I hate these pain in the a$$ problems.

Good luck,

Dear Santa: PLEASE, all I want for Xmas is my fuel sytem to work right

I've been following along with your predicament, and don't have the answer either. But if I were you I'd take two steps back and look at the big picture. It's something real simple and stupid! Your fuel system is adequate to run 8 second quarter mile runs back to back, and you know all the components are fine. I can't explain the air bubbles, but I've never looked for them either. Maybe all fuel pmps cavitate when they "dead head" and fuel isn't flowing. Isn't that why the carb's bowls are vented? Your engine should run for several minutes just off the fuel in the bowls, especially with 2-4s. Assume the fuel delivery is ok and look for something else. I might me all wet, but that's what I'd do. How about trying a boat gas tank temporarily positioned above the carbs and gravity feeding the carbs? It'll keep up and will totally eliminate the fancy fuel system. Good luck,

Rememeber guys, EVERTHIING relating to the fuel system is brand new and clean as a whistle. Now another half of the new system has been replaced three time. At this point it isn't the money anymore....it a damned quest and don't care what it takes to fix the problem!!!

[This message has been edited by Gary (edited 12-15-2001).]

quote:

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Originally posted by Gary:
How can three pumps and regulator be bad in a row? If so Iv'e gotten the worst luck!

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That's why I think your fuel system is fine! Although it may be overkill! A 5/16" line with a stock mechanical pump would work fine for your street/show thumper car. You could be over powering your needle valves if you're sure the gravity feed system would work fine. You do not need that much fuel to cruise on the street. My daughter's '66 uses a stock 5/16" line and a holley red pump and has never had a fuel problem running 12 second 1/4s. Other folks that I know can run a 1/4 mile drag race with no fuel pressure at all and 2 four barrels! So, all I'm saying is maybe less is more. 5 psi is way more than adequate for your needs.

When the floats are closed on our 351w's 750 holley the clear fuel filter is empty. (yep full of air) I dunno where the air came from, and I don't really care! Take two steps back and think about it Gary. Good luck, your car is AWESOME!

quote:

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Originally posted by Gary:
I snapped a pic of one of the ways the pump is installed. Note: the fuel level is quite abit higher then the pump and the weight of the fuel should always keep fuel to the pumps inlet. Iv'e even tried lowering the pump well past the fuel outlet of the tank with filter removed and still have my fuel delivery problem. With this pictured pump and line arrangment fuel should have no problem getting to the pump.
http://hometown.aol.com/garyslight/page1.html

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Have you replaced the line coming from the tank to the pump? I've had a braided hose fitting cut a nice flap inside a hose once that drove me as, well almost, as nuts as you are at this point.

What does the system do when you disconnect the carbs? Does it constantly deliver the same volume or does it still drop off after a while? If you connect a short line to the outlet of the pump does it still act up?

Just some thoughts.

Tracy

I shared your predicament with several of my racing friends yesterday. Two of these guys have been racing for 30 yrs. The consensus seems to be.

If you are going to run 1/2" fuel line on two 4s you need two regulators. One for each carb. It is a volume problem that one regulator cannot handle. (1 line input into 4 lines output)

Or

If you do not want two regulators. Run 1/2" line from the Fuel Cell to the Pump. From the Pump to the regulator change the line to 3/8" line. That will supply more constant pressure to the regulator and should solve the problem on a car that sees the track ever once in a while.

Re-install the clear test line from the tank-to-pump line...disconnect the regulator-to-carbs fuel line and run it into a clean 20 gal container...run the fuel pump and watch to see if air bubbles form on the tank side with the fuel pumping into the container...I'm not sure if your fuel cell would pump empty before air bubbles start forming in the clear tube, but if it does - then I'd be inclined to think that it is a matter of cativation due to deadheading at the carbs...

Maybe better yet (or easier to do) would be to simply install your cell-to-pump clear test line and install a temporary fuel return line from the carb fuel manifold (log) to the cell and run the pump to see if it would run more than the usual few minutes without producing the air or drop in fuel pressure. If it does not produce air bubbles in the clear test line over the usual few minutes, then try it with the engine running -- I agree with some of the other opinions; that your problem is related to deadheading and cativation.....

I tested all three pumps this way and get the same test each time, I tried the same test installed in my car but with pressure regulator so I would no overcome the needles and got the same results but starting from 6psi. The darn pump cavitates after running awhile which makes the pump loose it's prime evidently and will never recover. Ok now that I have figured this out how do I FIX the problem??? I read where I need two regulators with my application but how can that effect or change the cavitation problem of the pumps when your sitting at an idle not consuming much fuel and flow is at a minimum? This deal with fuild flowing over and through fittings and getting distrubed and or causing vapor lock may be true if the pump was open and free flowing but when the fuel barely moves that idea im sorry is N/A.

I'll try the dual regs but can't see how that fixes a pump that won't even maintain PSI. sitting at idle speed or a quick run around the block in first gear.
This is BS, I should NOT have this problem to such an extent where the car will eventually run out of gas due to lack of fuel pressure having it set-up the way I have it, im not trying to demand all the power from the engine at this point, just a ride around the neigborhood after two weeks of this crap would be nice.
Pump is going into the trash!!! I'll buy something else with less hassel. Iv'e wasted the last day (14 of them)im going to on this headache.
I bought everything new because I didn't want troubles like this, certainly did not expect all of this from such a simple install and basic idea. One reg two reg, it should still work with either or as long as there's one and better with two im sure, but NOT at all just doesn't cut it for me!
Im ordering a pump with a return line, and installing two regs. Hopefully that should cure my problem and won't have to listen to the WA-WA-WA of the other pumps.
Sorry I vented on this subject, im sure this pump would work great on a race car with the pedal to the wall but for both worlds I believe the line return style pumps would probably be a better choice for me.
Thanks for all the replies and help on the subject/s

[This message has been edited by Gary (edited 12-17-2001).]

I think the return line system is a better idea in that it lets the pump flow freely, you need only enough pressure to keep the bowls full... even 2 or 3 psi will be fine, you can keep your system almost as is, just run the regulator off the end of the fuel log and a hose/tube from it's outlet back to the tank. I'd also say running a larger inlet into the pump and a bigger tank to pump line is a good idea. I use 5/8" hard line and -10 hose into the pump and 1/2" tube and -8 from pump to reg.

A problem i had was the fuel pump uses fuel to cool and lubricate it too, run it out of fuel even momentarily and it won't work right afterwards. In my case the georotor pump (mallory) would actually let the rotors expand and seize in the housing...pump would stop. It'd work fine after cooling down.

Hope it works out for you.

BTW, cost for mod was 23.00 bucks! Alot cheaper than the cost of a return style reg. thats for sure and all the tubing and fittings. Also, Holley does not make a return style regulator...only return pumps.
Other wise your looking at using a Mallory reg. or other.

Good Luck!