Fuel Filter Replacement

[332bill]

I did not know when my newly acquired suburban had its fuel filter last changed, so I decided to change it. I followed the instructions in the manual. The old filter was filthy and there was a fair amount of sediment in the bowl. After cleaning out the filter bowl and installing the new filter, I put the cap on and attached a hose to the bleed valve. The instructions say that fuel should come out the bleed valve when the engine is cranked. A very small amount did, but not much. The engine started pretty quick, I didn't have to crank it for more than 15 seconds or so. After it started, it runs fine. In fact, after the filter change the engine seems to have more power and the turbo whine is MUCH more noticable (I could hardly hear it before). I took off the bleed valve so I could look into the filter bowl and the filter bowl is full to the top. So my question is, should fuel stream out of the bleed valve when it is open and the engine is cranked or running? If it is supposed to and it doesn't, what's wrong? Weak lift pump?

Bill

[Dimsdale]

I just changed mine as well (99 Sub K1500)

The fuel absolutely should flow out of the air bleed. Is it open enough?

When I do mine, I first make sure the engine is warm enough to prevent glow plug cycling. Clean the area around the filter as best you can. I unscrew the fuel filler cap just in case there is pressure or vacuum in the fuel tank. Then I drain the filter housing (bleed open, then drain into bottle. I put a tube on the air bleed and blow into it to force out the fuel. Very little left in bowl after that.) Then unscrew the big black filter nut, and carefully lift out the filter into a plastic bag. Clean out bowl if necessary. Clean the gasket surface around the top of the bowl. Reinsert new filter with FRONT facing, well, front. Screw down the big black nut. Close the fuel drain, and open the air bleed. I put a clear Tygon tube on it that feeds into a glass bottle.

At this point, per Charlie Peterson's instructions, I simply put the ignition to the run position (no cranking). The lift pump activates and fills the fuel bowl, purging the air out. When the fuel runs through the tube connected to the air bleed, turn off the ignition, close the air bleed, pinch the hose and remove it from the bleed nipple. Wipe any spilled fuel from the filter area, both to prevent the smell, and allow you to see any subsequent leaks.

Clear all your tools etc. from the area and start the enging. Look for leaks.

Worked for me yesterday anyway!

Good luck!

[332bill]

I drove it 300 miles over the weekend and it ran fine. But I'm gonna check the lift pump tonight.

Bill

[332bill]

I checked the lift pump the other night, fuel did flow out of the water drain hose, but there was almost no pressure behind it. I have ordered a new lift pump.

Bill

[jspringator]

You may want to consider a fuel filter before the lift pump to protect the pump. I use a Racor 645 with a 30 micron filter.

[damork]

I second the vote for a pre-lift pump filter as I installed the same on my truck. The argument for a better than 5 micron filter can probably be made with what some fuel systems engineers have been finding in fuel quality.

As refining techniques improve to squeeze every possible drop of fuel from crude, a byproduct known as "catalytic fines" is created which are small hard metal destroying particles that can wear away metal. They can be as small as 2-3 microns.

Companies using 10 micron filtration in the past have switched to 2 micron filtration, and not just for the newest fuel systems but to protect older ones.

I've considered a 2 micron Racor in place of the OEM on my 6.5 as well. I talked to a Stanadyne engineer a while back who was concerned about the sticking fuel driver solenoids they were finding that had some "contamination" on them and error codes like 35 and 36 were being observed on 95 vehicles.

[332bill]

I replaced the lift pump and now have 7psi at the water drain line. However, it seems that when I remove my fuel tank filler cap there is almost always a vacuum in the tank. Is this normal, or has my cap gone bad.

Bill

[catmandoo]

i'd say the cap took a s*#t,mine always has pressure.hows the 332 runnin bill ,just got mine out of storage,gonna change the hydro and sharpen the blades and she hits the lawn.

[332bill]

I did a search on fuel tank vacuum and found quite a bit of info. I did the old mouth check of the cap(after cleaning of course) and the check valve is working properly. It takes a bit of suction to open the valve, but not a lot. It holds pressure. As I said, there is some vacuum in the tank but not a lot. I think its OK.

The 332 has been out mowing for about a month. Been runnin' great!

Bill

[AndyL]

Originally posted by Dimsdale:
I just changed mine as well (99 Sub K1500)

When I do mine, I first make sure the engine is warm enough to prevent glow plug cycling. My GPs always cycle, no matter how warm. Wonder if I have something wrong?

[DickWells]

I thought all the 6.5s would cylcle the GPs when the switch is turned on. I don't even turn mine on to pump fuel out of the filter bowl. I just take off the power dist. cover, take out the fuel pump relay, and jump sockets 85 and 86 (?) together and that pumps fuel out as long as you want to keep them jumpered.
I've had the plastic filter from down under come out with the paper filter, and it's a bear to get back in so that you don't have a leak around the big plastic nut/gasket. I think I got down in there and took it out the first time, just to see what it was, and to wipe out the bowl. Shouldn't have done that! Soooo, back a couple of changes ago, I did indeed have a slight leak around the top. The gasket fell off, and I had to push it back into the groove. Twice! I could just barely turn the nut by hand enough to stop the leak.
I have the RaCor 645, too. I relied on it too much, and waited too long one time to change my OEM filter. I had thick amber liquid in there that came out the drain petcock first! I didn't like that either. Think it might be because I use additive with every fill-up? Looked like additive.
Just a few thoughts from this old fool's point of view.
Dick