91 gsx starts but then it dies right away

[90tsiawdturbo]

My buddy has a 91 gsx that starts but then dies and kind of sounds like it misfires a little and dies...took the iac off an cleaned the buildup and tested it (good) put it back on it started idled for about 3 seconds then died tried to restart it and it starts and dies right away...you can keep it running if your on the gas but you have to pump it...the fuel filter looks almost new...could it be the CAS? It has a walbro 255 on the stock fpr but it ran ok before besides idle surge, I have a fpr for it but I need the fuel rail adapter...any other opinions on what it could be?

 

[CellerDweller]

Is there a CEL? Have you checked to see if all plugs are firing?

This could be a variety of things. I had similar problems in the past - once it was a large boost leak which was an easy fix and found with a boost leak test, the other time it was a burnt valve. A simple compression test would rule out valves.

I'm not sure on the CAS as I've never had a failed one, but I would think that a CEL would come on if it outright failed and wasn't in it's acceptable range.

 

[slickers111]

Starting and dying is failure of the Crank position senor, or Cam sensor. Seeing as you got a 1G, its your CAM sensor that most likely failed.

Granted all your other Needs for a running motor are there.

 

[90tsiawdturbo]

Thanks slickers....was trying to avoid removing the CAS to test it because I don't have a timing light but looks like I'll have to find one...I'm gonna go test it tomorrow and I'll post the results...

No CEL and I'll check for boost leaks again too

 

[hionboost]

I also have had this same exact problem same symptoms... I was baffled no CEL, new fuel filter plugs. I was getting spark but was very weak! I took off my coil pack and too my surprise the wires on the back of the coil packs were frayed and bare wire was exposed arching off my intake manifold! Repaired the wires with a couple layers of heat shrink tubing, cleaned the screw terminals real nice. Now it stays running but is real choppy and laggy when revving. I'm running really rich do to a dead o2 sensor due to bad gas because the car has been sitting four 3 years! but now she runs and just needs an o2 sensor! Hope this helps you!

 

[2gs]

Fuel is a big part to new startup and builds. Make sure all hoses and lines are connected no leakage and that's my two cents.

 

[90tsiawdturbo]

Sorry if I was vague in the original post...this is NOT a first startup or any sort of build that didn't go as planned....it was running and driving fine one day(with the exception of bad idle surge) and then one day he went to crank it over and it was like this

 

[norcalboostin707]

I had the same.issue here recently... I ended up adjusting the cas by sound it.idled fine but would die at stop signs/lights... So i checked the BISS... which om my 1g is lpcated at the top front of the tb.. I tightened it all the way in and then did 2 complete revolutions out... Which it seemed fine but then my idle was off i did another 1 1/4 turn out and my car is idling around 750-800... I would say check the BISS screw.. Count the revolutions you put it in... I believe chilton and haynes call for 2 complete revolutions out...

 

[90tsiawdturbo]

I haven't even touched the BISS yet(I've heard that's like the last thing to touch) it look like someone put sealant over the screw head or something too

 

[4G63gst1990]

A cas on a 91 is not on the timing belt side its on the other side of the intake cam...i would also say check that the tps is still good and i would count the number of turns if you start playing with the biss screw

 

[90tsiawdturbo]

I know where the CAS is...!!! His tps reads accurately on his apexi safc so I assumed it was good...I will actually check the tps later today....

 

[VR4 Kev]

I would check for a boost leak as it is a MAS vehicle. If you have a major leak or a pipe blown off it will be pulling in unmetered air and thus not injecting the proper amount of fuel.

 

[bigbird94]

If you have another throttle body around with known working sensors Id swap it on.

 

[norcalboostin707]

I got a question about the tps.. If someone were to have put it on upside down would that cause vehicle to not start? I am trtin to narrow down my 2g and the tps looks like its upside down compared to my 1g

 

[jukebois]

make sure that the plumbing from mas to the turbo is perfect and there is no air leak .

 

[Lou98GSX]

i would do the basic checks first . scan for codes, boost leak test, valve timing and fuel pressure test.