[Vckline313]

Been having some backfire issues on the freeway and a loss of power when shifting into third at wot I'm thinking the quadrajet is running out of fuel. Then I noticed my filter (relatively new about 6 Mos). Is barely filling at idle. Even when I increase rpm the filter never completely fills. Is this normal or signs I need to replace my fuel pump? If so what kind is reccomended. It's a 400 engine with a pretty nice size cam and a smi built quadrajet. I did notice the loss of power after 3 and the back firing more apparent after I changed my hei curve to come all in at about 2800 rpm and my timing set at 36° all in. If the amount of gas is fine should I just fatten up the a/f screws on the carb? I have them adjusted with the vaccum gauge getting about 10hg at idle

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[Tom Vaught]

My recommendation would be:

a) to look at the filter inside the carb itself.

b) Get rid of that plastic filter as soon as possible and install a filter like used on a
Pontiac Tri-Power made out of steel, or something similar.

Tom V.

[Vckline313]

There is no filter in the carb

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[Holeshot71]

It’s hard to see in the 2nd pic, is that 3/8” vacuum port to the left of the fuel inlet on the carb open?

[Vckline313]

Originally Posted by Holeshot71

It’s hard to see in the 2nd pic, is that 3/8” vacuum port to the left of the fuel inlet on the carb open?

No there is a black cap on it

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[400 Lemans]

Originally Posted by Vckline313

No there is a black cap on it

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I would shorten up the pcv hose and put it on there in front of carb.

[steve25]

What is the cam specs?
What heads are you running?

Are they ported or not?

[77 TRASHCAN]

Originally Posted by Tom Vaught

My recommendation would be:

a) to look at the filter inside the carb itself.

b) Get rid of that plastic filter as soon as possible and install a filter like used on a
Pontiac Tri-Power made out of steel, or something similar.

Tom V.

If nothing else, do "b" please!!!

[Dragncar]

First thing you need to is get rid of that fuel filter if you care about your car. Seen one burn to the ground over one.
I run a steel fuel filter on my lawn lower. Plastic is not safe even there. Hate those things.

[Goatracer1]

Back to your question. Just because the filter (good or bad) is not full of fuel doesn't mean anything. In the past I have worked for dealerships where that type of filter came standard on all their cars. They were almost never full of fuel. You need to perform a volume flow test and see how much is actually being put out by the pump if you have doubts.

[Tom Vaught]

I HAVE SEEN A BUNCH OF FIRES (ON VERY NICE VEHICLES) over the years.

I even had one on a 1982 Mustang with the 302 cid engine.

Mechanical fuel pump diaphragm failed, gas dripped on the sheet metal under the car, bottom of the car was smoking.

I looked underneath and saw the fire. Vehicle was parked in the driveway. Grabbed a fire extinguisher and put the fire out.
(have posted this story before).

Changing that mechanical fuel pump was a royal PIA. Had to remove the whole FEAD system to replace the pump.
Lucky it happened in daylight vs at night or the car would have possible burned up in the driveway.

Put a steel filter on the thing, forget about all of the other vehicles that have installed that crap on their vehicles.
YOUR vehicle is the only one that is important.

Tom V.

[Vckline313]

The plastic filter was to keep an eye on the gas because the car sit for long time and when I first started to drive it I kept getting trash in the carb since all that has been sorted out i will change filters

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[NeighborsComplaint]

Filter needs to be dead level, not inclined.

[Brian Baker]

Get rid of all that rubber fuel line and run a steel line from pump to carb as well.

[Schurkey]

NeighborsComplaint and Brian Baker beat me to it.

The fuel filter has an air bubble trapped in it, it will NEVER go away as long as the filter is laid-over so the outlet is lower than the air bubble. When the filter is upright, the air bubble will pass harmlessly into the carb, and be vented out the float bowl.

Rubber hose on the pressure side of a fuel pump is a VERY BAD IDEA. GM almost never allowed that, they always used double-wall seamless steel tubing; sometimes connected to brass tees as needed. I've seen SHORT sections of rubber hose on other vehicles, (Ford and AMC come to mind) often right at the in-line fuel filter.

Those worm-gear clamps are popular, cheap, and they work for awhile. They destroy the hose they're clamped-to. Use "Fuel Injection" clamps as shown in the photo below; or at least use shielded worm-gear clamps so the little slots are covered. Oetiker makes fine clamps that are easy on the hose, (but very uncommon, expensive, difficult-to-install properly, and hard-to-source) and OEM-style spring clamps--the ones most guys throw in the trash--are severely under-appreciated.
http://hbassociates.us/Fuel_Pump_9.jpg