Hi everyone, im new to the forum, and need help with my GT

I have a 86GT 6cyl. When I drive my GT, and then park it, it will not restart untill it has cooled off for about 5 hrs or longer. Sometimes I can hear the fuel pump relay kick in and other times not. When I dont hear it it will not start. I jump it at the ALDL and it will start the pump most of the time, and the car will start. Sometimes even jumping the connection the pump still will not kick in and the care still will not start. I checked the fuel pressure when it does run and it was 44-45psi. When it runs it runs great and never stumbles or hesitates, but if I turn it off im stranded.

I dont know what to try next (im not a mechanic) but I have to do the work myself.

No codes generated except 12

I appreciate any help anyone can offer me.

If I didnt love my GT so much I would shoot it ")

Thanks

Parts I have replaced this week.

Cap, rotor
Coil MSD
Fuel Pump Relay
Oil Sending Unit

hello, IT more than likely is the pickup coil and/or Module. If you replace them go to GM and get them. They might be a hair more but worth the money. I got a module at autozone and the second one now is F'n up with in two weeks. Dave.

when it dont start, does it crank, and not fire, or does the starter not turn?
if it cranks, and dont start, you have leaky injectors
if the starter wont turn, you need a new (battery/battery cables/starter)

Still having problems restarting.

Ok I replaced the Ignition module today. I drove the car for about ten miles, pulled back into my garage turned it off and it would not restart. The starter is fine it cranks over lots of cranking power. I have spark. (OUCH)

When I turn the key I do not hear the pump or relay.
I can still hear the fuel pump relay click when I jump it at the diagnostic terminal, but the fuel pump does not kick in.

Since I cannot hear the fuel pump run when I jump it at the diagnostic link, does this mean the pump is bad?

After it cools down for several hours it will restart fine.

To date I have replaced the following

Cap, rotor
Coil MSD
Fuel Pump Relay
Oil Sending Unit
Ignition Module

Thanks 88formttp and Pyrthian for your input appreciate it.

What do I try next?

quote Originally posted by Sean GT: Since I cannot hear the fuel pump run when I jump it at the diagnostic link, does this mean the pump is bad?

try letting the pump run with the jumper connected to it for 15 minutes or so.
unplug your jumper and then try to jump it again.

i've never heard of a pump getting hot, but what the hell

I had a problem much like yours. After the car got hot it wouldn't restart when I shut it off. After a couple of hours it would start right up. Then, on a really hot day, it died on me and wouldn't restart. Next day it was fine. I tried replacing a lot of components without success. Here's what it was: hot air from the radiator flows underneath the car and heats the gas tank. The fuel pump would fail when hot. It took a long time to heat up all of that cold gas, but once it was warm it also took a long time to cool off. To check whether this is the problem check the fuel pressure once the car has stopped and won't restart.

Good luck,

Eric Johnson
Greene, NY

Hi Eric

What you have described is just what mine is doing.
I checked the fuel pressure after it wouldnt start and there is no pressure.
The pump wont even run jumped or wont start even when the oil pressure builds up.

What did you do to solve the problem?

I dont know how old the fuel pump is that is in it.

Well just tried to restart it this morning and it wont start. @#$&&&&%@@ Its always started before after cool down. (it cooled over night)
The pump is not running. Tried jumping the pump, it still didnt kick in.

This is my only car, so I have to figure this out.

Thanks

quote Originally posted by Sean GT: I checked the fuel pressure after it wouldnt start and there is no pressure. The pump wont even run jumped or wont start even when the oil pressure builds up.

Sean....I'm leaning toward your pump being bad, but first let's check a couple of things.

First, Check the electrical connection to the pump. There is a harness between the engine and the firewall that services the fuel pump and sending unit. Check it to see if maybe you have an intermittent connection that heat is aggravating. Remember, heat builds electrical resistance.....if your connection is flaky to begin with, heat will augment the problem. Also, is the heat shield in place between the catalytic converter and the fuel tank? Peek under the car and you should be able to see it.

No fuel pressure can only be caused by a few things.....

1. Fuel pump is good, but isn't running. Usually an electrical gremlin....ie fuse, relay, harness, or connector. Since you've jumped it at the ALDL, we can rule out everything but the harness and the wiring inside the tank.

2. Fuel pump is bad, or going bad. Again, heat causes resistance. If the pump is on the way out, it could run when cold, but cease when it heats up. Problem will get worse until it's terminal.....which is what I'm leaning toward on yours.

3. Regulator is bad, allowing pressurized fuel to return unrestricted to the tank. Pinch off the return line with a pair of vice grips and check fuel pressure. If it suddenly rises, reg is bad.

4. Restriction is pressure line...fuel filter, clogged screen around fuel pump, other obstruction in pressure line. Easy to check.

5. BADLY leaking injector(s). Unlikely they're leaking badly enough to cause no pressure, or you would have a massively rich condition when it is running, and associated DTC's stored in the ECM.

That pretty much sums up a no pressure problem. Now, that said, I'm a big believer in diagnosing a problem instead of throwing parts (read: money) at the problem hoping it will go away. We know it's fuel related, so start with the easy (free) stuff first. Check the regulator by pinching off the return line, check the harness at the firewall (for continuity and voltage....is it getting 12 volts when your pump refuses to run?)....is it solid voltage, or intermittent?

Now, since you can't hear the pump running and have 0 pressure, try this; Run a constant 12 volts to the fuel pump terminal on the ALDL and check for voltage at the harness. If you have a solid 12 volts, but the pump won't run, your problem is south of the harness....ie the pump or associated wiring. At this point, you will have to drop the tank.

Once it's down, hook your multi tester to the harness and pump and check for continuity. If you have good continuity to the pump, the pump is bad. $65 at Pep Girls for a Carter pump, Made in USA.

I just finished replacing a fuel pump yesterday on my 86 GT. Not a particularly hard job, but time consuming....have to wire a new connectors at the pump (pay close attention to the polarity).

Good luck and keep us posted. Hope this helps.

On my 88GT the fuel pump failed this way. Driving down the road and I could hear the fuel pump slow down and die. Let it sit for a few minutes and then it would restart and run for a bit and do it again. I've had starter motor like this too.

I replaced the fuel pup and the car starts fine now.

I'd bet long odds that your problem is the fuel pump going out.

Sean... bad news. You have to replace your fuel pump. Mine would start after a long cool-down period but that didn't go on for very long. Eventually it was just plain dead. Always. You'll have to drop the gas tank and replace the unit. Not too hard to do. While you're at it replace the straps with stainless. Check the fiero store. http://www.secureleadercom.com/fsstore/default.asp?goto=frontpage.asp Pump and strainer will cost you $86 and a pair of straps are $40.

Eric
Greene, NY

Had the same problem a couple of yrs ago. Oddly enough, it would start and continue to run if I shot a little gas into the throttle body opening--even if the engine was hot (warmed up) I did several things that seemed to help--for awhile, but after doing a fuel pressure test I found I only had 6 psi-with the return line squeezed off. New pump fixed it.

Thanks for all the input,

It looks like its fuel pump time.

I bought a Carter Fuel Pump. I hope this wont be a problem to put in.
I have to round up some jack stands and get started. Looks like I have a weekend project.

Im sure I will have more questions after I get started.

Will keep you up dated

Thanks again everyone

Sean

http://www.mtsu.edu/~mkr2c/fuelpump.htm

quote Originally posted by Sean GT: Thanks for all the input, It looks like its fuel pump time. I bought a Carter Fuel Pump. I hope this wont be a problem to put in.

Sean...I just finished mine last week. The only "problem" I really had was that the Carter pump has a different wiring setup than the original. It comes with a new harness kit, which isn't difficult to install, just watch your polarity. It wouldn't hurt to draw a diagram of how it's wired prior to unwiring it just so you make sure it's wired correctly.

Dropping the tank isn't difficult, the hardest part to me was removing the filler hose. I used a tranny jack to support the tank and did it without a helper. One thing that makes hose removal (and reinstallation) easier is to support the tank with a jack, undo the straps and lower it about 2". Gives you a little more clearance.

Also, the pressure line has two clamps and the return line one. Make sure you reinstall both on the pressure side.

Have fun!

Well got my fuel tank out, It wasnt all that difficult but not fun LOL.

The fuel line split while I was trying to get it off so I have to go find some fuel line this morning
Im still trying to figure out the wiring for the carter fuel pump.

well off to the parts store.

Frizlefrak I sent you PM

quote Originally posted by Sean GT: Well got my fuel tank out, It wasnt all that difficult but not fun LOL. The fuel line split while I was trying to get it off so I have to go find some fuel line this morning Im still trying to figure out the wiring for the carter fuel pump. well off to the parts store. Frizlefrak I sent you PM

Sean....you have a PM

I would take the carter back and get a ac-delco pump. Aftermarket pumps have a much higher failure rate and most tend to run lauder than the ac-delco units. Plus, you won't have to mess with the wires if you get the correct delco pump. No you don't have to replace the pulsater, but I would change the filter sock.

There are just some parts on a stock fiero that you should keep stock. Fuel pumps, ignition modules are two on a long list that should be kept gm or ac-delco.

[This message has been edited by RossT (edited 07-10-2005).]