Wierd problem in 88 GT

Hammer · 08-25-2002, 10:08 PM

Never seen this before, but maybe you guys have...

Turn on the ignition, all the self-test dash lights come on as normal... wait 5 to 7 seconds, the power resets (flickers out) for about a quarter to half a second and comes back on. Start the car, it'll fire up fine, but about 3 seconds later it'll die as my dash warning lights flicker. Fire it up again... same thing. I can keep it going through the "hiccup" by keeping the throttle down a bit. Funny thing is, once it's going for about 60 seconds.... it runs without a problem.
Get to the store, buy your groceries, get back in the car... same problem.

the exterior\interior\backlit dash lights are not effected. From what I can tell maybe its something with the computer since the instrument warning lights as well as the ignition seem to be affected? A common ground somewhere?

Thanks for any help you can give...

Old Guy with 87 GT · 08-26-2002, 05:29 AM

sounds like it could be a problem with the fuel pump or the pip signal that activates fuel pump at start up

when you turn on the key the fuel pump comes on for a couple of seconds ....but it won't come on after that till the ecu recieves a signal from the pip sencor (telling it the engine is turning over)

could be a short ,could be a problem with the voltage regulator interfering with the ecu on start up ,could be problem with the fuel pump relay, could be a pip signal problem ,could be a problem with the ecu harness or the ignition switch

get a volt meter and do some investagating in that area(fuel pump relay) check and see when and if fuel pump is coming on ,then check to see how many amps the fuel pump is drawing .......sounds like it could be a pain in the butte problem ,just a matter of eliminating things one by one that can caus problems

hope i helped

PKRWUD · 08-26-2002, 10:29 AM

I think he's on the right track, but I suspect the O2 sensor is shorting to ground. This can cause the ECM to jump into self test mode after start up, and kill the pip signal. It would likely be in the wiring connectors, rather than a bare spot in the wires. F-150's, for example, have a harness connector to the O2 sensors below the battery, and it is common for it to corrode over time due to overflow expelled from a hot battery, and create the problem you described. Check your codes, and look for a code 18.

Take care,
~Chris

95mustanggt · 08-26-2002, 10:31 AM

Can you check the codes on that car? That's where I would start. Narrow your search a little bit.

Electrical problems can be a real b-i-t-c-h to solve with out the error codes (although sometimes they don't even help).

95mustanggt · 08-26-2002, 10:34 AM

Dam that PKRWUD guy is fast...

Hammer · 08-26-2002, 09:21 PM

Thanks folks,
I'll start messing with it this weekend...

08-25-2002, 10:08 PM	#1
Hammer AKA "Dr. Evil" Join Date: Feb 1999 Location: South Fork Ranch Posts: 1,721	Wierd problem in 88 GT Never seen this before, but maybe you guys have... Turn on the ignition, all the self-test dash lights come on as normal... wait 5 to 7 seconds, the power resets (flickers out) for about a quarter to half a second and comes back on. Start the car, it'll fire up fine, but about 3 seconds later it'll die as my dash warning lights flicker. Fire it up again... same thing. I can keep it going through the "hiccup" by keeping the throttle down a bit. Funny thing is, once it's going for about 60 seconds.... it runs without a problem. Get to the store, buy your groceries, get back in the car... same problem. the exterior\interior\backlit dash lights are not effected. From what I can tell maybe its something with the computer since the instrument warning lights as well as the ignition seem to be affected? A common ground somewhere? Thanks for any help you can give... __________________ Uncle Sam "What the hell is up with all the gauges? Calling Captain Kirk, your ride awaits... Phasers on stun...."

08-26-2002, 05:29 AM	#2
Old Guy with 87 GT Registered Member Join Date: May 2001 Location: Harrisburg, Pennsylvania Posts: 379	sounds like it could be a problem with the fuel pump or the pip signal that activates fuel pump at start up when you turn on the key the fuel pump comes on for a couple of seconds ....but it won't come on after that till the ecu recieves a signal from the pip sencor (telling it the engine is turning over) could be a short ,could be a problem with the voltage regulator interfering with the ecu on start up ,could be problem with the fuel pump relay, could be a pip signal problem ,could be a problem with the ecu harness or the ignition switch get a volt meter and do some investagating in that area(fuel pump relay) check and see when and if fuel pump is coming on ,then check to see how many amps the fuel pump is drawing .......sounds like it could be a pain in the butte problem ,just a matter of eliminating things one by one that can caus problems hope i helped __________________ the "not so old",old guy 87 Mustang GT T-top >hanlon t-5, pro 5.0, centerforce clutch ,adj. cable/quatrant ,3.27s ,full 2 1/2 ex(off road H) adj. reg. ,e-cam ,70mm TB, cobra intake ,1.7rr ,ported/milled e7ets w/crane springs ,306 balaced/decked short block w/speed pro forged flat top pistons ...257rwhp/302rwt best et 13.7@102 (4/11 ) '80 Capri (future project,currently collecting parts for 351 moter)

08-26-2002, 10:29 AM	#3
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	I think he's on the right track, but I suspect the O2 sensor is shorting to ground. This can cause the ECM to jump into self test mode after start up, and kill the pip signal. It would likely be in the wiring connectors, rather than a bare spot in the wires. F-150's, for example, have a harness connector to the O2 sensors below the battery, and it is common for it to corrode over time due to overflow expelled from a hot battery, and create the problem you described. Check your codes, and look for a code 18. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

08-26-2002, 10:31 AM	#4
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Can you check the codes on that car? That's where I would start. Narrow your search a little bit. Electrical problems can be a real b-i-t-c-h to solve with out the error codes (although sometimes they don't even help). __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

08-26-2002, 10:34 AM	#5
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Dam that PKRWUD guy is fast... __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

08-26-2002, 09:21 PM	#6
Hammer AKA "Dr. Evil" Join Date: Feb 1999 Location: South Fork Ranch Posts: 1,721	Thanks folks, I'll start messing with it this weekend... __________________ Uncle Sam "What the hell is up with all the gauges? Calling Captain Kirk, your ride awaits... Phasers on stun...."

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