Just fired up the car after finishing the racetronix pump/hotwire kit over the past weekend. The car seems to be running fine, but I'm noticing a couple differences. As a note, I have an electric fuel pressure gauge mounted off the rail that I installed for the wet kit. Its running about 63 psi at idle, maybe 2-3 psi higher than stock. My concerns:

1. When I turn the key now to run (not start) just to prime the system, the pressure goes up briefly to 50, then immediately goes back to 0 (when the pump stops humming). With the stock pump, it would go up to 50, and slowly bleed down. Checked for leaks, not seeing any along the lines that I can tell. Is this normal?

2. I'm at 63 at idle, but if I hammer it in 1st or 2nd to redline, it'll drop to 55-56 psi or so at first and stay there. This is without the spray, just on the motor. Is the pump not keeping up? I don't remember the stock pump dropping any pressure. I'm concerned that if I'm dropping to ~55 psi on the motor, that its going to have more problems keeping up when the wet kit hits.

3. The car is starting harder. Turns over longer before it fires, i'm thinking this is because there's no fuel in the rails since its not holding pressure.

Any suggestions as to what could cause this? Any error in install? Tried to be very careful not to kink the tube, and made sure it didn't kink when I compressed the bucket.

Thanks guys.

 

Ok, I'm sorry to all because it looks like one of my points can easily be found in the search (it had been down the past few days, should've tried first, my bad). 55-56 psi at WOT appears normal, and due to the in-tank regulation. Though will the N2O hit cause that to drop further when the fuel noid opens?

But my other 2 questions stand. Should the rail pressure be bleeding off so quick?

 

I'm having similar problems starting too,but mine is a Walbro pump. Hard starting after the install. Pressure went to 63,but went down after driving for awhile back to 58. I'm going to change out the regulator on the pump assembly and see what happens. Don't really know if this is normal.

 

I'm wondering if there's an internal check valve or something in the pump, and maybe its bad, to let the pressure bleed out of the fuel rails. The only other thing I think it could possibly be is if the plastic tube in the bucket isn't clamped down well, and is leaking out pressure. I know I tightened the upper connection tight as heck, can't remember how tight I connected it to the pump, since Racetronix sent the kit with the hose attached to the pump, so I probably assumed it was tight enough.

Sucks, now I've got a full tank, and I'm going to have to drop it again. May do the trap door instead.

 

I can not remember where I read it but there is a install write up about aftermarket pumps.In the write up they put a check valve in the line between the pump and fuel tank cap. The artcle said that the stock pump came with a check valve.

 

I have been retuning a rebuild on the 402 and have been watching my FP during the tuning.

Mine is a 98 Racetronix PnP system on my 98 Camaro. I will hold 58 psi at idle and will drop to 54-55 psi after a few seconds of wot. After extended wot it will drop to 52 psi.

Racetronix by email tells me this is not normal, but have been unhelpful as to what the FP should be if the pump is operating normally or the likely places to check.

Perry

 

I'm using the FullThrottle Pump (same Walbro Pump as Racetronix) My FP at idle is up to around 63psi - haven't got the WOT results as it turned cold and snowed here yet again

I also noticed that with the stock pump the pressure stayed in the system all the time. With the Walbro the pressure drops to zero once the car is shut off.

 

[QUOTE=NHRATA01]Ok, I'm sorry to all because it looks like one of my points can easily be found in the search (it had been down the past few days, should've tried first, my bad). 55-56 psi at WOT appears normal, and due to the in-tank regulation. QUOTE]

I am pleased that you have been able to get the search function to work.

I have been trying to search this issue for weeks and the search function is continually down severely limiting the effectiveness of this forum.

Perry

 

Mine bleeds relatively quickly back to zero after the pump turns off. I don't know if it is any faster than the stock pump since I never looked at the fuel pressure until my stock pump failed! I don't really think this is too much of an issue since I'm not very concerned with the fuel pressure if the engine isn't running (it makes setting an external regulator a bit of a PITA, but, there you go). As soon as you move the key to the START position, the pump comes back on so no damage is done.

That's a little odd. I don't know why it would be any harder to start. Even with zero pressure, there still should be some fuel in the rails. There's just no force driving it with the pump off. And, if you go from KEY ON to START as normal, then the pump shouldn't time out anyway. Are there any other changes that you've made at the same time as the pump install?

 

Yeah, the in-tank regulator is a POS. Since it's just an orifice, the pressure vs. flow rate will change. It's probably better to go with an external, diaphragm-type regualtor.

 

The stock pump would take probably an hour or so to bleed down from 50 psi - I know this because I used it with my pres gauge to properly set my fuel pressure safety switch. (Installed the nitrous kit before the pump). The pump was the only change I made at the time. I had the nitrous kit in a few weeks earlier, but had run the car plenty since and tested it (just with the smallest jets and very briefly). I guess the only other thing of note is a new fuel filter.

Here's one other odd thing with regards to the quick pressure drop. When cold if I prime, it will drop from 50-20 psi right away, and then take a few minutes to bleed from 20 down to zero. When it was hot and I primed, it pretty much plummeted to zero instantly.

Its definitely starting harder, which that be the case I'm not overly concerned about. But I have read a few opinions that are concerned that when the pressure immediately drops from the rails when the car is hot, it can boil the gas and leave vapor in the fuel rails, making an even harder start and risking varnish/deposits getting left behind.

BTW, thank you all for the opinions!

 

My fuel pressure would stay exactly where it was right before the car was turned off over the entire winter season with the stock pump.

Now, with the walbro, it bleeds down to zero almost immediately. Not that it is necessarily a bad thing - just something different that what I have always seen. My car would fire with the first turn of the key with stock pump - I've only started the car a couple times since the new install - but it still fires right up even though pressure is at zero to begin with. As soon as the key goes to 'ON' before starting position you can hear the pump come on and prime the system - must pressurize it fast enough to yield same results as stocker - at least in the case of my car...

 

So,can any of you guys help and others to fix the "Hard start" problems? I would be really greatfull.

 

If you over tightened the clamp it will cause the tube to bind up and leak. This is why step # 26 in our manual states "Do not overtighten the gear clamp. Snug will do!" The crimp clamp on the pump is fine so do not remove it.

This problem could also be related to the in-tank FPR. The GM service manual has a very thorough procedure for isolating this type of problem.