Mercruiser 5.7L Fuel Pressure Regulator ?
#11
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iTrader: (1)
The only location that has any effect on air flow is when I connect the air source to the first option - the one that seats onto the cool tube. This does not allow any air through at 35-40 PSI, it starts to allow a slight air flow at about 40 PSI. At 43 PSI, it flows.
Is this the right test ? If so, it sounds like the FPR is OK. Is this a correct assessment ?
Is this the right test ? If so, it sounds like the FPR is OK. Is this a correct assessment ?
FUEL PUMP
If so, I will need to test my fuel pump. Something I loathe to do, just because I have to remove it from the h*ll hole its in. Is there an easy way to test the fuel pump while it's in place ? If not, and I pull the fuel pump - how do I test it while out ?
Do I provide a fuel source to pull from, connect to (+) and (-) source, connect PSI gauge to output side and read the results ?
Thanks !
If so, I will need to test my fuel pump. Something I loathe to do, just because I have to remove it from the h*ll hole its in. Is there an easy way to test the fuel pump while it's in place ? If not, and I pull the fuel pump - how do I test it while out ?
Do I provide a fuel source to pull from, connect to (+) and (-) source, connect PSI gauge to output side and read the results ?
Thanks !
Connect gauge (At least 100 psi) to fuel line coming from the pump
With Reg installed turn pump ON and pressure should hold steady.
If Reg is removed and hole is blocked with plate and gasket, pressure should be at least 60 psi with pump ON
Can also do it with pump removed on the bench and supply gas from a can. In all cases (except for test with Reg installed) need to bleed off the air for accurate test
#12
Hey all. I have now inherited this problem! I bought ABL1111's boat and have been trying to diagnose a hard start/low power issue as it seems he may have been too. My gauge tells me 20 psi fuel pressure at idle and above (neutral. out of water). Is there a link to somewhere to the troubleshooting steps for low fuel pressure? I cant find anything in the manual.
#13
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Hey all. I have now inherited this problem! I bought ABL1111's boat and have been trying to diagnose a hard start/low power issue as it seems he may have been too. My gauge tells me 20 psi fuel pressure at idle and above (neutral. out of water). Is there a link to somewhere to the troubleshooting steps for low fuel pressure? I cant find anything in the manual.
#14
If you pinch off the return line (from pressure regulator back to fuel filter head), while the pump is running (have to jump 12V to the positive side of the fuel pump relay), and the pressure increases, then the regulator is bad. Prior post by ABL seemed to indicate regulator was OK with air test so you probably just have a bad pump.
Also, I find it odd that there is a regulator on the fuel rail as well as at the cooler/main pump. Would I need to take that one out of the equation to accurately test the fuel pump?
#15
Registered
The regulator on the rail was a holdover from the old fuel system. When the "cool fuel" system on the lower port side of the motor was implemented (instead of the old VST system), Merc just put a blockoff in the fuel rail that made the old regulator useless (they then renamed it a pulsator). The regulator on the rail is a dead end. You don't need to touch it to test the fuel pump.
Definitive, well, mostly, yes. If you jumper 12V to trigger the pump, and while it's running, you pinch the return line and you can't get to 60 psi, the pump is weak / failing. A healthy pump should be very capable of hitting 60psi with the return line pinched off (and be sure to *immediately* release if you do in fact see 60, you never want to exceed that pressure.
Definitive, well, mostly, yes. If you jumper 12V to trigger the pump, and while it's running, you pinch the return line and you can't get to 60 psi, the pump is weak / failing. A healthy pump should be very capable of hitting 60psi with the return line pinched off (and be sure to *immediately* release if you do in fact see 60, you never want to exceed that pressure.
#16
The regulator on the rail was a holdover from the old fuel system. When the "cool fuel" system on the lower port side of the motor was implemented (instead of the old VST system), Merc just put a blockoff in the fuel rail that made the old regulator useless (they then renamed it a pulsator). The regulator on the rail is a dead end. You don't need to touch it to test the fuel pump.
Definitive, well, mostly, yes. If you jumper 12V to trigger the pump, and while it's running, you pinch the return line and you can't get to 60 psi, the pump is weak / failing. A healthy pump should be very capable of hitting 60psi with the return line pinched off (and be sure to *immediately* release if you do in fact see 60, you never want to exceed that pressure.
Definitive, well, mostly, yes. If you jumper 12V to trigger the pump, and while it's running, you pinch the return line and you can't get to 60 psi, the pump is weak / failing. A healthy pump should be very capable of hitting 60psi with the return line pinched off (and be sure to *immediately* release if you do in fact see 60, you never want to exceed that pressure.
So now. Fuel pumps. The OEM one is NLA. Is there one we like better than the Sierra? I see the prices are all over the place, and I assume quality somewhat follows that number. I typically don't buy junk if I can avoid it.
#17
Registered
I put in a cheapo from "the ROP shop", it works fine, delivers the same pressure as the OEM pump on my other motor. Durability remains to be seen, it's only been a month or so. Usually cheap is cheap, but I'm not convinced that all these pumps aren't coming out of the same Chinese factory anyway.
#19
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iTrader: (1)
Awesome. Thanks again. I did notice that the "return" was plugged after that reg. Funny tho. If you want to you can still pay $369 for it!
So now. Fuel pumps. The OEM one is NLA. Is there one we like better than the Sierra? I see the prices are all over the place, and I assume quality somewhat follows that number. I typically don't buy junk if I can avoid it.
So now. Fuel pumps. The OEM one is NLA. Is there one we like better than the Sierra? I see the prices are all over the place, and I assume quality somewhat follows that number. I typically don't buy junk if I can avoid it.
You can still get the old pump and Reg, just not from Merc. Merc sells only the conversion kits
The pump use to be made by Airtex
#20
Blocking off the return will cause the pressure to exceed the Reg setting and damage it. As you have found the return was plugged to try and compensate for a weak pump.
You can still get the old pump and Reg, just not from Merc. Merc sells only the conversion kits
The pump use to be made by Airtex
You can still get the old pump and Reg, just not from Merc. Merc sells only the conversion kits
The pump use to be made by Airtex