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05-08-2017
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#81 | |
 
Join Date: Mar 2014
Location: Warrington PA
Posts: 1,913
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Re: New option for fuel pump replacement
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What I would suggest is to make sure your getting the product you need and at the best cost possible. Case in point, Mike checked Amazon and the Denso 951-5006 unit is listed there for under $20, but their site mentions that it doesn't fit the LT5. The same (think they are the same) units I ordered are more than $20, and are a direct fit for the LT5. The one Denso listed on Amazon is made in China, the Denso unit that Mike used is made in Mexico. I am calling tomorrow to check where the units I have on order will be made. We would all like a quality product regardless where it is made and hopefully that is what we purchase. I would like to see more USA units made, as with some of the China based automotive products have been in question over the years concerning quality and reliability. That being said, ineffective quality control could take place anywhere. Also take note that there are many sites that do not distinguish the difference between the LT1 and LT5 fuel pumps in their specs. One exception appears to be Rock Auto that does show a difference in part #'s for the two engines. But one thing I found very interesting is that the PERFORMANCE ELECTRIC P240KC fuel pumps that are popular are listed for both the LT1 and the LT5, while other brands on their site do show different part #'s pertaining to the different engines. IMO, this is one of many instances where you really need to check everything out before making a purchase.
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Tom 1994 ZR-1 #009 "captured test fleet car" 1974 LS4 454 Vert 1982 L83 CFI...now a retired "dd"....Sold WAZOO Member Last edited by Roadster; 05-08-2017 at 11:20 PM. |
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05-10-2017
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#82 | |
 Join Date: Jul 2010
Location: Woodstock, Ontario, Canada
Posts: 1,275
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Re: New option for fuel pump replacement
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As soon as you go WOT the ECM would be commanding very high pulsewidths, with all 16 injectors firing the fuel system is fighting to supply them with fuel and it takes a moment to get the fuel pressure back up. Throwing some powershifts would eliminate your issue I'm guessing as the throttles remain open and there is no ramping up to full power. You would be looking for just under 52 psi at all times, IIRC the OEM regulator is set at 51.8psi for LT5. A fuel pressure gauge taped to the windshield would tell the tale. Cutting open fuel filters is a good idea as well. It doesn't take much to start to plug these high pressure fuel systems. I had a 66psi OEM GM system that woudnt rev over 4500rpm at WOT, I was surprised what was in the filter. Mr Haibeck says that you require 51psi plus or minus 1 psi at WOT 3000-7000rpm. If you see less that 47psi of WOT fuel pressure, reduced power and knocking and possible codes can result. He agrees with talking her for a spin with the gauge taped to the windshield, he does make a good point to use a passenger though. The fuel pressure should snap up to 51 +/-psi (from around 43psi during normal driving when engine vacuum is high) when you stand on the throttle, then you know the FPR is working, or if you are at idle and you disconnect the vacuum supply to the FPR, you will see 51psi or so.
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peace Paul ZR-1 Net Registry Member #1494 |
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05-10-2017
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#83 | |
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Join Date: Jun 2013
Location: Toronto
Posts: 782
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Re: New option for fuel pump replacement
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 but the hesitation was much more prominent. It still pulls decent with the hesitation but something is going on.
Last edited by 5ABI VT; 05-11-2017 at 03:11 AM. |
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05-11-2017
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#84 | |
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Join Date: Jul 2010
Location: Woodstock, Ontario, Canada
Posts: 1,275
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Re: New option for fuel pump replacement
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Used on everything GM from 1991-2012. Description "Fuel Rail Pressure Relief Valve Distributor-Breakerless ignition" US$18.26 GM p/n 12570619  This thread throws around some possible sizes. http://www.zr1.net/forum/showthread....=fuel+pressure Whatever your issue is, the engine sure recovers quickly afterwards. I can totally understand thinking it might be a clutch issue. After much digging, I found a thread that specifies the correct un regulated or WOT fuel pressure of 50.76 psi. So if you find 51 psi plus or minus 1 psi at WOT your golden. It was tpepmeie who reported the actual LT5 fuel pressure of 50.76psi. At 50.76psi of fuel pressure, the stock injectors will flow 22.14 lb/hr and at 43.5psi they would flow 20.5 lb/hr. This is the thread where I was referencing Mark Haibecks info. http://www.zr1.net/forum/showthread.php?t=14739 
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peace Paul ZR-1 Net Registry Member #1494 Last edited by Hog; 05-11-2017 at 09:54 AM. |
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I definitely will post up! I checked after reading your post that they did show available on amazon.ca for the correct part number. But with the strainers (likely wouldn't need another pair) it would have been close to the cost of the lpe pumps which on their website shows are included for the cost so I went with that. I spoke with Ken at lpe briefly and I was convinced (lol). I figured no one really talks about walbro or performance brands much so I at the least I could add something to the forums regarding that setup.
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