Long story short: I replaced my in tank pump with an in-line and ran a piece of steel line from where the pump used to sit to near the bottom of the tank. It's attached together with the rubber line that was in the tank between the fuel line in the tank and the pump. I don't think I used a clamp on this. I'm going to check fuel pressure tonight, because my car is running horribly, and I think this may be the problem. Did I screw up by doing this?

 

OH MY!!! BETTER GET OUT THE BOOK OF ROYAL SCREW UPS!!!!!!

Just kidding!!!

If the pump that you put in is a "puller". That means that it does just that. It pulls the fuel more than anything.

The stock pump is called a "pusher". It pushes more than pulls.

The "puller" is more prone to running weak if it isn't "bottom feed" from the tank. Basically that means that the pickup line should be fed through the bottom of the tank. If you try and do what you did, the pump won't be able to suck the fuel 'uphill' enough to feed the engine.

You can actually run them both. I've seen guys run the "puller" in line with the "pusher" feeding it. I would just make sure that you increase the size of the return line.

Maybe you just have an air leak in the line that you didn't clamp. If so then that will greatly lower the amount of fuel that is being feed, and in turn, lower fuel pressure.

I may be way off base myself. Someone else help or even elaborate, please.

AJ

[This message has been edited by AJ_92RS (edited October 29, 2001).]

 

I'd have to say that your explanation pins down what I thought it was, AJ, but I'd add that it's a lot easier to pump through rubber lines, than it is to pull. Creating a vacuum in the rubber line will cause it to constrict slightly. We're running a low pressure, but in conjunction with what AJ was talking about, it'll cause your symptoms.

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No guts, no glory.

 

I thought that would be problematic (sigh) sounds like I need an in-tank pump. I"ll probably go with a Walbro.


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91RS convertible 355 TBI 65# inj. custom compcam grind .480/.480, Edelbrock TBI manifold, open element, hedman hedders, Y-pipe, cheap cherry bomb muffler, Hypertech cop car thermomaster, Accel coil, wires. 2.02/1.6 cast iron heads. Engine specially made by Pflugerville machine shop. Forged bottom end, balanced. Coming soon: Vacuum controlled FPR, better exhaust, Torque converter, DIY PROM, bigger TB.

 

Oh yeah, I checked the fuel pressure, and it drops when I hit the gas. I have the Vacuum FPR, and thought that in conjunction with the fuel pump issues, I probably have a vacuum leak. The Fuel pressure guage in this case should also act like a vacuum gauge under load, right? In other words, you should be able to calculate vacuum off the FP gauge, knowing how much psi increases per HG" of vacuum, right?

 

You could do that but it isn't very accurate. Your MAP sensor is much better at giving a good vacuum or just go get a vacuum gauge, they're pretty cheap.
It definatly sounds like the fuel pump isn't doing it's job. Have you checked to make sure it's getting a good 12+ volts?