R.E.D Posted Saturday at 07:05 PM Share Posted Saturday at 07:05 PM Hello all , having some low fuel pressure issues. Narrowed it down to the check valve since it drips just by pressing the hand primer without even the needle on the pressure gauge registering any pressure.I know they were a few variants to the check valve.Does anyone have the right part number for the one I need and the opening pressure for it? 2001 etech , 427hp. Thanks in advance Red Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/ Share on other sites More sharing options...
fjh Posted Saturday at 07:30 PM Share Posted Saturday at 07:30 PM 25 minutes ago, R.E.D said: Hello all , having some low fuel pressure issues. Narrowed it down to the check valve since it drips just by pressing the hand primer without even the needle on the pressure gauge registering any pressure.I know they were a few variants to the check valve.Does anyone have the right part number for the one I need and the opening pressure for it? 2001 etech , 427hp. Thanks in advance Red Does yours have the plastic bleed back hose to it? 60-80 psi is good! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595674 Share on other sites More sharing options...
R.E.D Posted Saturday at 07:49 PM Author Share Posted Saturday at 07:49 PM Yes ... barely getting 20psi...at idle. I've already done the diag. I I tightened the jam nut on the check valve and it somehow jumped up to 70 .. but now it's back to low pressure. Hence why I'm needing the part number. I'm pretty sure the check valve should not open with the pressure from the hand primer , especially if that pressure is so low that it doesn't even register on the gauge that is hooked up to the fuel rail. Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595675 Share on other sites More sharing options...
fjh Posted Saturday at 11:40 PM Share Posted Saturday at 11:40 PM Post your vin Heinz will fix ya up! Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595688 Share on other sites More sharing options...
Joey Mack Posted Saturday at 11:47 PM Share Posted Saturday at 11:47 PM I bet this is it.. PAI sells them 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595689 Share on other sites More sharing options...
R.E.D Posted Sunday at 12:30 AM Author Share Posted Sunday at 12:30 AM 40 minutes ago, Joey Mack said: I bet this is it.. PAI sells them Well that's a problem. I've seen several for sale. The one you posted 691 GC225M seems to open at 44 PSI. There are some that are identical that open at 54 PSI. There must be a couple more different ones . I would like to know which one the truck should have. I know that there were some that were too high pressured and woud blow out orings. Vin 1m1aa18y61w139047 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595694 Share on other sites More sharing options...
Joey Mack Posted Sunday at 12:35 AM Share Posted Sunday at 12:35 AM Yep. Not the right pressure. Like fjh said, 60-80 psi is good. Im still looking for a chart or whatever is out there with pressure ranges.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595695 Share on other sites More sharing options...
fjh Posted Sunday at 01:57 PM Share Posted Sunday at 01:57 PM 13 hours ago, Joey Mack said: Yep. Not the right pressure. Like fjh said, 60-80 psi is good. Im still looking for a chart or whatever is out there with pressure ranges.. https://dieselpartscenter.com/products/valve-genuine-pai-2653?srsltid=AfmBOoprWQNF-CF2Fj3iSITdinzEhqn1x-K3VIqnQH0mYbAelhxaX6Jt Could be wrong but The one at 54 psi will likly be fine . I highly doubt 6 psi will make much difference ! As long as your transfer pump is strong it will run fine ! the gear on the transfer pump used to come loose And cause issues This also may be contributing to the issue! not there so I cant say! you could pull the pump and check that gear if the check valve don't cure the issue! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595740 Share on other sites More sharing options...
R.E.D Posted Sunday at 03:26 PM Author Share Posted Sunday at 03:26 PM 14 hours ago, Joey Mack said: Yep. Not the right pressure. Like fjh said, 60-80 psi is good. Im still looking for a chart or whatever is out there with pressure ranges.. 1 hour ago, fjh said: https://dieselpartscenter.com/products/valve-genuine-pai-2653?srsltid=AfmBOoprWQNF-CF2Fj3iSITdinzEhqn1x-K3VIqnQH0mYbAelhxaX6Jt Could be wrong but The one at 54 psi will likly be fine . I highly doubt 6 psi will make much difference ! As long as your transfer pump is strong it will run fine ! the gear on the transfer pump used to come loose And cause issues This also may be contributing to the issue! not there so I cant say! you could pull the pump and check that gear if the check valve don't cure the issue! Yes, I thought that as well. The one that is on there only has part number 225m4 stamped in it Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595746 Share on other sites More sharing options...
The Heinz Posted Monday at 07:07 PM Share Posted Monday at 07:07 PM On 5/9/2026 at 7:40 PM, fjh said: Post your vin Heinz will fix ya up! Not anymore good buddy, I can look up Volvo parts but only for trucks in my company's fleet. Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595854 Share on other sites More sharing options...
fjh Posted Monday at 07:15 PM Share Posted Monday at 07:15 PM 7 minutes ago, The Heinz said: Not anymore good buddy, I can look up Volvo parts but only for trucks in my company's fleet. Booo! You is slipping!😡 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595855 Share on other sites More sharing options...
R.E.D Posted 9 hours ago Author Share Posted 9 hours ago I found 691GC227M2 on the web , states that it's 70psi..Could anyone confirm 👍? I would call any of my local mack dealers and ask ,but they're as useless as tits on a boar hog and lazier than an upper jaw. Thanks Red. Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595926 Share on other sites More sharing options...
Mackpro Posted 8 hours ago Share Posted 8 hours ago There were 2 different fuel pressure relief valves for the standard 1998.5 to 2001.5 ETECH engine (Pre CCRS and ASET) these had the barb on them for the plastic push on fuel return line coming firm the cylinder head. I believe one was a 60 psi and the other was a 90 psi. Some of the 400 and 427 engines had a rough idle and Mack had us put in the 90 psi valve to smooth them up. Later some software updates and removing the center o-ring on the EUP’s solved the rough idle. Also the 90 psi valves caused the EUP o-rings to seep more fuel in the oil than they already do. By the time everything was figured out the CCRS engine was starting production and the problems were resolved. There is a service bulletin on this and I’ll see if I can find it. It was titled Fuel System Improvements or something like that. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595934 Share on other sites More sharing options...
Mackpro Posted 6 hours ago Share Posted 6 hours ago The 100 psi fuel valve is part number 63AM28 and the 80 psi valve is 691GC225M4. The bulletin number is SB-221-028 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595942 Share on other sites More sharing options...
Mackpro Posted 6 hours ago Share Posted 6 hours ago Here is the bulletin, this only applies to the original ETECH engine and not the CCRS or ASET engines. The parts numbers have probably changed to Volvo part numbers however. ETECH Fuel supply MACK-SB-221-028.pdf 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595944 Share on other sites More sharing options...
fjh Posted 5 hours ago Share Posted 5 hours ago 3 hours ago, R.E.D said: I found 691GC227M2 on the web , states that it's 70psi..Could anyone confirm 👍? I would call any of my local mack dealers and ask ,but they're as useless as tits on a boar hog and lazier than an upper jaw. Thanks Red. Dont think it has the fuel return barb! Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595945 Share on other sites More sharing options...
Mackpro Posted 4 hours ago Share Posted 4 hours ago The VIN listed above is a 2001 PRE-CCRS ETECH with the barb on the fuel regulator. So it looks like the 691GC225M is 44 PSI. The 691GC225M2 is 54 PSI. The 691GC225M4 is 80 PSI and the 63AM28 is 100 PSI. Fuelsystem.pdf 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595951 Share on other sites More sharing options...
fjh Posted 2 hours ago Share Posted 2 hours ago 2 hours ago, Mackpro said: The VIN listed above is a 2001 PRE-CCRS ETECH with the barb on the fuel regulator. So it looks like the 691GC225M is 44 PSI. The 691GC225M2 is 54 PSI. The 691GC225M4 is 80 PSI and the 63AM28 is 100 PSI. Fuelsystem.pdf 720.25 kB · 0 downloads Good info pro! Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595952 Share on other sites More sharing options...
Mackpro Posted 1 hour ago Share Posted 1 hour ago 1 hour ago, fjh said: Good info pro! Yea, I wrote that down in my notes for sure! Quote Link to comment https://www.bigmacktrucks.com/topic/76637-etech-pressure-relief-check-valve/#findComment-595956 Share on other sites More sharing options...
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