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Walbro 450 problems

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Old Jan 6, 2015 | 10:25 AM
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Default Walbro 450 problems

I asked this in the C5 tech section but it seems more people run this pump here. I have a 2004 and just put this pump in. When I turn the key on, the pump primes to 30 psi, then drops to 0 immediately after. I cant start the car to see what the pressure is because its taken apart for a clutch install also.

I was told the pump may not have a check valve but I got an email from Racetronix this morning confirming it does. Where should I start looking first?
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Old Jan 6, 2015 | 03:17 PM
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Originally Posted by ascastil
I asked this in the C5 tech section but it seems more people run this pump here. I have a 2004 and just put this pump in. When I turn the key on, the pump primes to 30 psi, then drops to 0 immediately after. I cant start the car to see what the pressure is because its taken apart for a clutch install also.

I was told the pump may not have a check valve but I got an email from Racetronix this morning confirming it does. Where should I start looking first?
To be honest I don't thing you will be able to get a constant number until the pump is completely on because when you put the car in the on position it will give it some pressure then turn off until it is started. Hopefully more people chime in.

-Curtis
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Old Jan 6, 2015 | 03:23 PM
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Jumper the fuel pump relay so it runs.
Use this for help https://www.corvetteforum.com/forums...interface.html

Last edited by slow ride; Jan 6, 2015 at 03:26 PM.
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Old Jan 6, 2015 | 04:29 PM
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Originally Posted by slow ride
Jumper the fuel pump relay so it runs.
Use this for help https://www.corvetteforum.com/forums...interface.html
I will definitely do that tonight. Is this going to give me a fuel pressure reading as if the car was running?

Thanks for the replies everyone, I was on the verge of buying a new pump assembly and calling it a day. Im sure the BAP and stocker can keep up with 488hp.
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Old Jan 6, 2015 | 04:52 PM
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Yes, engine off or on doesn't matter in this case.
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Old Jan 6, 2015 | 08:14 PM
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Originally Posted by ascastil
I asked this in the C5 tech section but it seems more people run this pump here. I have a 2004 and just put this pump in. When I turn the key on, the pump primes to 30 psi, then drops to 0 immediately after. I cant start the car to see what the pressure is because its taken apart for a clutch install also.

I was told the pump may not have a check valve but I got an email from Racetronix this morning confirming it does. Where should I start looking first?
If you haven't started the car yet after installing the pump, you probable have air in the lines and it will not hold PSI. Hold off until you can let it idle and see what she dose.
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Old Jan 6, 2015 | 08:49 PM
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You guys have given me hope! I was so scared I screwed up a perfectly running car by upgrading a few parts. Im headed to the garage right now to tinker with it. Thanks!!
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Old Jan 6, 2015 | 08:50 PM
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Did you remove the stock fuel filter?
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Old Jan 6, 2015 | 11:20 PM
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Yes, the new pump came with one that is outside the bucket. Is that ok? I followed a how to in the C6 section on installing the pump. Used a few tips on how to mod the bucket and filter placement.

I was gonna jump that relay for the pump but got caught up separating the tt from the tranny. Got it all apart and ready to reinstall into the new clutch. Getting excited (and very nervous at the same time).
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Old Jan 7, 2015 | 07:18 AM
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If the o ring in the fuel filter bucket isn't seated correctly, you'll have low or no fuel pressure ( had this problem). The oring may look in good condition, but it is likely swollen from being submerged in fuel for a few years. We had to have two of assemble the filter bucket making sure the oring didn't deform when it was clicked together. The bucket will slip together EASY if the oring is seated properly. Also, if the lines in the transfer pipe aren't seated properly, pressure will be low as well.

If you cycle the key, do you hear fuel splashing in the tank when the pump is running?
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Old Jan 7, 2015 | 08:57 AM
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Originally Posted by KLLRVET
If the o ring in the fuel filter bucket isn't seated correctly, you'll have low or no fuel pressure ( had this problem). The oring may look in good condition, but it is likely swollen from being submerged in fuel for a few years. We had to have two of assemble the filter bucket making sure the oring didn't deform when it was clicked together. The bucket will slip together EASY if the oring is seated properly. Also, if the lines in the transfer pipe aren't seated properly, pressure will be low as well.

If you cycle the key, do you hear fuel splashing in the tank when the pump is running?
Do you mean the filter at the top of the pump assembly? We had to take that apart to resolder a wire that got tugged on. It was a bitch to get back together. We sorta forced it on.

Ill bet thats my problem. I am visualizing all the fuel being primed and spraying right back out between that oring.

Last edited by ascastil; Jan 7, 2015 at 09:22 AM.
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Old Jan 8, 2015 | 10:57 PM
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Good news. I pulled the pump back out and blew through the fuel line from the top of the assembly and sure enough, fuel shot out from in between the 2 halves of the filter. I pulled it apart, lubed all the orings, and after about an hour of putting it on and taking it off, it snapped right in place and sealed tight.

There is bad news though. I decided out of curiosity to start blowing through the fuel lines just to see if they were leaking. I found a pin hole in one of the lines that is inside the tank, about an inch from the connectors to the crossover. It is a perfect tiny tiny hole, almost like its supposed to be there. Is that hole there for a reason, or does it need to be replaced/repaired? I didnt have any tools there so I cant imagine where it came from.
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Old Jan 8, 2015 | 11:10 PM
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Right next to the tip of the screwdriver. I cant imagine what would poke a perfectly round hole through that hard line. Thats the line that sits in the bucket.


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Old Jan 9, 2015 | 10:35 AM
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I'm 99% sure that i have that same hole
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Old Jan 10, 2015 | 02:07 AM
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Victory for the rookie Corvette guy!!!! Installed the pump tonight, turned the key on and the pressure jumped to 60. I would guess it didnt even hit 40 till about 6-7 minutes later, I wasnt timing it. The key has been out of the car now for close to 30 min and its still holding 40.

Thankyou KLLRVET, thankyou everyone who threw out suggestions!!!! Thanks!!!!! I am going to throw back a few beers and stop stressing!!!!!!!!!!!!!!!!!!

Last edited by ascastil; Jan 10, 2015 at 03:50 AM.
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