Galant GSX starts but won't stay running

[1990gsxna]

Hello I have a 1990 galant GSX which is like the VR4 but it's AWD non turbo. And is the title says it will start fine but won't run for more than 3-5 seconds. I've tried numerous things to try and fix it but I can't seem to figure it out. Parts that are new/tested good:
IAC
battery
Fuel filter
CAS
O2 sensor
MPI relay
FIAV bypass
TPS
ECT
ECU had the caps replaced 1 months ago at ECMTuning
Timing belt/balance shaft belt pulleys etc.

The only thing that I've done to this car modification wise is headers. So this is a bone stock 25 year old galant with a 4g63.

It started about 2 months ago just randomly. I did the FIAV bypass and it ran good for a week. Then had the same symptoms. After replacing the O2 sensor it worked good and ran great for almost two weeks then it started having the same problem. That's where I'm at now, list of things I've tested and replaced and it still doesn't run. I would love some help from the dsm gurus here. Hell of there's any dsm guys here in the west valley I'd be alright wth having you come over and take a look at it as well. Thank you!

 

[luv2rallye]

Sounds like fuel starvation. Check for leaky fuel pressure regulator, injectors, or fuel pump check valve.

 

[pauleyman]

Can you keep it running but just doesn't idle?

 

[dave_nz]

Agree - sounds like a fuel issue.

Really need to narrow it down systematically. If it was me I would first check that I'm getting plenty of fuel to the rail, if not probably fuel pump since you replaced the filter.

if you have plenty of fuel, remove one injector at a time (disconnect the rest) and check that the spray pattern looks ok.

If that looks good then it's probably the fuel pressure regulator.

 

[EGLTAWLN]

you should check your diagnostics port for a check engine code. sometimes it can help narrow down a problem.

 

[1990gsxna]

Agree - sounds like a fuel issue.

Really need to narrow it down systematically. If it was me I would first check that I'm getting plenty of fuel to the rail, if not probably fuel pump since you replaced the filter.

if you have plenty of fuel, remove one injector at a time (disconnect the rest) and check that the spray pattern looks ok.

If that looks good then it's probably the fuel pressure regulator.

To check if I'm getting fuel to the rail I pulled off the line going to the rail and the car wouldn't start obviously because the injectors had no fuel. But the pump works great good clean flow of fuel. But then I pulled off the line from the pressure regulator and the car started like normal then then before the car died I saw the flow from the line stop. So the car is dying from fuel starvation that's for sure. And I don't understand how to do the test where you pull out the injector to check for spray pattern? What's my next step fuel pressure regulator?

Sounds like fuel starvation. Check for leaky fuel pressure regulator, injectors, or fuel pump check valve.

No fuel leaks from what I can see, there is definelty a smell coming from the car that smells like gas. But I cannot see or feel any leaks. Could the smell be from some exhaust leaks from my header?

Can you keep it running but just doesn't idle?

Can't idle at all, it will start and run for only 3-5 seconds and stall.

you should check your diagnostics port for a check engine code. sometimes it can help narrow down a problem.

No codes at all!

 

[dave_nz]

Yeah sorry, if you want to test the injectors take the whole rail out and test all the injectors together. Just make sure you cable tie them onto the rail so they don't fly off with the pressure behind the fuel. Just point the injectors into a bucket or something and have someone turn the car over.

Since you saw the flow stop before the car died from the fuel pressure regulator back to the tank, there isn't much point in testing the injectors.

Wonder if the FPR is getting stuck? Sounds like too much pressure - stupid question - you do have the vacuum line connected from the manifold to the FPR? Do you have a spare FPR to try?

 

[EGLTAWLN]

does your check engine light come on when you turn the key and then go back out after a few seconds? if not it might be the ecu.

 

[1990gsxna]

does your check engine light come on when you turn the key and then go back out after a few seconds? if not it might be the ecu.

Yes exactly that, it'll come on for the few seconds and then shut off before the engine dies. So the ECU is functioning properly!

I'm going to replace the FPR tomorrow hopefully that fixes my crazy car!

 

[1990gsxna]

It took a week before i got the Fuel pressure regulater and i tossed it in today and still have the same symptoms. Does anyone have any other suggestions? Should i buy a new fuel pump and toss that in? Im at a total loss now.

 

[inthemidst]

You need to test the fuel pressure before you buy a pump.

 

[gofer]

You just buy this GSX from someone in Tucson?

 

[1990gsxna]

You just buy this GSX from someone in Tucson?

No the one with like 80,000 miles? That one looked super nice and i wanted to buy it.

You need to test the fuel pressure before you buy a pump.

I would test the Fuel pressure but right before the car dies fuel stops flowing entirely.

 

[gofer]

Well, that's good to know. I was just helping that guy fix his GSX problems prior to him trying to sell it, thought maybe the symptoms came back after he fixed the problem.

The symptoms you're describing are similar to the issues he was having, which he fixed before selling the car. I'm a fan of FREE troubleshooting checks, not popping and swapping parts shotgunning it until it's fixed, or worse, not fixed and you're out of money.

Test your MAS IAT sensor...

Intake Air Temp Sensor (IAT) : The factory IAT sensor is actually integrated into the stock MAS, to test it you'll do so through the MAS plug.
Cold 68*F = 2.7 ohms //// Hot 180*F = 0.4 ohms ​

This is the pin out for the N/T MAS, you'll test between pins 4 & 6 highlighted in red.​

You must be logged in to view this image or video.

​

Test your coolant temp sensor...

Coolant Temp Sensor (CTS) : There are 3 sensors in the t-stat housing IIRC, the lowest one that faces downwards towards the front of the car is the ECU's CT sensor.
Cold 80 to 100*F = 3.5 to 2.7 kOhms //// Hot 180*F+ = 0.3 kOhm




​

 

[canada4g63]

I would have someone put there ear to the tank when you turn the key to the on position and see if they can hear the pump running

 

[1990gsxna]

Well, that's good to know. I was just helping that guy fix his GSX problems prior to him trying to sell it, thought maybe the symptoms came back after he fixed the problem.

The symptoms you're describing are similar to the issues he was having, which he fixed before selling the car. I'm a fan of FREE troubleshooting checks, not popping and swapping parts shotgunning it until it's fixed, or worse, not fixed and you're out of money.

Test your MAS IAT sensor...

Intake Air Temp Sensor (IAT) : The factory IAT sensor is actually integrated into the stock MAS, to test it you'll do so through the MAS plug.
Cold 68*F = 2.7 ohms //// Hot 180*F = 0.4 ohms ​

This is the pin out for the N/T MAS, you'll test between pins 4 & 6 highlighted in red.​

You must be logged in to view this image or video.

​

Test your coolant temp sensor...

Coolant Temp Sensor (CTS) : There are 3 sensors in the t-stat housing IIRC, the lowest one that faces downwards towards the front of the car is the ECU's CT sensor.
Cold 80 to 100*F = 3.5 to 2.7 kOhms //// Hot 180*F+ = 0.3 kOhm




​

The intake temp sensor has 2.4 ohms at around 72*F. And the coolant temp sensor testedgood, cant remeber the ohms.

Is there any other tests i should accomplish?

I would have someone put there ear to the tank when you turn the key to the on position and see if they can hear the pump running

Listened for the pump with the key in the on position and i cannot hear pump running.
But from what I've researched the pump does not run in the on position, only after the car is running you will hear the pump in the on position. And i could be totally wrong here, just saying what I've read before.

And after the car is stated i hear the pump stop before the car dies.

 

[canada4g63]

you can always do a simple fuel pressure test. Pull the hose off the fuel rail two 10mm bolts coming right off the fuel filter and take that hoe and feed it into a empty bottle throw the a few cranks at the car to see if your getting fuel

 

[1990gsxna]

you can always do a simple fuel pressure test. Pull the hose off the fuel rail two 10mm bolts coming right off the fuel filter and take that hoe and feed it into a empty bottle throw the a few cranks at the car to see if your getting fuel

Fuel flow is good. Clean even flow while cranking, it doesn't stop or bubble.

 

[1990gsxna]

Does anyone have any other suggestions for me? Thank you!

 

[gofer]

Not sure if it's the same but, DSM's have a MFI/MPI relay that controls the pump. It's worth a test and can be found (on a DSM) bolted to the right (passenger) side kick panel of the center console.

http://www.dsmtuners.com/threads/mfi-mpi-relay.263224/