Caddy59

89 Firebird V6 doesn´t start anymore

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Hello everybody,

concerning a more modern car....anyway hoping for help. I´m German and I´m owning an 89 Firebird,3.1 L V6 , injected engine.

Recently the car broke down after a 30 miles trip, it started afterwards once whilst poor throttle response, broke down again immediately and didn´t start anymore at all (starter motor was working and engine cranked ok). Car was picked up by breakdown service, it´s now at home. Supposedly I think it might be a fuel pressure problem, there´s rather a bit of fuel once I have checked the testing valve at the fuel rail, but probably poor pressure.

Now I´ve provided a pressure testing gauge and try to find the fuel pump relais, but didn´t find it as yet. I use a Haynes Repair Manual, unfortunately something disappointing Information. I rather found  the testing connector underneath the dashboard,  fault code reading has been done, no code stored. According to Haynes Manual, the fuel pump should been activating by applying voltage to a pin within this testing plug ( with what the code reading has been done), but on the particular Position whats Haynes stated, there´s no pin at all. Furthermore, I don´t find the fuel pump relais to bridge the pump, but no link where it is located. Unfortunately, more likely disappointing and not that helpful. I have to activate the fuel pump anyhow to test the pressure, can anyone tell me how?

 

Probably someone is familiar with this engine and knows these symptoms. Additionally to say: When bridging a spark plug cable  to ground, it´s sparking like crazy, so I think it´s not a sparking problem.

 

Thanks a lot for your advices !

 

Udo

 

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How many miles/kilometers are on the car?  If it is in the 135,000 miles/ 200,000 kilometers, good chance it is a fuel pump.  Fairly typical.

 

The best way to check fuel pressure is to just turn the key to the on position, radio and everything off and if you listen carefully you should hear the electric fuel pump run for about 6 seconds and then turn off.  If you do not hear this, bad pump.  If you hear this then you need to check the fuel pressure.

 

Under the hood there is a Schrader valve connection to the fuel rail like a tire stem.  You will need to put a gauge on that to read the pressure in the fuel rail. I am guessing that it is a port fuel injected engine.  If it is a port fuel the fuel pressure must be at least about 45 psi/ 300 KPA.  Ideally it should be about 60 PSI / 400 KPA.  If you do not have these readings, then it is time to put a new fuel pump in the tank.

Edited by Larry Schramm (see edit history)

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Put a fuel pressure gauge on the fuel rail test port.  Attempt to start the car.  The electric fuel pump (located inside the fuel tank) is supposed to turn on for two seconds when you first turn the key to START to build pressure in the EFI system. If the pressure does not reach about 45 psi, either the pump is bad (not uncommon) or the relay is bad.  If the car actually stopped running while driving, I would strongly suspect the pump is bad.  The relay is only used during the start sequence. Once the engine is running, fuel pump current flows through an oil pressure switch and bypasses the relay anyway.

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Same thing happened to my '91 Camaro. Turned out the fuel pump went bad. It's in the fuel tank.

 

A real bugger to replace. You're supposed to drop the fuel tank, which involves removing all sorts of extra parts. Or you can take a shortcut and cut a 8" hole in the metal under the back seat and get access to the fuel tank from the top. Not supposed to do that but most mechanics will. 

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I wonder if the easiest alternative would be just to bypass the intank pump with an external pump that goes inline with the fuel line unless the pump in the tank would restrict any fuel draw.

It will probably only be needed to do once whichever way is chosen. I wonder how hard it will be to find a new fuel pimp in Germany?

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There is a diagnostic port near the steering column where you can plug in a computer. It will get codes from the car's computer telling you where the problem is. All garages and dealers have these diagnostic computers. If your local garage cannot diagnose your car, you can order the correct plug and wire to plug it into your laptop computer, and buy a program to load into your laptop. I believe your car uses the OBD1 system.

 

This will eliminate a lot of guess work, and help pin point the bad parts.

 

It is possible to get the codes without the scanner and without any tools except a short piece of wire.

https://www.thirdgen.org/service-engine-light-error-codes/

Edited by Rusty_OToole (see edit history)

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If the fuel pump does not run, no trouble codes will be set! BTDT.

 

My '94 Caprice did the die, restart but poor throttle response thing when its fuel pump died.

 

On some GM products, there is a 1/4" quick connect type connector hanging off the wiring harness near the underhood fuse box. This is the "hot" wire to the fuel pump, and putting 12 volts on it will power the pump, bypassing the relay (computer controlled).  Maybe 89 Firebirds do not have this.

 

A fuel pressure gauge is needed, as Larry says, connect it to the Schrader valve on the fuel rail. 

 

Three things needed to run, Spark, Fuel and Air. You have spark, probably have air (unless a mouse built a nest while you were driving down the road!), so I also think the fuel pump gave up the ghost.

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Guys, thanks for your advices. 

@Larry Schramm: The cars mileage is just 44000, but anyway 29 years old......

 

@Rusty_OToole: I blinked out the fault codes, but it only showed 12 what is just the standard code given out if there´s no fault at all. But I have to admit that i disconnected the battery in between before I tried to read the codes, shit happens. But: The fault lamp definitly didn´t burn when the car broke down.  Maybe the system will not store codes after reconnecting the battery when just cranking the engine, supposedly it has to run fired.

 

My most urgently question: How can I make the fuel pump work with bridging the relais or get access to do this with the fault reading code plug? I suppose that the fuel pump will not provide enough pressure to measure it with the gauge whilst just running the pump for some seconds in the starting mode. The gauge has to be bled out the air, then the pressure will raise down and I won´t get an evaluated pressure result. I´m rather sure that the pump should be bridged to run all the time to get real pressure readings. But how to do? Where´s the relay? How to make the pump work all the time?

Could i probably bridge the oil pressure switch to make the pump run? Where is the oil pressure switch? I didn´t find it as yet.

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If the pump has failed (the most likely cause of your problem) then no amount of bypassing, jumpering, or bridging will fix it.  You need to drop the fuel tank and install a new pump, period.

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If you put a fuel pressure gauge on the rail first and then turn the key to the on position, while it is running for the 6 seconds it will make enough pressure to tell you if it is good or bad.  It must build pressure immediately so the car will start quickly.  If it does not start quickly, the starter will just keep running for a while and then you have more  problems.

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I noticed on the web site Rusty point to, the only code for the fuel pump is about low voltage to it (54). There are three or four for other fuel problems.

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1 hour ago, Larry Schramm said:

If you put a fuel pressure gauge on the rail first and then turn the key to the on position, while it is running for the 6 seconds it will make enough pressure to tell you if it is good or bad.  It must build pressure immediately so the car will start quickly.  If it does not start quickly, the starter will just keep running for a while and then you have more  problems.

 

As noted back in post #3.  Unfortunately it sounds like the OP lacks troubleshooting skills and/or tools. And as I pointed out above, on GMs, the ECU only runs the pump for two seconds, not six.  The pressure builds in those two seconds.

Edited by joe_padavano (see edit history)

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And, you can can turn the key ON- OFF- ON- OFF several times to see if the pressure builds.

 

As I said, no fuel pump running is a NO CODE condition!.All the normal monitored functions are working (spark, signal to injectors, etc.) so no code will be set. BTDT!!!

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Now I´ve checked the fuel pressure as you adviced, Joe was right when he said that 2 sec. pump running are long enough to build up the pressure. It was immediately appr. 40 psi ( 2,8 bar).

So I suppose that neither the pump itself nor the filter is the problem. Then I removed the fuel rail completely with the injectors ( with a rag underneath ), left the fuel lines connected and let my wife start. There was no fuel coming out of the injectors, nothing at all. The injectors seems to be not activated at all.

BTW, I also removed the distributor cap to have a look to the finger  and to eliminate a mechanical problem ( broken or worn timing chain or sth.). That was not the case, but the distributor and the coils at the bottom of the housing  are in a terrible condition. The six induction fingers of the distributor are heavily rusted, and the isolation of the coil ist powdered. Even when the distributor would still work, it has to be replaced due to this condition. Does anyone know if the coils underneath has something to do with the operation of the injectors? Or what component might be broken if the injektors doesn´t work when starting and fuel pressure is ok? 

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55 minutes ago, Larry Schramm said:

40 PSI is not enough.  Should be in the 60 psi range.  Need to change the pump.

Sorry but that is not correct. The spec for the 1989 3.1 is 40-47 PSI. More to the point, if there is ANY fuel pressure and nothing is coming out of the injectors, the pressure is NOT the reason why the car won't run (or at least not the primary problem). Figure out why the injectors are not firing first.

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I think so, Joe. Even when the pressure would be at the lower range, the engine has to start and to run wobbling at least.  Since I have removed the throttle with the vaccum lines for the map sensor ( to pull out the injectors) , could it be that there´s no injection because the map sensor thinks the engine is not running? And hence needs no fuel? No vacuum, no injection? 

Or could it be - worst case - the ECU is broken? 

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The car isn´t running yet always ( less time to look for ;-() I´ve now a new distributor what I want to install tomorrow afternoon. I´ve found out in the meantime that the engine rpm sensor is not a real crankshaft sensor as on modern cars, the rpm information for the ECU comes from the distributor what is an induction typ with a small coil inside. The condition of the distr. was really terrible so I provided a new one, but I´m not sure if this will fix the problem of no injection.

Unfortunately, on the wiring charts the are rather all electric parts figured out, but the function inside is not explained, just "black boxes". So I have to go on with try and error and have to provide part after part from USA what is really a big expense, however Rockauto is a great shop and the shipping is really quickly.

If the distributor doesn´t help to make the engine run  again, does anyone know if there´s only the ECU what might be broken finally? Or could it be any other sensor such like throttle - Map - Water temp - air inlet temp  ? I think that a slightly wrong voltage signal might cause the engine to wobble or poor starting, but not to give no signal at all to the injectors? As a reminder, fuel pressure is ok and there´s pressure on the fuel rail, but the injectors doesn´t work at all once starting, not one droplet at the nozzles. Hopefully is there anybody who is experienced in these engine and have an idea.......

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On ‎4‎/‎29‎/‎2018 at 3:39 AM, Caddy59 said:

.Recently the car broke down after a 30 miles trip, it started afterwards once whilst poor throttle response, broke down again immediately and didn´t start anymore at all (starter motor was working and engine cranked ok).

 

OBD1 has a habit of deleting codes that are not hard engine threatening codes when the ignition is shut off and my favorite first roadside trick for this specific failure is to make sure the butterfly in the throttle body isn't stuck closed, the air filter is clean enough to pass air then unplug the air sensor and if the engine starts and runs replace the sensor before you ruin the catalytic converter.

 

More than a dozen things, some common and some you have to be kidding kind of odd can cause these same symptoms, a couple of the more common causes have already been covered. Unplugging the MAP forces default readings and if the engine starts you've found the problem, if not it eliminates one of the you've got to be kidding odd problems.

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@Joe Padavano: Sorry, what is VATS? (Remember I´m German :unsure:)

    If you should mean an immobiliser, yes, but it just bypasses the starter wiring. If it would have been failed, the car wouldn´t crank any more. But since it cranks, so I assume that it´s not the reason.

 

@Digger914: I think in any way the injectors have to work when cranking, I have the fuel rail removed (but connected to the fuel line) and can look when starting if the are injecting or not. Till now, they don´t, I will check it out the next days with the new distributor (hoping there was the rpm signal missing on the old one). I will try to look for the injector signal at the plugs. But if there is one, all injectors has to be broken what wouldn´t be realistic.

 

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3 hours ago, Caddy59 said:

@Joe Padavano: Sorry, what is VATS? (Remember I´m German :unsure:)

    If you should mean an immobiliser, yes, but it just bypasses the starter wiring. If it would have been failed, the car wouldn´t crank any more. But since it cranks, so I assume that it´s not the reason.

 

 

Vehicle Anti Theft System.  This is the factory-installed system that uses a resistor pellet in the key.  It disables the pulses to the injectors if the system does not detect the correct key resistance value. It also disables pulses to the injectors if the system is not working properly.  Once again, have you verified that you are actually seeing pulses at the injectors?  It's hard to provide helpful info if you won't answer questions about the car.  The mind reading still isn't working.

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Thanks.....I promise to give you the right info as soon as I´ve provided it. The cars key looks as there would be a resistor pellet inside the key, yes. Tonight, I will fit the new distributor and if it  still doesn´t run, I`ll check the pulses of the injectors.

In case there are none, what part seems to be failed then? Is it the ECU, or the key itself?

 

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3 hours ago, Caddy59 said:

Thanks.....I promise to give you the right info as soon as I´ve provided it. The cars key looks as there would be a resistor pellet inside the key, yes. Tonight, I will fit the new distributor and if it  still doesn´t run, I`ll check the pulses of the injectors.

In case there are none, what part seems to be failed then? Is it the ECU, or the key itself?

 

 

It could be the ECU, the key, the lock cylinder, or the VATS system itself.

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I have worked on thousands of cars in my life and still do.

However if my 03 Dakota wont start I will have to take it to someone that understands it. Same with my Powerstroke.

Some cars that are now considered to be antique cant be fixed without the right knowledge or trouble shooting tools, just like brand new cars.

I have an ASE certified nephew that calls me on occasion to ask me about carburetors or points.

Trying to save  buck on these things is futile.

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