Fuel Pump Check Valve Test

[Snax]

So I had decided that my fuel pump has failed since all of the lines to it were totally dry. Now I have it off the car however and all of the tests described in the manual test good except for the oil vent seal (but that shouldn't affect pumping right?), so I can only guess that the check valve is the problem. Does anybody know a good way to test it, or is it just a given since I have a full tank of gas, good lines, and barely a drop of fuel in the pump?

[Jarf]

Dude, you really need to brush up on your diagnostic skills.
You make many assumptions in your bid to find an easy repair, but this course of action will bankrupt the deepest pocket.
You really need to A) understand what your are working on and B) DIAGNOSE your faults.
Your car is VERY simple. There is a gas tank and 3 lines (feed,return,vent).
You have verified that you have no fuel at the pump, yet you keep wanting to replace the pump?
If you have no fuel at the pump, it is likely cause by something before the pump, no?
Follow the pump feed hose (that would be the big one that does NOT go to the carb) disconnect it and suck on it. If you get a mouthful of fuel than you likely do have a fuel pumping problem. If you do not get a mouthful then there is something stopping the fuel from traveling thru the line.
Over the other side of the engine you will find a fuel filter that is quite likely plugged solid (seen it before) if it is all good pull the feed line TO the filter and perform your taste test again. If still nothing, get under the car and find where the metal lines transition to rubber (around the rear axle), there you can pull the feed line and check it (can you blow through it?). (lines can get plugged but is is rare)
Keep working you way back till you find a real problem, fix it and retest.
Those fuel lines continue on to a pick-up flange (top of the tank) that also has a bad habit of rusting out.
One other thing to consider, the pump sits in a "sealed" circuit tank-pump-carb-tank.
While also rare, it is possible that the strainer on the pick-up tube has melted (ethanol can be nasty stuff, 10x as corrosive as gasoline) and is plugging the pick-up (seen that before too).
Go back and diagnose, then repair what is needed.
$20 might be a good deal for a pump, but if you don't need the pump it is $20 wasted.

[ARCHINSTL]

You might use a vacuum pump with the inline jar instead of the taste test - it works - I've done it.
There was a fairly recent thread on this clogging.
Tom M.

[scouttster]

I just replaced my fuel pump 3 days ago and went about all the diagnostic procedures that Jarf described and came to the conclusion it was my fuel pump.
The only thing I can add is this and this may help. With the pump removed from the car - I manually toggled the old fuel pump with my hand and I would get such a slight puff of air sensation blowing into my face. When the new one came in the mail ( rockauto $15 ) I manually toggled that it was a much stronger puff of air blowing in my face.. That pretty much confirmed for me that, the pump was the problem - and it was.. Car is back running..

[Snax]

Thanks for the input Jarf, but there is a reason people came up the KISS acronym - and a $20 fuel pump is a small price to pay vs. the labor of doing everything you describe. It's a 10 minute job to boot! (Or at least on mine, sans-emission controls with the Weber carb.)

That aside, it WAS THE PUMP! After 20 seconds of cranking it fired right up, so my guess was the check valve on the old pump quit working properly. It's the only thing that could explain it going from running fine one day to not running at all. If there were a starvation issue due to an obstruction, I probably would have noticed it long before. Also, air had bled back into the fuel filter, indicating a problem with drainback. So perhaps I failed to provide all of the details, but yeah, all indicators pointed to the pump.

[teranfirbt]

Sounds like the problem with my Tercel, if I let it sit for a couple days it takes forever to get fuel back up to the carb... Despite having a freshly cleaned and inspected tank with a brand new fuel filter.