4.3GLPFS does not reach max RPM

[bnicov]

After the issues I had previously (bad rotor causing no start) and popping at WOT (new cap and rotor, new rotor failed-and it was original VP) the boat ran great. Today, I splashed it to give it a shakedown, at idle, it ran a bit rough and did not sound right. Went for a cruise around the lake and at 3000rpms, it did not sound or feel right. It then felt like it jumped and the rpms went up by 200 or so and sounded and felt great- no change in throttle. I ran it up to wot and got to 4600rpms and about 46mph. Slowed, turned and wot again, this time, barely 4200 and just over 40mph and did not sound or feel smooth, it popped a bit and felt like it was stumbling a bit, then it raced forward and went to 4600. Cruising back in at 3000, it dropped to 2800 or so and ran rough. Weird issue. I pulled the cap and cleaned the contacts which were fine, the rotor was fine too. I checked all the plug wires and went out again, same sort of thing. Running a bit rough, then fine, then really rough then not bad. Any ideas out there?? The fuel has a double dose of marine stabil (about 5 gals from last yr and 5 gals fresh today).

 

[bnicov]

Correction, it is a 4.3 GLPEFS. I forgot the E. It is an intermittant type problem and that can be a real pain to diagnose.

 

[Maclin]

Sounds like a fuel delivery problem or water or other contaminants in the fuel problem. Remove the water separating filter and dump the contents in a larger clear glass container and take a look. I would not re-use it even if it looks ok.

 

[Bondo]

Sounds like a fuel delivery problem or water or other contaminants in the fuel problem. Remove the water separating filter and dump the contents in a larger clear glass container and take a look. I would not re-use it even if it looks ok.

Ayuh,...... Ditto,..... Change the fuel filter, 'n inspect the contents of the ole one,....

I use a quart size zip-loc freezer baggie,.....

Loosen the filter, slip the baggie 'round it, unscrew the filter, drop it in, 'n seal it up,.......
Later, flip it upside-down, 'n inspect the contents,....

 

[bnicov]

I will be changing the fuel filter and inspecting the contents next time I am up, also, what if plug wires were crossing each other?? There may be a couple wires either touching or crossing in the back. Could that wreak havoc with spark??

 

[Maclin]

Yes.

If you can, run it at nite or in a very dark area and lift the bonnet and watch all the plug wires along their entire path. Should not be much of a show...but if there is you have found a problem area.

 

[Bondo]

Ayuh,.... Touchin' plug wires should not cross-fire,...

If they are, they're junk,....

 

[bnicov]

So upon inspecting the plug wires, they were tangled up like spaghetti in the back. I cleaned them up and re routed them. Splashed it and fired her up, purred like a kitten, ran it up to 4500rpm without a hiccup after putting around and checking throttle respose. However, upon inspection to see how things were out back, I found water being flung by the water pump pulley, further inspection revealed the water pump leaking a steady stream of water. So, looks like I will be looking at rebuilding it. Thankfully, there are plenty of threads with the part #s etc....yay for IBoats!!