Could a fuel pump cause blockage?

[Dyno247365]

I think the fuel line between the gas tank and the fuel filter may be partially clogged, there's no gas coming out of it until I shake it and then there's only a little. I can't successfully drain or siphon the tank fromt the line. Someone suggested I need to drop the tank and replace the fuel pump($160-200). I don't want to do that. I want to know if a malfunctioning fuel pump could cause a block?

[UncleBob]

The simple answer to your question is no.

In order for something to block a line, it would be a bit of a challenge, since there is no obstructions in the line, so there is no where for "something" to get into the line and then lodge. Anything that can get into the line, would also be able to travel the length of the line and exit into the filter.

So you very well could have a bad fuel pump. But you'd want to verify that you have power (and ground) to it before dropping the tank.

[Dyno247365]

Originally Posted by UncleBob

The simple answer to your question is no.

In order for something to block a line, it would be a bit of a challenge, since there is no obstructions in the line, so there is no where for "something" to get into the line and then lodge. Anything that can get into the line, would also be able to travel the length of the line and exit into the filter.

So you very well could have a bad fuel pump. But you'd want to verify that you have power (and ground) to it before dropping the tank.

Ground to it? could you explain?

[dave92cherokee]

Get a voltmeter and where the power wires connect to the fuel tank with the ignition in the ON position check to make sure you have 12 volts on the positive and then set the meter to check continuity and check the ground wire on the pump to a clean metal point on the chassis. If that checks out then you probably have a bad pump, if there's no voltage at the pump check the fuses and relays to make sure they're good.

[curtis73]

Originally Posted by UncleBob

The simple answer to your question is no.

I hate to directly disagree, but I will The pump is indeed designed to be a restriction. If you think about it, if you run the car in the evening, then go down in the morning and pull a fuel line, you'll still have residual pressure in the lines. Its that much of a restriction. You can't siphon through a fuel pump for that reason. Proper procedure in the shop manual has you swap the wires to run it backwards for a few seconds to remove pressure from the line before you crack it open. Its also common to pull a line and then use the pump in its normal operating direction to drain the tank.

On a car with no in tank pump, when you blow on the fuel line you'll hear little bubbles in the tank. On a car WITH an intank pump, you'll just turn blue in the face.

Its possible that your fuel pump is failing, but if the only symptom is an inability to siphon fuel, there is no problem. Just use the in-tank pump to drain the tank into a gas can.

[UncleBob]

Originally Posted by curtis73

I hate to directly disagree, but I will

uh...you didn't disagree with me. The question was, could there be a restriction in the line itself. At least, that was the question I was answering

[curtis73]

Ah... misread But just to disagree.... UncleBob is neither an uncle, nor a bob... discuss.

[Dyno247365]

Originally Posted by curtis73

Ah... misread But just to disagree.... UncleBob is neither an uncle, nor a bob... discuss.

I've come to the conclusion that either I need s new fuel pump and there really is no block in the line, or there's something wrong with my ignition. Here's why. I tested the pump today by turning the key to the on position, and it turned on momentarily, I siphoned some fuel and then it turned off. I repeated this procedure and sometimes the fuel pump wouldn't turn on at all. This is the same problem I had with starting my engine from the start.

So it's either the pump, or the ignition, but now that I think about it, it can't be the ignition because I can use the power windows, locks, and other amenities when the key is in the on position. What do you think?

[UncleBob]

When the engine is cranking, the fuel pump will be running full time.

If the pump is running, and the car won't start, you need to test fuel pressure to see if its up to snuff.

BTW, GM fuel pumps are pretty famous for failing.

[Dyno247365]

Originally Posted by UncleBob

When the engine is cranking, the fuel pump will be running full time.

If the pump is running, and the car won't start, you need to test fuel pressure to see if its up to snuff.

BTW, GM fuel pumps are pretty famous for failing.

Now..see...I said I turned the Key to ON position, I didn't try to start the engine. I have the fuel lines apart right now and I'm siphoning the gas into a gas can. When I turn the fuel pump to on, it doesn't turn on every time. Someone suggested it could be the fuel relay. Does this mean I need a new pump?

[UncleBob]

Originally Posted by Quicksilver_28

Now..see...I said I turned the Key to ON position, I didn't try to start the engine. I have the fuel lines apart right now and I'm siphoning the gas into a gas can. When I turn the fuel pump to on, it doesn't turn on every time. Someone suggested it could be the fuel relay. Does this mean I need a new pump?

not sure what is this talk about syphoning.....it should be pumping out gas all over the place when you turn it on. 40 GPH is a crap load of gas that should be puddling all over the ground. If it requires you to suck on a hose to get gas out, then the fuel pump definitely isnt working.

The fuel pump will prime for 2 seconds when you turn the key on, but if you make multiple key cycles, it will stop priming, because the computer knows that its as primed as it'll be.

But when you crank it, the pump will always be running.

If you think it might be a relay, then you haven't verified power and ground to the pump. Again, verify that before going further.