7.4 MPI Fuel pressure regulator/damper?

[MikeMag]

Hello all-have been having rough running issues pop up on my Maxum 2800SCR.
Suspected the fuel pressure regulator (mounted below motor down on the fuel cooler), but when vacuum tube disconnected found fuel leaking out. The top regulator/fuel pulse damper is leaking fuel freely, I assume this is not normal? I cannot find this top regulator on any parts lists, any part number or info greatly appreciated. This is the regulator/damper mounted up top of the motor, tees off from the tube going from plenum down to the bottom regulator.

 

[alldodge]

Howdy
What is your motor serial number?

 

[MikeMag]

L 0655270. Thanks!

 

[Fun Times]

X2 on engine serial number and engine year? 1997 or 98?
Have a photo handy by chance?

From the description it sounds like you may have an L29 7.4L engine.

If so, are you sitting down for the cost of the regulator up top?
Item number 5

5

8M0069803

REGULATOR, Fuel Pressure

802630T

SS/ACT

$431.21

$405.69

1

 

[Fun Times]

0L655270. Thanks!

Yes the L29, https://www.mercruiserparts.com/7-4l-bravo-mpi-gen-vi-gm-454-v-8-199-1
It's a GM engine part so you ought to be able to search it out online for a better cost try EBay for example or a local auto parts store may have it. https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=802630T&_sacat=0

 

[alldodge]

Having fuel in the vacuum line could mean the cool fuel or the rail regulator could be leaking.

I would remove the one on the rail because it would be easier to get to and test

 

[MikeMag]

Thanks for the replies--yes, that top regulator will be a lot easier to get to for sure. To be clear, it shouldn't be spitting fuel out, correct? I'm thinking it is sucking extra fuel to the rail and making it run rich. I'm just not seeing the top unit I have online, I'll pull it out next chance and check it for a bad diaphragm.

 

[Fun Times]

No fuel regulator should be spitting out fuel under normal working conditions.

When they do spit out fuel, that is a sign the internal diaphragm is compromised and a new one is needed... You may as well check both the Fuel regulator down next to the oil pan and fuel damper up top by pulling off the easiest vacuum hoses you can get to in order to check both.

Also if at all possible on your end, check your fuel pressure before and after replacement/s just so you know what's happening now and for the next time.

 

[MikeMag]

X2 on engine serial number and engine year? 1997 or 98?
Have a photo handy by chance?

From the description it sounds like you may have an L29 7.4L engine.

If so, are you sitting down for the cost of the regulator up top?
Item number 5

5

8M0069803

REGULATOR, Fuel Pressure

802630T

SS/ACT

$431.21

$405.69

1

That is crazy, the price on this little unit!! Hopefully when I get it removed I can disassemble and fix the diaphragm....

 

[alldodge]

Do search around, as FT mentioned its a GM part. I search on just the old number and found it at Walmart and Amazon for 170 or so. Sierra has them for less

Should be a cross over to Mallory of Standard

 

[MikeMag]

Just wanted to follow up and thank you all for the help-it was indeed the top regulator went bad, a simple task to replace after removing the distributor to get access. I found the part for 180.00 on ebay. Though I'm sure I could've found a matching GM part for 20 bucks,, I was glad to have it fix all issues and running smooth again!

 

[raynald]

Just wanted to follow up and thank you all for the help-it was indeed the top regulator went bad, a simple task to replace after removing the distributor to get access. I found the part for 180.00 on ebay. Though I'm sure I could've found a matching GM part for 20 bucks,, I was glad to have it fix all issues and running smooth again!

Hi I just read your problem and I am pretty sure I have the same. You said you found the part on eBay what part number did you need. As I went to the Marine shop before taxes they want $785.00 . Would it be possible for me to call you to get more information. Thank-you

 

[raynald]

Hi I just read your problem and I am pretty sure I have the same. You said you found the part on eBay what part number did you need. As I went to the Marine shop before taxes they want $785.00 . Would it be possible for me to call you to get more information. Thank-you