my 85 elco wont start.

[85elcamino]

i have an 85 el camino, 305 v8. car has been sitting for about 3 1/2 years. put a new performer carb on it 600 cfm. new fuel pump and filter. the car starts when i pour gas into the carb but wont stay running or start on its own. acts like its just not getting gas after it runs out of what i dump in the carb. blew the lines out and they seemed free and clear. just wondering if there is something else i am missing. any ideas or info on this problem is much appreciated.

 

[87ChevyR10]

What kind of fuel pressure are you getting? Can you see the fuel jetting into the throat of the carb? I'd start at the fuel pump and go from there. I assume the fuel pump is mechanical?

 

[85elcamino]

Yes Mech Fuel Pump. Gas Isnt Even MaIng It Into The Carb. Guess I Could Have Got A Bum Fuel Pump The The Parts Store. Only Thing I Can Figure At This Point. She Runs When I Fill The Carb With Gas. Im A Bit Stumped.

 

[chengny]

Confirm that you can get flow from the fuel tank to the suction side of the pump.

Pull the hose off the pump inlet and blow back through the line. Do this with the gas tank open to atmosphere (fill cap removed). If you hear bubbling within the tank, and get air flow out of the fill pipe, you are clear all the way to the bottom of the tank.

Next, confirm flow in the normal direction.

This may seem kind of gross, but (unless you have some type of vacuum pump) it's the the quickest way. Attach an extension to the inlet hose and, using your mouth, try to suck some fuel from the tank.

If you get a mouthful of gas, the suction side is good. Reconnect the inlet hose and go to the carb inlet.

Disco the pump discharge tubing from the carb inlet and attach a hose. Put the other end of the hose in a beer bottle or some other container. Crank the engine for 15 seconds and observe flow into the bottle. After it has primed, the pump should deliver at least 8 ounces in a 15 second test period.

No flow into the bottle; then the answer is yes - you probably got a pump that is bad out of the box.

If you do get good flow all the way up to the test bottle; the problem is within the carb. Probably the float valve.

 

[85elcamino]

i already blew thru to the tank with the cap off and could hear it bubbling. but got cut short due to work.

 

[chengny]

You can probably skip the suction test on the inlet side. But what about the flow test?

I'm sure you know, as well as I do, what a pain it is to change the gas pump with the engine in the truck.

I would definitely do the flow test through the pump and up to the carburetor inlet - to confirm a bad pump before pulling it.

Mechanical fuel pumps rarely fail, so there is one other thing to check - even if it doesn't pump with the discharge line removed from the carb:

One other possibility that would prevent even a good fuel pump from delivering gas to the carb is air leaks in the lines/hoses on the suction side of the pump.

Even a small air leak will prevent the pump from creating enough vacuum to pull the gas up and out of the tank. You might want to recheck the condition of the gas line between the tank and pump. With air pressure applied, trace the entire line and listen for leaks (or spray a soap suds solution and look for bubbles).

 

[85elcamino]

no leaks in the lines. but I did some poking around and come to find out the plunger rod is stuck in the engine and seems to be slightly off center. idk if its supposed to be off center but it is and doesn't move in the slightest. everyone says it should damn near fall out when I remove the plate behind the pump. mine just is stuck in there. it was all the way against the plate if that tells you the position it was in. I believe this to be my problem. but have no idea how to remove a stuck plunger rod.

 

[chengny]

I don't know the history of your engine but it sounds like someone has locked the fuel pump push rod with a bolt. That probably sounds like nonsense but bear with me.

On earlier 350's there was a provision to hold the rod in place during fuel pump R & R. In the front of the block, RH side, way down near the oil pan rail - there are two tapped bosses. They can be used for mounting various accessories - like a smog pump bracket for example. There is an identical set on the LH side that accept the bolts for the P/S pump bracket.

Here is the part that may be your problem:

The top hole on the RH side often (but not always) extends all the way through the block. It is tapped all the way and lines right up with the push rod. So, if you screw in a long enough bolt, the tip will bottom out against the side of the rod and lock it in place.

Here are a couple of images showing the locations:

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When the bolt contacts the rod, the part of the rod that is not in it's bore will shift over a bit. This will make it appear off center.

If there is a bolt in that boss, remove it and see if your fuel pump push rod falls out - they usually do.