Murcruiser 5.0 mpi fuel pressure way down, and none after it sits

[Ebbtide01]

I have a 2005 Murcruiser 5.0 mpi with the cool fuel 2 system. Had the boat and only put about 10 hours on it and fuel pump went out. I bought a Quantum replacement pump after reviewing them for a week or so. But now when I run the boat my fuel pressure is low, 30 at idle, but boat runs perfect, my problem is that when I run it for a little bit, and turn it off, it want start back. And the fuel pressure gauge finally goes to 0. Can go out a few hours later, and it will start right up. I have also replaced the fuel pressure regulator on the rail. Could it be the one on the cool fuel cooler.

 

[alldodge]

Welcome
What is your motor serial number?

 

[Ebbtide01]

Welcome
What is your motor serial number?

OW061928

 

[alldodge]

Thanks
Having cool fuel 2 then should have an Alpha drive
You should also have 43 psi fuel pressure

Has the fuel pressure regulator been changed or tested?

Can also have a vapor lock issue going on but with VL you should have no issue restarting after 30 minutes. The restart issue might happen after an hour of so when heat soak sets in

 

[Ebbtide01]

Thanks
Having cool fuel 2 then should have an Alpha drive
You should also have 43 psi fuel pressure

Has the fuel pressure regulator been changed or tested?

Can also have a vapor lock issue going on but with VL you should have no issue restarting after 30 minutes. The restart issue might happen after an hour of so when heat soak sets in

I have changed the PR on the fuel rail, but haven’t changed the one on mounted on the cooler. Which I’m guessing operates the fuel return part of it. When it first started doing it, I could pull the PR off the end of fuel rail, and it would fire right up, and run fine till you cut it off again. I’m hoping I just have a bad Fo and replace it and all is good, but I’m going on and replacing the lower PR while I have the cool fuel assembly off. Is there anyone that makes a good FP with out having to spend 1000 on murcruiser parts.

 

[alldodge]

The FP Reg is the lower one on the pump. The upper one is a damper and doesn't do much but educe FP pulses

FP Reg cost under $200 which is a lot, and can be had with a automotive part for less
Merc 861126A1
Mallory 9-33206

 

[Ebbtide01]

The FP Reg is the lower one on the pump. The upper one is a damper and doesn't do much but educe FP pulses

FP Reg cost under $200 which is a lot, and can be had with a automotive part for less
Merc 861126A1
Mallory 9-33206

Yea I’ve looked at the regulators, CCP has them for 166. Factory ones. What is a good fuel pump, I don’t think this quantum is a very good fuel pump. I’ve been told EMP is a good one. Part# 1399-39519. I only want to do this one time. Because to change the regulator the hole assembly has to come out.

 

[Ebbtide01]

The FP Reg is the lower one on the pump. The upper one is a damper and doesn't do much but educe FP pulses

FP Reg cost under $200 which is a lot, and can be had with a automotive part for less
Merc 861126A1
Mallory 9-33206

The mercury fuel pump is what’s so high, do you know of a trusted brand. I have had 2 say EMP, but can’t find any reviews online

 

[alldodge]

Search for 861156A1 which is the old pump number, several will show up

You may have a good pump it's just the Reg is where the problem is, need to test. The pump may be able to output 60 psi of more, but if the Reg bleeds off all pressure except 30 that's all you will see.

 

[Ebbtide01]

Search for 861156A1 which is the old pump number, several will show up

You may have a good pump it's just the Reg is where the problem is, need to test. The pump may be able to output 60 psi of more, but if the Reg bleeds off all pressure except 30 that's all you will see.

10/4 thanks, I will check this weekend. Going to pull assembly out this weekend.

 

[Ebbtide01]

Search for 861156A1 which is the old pump number, several will show up

You may have a good pump it's just the Reg is where the problem is, need to test. The pump may be able to output 60 psi of more, but if the Reg bleeds off all pressure except 30 that's all you will see.

Tested the fuel pump and regulator today, plugged the return line, and pump is pumping 95psi. So ordering a regulator, that should fix me up. Thanks for your help.