Car cranks but won't start...

[96Firebird]

2002 Trans Am, 5.7L LS1, 6-speed

Ran fine yesterday, pulled into the garage after work and left it there overnight. Go out this morning to go to work and it won't start. It will crank just fine, but won't fire. Had about 3/4 tank of gas in it yesterday, so it's not out of gas. I didn't have time to check anything, as I was already running late for work, so I just hopped in my winter beater and will check things tonight. What are the things I should check first? Obviously I will check fuses, what else should I look for? Thanks for any help, hopefully it's not something serious... I don't have many tools at my house, so I want to do the simple stuff first.

 

[AdamK47]

Could be the fuel pump. If it works, you can usually hear it prime when the key is in the on position.

 

[96Firebird]

Is it common for a fuel pump to just die like that though? It always used to start right away, and I never had any signs of it dieing like I had on my old Firebird. I will listen to it when I get home tonight, see if it makes any noise. I really don't want to replace the fuel pump, big PITA. I'll probably just buy a fuel pressure tester to make things easier...

 

[AdamK47]

From a quick search on LS1Tech, it does appear to be a somewhat common problem. You can check fuses and wires. Could be that as well.

 

[96Firebird]

Checked the fuses and relays and everything seems in check, can't hear the fuel pump prime at all...

Weird that it would just stop working like that, and it is a huge PITA to replace. I have to make a decision to either drop the rear end and remove the tank, or cut an access hole in the rear of the car and swap it out through there...

 

[SpatiallyAware]

I would want to be 100% sure it's the fuel pump first.

I'm not saying this is the best way to do it, but you can have one person try to start it while another 'burps' the valve on the fuel rail. If the pump is bad = no fuel. If the pump is good = gas spraying out full force.

 

[exdeath]

Check for spark and fuel pressure. Easiest condition to troubleshoot.

 

[exdeath]

I would want to be 100% sure it's the fuel pump first.

I'm not saying this is the best way to do it, but you can have one person try to start it while another 'burps' the valve on the fuel rail. If the pump is bad = no fuel. If the pump is good = gas spraying out full force.

It really doesn't spray out like that. Even with the key on and pump running it will just dribble out of the test valve. There is no pressure in the system when its open and free flowing like that. (Or no velocity I should say correctly)

 

[RockinZ28]

Is it common for a fuel pump to just die like that though? It always used to start right away, and I never had any signs of it dieing like I had on my old Firebird. I will listen to it when I get home tonight, see if it makes any noise. I really don't want to replace the fuel pump, big PITA. I'll probably just buy a fuel pressure tester to make things easier...

Yeah my '01 showed no sign of trouble prior. Died on me on the freeway out of no where, half way between LA and San Diego. Great way to start a vacation...

 

[96Firebird]

Considering I don't hear the pump prime at all, I'm pretty sure that is what it is. I am still going to get a fuel pressure tester to be certain, but chances are good that is the culprit.

 

[LTC8K6]

Maybe it's the relay? Can you swap relays?

Does it have one of those inertia fuel pump cutoffs?

 

[96Firebird]

I swapped the fuel pump relay with the AC compressor relay and it still didn't fire. Not sure what the cutoff you are talking about is, so I guess I can't answer that question.

 

[5150MyU]

You need a test light or DVOM--Unplug the connector at the fuel pump- you need to see 12volts between the GRY(B) and BLK(C) wire.

(B)+(C) are the pins at the connector.

Test light should light for about 3 seconds when the key is turned on(DVOM should read 12 Vlts.)

While cranking it should always have 12 Vlts. or the light should be lit.

If you have voltage verify no fuel pressure.

Usually I verify no fuel pressure before I crawl under the vehicle.

 

[wirednuts]

yeah before you replace the pump, please check voltages on the wires leading to the pump first. it might save you a ton or work.

 

[LTC8K6]

I swapped the fuel pump relay with the AC compressor relay and it still didn't fire. Not sure what the cutoff you are talking about is, so I guess I can't answer that question.

GM apparently didn't use them. Ford and others did.

It was a switch that shut off the fuel pump if it felt a shock above a certain number of G's.

http://en.wikipedia.org/wiki/Inertial_switch

 

[ndmrpwr]

There should be a gray wire near the firewall to test for 12 volts to the fuel pump. It usually is somewhere near the heater aircon box on most gm cars. Good Luck!!

 

[5150MyU]

It really doesn't spray out like that. Even with the key on and pump running it will just dribble out of the test valve. There is no pressure in the system when its open and free flowing like that. (Or no velocity I should say correctly)

Not true :that is how you check fuel pressure.
KOEO-as ford would say(Key On Engine Off)=X psi
KOER-as ford would say(Key On Engine Running)=X psi

Thatis what the shrader valve is for.

 

[exdeath]

Not true :that is how you check fuel pressure.
KOEO-as ford would say(Key On Engine Off)=X psi
KOER-as ford would say(Key On Engine Running)=X psi

Thatis what the shrader valve is for.

When you have a gauge hooked up its a closed system and will register pressure. Duh.

But if you just push it open it doesn't spray everywhere like a super soaker like people believe, it just bleeds.

 

[LTC8K6]

IIRC, just opening the valve could cause the fuel pump to shut off. I believe some systems expect to see a certain minimum pressure. If there's no pressure, the system assumes a leak, and shuts the pump off.

 

[5150MyU]

It's a shrader valve: unless it leaks it is either opened or closed.
Therefore you either have pressure or you don't.

 

[exdeath]

I'm just saying opening that valve while running doesn't result in fuel spraying everywhere like everyone seems to think. It just trickles out.

People act like it will spray 30 feet.

 

[Rifter]

You can try hitting the fuel tank with a rubber hammer while someone cranks it over, if it fires up its definatly the fuel pump. The vibrations will usually get it to run even if its in the process of dieing on you, and will confirm the issue.

 

[85firebird]

I have a Pontiac Firebird S/E with the 5.0L 305 and i pressure washed the engine and it started up and i drove it for maybe 10 minutes and it shut off now it wont start back up. It turns over and the carburator is spraying gas fine but it just wont run. Its got the electronic plug in on the distributor cap and its got the plug in for the quadrajet carb. any ideas why it wont run now after it was running fine?

Please start your own new thread as this one is over a year old...
We consider this a "necro" thread...

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