2004 8.1l VP Gi-EF (375hp) 1048 hrs Won't Start

Whole story: Overheated last winter when lower unit intakes were frozen (left duo prop tipped up and it got COLD). Returned to dock at idle, and replaced smoked impeller. Took out again and it was still frozen, overheat alarm in harbor. Hauled out and parked until warmer weather (3 months later). Started with hose hooked up and ran like absolute crap. Shut down and did some research. Found out the whining high pressure fuel pump (had whined since I bought it) was a bad thing. Guy I bought it from had terrible hearing and didn't know it was whining. I didn't know it was an indicator of a failing fuel cell. Checked fuel pressure at rail, 52 psi on key on, and tried to start again. Would not start.

Paid for a scan, had DTC 33, MAP sensor. Cleared and replaced MAP. Still won't start. Inquired for new fuel cell, and backordered in North America, back ordered in Europe, and $1394 plus freight. Ordered aftermarket replacement. Installed. Either my fuel injection fuel pressure gauge is broken, or there isn't sufficient rail pressure. Gauge shows no pressure and yet the Schrader valve spews gas when connecting and the gauge bleeds off plenty of gas.

Have heard of paint dissolving from insides of fuel pumps and clogging the regulator. Took out the original regulator and cleaned gently, reinstalled. Nothing. Acts like it almost wants to start...a little.

Bought a Rinda handheld scan tool, and it shows no codes. Pump cycles with key on, two alarm beeps like normal. Completely at a loss. If this had a Holley 4 barrel and a distributor like an engine should have, it would be a no brainer and burning the $5.50 gas like only a big block knows how. This electronic bs has me perplexed. I have not checked spark, and my next thought was to check compression on the cold cylinders. It rolls over like normal (I've heard hydrolocked engines with bent valves try to start and it doesn't give me that impression).

Anyone else have a VP with an MEFI 4 ECM that just won't tell you why it won't start even with the electronics scanned and telling you it's ok?

Sounds like it is time for a new pressure gauge...

You need spark so testing a few of the coils would be a prudent next step.

You also need 'fresh' fuel...and not having the history there makes it hard to estimate if this is the case. The RINDA tool gives you the ability to 'see into the ECU' and can be useful when there are no DTCs present.

If you have good fuel and a hot spark, a compression test would make sense for the next test. and it wouldn't hurt to have the MEFI4 manual if you haven't down;oaded one yet.

Testing the coils today. Haven't pulled any plugs after trying to start to see if they are getting wet and just not firing. Gas is newer, and both tanks were treated with ethanol treatment before winter and kept full. Water is always a concern up here in the rain forest, so both the Racor and the water separator on the fuel cell are brand new.

Have spark...and now feel like a rookie asking for advice on hitting a curve ball. I took off the original fuel cell and cleaned, then reinstalled. I'm wondering, and feeling ashamed, if I put the fuel lines on backwards. I don't have the EFI manual...the guy I bought the boat from repowered the boat and had all the manuals...for the original Ford VP engine. None of them obviously help me with the GM. I didn't mark the lines when I removed them the first time. Rookie rookie rookie mistake. Does the high pressure pump (one that's replaceable and has the DC wiring plug on it, go to the line that goes into the fuel regulator? It must...I think. I miss Diesel engines....

Honestly, I can't say I've touched that particular engine so I can't say for sure...taken a quick look at the parts diagram, I'd suspect the two hoses going up to the fuel rail do NOT interchange (due to both the hoses and the o-rings having separate part numbers)... the HP pump's output should go to the rail and the regulator's output should return to the pump (smaller hose would be my guess)...Hope that helps..

I appreciate the help! I'll take a look at it again...I'm pretty sure I have them backwards...and if I do, then I'm going to kick my own ass. Still miss diesel...haha

Fuel lines were correct, they are different size line connections. Regulator is fine. Fuel pressure was not coming up to the rail at proper PSI...due to the ground side prong of the plug pushing back and not making contact. Fixed the plug and plenty of fuel.
Chased every sensor. Checked every ground. CPS and CMS seem fine. Noid checked a couple of injectors. Temp sensor doesn't OHM out with as much resistance as it looks like it should, but the temp is correct on the Rinda scan tool so figure its ok. Checked 5 coils with spark sensor between coil and wire and all were strong.
Squirted fuel into the throttle body with WOT, half throttle, no throttle. No fire. Pulled number 1 cylinder plug, a little rusty and over gapped .009" (worn out), wire wheeled and checked spark on the wire and was strong. Pulled number 6, cracked electrode porcelain, kinda rusty, .018" over gapped. Pulled number 8, .011" over gapped and a bit rusty. Rolled engine over to check spark with the cracked plug, and the engine tried to start with 3 empty holes. Sooo, after all this, possible the worn out plugs and being so far out of spec the ECM wouldn't let it start? Marine engines, saltwater, headaches.

For all interested...plugs were the culprit (though the old high pressure pump was indeed worn out). Any time I've worked on a 2 stroke engine and it won't start, first thing I've checked. We checked spark, but not at the plug. Put 8 brand new OEM plugs with correct .060" gap, and she purrs better than perhaps it has since I bought it.

Moral of the story, VP ECM would not let it start with so-so spark at the plug. Sat overwinter and fouled the plugs bad enough to not let it run. Now I know.