I've changed several fuel filters and it seems harder and harder to get the lift pump to prime the filter. I bump the engine over and over about 10 times and then there seems to pressure on the lift pump handle and then the fuel starts to flow. I have 220K on the original pump so I'm wondering if it's starting to get weak. Anyone else experience this?

I did an Advance Auto Parts search and the lift pumps were $75 new.

 

By the way, it's a 93 with a 5 speed and my first tank of B100. (so far so good)

 

Rather than bumping the engine, you need to use the lift pump lever to remove the air. Use the air bleed screw at the top of the filter housing. It's at about the 7 o'clock position if you look down on the housing. It's a small screw with a notch in the threads. You only have to loosen it a few turns, then pump the lever until fuel appears from the notch. If that doesn't work then, yes, your pump is getting weak or you've got a small leak in the fuel line between the pump and the tank. Bumping the engine is not recommended since this activates the injection pump and introduces air into the injection system. Could cause potential problems with air locks and such. And the VE doesn't like the no-lube condition of air!

 

Tuck,
When I pump the lift pump lever, there is no resistance (no fuel flow). That's why I have to bump the engine over. I'm aware of the bleed screw.

I feel like the injector pump is what's actually priming the fuel filter. I saw on here where the injector pump actually produces enough suction that it can by-pass the lift pump.

 

Um...yes, I think the injection pump can create enough suction to overcome a bad lift pump. But you'll sure notice under load and high rpm situations...it just won't give you enough fuel.

Are you filling up the fuel filter with diesel before you install it? I'm just wondering if the "no resistance" is actually moving fuel into the filter. It will take a while.

Don't ge me wrong, you certainly could have a bad lift pump...that's a lot of miles and many many gallons of fuel the pump has lifted. Just offering suggestions.

 

I haven't been filling the fuel filter before replacing. I normally don't even crack the bleed screw, I just leave the filter unscrewed a bit to allow fuel to seep out the top. That tells me the filter is full of fuel.

 

unclet, My 91 has almost no pressure on the priming lever untill the filter is full and I think the line going to the IP as well, seems to take forever before there is any resistance. By prefilling the filter, you can sure save yourself alot of potential headaches caused by air getting sucked into the lines and IP.

 

I always fill my new filter before installing it. Have had no problems starting after words. 220,000 miles on mine.

 

The pump rides on an eccentric lobe of the cam and if it happens to be on the high side the pump may seem like it has no resistence and won't pump. Bumping the engine over so the pump is on the low side will fix this. I would do the bumping before changing the filter.

Edwin

 

I appreciate the help and will try and fill the filter before priming it with the lift pump.

UT