2001 21v Running rich 350 Mag MPI Ski

[snowmandopeman]

Yes changed out the IAC didn’t replace the fuel pump yet pressure seems good across the board.
As of now
Replaced
IAC
IAC muffler
MAP
thermostat
coolant temp sensor
coolant temp sender
manifold air temp sensor
plugs
cap
rotor
plug wires
fuel water separator
ignition pick up (3 wire)
cleaned the throttle body
fuel test came back fine no water in the tank.

really the only things left are the fuel pump and fuel injectors and fuel pump is checking out fine from pressure tests. Really wish I could just take it some place to have it scanned but everyone is a month or 2 out. Going to take the injectors out and send them in for cleaning this weekend. I’ll add a video of it running to YouTube and post it here.

[snowmandopeman]

gumby
boatwakes

https://www.youtube.com/watch?v=ApYQtbKZRJ0

[USWaker]

Sound like you have a bad voltage reference somewhere ie bad block ground or something. Do some voltage drop tests between grounding points on the block and the battery and other various points that should be of equal potential.


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[snowmandopeman]

What is the voltage on your battery when the boat is on? At idle my voltage is right at 13.72

[boatwakes]

For reference, firing order is 1-8-4-3-6-5-7-2 and the rotor spins clockwise as you're looking down on the distributor. It is tough to tell what sounds I'm hearing in the video but it sounds like an odd firing, crossed wire or something of the sort. However, a hung or stuck valve will cause an intermittent backfire through the intake but your compression values do not indicate there's an issue. I would suggest the basics first and not to insult anyone's intelligence or knowledge base on this, check the wires are in their correct position. Cylinder 1 on a v-drive is starboard side of the vessel and all the way aft. Conversely, cylinder 1 is on the port side all the way forward on an inboard powered vessel. 1, 3, 5, and 7 are all on the same side as 2, 4, 6 and 8 are also all on the same side opposite their odd numbered brethren. However, this only applies to GM engines so anyone with a Ford, this is not the case.

[snowmandopeman]

Okay so checked the plug wires again and all are exactly where they need to be. But I think we have finally figured out the problem!!! Spoke with my fuel injector guy and he literally started laughing when I asked how they check out. He referred to one as a garden hose and wolf never actually close, and most of them were leaking or had terrible spray. Looks like the previous owner purchased the good ole china special fuel injectors. Picking them up today and I’ll report back.

[boatwakes]

Nice!!!!

[snowmandopeman]

Okay so Iv a bout had it haha. Fire up idled great for a few mins but now it’s dieing after idling for about 5 seconds. I’m going back to check out the firing order and spark plug wires. is this cylinder 1 in your boat also?

[snowmandopeman]

gumby hey can you take a picture of your distributer cap and point out which wire goes to cylinder one on your boat. I think something might be funky with mine.

[snowmandopeman]

Okay so I did do it correctly, so after I find TDC I just go counter clock wise one post after another to the corresponding cylinder 18436572 and Tada firing order is correct. Figured I would check it a third time. I’m about to throw in the towel. Every time I find something wrong and fix it, it starts up with a new problem. First it was running rich but idling fine now I cleaned and replaced injectors and it ran amazing for about 5 mins then it went back to rough running missing cylinder #7 and stalling after about 10 seconds of idling. This thing has me stumped.

[snowmandopeman]

Pulled the fuel pump it’s some sort of knock off one so I’m gonna replace it while I have the cool fuel out I did notice a little bit of gunk on the regulator screen but didn’t seem like enough to cause fuel issues. Do the fuel pressure regulators go bad very often and is it worth replacing, they want like 190$ for it is the reason I’m asking .

[boatwakes]

Just for clarification, after you determine where TDC is AND attach the number 1 spark plug wire there, you go CLOCKWISE 1-8-4-3-6-5-7-2 around the cap as you look down on it from above. Above you listed you went counterclockwise and if you did it that way, it will run but not run very well.

[snowmandopeman]

yes sorry I meant to say clockwise. I have taken apart the entire fuel system and cleaned it out very well. Figured while I’m waiting on parts try and get this thing is the best shape I can. Do you think I should replace the fuel pressure regulator while I have everything apart or do they not typically go bad.

[boatwakes]

We replace them because typically the brass fitting that screws into the old pump will break when trying to remove it. They're expensive at around $280 for all the fittings and regulator but again, not easily accessed and definitely worth the piece of mind.

[snowmandopeman]

well shop said it seems like the ECM is failing, so they are going to send it out for testing and possible repair, if it cant be repaired its seems like I might be SOL