View Full Version : Fuel Pressure reading MCX

07-22-2007, 05:33 PM
2004 MCX engine

What fuel pressure reading(s) should I see at the schraeder valve on the fuel rail?


07-22-2007, 07:18 PM
I think in 2004 they changed to the higher pressure fuel pump. Your fuel pressure should be 60psi.

07-22-2007, 08:59 PM
Well, you'd be amazed at what's in one's owner's manual.

for the 2004 MCX 35-45 psi operating pressure.

07-22-2007, 11:11 PM
I am pretty sure the MC manual is incorrect. In 2003 the fuel pressure was 40 psi and in 2004 the fuel system was changed to 60 psi. Send Engine Nut on here a PM as he will know for sure.

07-22-2007, 11:19 PM
I just looked at the Indmar owners manual online and it also states that the min fuel pressure for the MCX is 60 PSI. The manual is supposed to be 2003 to present, however like I said my 2003 had a 40 psi pump not the 60 psi. Here is a link to the manual. The information on fuel pressure is on page 83.

2003 to Present Owners Manual (http://www.indmar.com/About/ContactIndmar/Manual_2003_Presentweb.pdf)

07-23-2007, 08:10 AM
I noticed that also:

Mastercraft owner's manual sez 35-45 Operating Pressure
Indmar 2003 manual (OMO502-04) sez 50 psi at keyup (not operating pressure)
Indmar 2003 manual (OME0502-07) sez 60 psi at keyup

We need to be careful to not get the two test states mixed up (Keyup vs Operating Pressure). Both are important for testing purposes, but I'd worry more about the "operating pressure". I've got an email out to my dealer, but I will PM Engine Nut (great idea...thanks).



07-23-2007, 09:04 AM
I've got an email out to my dealer, but I will PM Engine Nut (great idea...thanks).

Please let us know what you find out.

07-23-2007, 02:17 PM
I was told that in 2005 some mcx's use 40 and some use 60 due to different fuel different injectors which require higher pressure. The dealer mistakingly have me a 40 psi replacement pump for a 60 psi mcx and it ran like crap until they realized what was going on. You should be able to tell what the psi is by looking at the fuel pump label...

07-23-2007, 08:18 PM
Per my dealer 55-62
Per Engine Nut 57-62

I've asked Engine Nut to confirm "keyup" vice "operating pressure"

07-24-2007, 08:09 AM
We should see the psi range at:

idle, and
everything up to WOT.

Thanks Engine Nut!

07-29-2007, 09:42 PM
AndyG, Thanks for sharing that you suspected that the manual was in error.

Engine Nut, THANKS!!!!

Went out today. 60 psi. inexpensive fuel pressure tester at Advance auto that screws right onto the schraeder valve.

Now to locate the AC Delco fuel pump as a backup and rebuild the fuel pump assembly I pulled out.

Cheers all!