Tips on checking fuel pressure?

While i'm still searching for the correct adapters i need to check the fuel pressure, i began to take a look at the fuel cooler housing where the FPR is located. Does anyone here have experience taking off the housing around the fuel cooler/pump/FPR? There appears to be a bracket with a plastic housing attached, but i'm unsure how to get that housing off. Looking at the attached diagram, #21 is located up against fiberglass and can't be moved.

Does the entire bracket come off? Whats the trick?
 

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Pull that whole thing out as a unit with the bracket, 2 nuts and all the hoses come off
 
Pull that whole thing out as a unit with the bracket, 2 nuts and all the hoses come off
The outside plastic cover snaps on with latches on top and bottom and exposes the assembly. But as scoflaw states, the whole thing can be unbolted and you can work on it on a bench.
 
Thanks for the replies. I'm leaning more towards only removing the plastic cover. The boat is in the water and i don't want to be removing water lines and the entire assembly, since all i need access to is the FPR. The outside cover appears to be unlatched already as it is loose and wiggles around, but it is sandwiched between fiberglass and the rest of the unit and i have not been able to get it free. I will keep working at it, there must be a way
 
Here is a thought for you, actually a couple -
If it is necessary to disconnect a hose to install a test tee you should replace the hose(s) when you are done. Your boat looks to be a 2002 and the fuel hoses probably are original. It's quite likely the hose will get damaged doing the test (cracks and liner separation); fuel leaks on the HP side of a FI system is hugely bad from a safety perspective.
Secondly, the test while not complicated considers a couple of things - First connect the test tool with the batteries turned off. Then after it's installed and secure turn the batteries back on then turn the engine ignition on; don't start the engine. Make darn sure there are no fuel leaks. The fuel pressure should come up and read per the spec - @scoflaw probably knows what reading should be. Then turn the ign back off and monitor the pressure for at least ten minutes; you should see no more than a 5 psig drop. If the gauge indicates a significant drop in pressure with the ign off then something (injectors, check valve) are malfunctioning which is another level of diag. Also when the ign is turned on the fuel pump (in the cool fuel unit) should activate bring the pressure to spec then shut back down; do the pressure retention test after the pump has shut down and ign is off. Ok next is the running pressure (you should again shut down the batteries). Then repeat bleed down the pressure then turning on the ignition and start the engine. The fuel pump should maintain the specified pressure at idle. Then you need to take the boat out and put a load on it. Putting a load on it exercises the fuel pressure regulator in that it raises the pressure based upon intake manifold pressure and consequently provides the injectors higher pressure/flow as a ratio of the engine's load. The lower the intake manifold pressure (below atmospheric) the higher the fuel pressure, an inverse function. That pressure is controlled by a small diameter hose between the manifold and regulator. This is a critical test to verify the pressure regulator is being controlled by the manifold pressure. You will need a good vacuum gauge in addition to the fuel pressure gauge; inexpensive. Again @scoflaw can probably get you the rise rate that you should see.
 
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I wouldn't change anything until you get an accurate read on the pressure. 43 psi and could drop 5lbs. depending on manifold vacuum. If you do pull the fuel pump assembly pull a water hose at the power steering cooler this will create a syphon break so water won't come into your boat when you pull the hoses off the fuel cooler.
P
-ull pin #11 and slide fuel line #8 out. Rest is strait forward removal of the hoses.

I could be wrong about the 43 that's an MPI number. Some systems are 36. Call merc customer support with your engine number to confirm.
 
@ttmott Appreciate the post and thoughts, especially the safety tips. Once i can find a pressure gauge with adapters that fit i will certainly take your advice.

I do have one question regarding the vacuum and how the FPR works (in my boat). I have done lots of research on how the FPR works and how it relies on vacuum to open and close the valve (high vacuum at idle, lower vacuum as the load increases). With the research i've done, i see that the vacuum line from the FPR typically connects to the manifolds, however in my boat, the "vacuum" line coming off the FPR runs to the flame arrestor and the manual for this engine calls it a "diaphram rupture line". I'm confused as to how vacuum is created inside the flame arrestor/TB, and if it isn't, how does the valve inside the FPR move up and down? (I do see a separate line going from the front of the TB to the manifold, but i thought that was to vent manifold odors.)

@scoflaw Good info about creating a siphon break. If i end up going the route of pulling the entire unit out, i will be sure to take that advice. Regarding fuel pressure specs, my manual and other resources call for 30psi at 1800 RPMs for this engine.
 
@ttmott Appreciate the post and thoughts, especially the safety tips. Once i can find a pressure gauge with adapters that fit i will certainly take your advice.

I do have one question regarding the vacuum and how the FPR works (in my boat). I have done lots of research on how the FPR works and how it relies on vacuum to open and close the valve (high vacuum at idle, lower vacuum as the load increases). With the research i've done, i see that the vacuum line from the FPR typically connects to the manifolds, however in my boat, the "vacuum" line coming off the FPR runs to the flame arrestor and the manual for this engine calls it a "diaphram rupture line". I'm confused as to how vacuum is created inside the flame arrestor/TB, and if it isn't, how does the valve inside the FPR move up and down? (I do see a separate line going from the front of the TB to the manifold, but i thought that was to vent manifold odors.)

@scoflaw Good info about creating a siphon break. If i end up going the route of pulling the entire unit out, i will be sure to take that advice. Regarding fuel pressure specs, my manual and other resources call for 30psi at 1800 RPMs for this engine.
Yes TBI's operate at lower pressures than the MPI's. That line to the flame arrestor is the cool fuel vent if I remember correctly. The pressure regulator should be a 1/8" rubber tube. Now there were some early TBI's (not sure about Merc) that sensed manifold pressure at the TBI base plate and all integrated with the TBI unit. So if you have the cool fuel module that pressure regulator should be on top of it.
 
This picture is my outboard (it is an early EFI Merc 225) but they are similar. That tiny hose disconnected is the manifold pressure to the regulator dashpot. The hose on the right of the electrical plug is the fuel supply from the lift pump. The hose on the far left is from the pump and the hose next to it is the rail return to the pressure regulator.
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@ttmott My system has the fuel cooler with the FPR mounted to it. Based on the symptoms of my engine i'm assuming i have high fuel pressure and that's why i'm looking into this. I have also purchased a new FPR just in case (and as someone else mentioned on here, wouldn't be a bad idea to replace on a 20 year old engine).
 

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I'd bet the fpr is not your problem, and as you can see, it's no joke to replace it. Test it, then move on.
 
@ttmott Thanks for those links. I purchased a similar branded fuel pressure gauge as that one but the adapters didn't fit securely, there was too much wiggle (even with washers inserted) for me to feel comfortable priming the fuel pump. I have another one in delivery that i'm hoping will work. I have not checked out the vacuum testers yet, so i'll look into that.
 
This is what i've gone off of when looking for parts on the BAM website

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Having some issues with shipping on that fuel gauge, so in the meantime i decided to check my compression again (i did this a year and a half ago and it checked out fine). Well, i found my issue. Cylinder #4 has 0 compression. I didn't have any oil on me to try a wet test but the needle never moved during cranking. Not sure what that means other than it's going to be expensive, i'm sure of that.
 
It means you have a valve stuck open. Common problem, pull the valve covers and see what the rockers and valves are doing on that cylinder
 

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