4th gen Fuel Pump work in a 3rd gen tank?
Thread Starter
On The Tree
Joined: Apr 2005
Posts: 144
Likes: 0
From: Austin, Tx
4th gen Fuel Pump work in a 3rd gen tank? Cliff Notes: I have a 00 Camaro tank, and a 91 Camaro with LS1. I had a walbro fuel pump that died, and I'm wondering if I can just take the 4th gen pump out of the 00 tank and just replace my crapped out Walbro out of my third gen tank.
Long story:
I purchased a Walbro 255 fuel pump for my LS1 swap. Its been in the car less than a year, less than 10k miles, and I'm pretty sure its dead. I was driving along after a long day of spirited driving. I was just sitting there at a light and all of a sudden the car dies. I'm like, ohh maybe the A/C pulled the RPMs down too low and the stall saver didn't catch it. So I try to restart and it just cranks and cranks. So I look over at my fuel pressure gauge and its at 0. So I turn the key off and back on, and the fuel pump didn't prime at all. Luckily I was on a bit of a down hill so I just let the car coast out of the way of traffic. By that time I was rolling at a good 10-15MPH, so I dropped the clutch and the car sputtered to life. I held down the gas pedal down about half way and was able to get into a parking spot, as soon as I put the clutch back in and the weight of the car was off the motor it surged maybe once or twice and then died down. That whole time the fuel pressure gauge was showing 20-30 PSI tops, and once it died fuel pressure was down to 0.
So I purchased this stock 00 tank and I don't really feel like having to fix the fuel sending unit, etc. So I'm wondering if I can just pull the stock pump out of the 00 tank and put in my 3rd gen tank so I can having a working level gauge.
Ideas, comments?
Long story:
I purchased a Walbro 255 fuel pump for my LS1 swap. Its been in the car less than a year, less than 10k miles, and I'm pretty sure its dead. I was driving along after a long day of spirited driving. I was just sitting there at a light and all of a sudden the car dies. I'm like, ohh maybe the A/C pulled the RPMs down too low and the stall saver didn't catch it. So I try to restart and it just cranks and cranks. So I look over at my fuel pressure gauge and its at 0. So I turn the key off and back on, and the fuel pump didn't prime at all. Luckily I was on a bit of a down hill so I just let the car coast out of the way of traffic. By that time I was rolling at a good 10-15MPH, so I dropped the clutch and the car sputtered to life. I held down the gas pedal down about half way and was able to get into a parking spot, as soon as I put the clutch back in and the weight of the car was off the motor it surged maybe once or twice and then died down. That whole time the fuel pressure gauge was showing 20-30 PSI tops, and once it died fuel pressure was down to 0.
So I purchased this stock 00 tank and I don't really feel like having to fix the fuel sending unit, etc. So I'm wondering if I can just pull the stock pump out of the 00 tank and put in my 3rd gen tank so I can having a working level gauge.
Ideas, comments?
Thread Starter
On The Tree
Joined: Apr 2005
Posts: 144
Likes: 0
From: Austin, Tx
Ohh, this is probably pretty important...doh.
After I parked and couldn't get the car to restart I called up my parents and had them take me to the place I was heading. A few hours later I decided to go try the car one more time before calling a tow truck. I got in the car, turned the key forward and it primed right up to 55-60lbs like normal. Turned the key forward and it fired normally. I then drove the car home for 20 minutes and ~ 15-20 miles. Ran perfectly
I parked it in the garage in disgust when I got home.
Then a couple weeks later I decided to try it out again, and the car was lazy on the cranking cause the battery had died down a bit. It fired, but I had to hold the gas pedal at about 10% to keep it running, that was about 1500 RPM. If I tried to let up slowly to get back to idle it would sink below the target RPM and start surging until it finally died. At that point I turned it off and said **** it.
After I parked and couldn't get the car to restart I called up my parents and had them take me to the place I was heading. A few hours later I decided to go try the car one more time before calling a tow truck. I got in the car, turned the key forward and it primed right up to 55-60lbs like normal. Turned the key forward and it fired normally. I then drove the car home for 20 minutes and ~ 15-20 miles. Ran perfectly
I parked it in the garage in disgust when I got home.Then a couple weeks later I decided to try it out again, and the car was lazy on the cranking cause the battery had died down a bit. It fired, but I had to hold the gas pedal at about 10% to keep it running, that was about 1500 RPM. If I tried to let up slowly to get back to idle it would sink below the target RPM and start surging until it finally died. At that point I turned it off and said **** it.
Wow look a couple posts down and there is the exact same post.
https://ls1tech.com/forums/conversions-swaps/771543-putting-99-02-fuel-pump-95-z28-s.html
https://ls1tech.com/forums/conversions-swaps/771543-putting-99-02-fuel-pump-95-z28-s.html
its somewhat unlikely, but you might want to swap the fuel pump relay with another relay, (like the fan for example) and see if thats the problem first.
otherwise.. yea.. sounds like its probably the pump.
the 93-98 fuel pumps are identical enough to work. the 99+ pumps are in a "fuel bucket" system that uses a bleed off port and is JUUUUST diffrent enough that it wont work.
to be honest, id eat the $100 and buy another walbro.
otherwise.. yea.. sounds like its probably the pump.
the 93-98 fuel pumps are identical enough to work. the 99+ pumps are in a "fuel bucket" system that uses a bleed off port and is JUUUUST diffrent enough that it wont work.
to be honest, id eat the $100 and buy another walbro.
Originally Posted by stealth71
Wow look a couple posts down and there is the exact same post.
https://ls1tech.com/forums/showthread.php?t=771543
https://ls1tech.com/forums/showthread.php?t=771543
95 z28 != thirdgen...
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
Originally Posted by MrDude_1
the 93-98 fuel pumps are identical enough to work. the 99+ pumps are in a "fuel bucket" system that uses a bleed off port and is JUUUUST diffrent enough that it wont work.
I am running a 99 f-body pump in my El Camino tank.....ya just have to find a way around the bleed off port
. I just made my own bleed off point. Hook the 3/8" output from the pump to the sending unit same as with any other pump. Then hook the small black bleed off line to the output on the pump. Now for the other end ouf the bleed off line that would normally go to the fuel bucket.......go to the hardware store in the brass section and find a compression fitting that will fit on the end (IIRC its 1/8", but don`t quote me on that its been a couple years since I put this in). Once you have a compression fitting find a cap to block off the other end. Now drill a 1/16" hole in the end of the cap so that it will bleed off pressure just like the factory venturi 
. Put the compression fitting on the line with the cap and tie it off to the pump so that it will not interfere with the float or aerate the fuel near the pump. Theres pics of this on my fquick account. I have had this system in place on my El Camino for 20k miles. I wanted to use a GM delco pump because of reliability and found a great deal on a new f-body pump(not the whole sending unit just the pump). In retrospect I wish I had found a whole sending unit and swapped the complete bucket in.....the baffles in EFI El Camino tanks suck 
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Originally Posted by G-Body
Is the size of the pump physically different? I know that the 99+ uses a bleed off port, but was anything else changed?
Originally Posted by G-Body
I am running a 99 f-body pump in my El Camino tank.....ya just have to find a way around the bleed off port
. I just made my own bleed off point. Hook the 3/8" output from the pump to the sending unit same as with any other pump. Then hook the small black bleed off line to the output on the pump. Now for the other end ouf the bleed off line that would normally go to the fuel bucket.......go to the hardware store in the brass section and find a compression fitting that will fit on the end (IIRC its 1/8", but don`t quote me on that its been a couple years since I put this in). Once you have a compression fitting find a cap to block off the other end. Now drill a 1/16" hole in the end of the cap so that it will bleed off pressure just like the factory venturi . Put the compression fitting on the line with the cap and tie it off to the pump so that it will not interfere with the float or aerate the fuel near the pump. Theres pics of this on my fquick account. I have had this system in place on my El Camino for 20k miles. I wanted to use a GM delco pump because of reliability and found a great deal on a new f-body pump(not the whole sending unit just the pump). In retrospect I wish I had found a whole sending unit and swapped the complete bucket in.....the baffles in EFI El Camino tanks suck .i feel ya on the tank thing... 91 fbodies like mine are factory EFI, but they dont have tank baffles either.. i have to run a half tank at the track to not suck air.
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Verdad Gallardo Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
Yeah if I ever did it again I would just cut the tank and put the whole sending unit in. It only took about a month of driving it before I was kicking myself for using the factory EFI tank with baffles. It would have been much easier to cut the tank and use the fuel bucket setup, instead I took forever finding a EFI sending unit for an El Camino, had to rebuild the whole thing because the lines were rusted out and now the fuel sloshes away on expressway ramps anyway 
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Staging Lane
Joined: Aug 2007
Posts: 73
Likes: 8
tanks im working on a swap like yours.i have two whole cars. somebody sugared my 4th gen so i took out the tank to clean it . while it was out i compared it to a 3rd gen tank they looked close enough to being the same exept for the evap can so i intend on using the 4th gen tank in my 3rdgen when i put in the LS1. maybe thats something you should consider
You will have to use a 93-97 tank/sending unit. The LS1 fuel sending units are 70-240 ohms and the LT1 tanks are the more traditional 0-90 ohms.
The pumps in ALL the 4th gen cars run in a biucket. I just installed a Racetronix kit in my 94 tank.
Re'
The pumps in ALL the 4th gen cars run in a biucket. I just installed a Racetronix kit in my 94 tank.
Re'
If your still thinking of using a fourth gen tank in your third gen then follow this link:
http://www.thirdgen.org/techboard/lt...k-plastic.html
and to modify the LS1 fuel sender to work with your third gen just follow this:
http://www.thirdgen.org/techboard/lt...-ls1-fuel.html
http://www.thirdgen.org/techboard/lt...k-plastic.html
and to modify the LS1 fuel sender to work with your third gen just follow this:
http://www.thirdgen.org/techboard/lt...-ls1-fuel.html
Joined: Mar 2002
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Thread Starter
On The Tree
Joined: Apr 2005
Posts: 144
Likes: 0
From: Austin, Tx
Time to resurrect a really old thread 
So, I swapped tanks... but I fear I've screwed the pooch on this.
For some reason instead of searching around and using the thirdgen.org thread, I decided I would remove all the extra "stuff" from the LS1 tank
The way I did it, I removed the coal canister (god I'm a moron), hooked the feed and return lines up to the stock connections going to the front. I have the evap on the front of the car hooked up, but its disabled in the PCM.
I have the relief valve open to air using the thirdgen one way plastic valve thingy.
Now, I can't fill the car up, I get about 3 gallons in before it starts spitting it back up the filler. Also, the cap lets a lot of air out when I open it after a short drive.
Suggestions? Do I just go buy another 4th gen tank and do set it up like the above picture?
Should I be doing this for the return line instead of sending it up to the front of the car?
any insight is appreciated.
So, I swapped tanks... but I fear I've screwed the pooch on this.
For some reason instead of searching around and using the thirdgen.org thread, I decided I would remove all the extra "stuff" from the LS1 tank
The way I did it, I removed the coal canister (god I'm a moron), hooked the feed and return lines up to the stock connections going to the front. I have the evap on the front of the car hooked up, but its disabled in the PCM.
I have the relief valve open to air using the thirdgen one way plastic valve thingy.
Now, I can't fill the car up, I get about 3 gallons in before it starts spitting it back up the filler. Also, the cap lets a lot of air out when I open it after a short drive.
Suggestions? Do I just go buy another 4th gen tank and do set it up like the above picture?
Should I be doing this for the return line instead of sending it up to the front of the car?
any insight is appreciated.
