Nitrous cutting out

I have a '90GT with aftermarket heads/cam/intake. I went to my local drag strip on Fri. night. I recently installed a bottle warmer kit in hopes to get the most out of my nitrous system & finally get some consistent performance out of my NOS #5115 150 dry shot. Well the bottle warmer did help out. My car went quicker down the 1,320' for sure. The nitrous worked perfectly right off the launch, through 1st, 2nd & 3rd gear...but when I shifted into 4th it pretty much felt like the nitrous turned off. So I tried one more run on the juice only to find out that the nitrous wasn't even working this time. At first I thought the problem might be that the vacuum line had blown off the nitrous regulator, which would have made sense seeing how that vacuum line is what boosts the fuel pressure up to 85psi. to mix with the incoming nitrous oxide. No such luck. The vacuum line was secured and in place. I continued to look at all the vacuum lines in hopes to find one that had fallen off of the manifold or dried out & was cracking. But...everything looked fine. Then it dawned on me that it has been years since I've rebuilt my nitrous solenoids. Do you think this could be my problem? Oh, & I have plenty of fuel voume & pressure. I have a 155lph intank fuel pump and an MSD 200gph inline fuel pump. So it's not the fuel pressure safety switch shutting off the flow of nitrous due to inadequate fuel pressure.

[84gt347]

the solinoid makes sense, do you have a filter on the nitrous? Maby its clogged. how much bottle pressure are you spraying with?

Originally Posted by 84gt347

the solinoid makes sense, do you have a filter on the nitrous? Maby its clogged. how much bottle pressure are you spraying with?

Yeah, I can't believe I didn't remember to check the nitrous filter while I was at the track. I'm going to check that out tonight for sure. Even if there is something in there...I think rebuilding the nitrous solenoids might be a good idea. How often do they need to be rebuilt? Is it a normal thing to need to rebuild them every 5 years of so? Actually it's probably been a good 7 years since I've rebuilt mine. I'm running 900psi. now that I have a bottle warmer. But, like I said before...it worked great through 1st, 2nd & 3rd gear. It just seems weird that I'm still having intermittent problems with this system I've had for years.

[84gt347]

i dont know about a rebuild schedule on those. It would be interesting to know if you are getting a black cloud with those cut outs, kinda indicating a rich condition, that would also indicate the nitrous cutting off or running low

Originally Posted by 84gt347

i dont know about a rebuild schedule on those. It would be interesting to know if you are getting a black cloud with those cut outs, kinda indicating a rich condition, that would also indicate the nitrous cutting off or running low

As far as I know there were no black clouds. I had quite a few friends watching the race when it cut out and no one mentioned seeing anything like that. From in the car it definitely felt like a rich condition was occuring. 1st, 2nd & 3rd gears were insane...sticking me back in the seat. I shift into 4th and the nitrous definitely had shut off. It felt REAL slow all of a sudden being back to just on motor, running 8 degrees of timing...with the rich condition, from the second I shifted into 4th, all the way to the finish line.

[84gt347]

well, id start with the things we've gone over so far and move on to other things if its still not solved. i'll bet its one of the things we mentioned already.