Best place for an in-line fuel filter?
#1
Le Mans Master
Thread Starter
Best place for an in-line fuel filter?
I want to get rid of the filter between the pump and carb, but I can't figure out the best place to put an in-line filter. What have you guys done? Mine is a '68 vert.
Thanks.
.
Thanks.
.
Last edited by sperkins; 01-27-2008 at 12:04 AM.
#2
Racer
If you've got soft hoses anywhere under the car, put it in under there. The engine compartment's the last place you'd want to put a fuel filter unless it was securely bracketed to something so that the lines don't pull out of it or the glass/plastic doesn't hit anything hard and crack.
#3
Instructor
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You don not want to put a filter on the suction side of the fuel pump.
A inline fuel filter between the pump and the carburetor is where it needs to be placed.
Try an advance search for fuel filter in the tech forum check the archive box at the bottom you will find a lot of good ideals there. Do not put a glass one with rubber hoses. Use hard line all the way.
A inline fuel filter between the pump and the carburetor is where it needs to be placed.
Try an advance search for fuel filter in the tech forum check the archive box at the bottom you will find a lot of good ideals there. Do not put a glass one with rubber hoses. Use hard line all the way.
#4
Racer
#5
Melting Slicks
The proper location of the fuel filter is just before the carb, this ensures clean fuel to the carb. Any other configuration does not provide the intended protection.
#6
Race Director
Thats correct, between the carb and pump is probaly the logical best place. But not me, I put a good Fram filter in the rear back at the tank in the existing factory rubber line. I didn`t want it in the engine compartment for cosmedic reasons as they stand out like a sore thumb. Also the reason for this post wanting to know what others did about the damn thing. My solution, "Out of sight out of mind". I`ll drink to that.
#9
Le Mans Master
Thread Starter
1. I can't run a hard line from my mechanical pump to the carb due to my setup.
2. I'm not interested in one of those "filter in the fuel line" parts that connects to the carb.
3. I'd rather tow it home with a clogged carb than have it burn to the ground.
Anyone have any pictures of their in-line filter install?
Thanks again guys.
#10
Melting Slicks
#11
Le Mans Master
I always ran a plastic see-through GF-538 filter in an easy to get to place between the pump and the carb in the old days. Lately I run the stock in-carb filters and hard lines all the way.
Anyone want to about glass filters again?
-Mark.
Anyone want to about glass filters again?
-Mark.
#12
Instructor
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I think the key for you is to find some place down low AFTER the pump where you can't really see the filter. Just keep it away from your headers.
Hard lines, metal filter can. That's the answer!
#13
Le Mans Master
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St. Jude Donor '09
Thats correct, between the carb and pump is probaly the logical best place. But not me, I put a good Fram filter in the rear back at the tank in the existing factory rubber line. I didn`t want it in the engine compartment for cosmedic reasons as they stand out like a sore thumb. Also the reason for this post wanting to know what others did about the damn thing. My solution, "Out of sight out of mind". I`ll drink to that.
#14
Racer
My inline filter is near the gas tank under the car, it is a little hard to inspect. My reasoning is I prefer to filter any contaminants as early in the fuel system as possible.
#15
Tech Contributor
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If you're running a stock-type engine-mounted mechanical diaphragm pump, you do not want a filter anywhere on the suction side of the pump - the filter needs to be between the pump and the carb. For 2 reasons:
1. Diaphragm pumps are not positive displacement, and they do not "suck" well. Any filter restriction on the suction side will cause a dramatic drop in fuel pressure and flow.
2. Modern pump gas typically has ethanol added to it. The vapor pressure of ethanol is higher than straight gas, so the ethanol has a tendency to vaporize - especially when you lower the pressure on it. When you install a suction side filter, you pull a lower pressure on the fuel in the feed line to the pump, and the fuel has a tendancy to vaporize in the line between the pump and the tank (vapor lock), especially on hot days or when driving up steep hills or when fuel flow demand is high (WOT).
It is for these reasons that the auto manufacturers never installed filters on the suction side of the mechanical pumps - they are always on the pressure side. It would be very easy, and cost-efficient, for the manufacturers to install an in-line filter somewhere between the tank and the pump, yet none of them ever did: Ford, GM and Chrysler always installed the filter on the pressure side of the system... maybe there was a reason for this...
Moderns cars have the filters in the fuel feed line because they have electric pumps in the tank - the filters are still on the pressure side of the system - never on the suction side.
Although a suction side filter may work on many occasions, I can also tell you that I have seen a ton of problems caused by this - I have removed dozens of suction side filters to solve fuel delivery and drivability problems over the years.
Here is a filter installation on my latest engine build - tucked up underneath the alternator bracket to get it out of sight - nothing wrong with running the filter betwen the pump and the carb - you need it there with a mechanical pump:
1. Diaphragm pumps are not positive displacement, and they do not "suck" well. Any filter restriction on the suction side will cause a dramatic drop in fuel pressure and flow.
2. Modern pump gas typically has ethanol added to it. The vapor pressure of ethanol is higher than straight gas, so the ethanol has a tendency to vaporize - especially when you lower the pressure on it. When you install a suction side filter, you pull a lower pressure on the fuel in the feed line to the pump, and the fuel has a tendancy to vaporize in the line between the pump and the tank (vapor lock), especially on hot days or when driving up steep hills or when fuel flow demand is high (WOT).
It is for these reasons that the auto manufacturers never installed filters on the suction side of the mechanical pumps - they are always on the pressure side. It would be very easy, and cost-efficient, for the manufacturers to install an in-line filter somewhere between the tank and the pump, yet none of them ever did: Ford, GM and Chrysler always installed the filter on the pressure side of the system... maybe there was a reason for this...
Moderns cars have the filters in the fuel feed line because they have electric pumps in the tank - the filters are still on the pressure side of the system - never on the suction side.
Although a suction side filter may work on many occasions, I can also tell you that I have seen a ton of problems caused by this - I have removed dozens of suction side filters to solve fuel delivery and drivability problems over the years.
Here is a filter installation on my latest engine build - tucked up underneath the alternator bracket to get it out of sight - nothing wrong with running the filter betwen the pump and the carb - you need it there with a mechanical pump:
Last edited by lars; 01-27-2008 at 02:28 PM.
#16
Le Mans Master
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St. Jude Donor '11-'12-'13-'14-'15-'16-'17-‘18-'19-'20-'21-'22-'23-'24
If you're running a stock-type engine-mounted mechanical diaphragm pump, you do not want a filter anywhere on the suction side of the pump - the filter needs to be between the pump and the carb. For 2 reasons:
1. Diaphragm pumps are not positive displacement, and they do not "suck" well. Any filter restriction on the suction side will cause a dramatic drop in fuel pressure and flow.
2. Modern pump gas typically has ethanol added to it. The vapor pressure of ethanol is higher than straight gas, so the ethanol has a tendency to vaporize - especially when you lower the pressure on it. When you install a suction side filter, you pull a lower pressure on the fuel in the feed line to the pump, and the fuel has a tendancy to vaporize in the line between the pump and the tank (vapor lock), especially on hot days or when driving up steep hills or when fuel flow demand is high (WOT).
It is for these reasons that the auto manufacturers never installed filters on the suction side of the mechanical pumps - they are always on the pressure side.
Moderns cars have the filters in the fuel feed line because they have electric pumps in the tank - the filters are still on the pressure side of the system - never on the suction side.
Although a suction side filter may work on most occasions, I can also tell you that I have seen a ton of problems caused by this - I have removed dozens of suction side filters to solve fuel delivery and drivability problems over the years.
Here is a filter installation on my latest engine build - tucked up underneath the alternator bracket to get it out of sight - nothing wrong with running the filter betwen the pump and the carb - you need it there with a mechanical pump:
1. Diaphragm pumps are not positive displacement, and they do not "suck" well. Any filter restriction on the suction side will cause a dramatic drop in fuel pressure and flow.
2. Modern pump gas typically has ethanol added to it. The vapor pressure of ethanol is higher than straight gas, so the ethanol has a tendency to vaporize - especially when you lower the pressure on it. When you install a suction side filter, you pull a lower pressure on the fuel in the feed line to the pump, and the fuel has a tendancy to vaporize in the line between the pump and the tank (vapor lock), especially on hot days or when driving up steep hills or when fuel flow demand is high (WOT).
It is for these reasons that the auto manufacturers never installed filters on the suction side of the mechanical pumps - they are always on the pressure side.
Moderns cars have the filters in the fuel feed line because they have electric pumps in the tank - the filters are still on the pressure side of the system - never on the suction side.
Although a suction side filter may work on most occasions, I can also tell you that I have seen a ton of problems caused by this - I have removed dozens of suction side filters to solve fuel delivery and drivability problems over the years.
Here is a filter installation on my latest engine build - tucked up underneath the alternator bracket to get it out of sight - nothing wrong with running the filter betwen the pump and the carb - you need it there with a mechanical pump:
#17
I have an 82. The in line filter is on the passenger side frame. If you were sitting in the passenger seat of the car it would be located right below your right foot under the floorpan. The filter would be available from almost any auto parts store and attaches with small pieces of fuel line hose. Make it easy.
Good Luck
Steve
Good Luck
Steve
#18
Tech Contributor
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Your '82 is fuel injected ("Crossfire" throttle body injection) with the fuel pump in the tank, so your filter is on the pressure side of the system as noted in my previous post. If the system is stock, the filter is not attached with hose - it has steel screw-in connections with rubber O-rings on the fittings - same fitting style as used on air conditioning tube connections..
Last edited by lars; 01-28-2008 at 10:20 AM.
#19
Team Owner
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I have a 68 also. I don't have a rear sway bar, but the frames are all ready drilled with welded in nuts. So I made a bracket out of thick aluminum sheeting. The bracket has a "L" cross section and with bolted to the frame using the unused sway bar attach points. I mounted an Aeromotive Street and Strip electric fuel pump and large Aeromotive cartridge fuel filter on this bracket. Ran metal lines from the fuel tank output to the pump and a metal line back to the stock fuel line to the engine.
#20
Melting Slicks
I will get shunned for this but I have a high flow Mallory fuel filter (looks like an oil filter) mounted right outside the tank on my 68 on the suction side. Right before the fuel filter is a fuel cutoff valve for security/safety reasons and for ease of changing the fuel filter. I am running a RacePump mechanical fuel pump on the 509 which pumps into a Russel high flow inline solid fuel filter then into the regulator then the carb.
I have had no problems with this setup at all.
And the fuel cutoff valve works great, engine dies after 40 seconds...ask me how I know.
Not the best pics....
mock up...
I have since replaced that crapy gauge.
I have had no problems with this setup at all.
And the fuel cutoff valve works great, engine dies after 40 seconds...ask me how I know.
Not the best pics....
mock up...
I have since replaced that crapy gauge.
Last edited by 68 NJConv 454; 01-28-2008 at 01:52 PM.