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Fuel pump removal and install-tips?

Old 05-04-2018, 09:36 AM
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1993C4LT1
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Default Fuel pump removal and install-tips?

Have the racetronix 255 pump, and a day off today. Having never installed or removed a fuel pump in my life, does anyone have suggestions or tips?

93 LT1
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Old 05-04-2018, 10:10 AM
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Do you need any instructions on how to get the pump unit out of the tank? Or are you good with that.

Follow the electrical instructions on the electrical connections.

Make some ohm meter readings before you take things apart so you know where the ground is on the external connector, sending (float) unit and pump motor. This is so when you install your new pump in the unit, you can make the same resistance measurements to make sure things are connected correctly before applying power.

If all looks gook apply power (key ON), the pump should run for 2 seconds, and check out the float unit for gauge movement.

Make sure any ground connections are good if removed/and or checked. Clamp the hoses well as instructions. And if all is good, install the unit back in the tank.

Don't drop anything in the tank.

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Old 05-04-2018, 10:18 AM
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I've done it several times. It is a 45 minute job-ish. Other than the step -by-step, here are a couple of things I learned along the way.

1) Read the FSM. Pretty straight forward
2) Cover your deck lid and make sure you only have about 1/4 tank of gas.
3) Loosen your fuel hoses prior to removing the mount bolts. You may need to push a small screw driver in between the rubber and metal if this is the first time off. Don't remove the hoses yet.
4) Remove the bolts and then "slide" the fuel pump to the left and then right to remove the loosened hoses. The extra distance moved (about 1.5 inches) will make a difference in disconnecting the hoses.
5. When you pull the pump out, you will need to "twist" it to the side and snake it out. It will make sense when you do it.
6. After you replace the pump but before installation, plug the harness in and flick the key briefly... you will want to hear the motor spool up to make sure it works.
7. during installation make sure you have the gasket notch lines up with the metal notch so you have a good seal.
8. Put some lube on the metal gas hoses and on the inside of the rubber gas hoses. It will aid in installation. Again, slide the pump side-to-side for ease of hose installation.
9. "Double clamp" the high pressure side of the fuel hose to make sure that the hose never blows off.

Also, if your gas gauge is wonky, you could clean the sending unit while the pump is out. It takes about 10 minutes and is pretty good PM. You will need to take a cotton ball soaked in WD40 and gently clean back and forth the calibration wires after you take the unit apart. Light sand paper on the contact point helps, but NEVER use sand paper on the sending wires.

Good luck!
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Old 05-04-2018, 05:08 PM
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Having a hell of a time removing the rubber fuel hoses. But I'll get them off. To those with the racetronix 255lph pump, are running stock size fuse?
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Old 05-04-2018, 06:01 PM
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Originally Posted by 1993C4LT1 View Post
To those with the racetronix 255lph pump, are running stock size fuse?
My recommendation is to not change your fuse. I worry that if your were to have a problem, a larger fuse would cause your wire harness to melt.
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Old 05-04-2018, 10:51 PM
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Well top hose was a massive PITA. I had been trying to get it off since 4pm, roughly. Once I saw it had a cut from me pulling, I decided it was time to cut it off. Really had no choice. At least with the skill level I have. Looks I'll have to replace the whole fuel line


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Old 05-04-2018, 11:31 PM
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Originally Posted by 1993C4LT1 View Post
Having a hell of a time removing the rubber fuel hoses. But I'll get them off. To those with the racetronix 255lph pump, are running stock size fuse?
Yes. Same fuse.

Here is a tip. Don't smoke while doing it.

Don't worry about the cut line. I believe there is enough line to survive that small ***** cut off. If you are really worried, maybe change all the lines? IIRC it might be better to take the taillight housings and the license plate out for better access.
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Old 05-05-2018, 12:06 AM
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Be sure to check the IN TANK wiring harness connector where it attaches to the top plate. Un plug it and LOOK at the terminals. If you see any discoloration, replace the harness. Airtex makes one, I'm surprised Racetronix doesn't provide one with the pump. These get burned all the time.

Be sure your fuel pump fuse is 15 Amp. I have 20+ years experience with Syclone and Typhoon. The 91 Syclone and 92 Typhoon had 10 amp fuses stock. Back in the day, it was very common to upgrade to the Walbro 255 fuel pump in those. Within a few weeks of the change peeps would report they had blown the 10 Amp fuse. The 93 Typhoon had 15 A fuse stock, my 93 Ty has had a Walbro since 97 and never blown the fuse. The Racetronix 255 is the same pump with a purple bottom. You need a 15 A fuse for it.

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Old 05-05-2018, 12:28 AM
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Originally Posted by aklim View Post
Yes. Same fuse.

Here is a tip. Don't smoke while doing it.

Don't worry about the cut line. I believe there is enough line to survive that small ***** cut off. If you are really worried, maybe change all the lines? IIRC it might be better to take the taillight housings and the license plate out for better access.
Sounds good. It's at least an inch that had to be cut.
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Old 05-05-2018, 12:29 AM
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Originally Posted by ihatebarkingdogs View Post
Be sure to check the IN TANK wiring harness connector where it attaches to the top plate. Un plug it and LOOK at the terminals. If you see any discoloration, replace the harness. Airtex makes one, I'm surprised Racetronix doesn't provide one with the pump. These get burned all the time.

Be sure your fuel pump fuse is 15 Amp. I have 20+ years experience with Syclone and Typhoon. The 91 Syclone and 92 Typhoon had 10 amp fuses stock. Back in the day, it was very common to upgrade to the Walbro 255 fuel pump in those. Within a few weeks of the change peeps would report they had blown the 10 Amp fuse. The 93 Typhoon had 15 A fuse stock, my 93 Ty has had a Walbro since 97 and never blown the fuse. The Racetronix 255 is the same pump with a purple bottom. You need a 15 A fuse for it.
Will do, thanks for that. I'll post pics of the in tank connector. How about see what she does with the stock 10A fuse, and if it blows, go 15A?
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Old 05-05-2018, 12:34 AM
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1) The standard rule of electronic stuff is: The Load Is What The Load Is..

So, if you are changing fuses, be sure the wire gauge is adequate.

If you overload the wires, THEY become the fuse. This is "bad"

2) Don't use "continental" fuel line hose for anything. I had such a bad experience with them recently, I will never buy anything from them. Gates is it, and the ratings matter.

Good Luck!!!
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Old 05-05-2018, 12:51 AM
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Racetronix has an aftermarket booster harness available. It uses the stock wiring to trigger a new relay that is installed adjacent to the fuel tank, and a heavier gauge power wire is run from the battery or alternator to the relay. (On a C4, I'd probably connect to the power stud by the battery where all the fuse links connect). The original wiring only carries the current to close the relay. The new wire carries the fuel pump load.

If you're handy with electrical stuff, you could probably make your own setup and save a bunch of money. And if you were REALLY handy, the hatch-release relay has a stand-alone 20 Amp circuit to the relay, and the relay is about 6" from the fuel tank. MIght provide a suitable power source for a booster relay set up without running wires to the rear of the car.

Check the wire gauges of the stock fuel pump circuit, but I don't think this is a big concern to go to a 15A fuse in a stock Corvette. In the SyTy's, empirical evidence suggests that the pumps run slightly above 10 Amps. So you aren't really increasing the load much beyond the original protected level. I have a Syclone with a Walbro and a 15A fuse since 2004. The stock wire is smaller than they used in the 93 Ty, but nothing has burned or blown in it in 15 years either. But I don't drive it as much as the Ty.

There's some more food for thought.
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Old 05-05-2018, 12:55 AM
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PS: It is like wiring your house.. An electrician can glance at your breaker box and just instantly rattle off:"Well that's wrong. That's the wrong breaker/fuse."

How does he know?

It is very simple: He knows the ampacity rating for the conductors he sees there.

Because we match safety devices (Fuses, breakers) to the safe load carrying capacity of the conductor in question..
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Old 05-05-2018, 12:56 AM
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Originally Posted by ihatebarkingdogs View Post
Racetronix has an aftermarket booster harness available. It uses the stock wiring to trigger a new relay that is installed adjacent to the fuel tank, and a heavier gauge power wire is run from the battery or alternator to the relay. (On a C4, I'd probably connect to the power stud by the battery where all the fuse links connect). The original wiring only carries the current to close the relay. The new wire carries the fuel pump load.

If you're handy with electrical stuff, you could probably make your own setup and save a bunch of money. And if you were REALLY handy, the hatch-release relay has a stand-alone 20 Amp circuit to the relay, and the relay is about 6" from the fuel tank. MIght provide a suitable power source for a booster relay set up without running wires to the rear of the car.

Check the wire gauges of the stock fuel pump circuit, but I don't think this is a big concern to go to a 15A fuse in a stock Corvette. In the SyTy's, empirical evidence suggests that the pumps run slightly above 10 Amps. So you aren't really increasing the load much beyond the original protected level. I have a Syclone with a Walbro and a 15A fuse since 2004. The stock wire is smaller than they used in the 93 Ty, but nothing has burned or blown in it in 15 years either. But I don't drive it as much as the Ty.

There's some more food for thought.
A good idea.. ^^^

Check this .
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Old 05-05-2018, 01:06 AM
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I don't mean to nit pick on this point, so I'll say this and I will shut up..

I was a warehouse manager once, and I know when this was done because I know EXACTLY when the wiring was installed, and modified. A fresh space, done just for us.

I was sitting in my office when the roof caught fire.. I heard a VERY LOUD "FTTTTTTT!!!" sound and the lights went out. We rushed the customers out from the storefront in front.

What had happened was a years long overloading of the wires above the ceiling. It took years. Nothing was obviously wrong, but the electricians wiring didn't work, so the plaza maintenance man jumped two very large banks of lights together, then put in a larger breaker to keep it from tripping.

And it held for years.. It worked perfectly. You would neve rknow there was a problem at all.

Till that day the wires became the fuse, and they failed instantly from one end to the other and started a fire.

So, that's all I have to say.

Good luck!!! I wish you well.
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Old 05-05-2018, 12:18 PM
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Anyone see anything wrong? Factory pump in these pics
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Old 05-05-2018, 12:44 PM
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I'd be concerned that the rust may effect electrical connections. A quick clean should do the trick.
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Old 05-05-2018, 12:54 PM
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Alright will do. How clean do we need the gasket surface? Would be pretty hard to clean without stuff falling inside.
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Old 05-05-2018, 12:56 PM
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Old 05-05-2018, 01:06 PM
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Originally Posted by 1993C4LT1 View Post
Alright will do. How clean do we need the gasket surface? Would be pretty hard to clean without stuff falling inside.
I used this as an excuse to drain mine and sponge out little rust flakes and what have you.. You can reach pretty much the whole inside of the tank. If you see anything in there, it's a good time to remove it.

Otherwise, you could hold a rag in one hand and scrape into it with the other?
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