More fun with a 2006 40EFI 3 cyl 4 stroke

[52wrench]

Got this thing running after the problems with the ignition. Now on to fuel problems. It won't idle, stalls putting in gear. First thing I checked was the lift pump. Took it off, put my finger over the inlet port and pumped the plunger. No vacuum so took it apart. These have two rubber "rivets" that hold the round check valves in place. They were non-existent other than a blob of black sh&% in the bottom of the pump body. The check valves were just sitting in there doing nothing. The ethanol lobby strikes again! So I ordered a lift pump along with an IAC. In the mean time I "rebuilt" this pump. I used an aluminum pop rivet to hold the check valves in place. Put it back in and it works. Still has some problems idling so hopefully the new IAC cures that.

Now I need a prop, it's over propped, won't go over 3000 rpm at WOT. This is on a 20' 'toon. It has a four blade prop of some sort on it, haven't got it off yet to check the size. It should have a 3 blade 12.25x 9.

Another thing. The water separator always seems to have air in the top of it, is that normal? It runs fine. I have a Yamaha F200XCA on another boat and the separator on that always seems to stay full but that has an electric lift pump. I am thinking of putting a 12v Facet cube pump on this to do away with the mechanical lift pump all together.

 

[52wrench]

It has a Michigan Vortex 11.5x10 four blade, not off too much from a 12.25x9 but four blade. I think I will check the HP pump and the VST next.

 

[52wrench]

Checked the HP pump pressure, about 45-46 psi and the VST is clean so that is not the problem. Pump screen had a little crud on it but not bad at all. Checked the TPS and it reads 0.6 volts at idle and is smooth all the way to about 4.5 volts at WOT. No problem there. Checking the engine coolant temp sensor next.

 

[52wrench]

I checked every sensor on it, TPS, MAP, IAT, ECT, CPS, etc. All fine. I checked the ohms on the IAC and took it apart to look at the plunger, no problem. I Installed a new LP pump and IAC anyway. Still very low idle and stalling when going into gear. So I decided I would get rid of the "set at the factory" idle adjuster. I removed the throttle body from the intake to have a look at the stop they put in there. It requires a special wrench to adjust it and they put a locking compound on it. I have a set of security torx bits but it looks has a five point star. So I pressed the brass sleeve out from the TB with the screw and heated it up with a propane torch and the screw came right out. It's a 5mm thread. I took a 5mm bolt and rounded the head so it would fit in the hole in the intake and cut a slot in it and wrapped some teflon tape so it's a tight fit in the sleeve. Then drilled out the other end of the hole in the intake that the adjuster fits into. Pressed the brass sleeve back into the TB with my adjuster and put it all back together. I set it so I now have an idle of 900 or so. No more stalling when putting in gear. Still no explanation of why only 3k at WOT though. I'm going to try a 12x9 3 blade prop and see what happens.

 

[52wrench]

I did a comp. and leakdown and that identified the problem of why it won't run over 3k at WOT. Low compression and very high leakdown (85-90%) on all three holes. Tore it down and all three pistons have cracked lands between the top and middle ring. Evidence of det. in all three chambers. This boat was run way over-propped. Amazingly the bores look and measure like new along with the shells with the exception of #2 rod which shows a little distress. I Plastigaged all the shells and they are all like new specs! The ring gaps were even only a few thou over spec. The valves and chambers were heavily carboned so I removed and cleaned all the valves and chambers. All three chambers hold gasoline now with the valves in place with no springs. So I'm waiting for three pistons, rings sets, #2 rod shells and a few gaskets. I'll do a quick hone with a Brush Research flex hone and put it back together. The four blade 11.5x10 prop will not be going back on.