I sprayed for the first time tonight, I started in 3rd at about 2500, and I have my window switch set at 3200. There is a FPSS on the car set at 35 psi. When it would rev up to activate the switch and solenoids, I could feel an immediate jump in power, then it would die back down like it didnt have any nitrous. Then it would come back on, and shut back off, and continuously did this. I am thinking maybe my fuel pressure is jumping around and shutting the system off and turning it back on. I am running a 100 shot Harris Speed Works kit on a stock pump. Anyone got any ideas on what may be the issue?

 

it could be the fuel pressure like you said, you have to get a guage on it, the stock pump is probably at it's limit, check the WOT switch too to make sure it's not loose

 

did you adjust the FPSS after install?

It does sound like a fuel pressure/FPSS issue

 

No I left it at 35 psi where it was set when I bought it. Im gonna try changing my fuel filter and see what that does, I havent changed it in about a year.

 

I would do what the others suggest and put a gauge on it. A clogged year-old fuel filter is possible, but not likely.

 

Are you sure it was set at 35psi? Did you test it? That's the only way you will know if its set correctly.

 

That is what HArris speed works claimed it was set at.

 

How would you test it?

 

Make sure that your bottle pressure is up to 950 psi and your running a set of colder plugs gapped correctly. One quick way would be to take the FPSS out of the mix and test. To do so take the two wires off the FPSS and attach them. By pass any window switch that you have and have some one help you. Take the nozzle out of the nozzle holder and aim it into a bucket/catch can. Close the bottle valve and empty any nitrous that may still be in the main feed line. Start the car up and hit the WOT switch, you should have fuel coming out (be careful when doing this!). If the fuel is constant when the WOT switch is pushed I would suggest getting a fuel pressure gauge on and monitoring it when you spray, along more then a few PSI drop get out of it. If you are still having problems with the FPSS by passed start going over the electrical connections for a bad one.

Matt

 

I will give it a try. I tried it again, and it is popping real bad. I am guessing detonation so I let off. I am running TR6's and pulling 7 deg's of timing b/c it popped pulling 5.

 

I have a 1/8" NPT port on my compressed air system. I screw in the FPSS, hook my multi-meter across the teminals, and drop the pressure with the air systems pressure regulator, until the switch opens.

 

2,500rpm is really low to spray at, IMHO. Spray at low rpm is much more likely to break parts than at high. I usually bring mine on 4,200-6,500.

Rich

 

He is set @ 3200

 

Do you have a MSD box or anything else installed for more spark?

Could be he's blowing out the plugs and needs a hotter spark.

 

Almost sounds like bottle pressure is way too low causing you to run very rich. That is a lot of timing to pull too, was your timing advanced quite a bit? If it has not been advanced any you don't need to pull any.

Matt