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Fuel Injector service

Old 05-13-2020, 08:00 AM
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Default Fuel Injector service

Have 1997 32' Fountain with 2-502's . The boat/engines have 265 hours on them. Aside from regular maintenance the injectors have never been serviced. Is this an easy job? It looks like just the top of the plenum has to come off correct?
I have been reading the other posts on here and the general consensus is that this should be done.
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Old 05-13-2020, 09:28 AM
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Originally Posted by nygman11 View Post
Have 1997 32' Fountain with 2-502's . The boat/engines have 265 hours on them. Aside from regular maintenance the injectors have never been serviced. Is this an easy job? It looks like just the top of the plenum has to come off correct?
I have been reading the other posts on here and the general consensus is that this should be done.
Yes, your motors are 23 years old and have probably NEVER had injectors serviced. Pull plenum tops, gently unplug all injector plugs, unbolt the rails and work them out of place. Make sure everything is clean before you do this too so you don't allow any dirt to go into the motor. My customers pull them and send them without issue all the time when I do them. Make sure you key it up/prime fuel pump to full pressure BEFORE putting plenum tops back on. Gen 5/mefi 1's (which Im going to assume you have, ie, 1997) have very sharp edges on rails where injectors go in so you have to absolutely check for leaks with plenum tops off, its easy to cut a oring. When I do them, I also convert them to press in screens, its hard to keep the little floating screens in place when your putting them back in in the boat, Smitty
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Old 05-13-2020, 10:51 AM
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Smitty's done several sets for me, top notch work
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Old 05-13-2020, 11:21 AM
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So the dissassmbly and assembly are pretty straight forward but when you say pressurize the fuel system I am assuming you mean crank the engine over with the ignition key but how long does it take to build the pressure up to do the check?
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Old 05-13-2020, 12:43 PM
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if you like you are welcome to call me after hours. 31 years - zillion of injectors and zillion of boats have ran thru my hands. ENGINE serial number is important as well. This determines your set up from OEM stock form. I am busy so as always take calls even late nite to help boaters or you can text. No big deal as this is the norm for me. . there will be a few things you will have do before and during pulling out your injectors and again this determines exactly what you have for a set up.

eight - one - 7

six - 5 - eight

7 - seven - two - 1

Injector service is a maintenance item but taking proper fuel samples is how all this is determine as well for it. if one needs to have it done earlier. Even marine oems in classes say every 7 years min for boaters should have the fuel injectors tested and service and especially for rebuilds and longblock change outs. Same goes for carb engines as well.

Last edited by BUP; 05-13-2020 at 12:49 PM.
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Old 05-13-2020, 01:13 PM
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Originally Posted by nygman11 View Post
So the dissassmbly and assembly are pretty straight forward but when you say pressurize the fuel system I am assuming you mean crank the engine over with the ignition key but how long does it take to build the pressure up to do the check?
When you turn your key to "ON" you should hear the fuel pump start running for about 5 seconds which pressurizes the system before you start cranking. That is what he is referring to as the method for "leak checking" once injectors, rail and fuel line are reinstalled. And it is very important step before bolting the upper plenum back on. not hard at all to screw up the fuel line o-rings.

Smitty (articfriends) is a great guy and will get you taken care of. He is why my tired 1000 hour 502 MPI motors run so dang well still!
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Old 05-13-2020, 02:40 PM
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Originally Posted by nygman11 View Post
So the dissassmbly and assembly are pretty straight forward but when you say pressurize the fuel system I am assuming you mean crank the engine over with the ignition key but how long does it take to build the pressure up to do the check?
Yes, the first key cycle the mefi primes fuel pump for 5 or 8 seconds, after that you need to "click key:" just enough to nudge motor usually to get pump to cycle on again. IF you dont do this and there is a leak, it will be a PIA to take plenum back off or worse, leaking fuel and possibility of a fire, Smitty
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Old 05-13-2020, 03:03 PM
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When reinstalling my injectors I installed all of them in the fuel rail with KY jelly on O rings. Then installed the large sealing rings on only one side of the injectors, and the other side place them in the manifold holes. They will all not go in at the same time. Doing this method it made it easier to install one side then tilt over to the other.

Guess I could have just placed all of them on the injectors and may have made it even better, don;t know but Smitty probably knows a great way
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Old 05-14-2020, 06:43 AM
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Do you disconnect the fuel line from the rail or leave it attached?
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Old 05-14-2020, 07:01 AM
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Disconnect
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