1990 Pontiac Grand Am Won't Start Unless Gas is Poured in Ca

PCADDICT

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1990 PONTIAC GRAND AM
4 CYL
FWD
AUTOMATIC
87,000 MILES

I have a 1990 Pontiac Grand Am that won't run. If you pour a small amount of gasoline in the carb, it will start and run for a short period of time. I was told by the previous owner that about four months ago it was running fine and then he got on it, discovered there was a leak in the break line, coasted home, and it wouldn't start after that.

I have a service manual for the car which offers troubleshooting tips like checking the fuel pump relay by using the test terminal. I thought that was a good place to start but don't know what I am looking for and spent two hours trying to find it.

When I have someone turn the key and I am laying right near the gas tank, I cannot hear the fuel pump kick on.

I also cannot drain the full gas tank because I can't get a hose all the way down the feed neck due to the fact that it gets stuck somewhere. I also cannot remove the rubber flexible hose that goes between the rigid feed neck and the tank. I loosened the hose clamp but the hose won't budge.

I spent about 6 hours on this car only to accomplish changing the fuel filter(which didn't help by the way and was still a pain due to the amount of rust on the nuts). Any help would be greatly appreciated including tips on breaking loose rusty bolts so I can drop the fuel tank if it is a fuel pump issue.

Also, is there a way to read the computer codes without buying an expensive reader?

7 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Carb? Or f/i?

The fuel pump relay should be in the relay bracket that is attached to the firewall for the 2.3 motor and the right front area near the headlight for the 2.5 motor.

I don't think the codes are going to be off much help for the no start. You know it's a fuel issue. IF it turns you to be the pump, your in for a tough job due to the corrosion. Probably better off cutting the straps and getting the tank out if the bolts don't move. Penetrating fluid may help, but would be surprized. Once the tank is out of the way, you may be able to torch the bolts out. Hard to say with out seeing it.

Don't be surprised that you make crate leaks during the process as lines are being touched that are probably weak, brake and fuel lines that is. This can turn into a nightmare. But you never know. I would suspect the tank, and sending unit will be in poor shape and may be worth while replacing those at the same time.

Note: I am assuming the is fuel injected even though you said carb. IF you really do have a carb, then you have a mechanical pump mounted to the engine and will not have a fuel pump relay.

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Sunday, December 9th, 2007 AT 7:32 PM

PCADDICT

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Sorry. It uses a Throttle Body Injector. I misspoke when I said carb due to my lack of knowledge of the newer cars that don't use carbs. You take the air cleaner cover off and right there is the orifice that I pour the gas down. Not sure what it is called.

Thanks for the help. After posting this, I found a diagram in the service manual that shows a general location of the fuel pump test connector but I have no idea what it looks like.

My father was a mechanic for several years back in the 70s and through half of the 80's. He said that it may be oil pressure too because sometimes that prevents the fuel pump from kicking on. Thoughts?

As far as the tank goes, the tank itself appears to be in pretty decent shape. The straps and bolts that hold the tank up are pretty rusty. What would I use to cut the tank straps? I am not sure what they are made of besides rust at this point. ;) After I cut the straps and maybe the bolts, can I get new straps and bolts from an auto parts store?

As far as I can tell based on the wiring diagram in the service manual and the diagram of the component locations, the relay is located on the firewall. I think it is a small black plastic piece about 1" square with wires coming out of the bottom of it. You can take what I call the cap off and see terminals on the cap. Am I in the right neighborhood or completely off base?

As soon as I figure out why my website isn't up, I'll post a scan of the two diagrams I am talking about. I tried using the upload image option while posting but it is too small.

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Sunday, December 9th, 2007 AT 8:13 PM

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The fuel pump pressure test port, looks like a schrader valve that would be similiar to the valves on a wheel. Looks like you already confirmed no pressure though.

The relay is the direction you want to go to, and yes it sounds like your going in the right direction on that.

Is that the 2.3 or 2.5 motor.

Your father is right on the oil pressure, however that is a secondary failsafe and wouldn't explore that just yet. Work on locationg the relay so you can bypass to see if the pump will fire.

Sometimes you can bang on the bottom of the tank and jar a seized pump to temporarily work.

Straps are steel and a hacksaw will cut them or power hacksaw, sabre saw etc. But try the bolts first.

Before you start cutting, start locating parts, aftermarket stores should be able to provide them.

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Monday, December 10th, 2007 AT 6:05 AM

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It is a 2.5 engine. I haven't ruled out pressure yet because I haven't actually tested it. I guess I am too cheap to buy a $40 pressure tester only to use it once. I can't find someone that rents one. If after hopefully replacing the fuel pump I still can't get it started, I may break down and spend the $40.

I remember seeing somewhere in the service manual where you could force the pump to come on by using the relay I think. I have to locate it and mark the page this time. ;) It seemed like it was something about applying 12V to a particular terminal but I don't exactly remember. Before I do anything, I'll find the instructions. Is that relay replaceable?

I planned on taking a breaker bar and my electric impact wrench the next time I go over. I will cut the straps as a last resort and as you suggested only after verifying that I can replace them.

Is there a trick to removing the flexible hose that is between the rigid fill neck and the tank? I loosened the clamps but couldn't budge the rubber hose. I really don't want to drop a full fuel tank as I suspect it will be a little heavy. I have had rubber hoses stick before, like on the radiator, but never to the point where I couldn't even budge them. I assume it is just from years of deterioration and not some kind of sealant.

Thanks for your suggestions and assistance.

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Monday, December 10th, 2007 AT 7:17 AM

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Yes the relay is replaceable and yes that is how you bypass it by appying the 12 v source. Find that procedure. The relays can be swapped with another similiar one also. Assuming the other relays is good.

To get the hose off there is a special tool that has a few bends in it and a sharp point. However you can improvise with a screwdriver by separating the hose from the neck by sticking it between them and working around until it has loosened it grip.

The reason I say you have no fuel pressure is becasue you can't hear the pump run and that it will start when you maunally add fuel to the throttlebody.