10PSI in the ON Position at Fuel Rail
Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
10PSI in the ON Position at Fuel Rail Well I went and rented a fuel pressure test kit...
I did this while the car was "cold" so maybe I need to run it and then test the pressure. But the point is. I only got 10PSI when I turned the ignition to ON. 10. It built pressure as I turned it on and off. But it bled off fast. Really fast.
I didn't even bother to crank it. I know where my issue is - could be an install error since it is a Racetronix pump/hotwire kit.
But that would definitely mean the injectors are smaller than the PCM thinks, would account for my hard start issues, and my VE table problems (I'm seeing numbers in the 140s).
Car seems to run fine but I haven't really pushed to upper RPMs because of the issues. One thing that is weird - I had to realllly lean it out for it to have lean idle. Seems like that's counter to having smaller injectors than what the PCM sees? So could it be a leaky injector? Although at the rail, the pressure never built. Tomorrow, I'll start it and monitor it as fuel is delivered.
Any ideas? Is this a pinched line in the tank? A leak in the tank?
I did this while the car was "cold" so maybe I need to run it and then test the pressure. But the point is. I only got 10PSI when I turned the ignition to ON. 10. It built pressure as I turned it on and off. But it bled off fast. Really fast.
I didn't even bother to crank it. I know where my issue is - could be an install error since it is a Racetronix pump/hotwire kit.
But that would definitely mean the injectors are smaller than the PCM thinks, would account for my hard start issues, and my VE table problems (I'm seeing numbers in the 140s).
Car seems to run fine but I haven't really pushed to upper RPMs because of the issues. One thing that is weird - I had to realllly lean it out for it to have lean idle. Seems like that's counter to having smaller injectors than what the PCM sees? So could it be a leaky injector? Although at the rail, the pressure never built. Tomorrow, I'll start it and monitor it as fuel is delivered.
Any ideas? Is this a pinched line in the tank? A leak in the tank?
Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
I used the VCM bi-directional controls to turn the pump on (got home late and didn't want to fire it up). It builds to 58 PSI. But as soon as I turned the pump off, it dropped to 0 very quickly and didn't hold any reserve in the line. I'm taking less than 5 secs it was back to 0. None in the rail so that when I hit the pressure release on the fuel pressure tester, no fuel came out.
I need to crank it and see if it holds steady - this would explain my cold start issue, VE table issue, and my warm up issue. If the fuel pressure fluctuates it's hard to tune with that variable.
I'm betting there is a small leak somewhere. I don't think the injectors are the culprit, but maybe they are. I'll check them. I'm inclined to think I have a hole in the line in the tank or my FPR is going south. Or the check valve is gone in the Walbro pump. I'll see tomorrow how it holds pressure.
I need to crank it and see if it holds steady - this would explain my cold start issue, VE table issue, and my warm up issue. If the fuel pressure fluctuates it's hard to tune with that variable.
I'm betting there is a small leak somewhere. I don't think the injectors are the culprit, but maybe they are. I'll check them. I'm inclined to think I have a hole in the line in the tank or my FPR is going south. Or the check valve is gone in the Walbro pump. I'll see tomorrow how it holds pressure.
Last edited by JakeFusion; Apr 22, 2015 at 11:15 PM.
Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
Well, the racetronix pump is supposed to have a check valve. But that may be a different problem. At idle it holds 60 psi and when i rev it doesn't move off 60.
So I guess I'm back to the injectors being problematic.
So I guess I'm back to the injectors being problematic.
If it was the injectors you would have an extended crank, (worse when the engine was hot due to vapor lock), run rough, miss and smoke like hell when started.
I can't remember how the regulator is setup in the tank. Obviously the pump has a check valve in it but some intake regulators do too. It could be the hose between the pump and the top of the fuel pump module.
I can't remember how the regulator is setup in the tank. Obviously the pump has a check valve in it but some intake regulators do too. It could be the hose between the pump and the top of the fuel pump module.
Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
I think it's the hose between the pump and the fuel pump module.
Stopped raining today and I was able to go do some blasts down the highway with a mechanical fuel pressure gauge taped to the windshield. Moderate throttle and I'm seeing it drop 10+ PSI. That's why my VE table is so far off in the upper RPM. It's losing even more the more throttle I give it.
Stopped raining today and I was able to go do some blasts down the highway with a mechanical fuel pressure gauge taped to the windshield. Moderate throttle and I'm seeing it drop 10+ PSI. That's why my VE table is so far off in the upper RPM. It's losing even more the more throttle I give it.
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Verdad Gallardo Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
It's the GM flex line that comes with the Racetronix pump.
If it's not that, then either I'm losing voltage with the hotwire kit or the pump is somehow bad or was installed wrong (even though Racetronix gives you about 19 steps to install it).
If it's not that, then either I'm losing voltage with the hotwire kit or the pump is somehow bad or was installed wrong (even though Racetronix gives you about 19 steps to install it).