re-do it.

Steve

 

[revhardSHO]

No the pump is not priming at all.

The IRCM is getting power (and came out of a running SHO, same rev code). I shorted the fuel pump circuit with the ECC connector and the relays clicked, so the IRCM is working. What is past the IRCM that would be causing the pump not to get power? Any fuseable links AFTER the IRCM? Is this most likley a ground issue? Thanks for the help so far.

http://www.shoforum.com/showthread.php?t=51310&highlight=Code+fuel+pump+circuit+open
This is a good thread, seems like he is having a similar issue but I know my IRCM (I am assuming its the same as CCRM) is good, and getting power. damnit!

EDIT:

If no voltage was measured at pin 5 earlier, ground and remove the jumper from the FP test pin several times while listening for any clicking from the relay module. If clicking is heard, either the relay module is defective or there is a wiring harness fault in the supply circuit to pin 12.

If no clicking is heard, check the 60A fuse "COOLING FAN" in the engine compartment fuse box.

In regards the above quote: I havent tested power at pin 5, but I do hear a clicking noise when do the FP self test. Maybe I am confused (lol) but it seems like this means I have a wiring harness fault in the supply circuit to pin 12. Any insight steve?

Silas

 

[revhardSHO]

As far as I can tell, all the fuseable links look good. This includes the one running off the positive terminal, and the ones over by the soleniod.

 

[revhardSHO]

I am not making progress. I have ruled out the DIS, IRCM, fuseable links, battery, engine ground wiring, soleniod, etc.

The car sat for about a year before I made the 500 mile journey home yesterday. Is it possible that the pump just died on me in the driveway last night? It sounded fine on the way home. I dont know, I am at a total loss.

 

[Aaron R.]

With a buddy try banging on the bottom of the gas tank while tuning the key on and off, see if you can hear it prime. also I am not qite sure wich pins they are but on the diagnosic connector, if you cross two of the pins you can make the fuel pump run all the time.
try that and see what you come up with,
aaron

 

[projectSHO89]

Just because you hear the click of the relay in the IRCM doesn't mean it's working. It only means the relay is being eniergized. You still have to make certain it is receiving the input supply and that, when energized, is connecting the load to the supply.

Check supply, IRCM pin 8 (YEL). This is the FP supply via fuse link M.

With FP relay energized, check IRCM pin 5 (PK/BK).

Keep in mind, that the 89 (only) used both the low and high speed FP drive circuits. The low speed relay uses that large resistor at the top center of the firewall as its dropping resistor. If it is unplugged or is open, the low speed circuit will be open.

Check these points with your meter and quit swapping parts.

Steve

 

[revhardSHO]

The low speed resistor checked out fine.

I jumpered the fuel pump circuit and took some readings:
Pin 5 read ~12 v
Pin 8 read ~1 (one) v <----- Is this a problem?
Pin 12 read ~12 v

Where should I go from here?

Can I hotwire the wires to the inertia switch to see if I can get the pump to prime with direct 12v? I just want to test the pump to make sure its working.

 

[projectSHO89]

Hmm..

Pin 8 should be hot at all times via fuse link J. This supplies HS FP relay. The fan dropping resistor is tied to this same supply. The load side of the resistor is connected to pin 10 as the supply for the LS relay. The outputs of both relays are tied together internally to the IRCM and feed out via pin 5.

Pin 18 is the LS relay drive signal, active ground. This is the FP pin on the EEC test connector. Also goes to ECA pin 22.

Pin 11 is the HS relay drive signal, also active ground from ECA pin 41.

For you to have 12v at pin 5 but nothing on pin 8 is not logical. Can't have an output voltage without an input....

Can I hotwire the wires to the inertia switch to see if I can get the pump to prime with direct 12v? I just want to test the pump to make sure its working.

Yes, if you're comfortable doing so.


Steve

 

[revhardSHO]

The little wire that runs off the positive battery terminal is connected to pin 5, as tested with the voltmeter. There is no power to pin 8 unless you run a direct line from the positive terminal. I did that and the car seemed to fire over for a second and then just cranked again.

I also found a stored code in the memory (along with code 95):

'89: NPS circuit open; A/C input high... is this related?

 

[projectSHO89]

"89" is a bogus code on an 89 SHO. It's only valid on automatics.

Need to fix the pin 8 circuit. It's the one that supplies your fuel pump.

Steve

 

[tominos]

is there power in and out of the intertia switch? test w/ multimeter. my car died, turned out the fuel pump connector harness at the pump came loose. plugged it back in and came back to life.

check this thread out, might help you.
http://www.shoforum.com/showthread.php?t=60521

 

[revhardSHO]

Thanks for the link, good info.

Okay here is the scoop (if you dont want to read above)

1) 500 mile drive car ran perfect, sits overnight, no fuel pump prime next day.
2) Code 95 is thrown - Fuel pump secondary circuit failure ( ambiguous code - not very specific)
3) No power to inertia switch
4) IRCM clicks when fuel pump circuit is jumpered
5) Pin 5 is ~12 v
Pin 8 is open (no voltage)

I did the IRCM pinot with a voltmeter (with the fuel pump circuit jumpered). Here are the results:
Pin 1: ~12v
Pin 2: no voltage
Pin 3: ~12v
Pin 5: ~12v
Pin 8: no voltage <------ Troubleshooting help?
Pin 9: no voltage
Pin 10: no / v
Pin 11: ~12v
Pin 12: ~12v

Bottom Row:
Pin 13: ~ 4v
Pin 14: no /v
Pin 15: no /v
Pin 16: no/v
Pin 19: 4v
Pin 21: no /v
Pin 22: no /v
Pin 23: no /v
Pin 24: no /v

I then tested it over again with just the ignition on (FP circuit NOT jumpered)
Only difference was Pin 19 showed no volts where as before it showed ~4 v.

I need direction. I assume that I should start with pin 8. Where is fuse link J? I cannot find its location in a search.
Would bad 02s short out the fuel pump circuit for some reason? How about the AIB valve?

Any help is greatly appreciated.

silas

 

[revhardSHO]

For reference, I have made a little diagram to show the pinout readings (I was not able to find a decent templete with a seach):

Pin#.....Circuit#.....Wire color code.....What it controls

Pin 1 - Cir 38 - BK/O - 12 volt battery supply
Pin 2 - Cir 38 - BK/O - 12 Volt battery supply
Pin 3 - Cir 181 - BR/O - Cooling fan motor feed
Pin 4 - Cir 181 - BR/O - Cooling fan motor feed
Pin 5 - Cir 787 - PK/BK - Fuel pump safety switch to fuel pump
Pin 6 - not used
Pin 7 - not used
Pin 8 - Cir 37 - Y - Battery to load
Pin 9 - not used
Pin 10 - Cir 922 - W/R - Fan dropping resisitor
Pin 11 - Cir 926 - LB/O - EEC module
Pin 12 - Cir 38 - BK/O - 12 volt power supply
Pin 13 - Cir 16 - R/LG - Ignition switch to ignition coil "battery" terminal
Pin 14 - cir 197 - T/O - Coolant temperature switch to control relay
Pin 15 - cir 57 - BK - Ground
Pin 16 - Cir 57 - BK - Ground
Pin 17 - not used
Pin 18 - Cir 97 - T/LG - Feedback carburetor control (really?)
Pin 19 - not used
Pin 20 - not used
Pin 21 - Cir 883 - PK/LB - A/C control relay
Pin 22 - Cir 331 - PK/Y - WOT cutout relay
Pin 23 - Cir 347 - BK/Y - Compressor clutch feed
Pin 24 - Cir 361 - R - Pwer relays to EEC module

Pinout order:

Top
1.....2...3....4...5....6....7...8...9...10..11..1 2

13..14..15..16..17..18..19..20..21..22..23..24
Bottom

 

[revhardSHO]

nobody?