34' Searay 2001 6.2 MPI Port engine won't rev up

JByers

JByers

New Member
Oct 14, 2008
29
Woodstock, Ontario, Canada
Boat Info
340 Sundancer 2001
Engines
6.2s 320hp
I've got a problem with my port engine since it came out of winter storage. It seems to run fine until you try to power up, to get in a plane and I'm only getting 3000 RPMs. I've changed the fuel filters the mechanic put his computer on it and it didn't show any codes. Change the distributor cap, rotor and checked the plugs. I'm in the process of analyzing the fuel system I'm only getting 28 pounds pressure on that engine but the starboard engine which is working fine is only showing 24 pounds. The dealer is showing a service bulletin on their system which upgrades the fuel pump and the cooling unit, I could have two bad fuel pumps. I only have 280 hours on the engines. It seems to be running rich at an idol, so I'm thinking it's the fuel pressure regulator but that's located in the cool fuel box under the engine with the fuel pump (not a friendly place to go). Another strange thing that happened, the alternator on the port engine burned out about the same time, got it rebuilt, I was hoping that would fix it. The engine seems to surge up-and-down occasionally, while under load. I dumped four cans of Seafoam in the gas tank and that seemed to help a bit.
Any ideas would be greatly appreciated before I spend $700.00 on a new cool fuel pump kit. Thanks John
 
You need 38-42 psi on the rail , have the injectors been checked for leak down. Install a rail gauge, turn key to on to cycle the pump .Pressure should not drop.Dropping pressure is leaking injectors ,
And you dont need a full kit just the Airtex E11004 Hi Pressure pump $100 USD
 
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I checked the pressure at the rail and only had 22 psi, I didn't notice the pressure dropping when I was there, I'm going back to do more testing. I'll check that part number out with my marine supplier, he said the Mercury pump was discontinued and replaced with the entire kit. Thought it may also be the fuel pressure regulator because it's running rich at idol, I'll test that too. The starboard engine is running fine but it only had 22 psi when I cycled it, I may be changing both pumps. Thanks for the information the mechanic that was looking at it wasn't that knowledgable about fuel system problems and I've had to educate myself on troubleshooting.
 
I recently had a bad fuel injector on one of my 6.2 engines....it would start fine and idle fine but it would not rev past 3,400 rpm.....new injector and all is well.....

cliff
 
When you gentlemen are talking about "reving" to 3500 RPMS, are you talking about in gear in the water or ?
 
JByers said:
In the water, it will rev higher with no load.
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yep....in the water under load the max rpms were around 3,400 with a bad injector.....

cliff
 
I've pulled the injectors out, checked them with the ohm meter, there all within .1 ohms. Flushed them with carb cleaner backwards and forwards, they all spray and switch fine. I was getting a drop in pressure on the fuel rail, before I pulled them, of 1lb. every 4 minutes, this is the same on both engines. When you had the bad injector did it just stop working? I'm going to put them back in and try it. The fuel pumps are still reading too low and that's the same on both engines. Think I might pull out one of the Cool Fuel boxes and replace one of the pumps, doesn't look like a fun job under the engines. Any other ideas would be greatly appreciated. Thanks John
 
Check compression I've seen 2 different 6.2 mpi such in a valve seat


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JByers said:
When you had the bad injector did it just stop working?
Click to expand...

can't answer that for sure....since 99% of our boating is at slow 'cocktail' cruising speeds I did not discover the issue until I tried to plane the boat.....the problem could have been developing several weeks prior to that but I don't know for sure....even with a bad injector the engine started fine and idled fine and ran fine up to 3,400 rpms......

cliff
 
I put my fuel gauge on the fuel line coming directly from the pump and it's losing pressure at that point, I'm going to put a new cool fuel box on, which will give me a pump and regulator, hopefully that will fix it. Pulling the fuel injectors off and cleaning them had no effect at all. If this doesn't work I guess I'll be doing compression tests. Thanks again for the help, John
 
I broke down and purchased the cool fuel kit from Mercury and was very disappointed, all I got was a pump, the cooling tube and a bunch O-rings. The dealer thought I would've got the fuel pressure regulator, since it was listed as a kit. I though I'd get the whole box assembly. I installed it all and it didn't even change the fuel pressure. Has anyone heard of the fuel pressure regulator leaking fuel back to the fuel separator, through the shut off valve, when there's no vacuum?
Did a compression test on the engine and it was fine, so I changed the spark plugs at the same time. The spark plugs didn't look bad, but once I replaced them the boats running fine now, must have been a bad plug or two. I can't figure out why the engine wasn't shaking or misfiring if the plugs where that bad, but I'm glad I found the problem. I still have low fuel pressure in both engines.
 
JByers said:
I can't figure out why the engine wasn't shaking or misfiring if the plugs where that bad, but I'm glad I found the problem.
Click to expand...

I experienced the same when a fuel injector went bad.....the engine showed no signs of a problem other than not reaching the expected WOT range....

cliff
 
I bench tested the fuel pump and it was over 55 pounds pressure when it started to stall, so the fuel pumps not the problem it's got to be the fuel pressure regulator. The regulator is $274 here in Canada does anyone have a part number for an alternative unit that would match. Thanks John
 
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