clear fuel filter frustration!

[Dale .D]

Hello ,not sure if I have a problem or not!.Problem is the clear filter almost goes completely dry when idling after a while then i rev it up & gets half full & does it again but never dies. Is this normal.Can't take it for a real run yet until spring.This is what ive done so far.Checked pump screen perfectly clean.Pump new last summer.gas flows freely to the pump by gravity.Tried gas cap off, no difference. runs fine. shaved intake & exhaust manifolds & new gaskets,all new hoses.new sprint. Eliminated the heat sheild.every sure there are no vacuum leaks.just want to know if this is normal or not.Maybe it was better with the other metal filter where I was oblivious to this issue.If it looks like this might be a problem .I'll be doing the electric pump thing & thankyou to tekenaar for finding me the article on removing the tank sock without removing the tank . Cheers Dale

[MICAH1]

I have had the clear fuel filter for four years with the mechanical and electric fuel pumps and the gas level is the same as yours.

[Dale .D]

that's good news but why wouldn't the filter be full all the time?

[MICAH1]

Is you filter the clear glass or clear plastic with the paper filter??? To answer the other question.... how do we know the metal filters are full with gas? Their levels may be the same as the clear ones.

[GTJIM]

They often run like that - looking empty. I have a feeling that it is trapped air or perhaps fuel vapour.
You could try filling the filter with fuel before attaching the second hose ... though it does not seem to make any difference to the runing of the motor.

[Dale .D]

Your right & can shut the motor off with hardly any gas in the filter & when I come back the next it's conplettly full. Must just be expantion and the heat after you shut things down.

[namba209]

This begs the question: Is your filter horizontal or vertical? On Willit? I've got mine mounted vertically with the fuel inlet at the bottom and outlet at the top, so the fuel has to go from bottom to top, through the whole filter element. The reason the filter fills up after you shut down the engine, is because the fuel will drain back from the carb, which is higher than the tank, to the tank until it seeks its own level, which will be about the level of the original fuel pump or maybe even lower. HTH.

[newman27]

What a timely thread - I just happen to be struggling with this same issue...

I put the clear plastic fuel filter on my car (the one with the paper cone shaped filter from Purolator) while trying to debug the vacuum issue in my gas tank. After fixing the vacuum issue, I left the clear filter on the car and have been monitoring the fuel level (obsessively BTW). What I noticed is that the filter was completely full (not even an air bubble) just after fixing the vacuum issue. The filter then drained to practically empty after my first drive and remained there over the next several days. This is when I started experiencing stuttering due to fuel starvation.

So, I next turned my attention to the fuel pump. I swapped out the fuel pump last night (which was only four months old) with a new fuel pump. Same thing, the fuel filter went to completely full and then drained to almost empty after my first test drive. HOWEVER, unlike with the old fuel pump, the car idles just fine even when the filter is practically empty. My conclusion is that the old fuel pump was not creating enough pressure to feed fuel to the carb and that was the reason for fuel starvation. The status of the level of fuel in the filter seems to be irrelevant as my car runs better now with the new fuel pump even though the level of fuel in the filter is the same as with the old fuel pump.

My plan now: ignore the damn thing unless I start having fuel starvation issues again. You can become obsessed with looking at that clear filter...

Matt

[MICAH1]

Matt,
Your words just about say it all !!!!! And you are right, gazing at those clear fuel filters can just about drive one nuts!!!

[opelnut10]

The fuel pump is driven off the dist. shaft and the faster the shaft turns (RPM's) the more fuel the pump pumps. The line has fuel pressure controled by the pump and is designed to supply fuel at a rate according to demand. the lower the RPM's the less less fuel is pumped and the venturi being shut the less fuel you have in the bowl thereby restricting the fuel flow through the needle and seat (IMO). In the case of an electric pump the pressure to the carb. is controled by the the maximum pressure of the pump that is why you run a low pressure pump so as not to override the needle and seat which controls fuel to the bowl.

[OriginalOpelGTOwner]

I replaced my fuel pump, filter, and rubber hoses summer of 2006 with parts I bought from OGTS. My fuel filter is mounted vertically same as stock. The fuel level in the filter varies from sometimes 75% full to 20% full. I have never had a fuel starvation issue even running the car on the freeway between 85 and 95 MPH for miles. Actually ran up to 100 mph for a brief instant last summer and it ran like a champ and the car was still increasing in speed when I backed off the throttle.

[newman27]

Is the primary advantage to a vertical orientation of the fuel filter better filtration or are there other benefits? Also, in several pictures of GTs, I have noticed the fuel lines being run right over the valve cover!?! Was this the stock arrangement as well or did it run in front of the valve cover?

Matt

[RallyBob]

Originally Posted by newman27 Is the primary advantage to a vertical orientation of the fuel filter better filtration or are there other benefits? Also, in several pictures of GTs, I have noticed the fuel lines being run right over the valve cover!?! Was this the stock arrangement as well or did it run in front of the valve cover? Matt

OEM fitment is a metal tube that wraps around the front of the head, and this tube is held via a metal bracket that is secured by the upper bolts on the front camshaft cover plate. There is a section of rubber hose between the stock fuel pump and the hard metal line, and another section of rubber hose between the hard metal line and the fuel filter, then one last section of rubber hose to the carburetor itself.

HTH,
Bob

[newman27]

Originally Posted by RallyBob OEM fitment is a metal tube that wraps around the front of the head, and this tube is held via a metal bracket that is secured by the upper bolts on the front camshaft cover plate. There is a section of rubber hose between the stock fuel pump and the hard metal line, and another section of rubber hose between the hard metal line and the fuel filter, then one last section of rubber hose to the carburetor itself. HTH, Bob

Thanks Bob. That is exactly how Keith did my car. I guess some people just decided to slop some fuel line over the engine and be done with it (I've seen enough pix like this that I thought it might be the way it was done originally).

Unfortunately (and this was a real bummer for me) I had to swap out the nice metal fuel lines in the engine bay for rubber fuel line all the way from the fuel pump output to the carb due to what I believe was a vapor lock issue. The metal lines sure look a lot nicer and I wish I could go back to them but I hesitate to mess with what I have now as everything is working so well.

Matt

[ungermm]

I noticed the condition too with the clear glass filter located horizontally near the carb and an electric fuel pump near the tank. I was thinking that putting in an inline one way valve just before the filter would prevent the flow back.
Jerry

[tekenaar]

Originally Posted by newman27 Originally Posted by RallyBob OEM fitment is a metal tube that wraps around the front of the head, and this tube is held via a metal bracket that is secured by the upper bolts on the front camshaft cover plate. There is a section of rubber hose between the stock fuel pump and the hard metal line, and another section of rubber hose between the hard metal line and the fuel filter, then one last section of rubber hose to the carburetor itself. HTH, Bob Thanks Bob. That is exactly how Keith did my car. I guess some people just decided to slop some fuel line over the engine and be done with it (I've seen enough pix like this that I thought it might be the way it was done originally). Unfortunately (and this was a real bummer for me) I had to swap out the nice metal fuel lines in the engine bay for rubber fuel line all the way from the fuel pump output to the carb due to what I believe was a vapor lock issue. The metal lines sure look a lot nicer and I wish I could go back to them but I hesitate to mess with what I have now as everything is working so well. Matt

Here's the stock fuel line routing in my Kadett . . . same as GT, BTW . . .



. . . and here's my solution to the "metal fuel line" vapor-lock problem . . . works even in Texas summertime!

[namba209]

Originally Posted by ungermm I noticed the condition too with the clear glass filter located horizontally near the carb and an electric fuel pump near the tank. I was thinking that putting in an inline one way valve just before the filter would prevent the flow back. Jerry

IMHO a one-way check valve is not necessary, if you drive the car once-twice a week. The fuel in the carb bowl should be sufficient to start the car and keep it running for a minute or two, long enuff for the pump to pick up a prime and get the fuel flowing to the carb. Even with a check valve, the carb bowl being vented to the atmosphere, will eventually evaporate the fuel in the bowl away. On my monza, if I haven't driven it for a week, I have to crank the engine until the oil lite goes out, and the pump in the tank turns on, wait for the lite to come on, pump quits running, crank again, 'til the lite goes out, and continue until the engine finally starts. On Willit? the pumps are turned on for 5 seconds by the computer to pressurize the fuel rail prior to starting. I can repeat that sequence by turning the key off for 10 seconds, then turn it on, or I can continue to crank the engine until it starts. The pumps will run in the start mode. The reason for having both my fuel filters vertical is simple, I just want the full element filtering the gas, not just part of it, which I have seen with them mounted other than vertical. It's just my personal preference.

[Dale .D]

Does make perfect sense. probably makes the filter last longer & filter more evenly.

[Girly_with_style]

i just replaced my fuel filter and it stays full of fuel. i had an part guy tell me that if you have it on the wrong way that it will fill only half full and that if its on right that it should stay full. dont know if that helps any.

[Dale .D]

I'll double check that.That would be funny if I messed that up.

[tekenaar]

Originally Posted by namba209 IMHO . . . The reason for having both my fuel filters vertical is simple, I just want the full element filtering the gas, not just part of it, which I have seen with them mounted other than vertical. It's just my personal preference.

. . . though most manufacturers will mount them either way, primarily dictated by amount of room where the filter is mounted . . . and many are horizontal.

[newman27]

Originally Posted by Girly_with_style i just replaced my fuel filter and it stays full of fuel. i had an part guy tell me that if you have it on the wrong way that it will fill only half full and that if its on right that it should stay full. dont know if that helps any.

Mine is definitely pointing the right way (just rechecked it) but will still go practically empty at times. The new fuel pump solved the last of my problems.

[namba209]

Very true Otto, and they'll work just fine. I just tried to get as much of the air bubble out of mine for the FI system I'm running, and use as much of the filter as I could on both of them. Luckily I had the room to put them in as close to vertical as I could. The clear, low pressure filter, prior to the "boost" pump has the filter element totally submerged in fuel, the high pressure filter, IDK it's a closed can, but, it too is mounted vertically. Hopefully, using the flow arrows on the can, it won't have an air bubble in it. Like I said, it's just my personal preference.

[yellaopelgt]

I have a clear filter as well (Purolator) with a brand new mechanical fuel pump. I noticed a difference in the amount of fuel from vertical vs. horizontal(horizontal being the fullest) The best I could do with the original fuel line placement was a 45 degree and this seems to be a happy medium for me. It still gets a bit low, maybe 1/2 under a high load, but quickly fills back up at idle (completely, no air bubbles at all). I also have another clear filter directly before the fuel pump and that one is totally horizontal and always stays full regardless of load. I will be switching to an electrical pump this summer so we'll see what happens then, I guess. Could this possibly be an issue with the ID size of the fuel line? Pressure is one thing, but volume is completely different. Just a thought, because the issue seemed to go away once I replaced the entire line with a slightly larger one.
Joe.

[Dale .D]

What size in fuel line did you put in.Is it all the way from the tank to the pump.This is simple resonably cheap thing to do if it increases flow!I still have the original lines.Should they be replaced.?Which kind of line is best?