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Driver
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Discussion Starter · #1 ·
I thought I remember talk of this before, but I can't find it. My 32/36 on my 73 GT is stumbling when I kick in the secondary. I changed the jets as Otto suggested, and it was fixed. Now it is doing it again. :mad:
I have a clear filter before the fuel pump. It looks empty wether off, idling or any condition. I pull it off and then fuel will flow out of it. I removed another filter I had back by the gas tank and fuel flows well from the tank. I blew out the line and there seemed to be no restrictions. Replaced the clear filter and it filled up mostly when I had the line disconnected from the fuel pump. I started the car idles great, level in filter stays the same. Take it out for a drive and it seems more peppy, but still stumbling with secondary. Pop the hood and the filter is empty again. It is passing enough gas to run fine just not great. It seems to me like the filter should be full, right? Is this normal and I am chasing the wrong problem? Help! :confused:
 

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Opeler
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Empty Fuel Filter

Hi George,

I'll be anxious to see what the group members say about your empty fuel filter. Because, this also happens with my 73 Opel GT.

I see you have a 73 GT. Did you disconnect your return fuel line to the gas tank?
 

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Thats the most frustrating problem on my Opel. Hapens all the time. First it was the fuel pump piston that was worn and couldn't pump fast enough. I replaced that (thanks Otto!) But the real problem is the tank gets rusty from the inside and little pieces of rust get stuck in the fuel line.
I used to have 4 little fuel filters at different locations that i would change every 3 days, I still had great problems, once had to rev at 3k in 1st gear to get back home or the car would stall. once had to take the car apart in the middle of nowhere in the rain and unblock the tank suction pipe with pieces of branch to get it home. But if you have a clear filter i guess you would find pieces of rust in it then. Maybe the air opening in the tank is blocked and the air can't escape fast enough, on a new car this would deform the tank, but i don't think these opels have a strong enough pump, so petrol just doesen't come out unless air can come in to replace it. Just a thought.
 

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boomerang opeler
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do you have the filter mounted vertical as they only work right if all the element is fully submersed
if its going empty then you must have a small air leak (as its before the pump it won't leak fuel but will suck air in to the fuel line) this will give you the empty fuel line and can reduce the fuel flow as the air is easier to pull than the fuel (less dense pulls better into a vacume pump[the gas pump])
 

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Driver
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Discussion Starter · #5 ·
baz said:
do you have the filter mounted vertical as they only work right if all the element is fully submersed
if its going empty then you must have a small air leak (as its before the pump it won't leak fuel but will suck air in to the fuel line) this will give you the empty fuel line and can reduce the fuel flow as the air is easier to pull than the fuel (less dense pulls better into a vacume pump[the gas pump])
No, I don't, it is horizontal. OK, that is an easy fix. But a strange thing, when trying to get the filter full, I disconnected it from the pump and turned it vertical. That is how I got it as full as I did. But fuel started running out of it before it got all the way full.
I agree it is somehow filling the filter with air. I have those little spring steel hose clamps in a couple spots. (I should replace them wth the ones you tighten.) So would it be possible if one of those little spring steel clamps not being tight enough that it could suck air in but no fuel is getting out? I have no leaks.
I'm going to need to buy some more fuel line to mount the filter vertically. But thanks for the idea. I think I will replace all those clamps while I am at it.
 

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Driver
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Discussion Starter · #6 ·
SoCalOpelGT said:
Did you disconnect your return fuel line to the gas tank?
The tank is not a '73 tank. It is from an earlier GT. My original tank had too much rust in it and was clogging the filters up way to fast. I got a hold of an earlier tank that was clean so I put it in. If I'm not mistaken the 73 has the return but others did not.?
 

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Driver
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Discussion Starter · #7 ·
SoCal emailed me and said he had the same problem. He inverted the filter, checked and tightened all clamps, got the filter full and after a drive it was empty. Any ideas? Otto? RallyeBob?
I haven't been able to work on mine yet. Closed on a house today and the GT and all the stuff have to get moved to their new home.
I want to have her runnin' just right when I put it on the Dyno at the Texas Opel meet Memorial weekend. :cool:
 

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4ZUA787
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hey i have one of those cleear filters about 3 inches from my weber 32/36 it stays 75% full when i turn it off and about 50 % or so full while in driving condition and about 95 % full while at idle. i have an electric fuel pump installed which befor i had the mechanical and i cant tell a diffrence in the filter level but i can totally tell in performance mount it back under the rear left of the axle and put one of those cheap filters there also then run new line to front of car run to clear fuel filter then into weber. hope u find ur problem.
 

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George, let me see if I have this right. You have a filter at the gas tank and one just before the fuel pump. So, in a matter of speaking you have two filters between the tank and the fuel pump. May I suggest you take the clear filter from in front of the pump and put it between the pump and the carb. Theoretically (sp) the pump would not allow the fuel to return back to the tank, because the tank is higher than the pump supposedly, but thermal expansion may negate that. With the second filter between the pump and the carb in a position where you could see the fuel flow, with the hood open, you may be able to see what's happening while the engine is running. There is a possibility that the diaphragm in the pump has a pin hole in it that allows the fuel to return towards the tank. HTH.

Ron
 

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Opeler
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Electric Fuel Pump

Hi pvcar,

Thanks for your input. I'm using a fairly new mechanical fuel pump on my GT. Not sure how to confirm it is in good working order.

I'll read some threads and see if I can check that.

Which Electric Fuel Pump did you install?
 

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Driver
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Discussion Starter · #11 ·
I removed the filter that was back by the tank. It was full of crud and I only had one spare, so I just removed that one completely. I have a clear one about 3-4 inches before the fuel pump. I can see it with the hood up and the engine running. It is currently just a little off horizontal. Looking from the top, it looks dry, I can't see any fuel. From the bottom you can see it has fuel going through it. This is the case wether off, running idle, or 2K RPM's. No change in the fuel level. Since I took off the back one I want to keep this one before the fuel pump to keep any crud out of it.
I wish I could go out and play with it, but the house moving has me swamped. And it's not "5 minutes here or there" because I end up smelling real nice after playing with fuel lines. :D
George


namba209 said:
George, let me see if I have this right. You have a filter at the gas tank and one just before the fuel pump. So, in a matter of speaking you have two filters between the tank and the fuel pump. May I suggest you take the clear filter from in front of the pump and put it between the pump and the carb. Theoretically (sp) the pump would not allow the fuel to return back to the tank, because the tank is higher than the pump supposedly, but thermal expansion may negate that. With the second filter between the pump and the carb in a position where you could see the fuel flow, with the hood open, you may be able to see what's happening while the engine is running. There is a possibility that the diaphragm in the pump has a pin hole in it that allows the fuel to return towards the tank. HTH.

Ron
 

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4ZUA787
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well about what type of fuel pump i used basiclly i went to my local kragen and asked for just a generic electric fuel pump which i had a part # for, well they bring me out three boxes they all have the same part number on the box but each one had a completly diffrent pump inside. i chose this nippendenso rip off looking one that uses an actual spining type function to move the fuel instead of a pulsating type, it works great runs on 12 volts so i jus hooked it up to the same place i hooked my electric choke wire too. i also rubber mounted the pump to the body to help elimantate the humming noise created by electric fuel pumps it pumps about 4 to 7 psi. it was about an hour job to install it all, although my mechanical pump which i thought was good well i took it off and found that the diaphram was totally disengrating insideand was what was leaking from under my car.
 

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I used one of those cheap semi-clear filters on the supply lineright off the tank when the tank was still releasing lots of crud. Removed it as things got better.

But I've always had a clear glass filter near the carb where its easy to clean and install without draining the tank down. Use an electric fuel pump as well.

And as you guys have found, there's always an air bubble in it. But the carb bowl remains full. Just figured I hadn't bled the line. As long as the carb doesn't starve, shouldn't be a problem.
 

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boomerang opeler
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this is what i was on about with the filter
it will only be full if mounted vertical as the fuel just goes to a line between the inlet and outlet
as george has said if its horizontal you will only get a half full filter which is only half working as the top half has no fuel in it
 

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Fuel filter mounting attitude . . . er, orientation

baz said:
this is what i was on about with the filter
it will only be full if mounted vertical as the fuel just goes to a line between the inlet and outlet
as george has said if its horizontal you will only get a half full filter which is only half working as the top half has no fuel in it
I think we're off on a tangent here, guys. "Figure 6C-3 Fuel Filter" in the '73 and '74 FSMs shows the filter mounted at a 45 deg angle and states that "Proper installation of the filter is essential. The vapor return line connector must be on top (highest point) for proper operation.

I've seen modern, flow-thru fuel filters mounted in a variety of positions other than true verical and, as long as pump volume and pressure are "as specified" for the carburetor, it doesn't appear to affect anything at all . . . other than the visual effect in a clear type as stated, that is. M$/50W
 

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Rats, Darn it, Otto, I was planning on mounting the fuel pump and filter side by side on the exterior, shielded, next to the fuel tank outlet line. Now I've got to revamp my thinking and find somewhere that I can mount both vertical. :confused:

Ron
 

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Driver
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Discussion Starter · #17 ·
namba209 said:
Rats, Darn it, Otto, I was planning on mounting the fuel pump and filter side by side on the exterior, shielded, next to the fuel tank outlet line. Now I've got to revamp my thinking and find somewhere that I can mount both vertical. :confused:

Ron
Ron, I think Otto is saying you don't have to mount them vertical. I'm just trying find out if it's normal for my filter to have so little fuel in it during any condition, running or off. At this rate the top of the filter element is not even getting used. I could just roll it over and have a whole new filter. :rolleyes:
 

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See-thru filters

opelenvy said:
Ron, I think Otto is saying you don't have to mount them vertical. I'm just trying find out if it's normal for my filter to have so little fuel in it during any condition, running or off. At this rate the top of the filter element is not even getting used. I could just roll it over and have a whole new filter. :rolleyes:
Well, not really. If you did try flipping it, you'd push all the junk collected on the outside of the filter element right to the pump or carb because you're essentially "reverse flushing" the filter . . . you're kidding, right? :D

Guys, don't worry about filter orientation. You'd never have considered this as a potential problem if we only had metal can filters. It is NOT an issue.
 

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Actually Otto, I was looking to mount them vertically anyway, all the hose nipples are on the top of both the fuel pump and the filter. It just looked easier to put them horizontally at the fuel tank outlet, but I may go inside the tailight area for security and road debris protection. It's just that I'll have to make a u-turn somehow with the fuel tank outlet line. I've got to have a fuel pump return and a fuel rail return back to the tank, so I've got some plumbing to do anyway. Once I get serious about it, I'll do what it takes to make it neat and functional. :)

Ron
 

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Driver
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Discussion Starter · #20 ·
namba209 said:
Actually Otto, I was looking to mount them vertically anyway, all the hose nipples are on the top of both the fuel pump and the filter. It just looked easier to put them horizontally at the fuel tank outlet, but I may go inside the tailight area for security and road debris protection. It's just that I'll have to make a u-turn somehow with the fuel tank outlet line. I've got to have a fuel pump return and a fuel rail return back to the tank, so I've got some plumbing to do anyway. Once I get serious about it, I'll do what it takes to make it neat and functional. :)

Ron
Otto, I was kidding, but I was referring to rolling the filter over, like a barrel roll, not changing input and output. Mounted horizontally, the thing isn't even half full, therefor the top of the filter is completely unused.
Ron, if you mount it inside the tail light you will hear the electric pump in the passenger compartment of the car. Some of them are quite noisy, that is why they are mounted outside the car.
Something to consider.
 
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