HappyAndy
HappyAndy Dork
8/28/12 10:22 p.m.

One of my neighbors seems to have been ripped off by a local garage that claimed to have replaced a bad fuel pump on his 89 T/A GTA. It still doesn't start due to low/ no fuel pressure. The shop claimed to have replaced the fuel pump, but I crawled undeneeth and saw no signs of the exhaust pipes or the fuel tank heat shield having been touched. Is it possible to replace the pump on these with out dropping the tank? I pulled up the carpet from behind the rear seats and saw no signs of an access hatch.

Also the plug for the fuel pump relay is half melted. The relay is still working, but in my opinion the relay and its socket need to be replaced. Does anyone know where I could find a replacement socket?

Lastly, does anyone have a good wiring diagram that they could share? All I have to go on is a schematic from a haynes manual, which is weak to put it politely.

Thanks in advance for the help.

.

Gearheadotaku
Gearheadotaku SuperDork
8/29/12 7:11 a.m.

Yeah, don't ever go back to that place. Try to find a factory manual, some libraries have a surprising selection.

81cpcamaro
81cpcamaro Reader
8/29/12 7:58 a.m.

Definitely have him go somewhere else. The pump can be changed by cutting an access hole in the floor, check thirdgen.org for more. If they had dropped the tank, you should see the evidence on the exhaust, fuel tank straps and at least the shocks as the rear axle needs to be lowered for the tank to come out. Rockauto sells the relay connectors under electrical connectors section. GM dealers should also have them.

Aeromoto
Aeromoto HalfDork
8/29/12 9:08 a.m.

Please do not hack a hole in the floor. To remove a 3rd gen tank you must get the rear of the car as high as safely possible on jack stands, drop the exhaust, remove the panhard bar and lateral brace, and heat shield. Then you remove the lower shock bolts and lower the rear end but be careful not to stretch the brake hose. You must also remove the fuel filler sleeve behind the fuel door. You can then remove the tank straps and lower the tank passenger side first and pul;l it down and sideways. It can take a bit of finesse to get the filler tube to come out without snagging.

If you say that the relay is working and voltage is leaving the relay on the 87 terminal, other than the melted connector, there can't be much else. As far as finding a new connector, the relay connectors are the same on the TPI and TBI V8 cars, as well as the MPFI V6 cars, so a quick trip to the u-pull-it should take care of that. When you get the tank lowered, remove the elec connector and test voltage there as well before buying a new pump.

When you say it has low fuel pressure, what exactly is the fuel pressure? (did anyone put a guage on it?) A real GTA is going to be a TPI, and a TPI usually around 35-43 psi at idle as measured as the shrader valve

hrdlydangerous
hrdlydangerous Reader
8/29/12 11:29 a.m.

The melted connector may be the result of bad pump that is drawing too many amps.

Knurled
Knurled SuperDork
8/29/12 12:31 p.m.
Aeromoto wrote: To remove a 3rd gen tank you must get the rear of the car as high as safely possible on jack stands, drop the exhaust, remove the panhard bar and lateral brace, and heat shield. Then you remove the lower shock bolts and lower the rear end but be careful not to stretch the brake hose. You must also remove the fuel filler sleeve behind the fuel door. You can then remove the tank straps and lower the tank passenger side first and pul;l it down and sideways. It can take a bit of finesse to get the filler tube to come out without snagging.

Having done a couple 3rd-gen tanks: You make it sound a lot easier than it really is.

There's some points where it appears to be geometrically impossible.

The LAST one i did, I didn't bother to pull the tank all the way out, just pulled it down enough to snake the sending unit/pump out. Even that still required dropping the axle and whatnot.

I disconnect the brake hose for more drop-room.

Aeromoto
Aeromoto HalfDork
8/29/12 12:37 p.m.
Knurled wrote:
Aeromoto wrote: To remove a 3rd gen tank you must get the rear of the car as high as safely possible on jack stands, drop the exhaust, remove the panhard bar and lateral brace, and heat shield. Then you remove the lower shock bolts and lower the rear end but be careful not to stretch the brake hose. You must also remove the fuel filler sleeve behind the fuel door. You can then remove the tank straps and lower the tank passenger side first and pul;l it down and sideways. It can take a bit of finesse to get the filler tube to come out without snagging.
Having done a couple 3rd-gen tanks: You make it sound a lot easier than it really is. There's some points where it appears to be geometrically impossible. The LAST one i did, I didn't bother to pull the tank all the way out, just pulled it down enough to snake the sending unit/pump out. Even that still required dropping the axle and whatnot. I disconnect the brake hose for more drop-room.

Before you completely drop the tank, you have to rotate it into a small and hard to find sweet spot, and it will drop right out. I'll admit that sweet spot is hard to find until you've done about a dozen of them

Quasimo1
Quasimo1 New Reader
8/29/12 1:41 p.m.

As other have said the only way to change a fuel pump on a 3rd gen is to drop the tank or cut a hole in the floor. Dropping the tank is a PITA and will take some time. Having a helper will make the whole process easier.

Gearheadotaku
Gearheadotaku SuperDork
8/29/12 1:51 p.m.

...and make sure to empty the tank first

HappyAndy
HappyAndy Dork
8/29/12 3:06 p.m.

Update: NAPA has a replacement socket for the relay. As for the fuel system pressure test, it was done ghetto style, with a screw driver ,just a dribble of fuel after 20 seconds or so of cranking. Lights up every time on carb cleaner spray.

BTW, where is the pump motor grounded?

BoostedBrian
BoostedBrian Dork
8/29/12 5:26 p.m.

It grounds to the body just above the axle, I think.

I tried the "cut a damn hole!" method, but my fuel pump sender didn't have short little hard lines, they were about 2 feet long and went over to the corner of the tank, so there was no way it was coming out from the top. Unfortunately I had already cut the hole.

We wound up loosening the track bars, cutting off the exhaust (it's still cut off) and knocking loose the fuel pump ring, holding the tank by the hole and with dad's help lowered it onto the ground. I did a little bit of both methods. I wound up not having to lower the axle, and I caulked the piece I cut out back in. We used a drill bit to start the hole at all four corners, and snips to cut out the panel.

Not too terribly hard, and a little redneck engineering, but now it drives again.

Now it just needs tires and exhaust.

Trans_Maro
Trans_Maro SuperDork
8/29/12 7:43 p.m.

Cut the damn hole, I've done it a few times.

Think of it as adding a service hatch that should've been there in the first place.

If it has hard lines to the sender, Cut them with a tubing cutter, add a small flare to hold the rubber hose and splice with some EFI rubber hose and the proper clamps.

No draining the tank, dropping the axle or removing the exhaust.

I know one way is the right way but this way is the fast, easy and cheap way.

I flipped a few third-gen cars this way a few years ago.

HappyAndy
HappyAndy Dork
9/2/12 7:36 p.m.

Update! I replaced the pump, relay and connector for my neighbor. I did it with the hole in the floor technique, and it wasn't to bad.

It was obvious that the other "mechanic" had never been in there. There was a half inch of dust on top of the tank. The pump had a split open strainer & had obviously been sucking dirt.

The problem now is that the new pump did no completely solve the problem. I found that the 3 pin connector on the underside of the pump holder is burned up. New connectors and wires for the in-tank harness were included with the pump, and were used. The problem is in the connector made into the bracket. The connection to ground has about 30 ohms resistance. If the wires at the base of the connector are wiggled around resistance drops and the pump will run, and the engine starts right up.

Is there a way to repair or replace that connector with out a whole new pump bracket and sending unit?

.

HappyAndy
HappyAndy Dork
9/4/12 6:33 a.m.

Bump

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