VP 3.0 GSPWTR starts, wont' run; fuel filter, bad gas; post winterizing issue?

[insttech1]

This is now FIXED! Somehow I swapped plug wires 1/2....what a hassle:facepalm: But at least I have a new fuel filter....and hopefully this didn't screw up anything else....

I've read as many posts as I can, and am looking for some additional advice.

So here's the symptoms:
Cranks but won't start often. When it runs, it's 10 to 30 seconds, and have to play with throttle to keep running.
Backfires too frequently (sign of lean fuel condition, but I've add some fresh fuel to tank).
Very brief occasional startup squeal from a pulley on the block, but so brief I don't know which.
Can't keep running long enough to try and tune carb, if that is even the issue.

Here is what's been done:
Winterized last season. Put sta-bil stabilizer in just gas tank per instructions. Ran engine long enough to get stabilized gas all the way into the carb.
De-carbonized engine twice with sea foam, per instructions.
Fogged cylinders/block per instructions.
New impeller. Old one starting to wear, but no missing vanes.
Added 5 gallons of fresh gas to tank today.
New plugs today. Gapped to .045.
New rotor/cap last year toward end of season.
Carb rebuilt very thoroughly last year, and tuned well w/ vacuum gauge. Was running quite well.
Pulled flame arrestor and manually engaged throttle; carb squirts two good shots of gas.
Pulled drive; replaced drive lube, greased everything; new bellows, inspected gimbal, etc... Drive went back on relatively well for doing it for the first time myself.
Belts are nearly new; in very good shape.

What I haven't done yet:
Compression test. (No tools...yet)
Timing check. (But boat met all OEM spec's for performance/RPM at end of last season, with OEM prop.)
Replaced/checked anti-siphon valve.
Completely drain fuel tank.
Replace fuel filter. (I understand there is a Napa crossover for the 3.0 manual pump that I can buy locally, any info on this or something from Autozone would be appreciated!)
Pulled the carb.

What I suspect might be the issue:
Fuel condition. It had sta-bil but per VP service bulletin, that goes bad after 6 months? It's been about 8. But I thought adding some fresh fuel would help dilute the old?
Carb tuning? Gummed up carb? But carb shoots two good squirts of gas manually. Was well tuned at end of season.
Bad fuel filter? Again, carb shoots gas, but will fuel filter keep pressure too low to maintain fuel?
Water in fuel? But I don't suspect it. Had no issue with this last year.

So I know I need a fuel filter, so I'll try and get one locally tomorrow.

Any other thoughts would be appreciated!!
Thanks

 

[insttech1]

Re: VP 3.0 GSPWTR starts, wont' run; fuel filter, bad gas; post winterizing issue?

So here's an update:

I've found no water in the fuel.
I replaced the fuel filter. Wasn't getting fuel to the carb, so I pulled and filled the lines with gas; now I'm getting fuel.
Engine will run, for about 30 seconds, and still backfires significantly when it stalls out.
I can't get it anywhere near idle; it will only run 2 to 3k rpm. I have to modulate the throttle a lot to keep it going.

Since I filled the lines with brand new gas, I'm not really suspecting fuel condition anymore. Maybe the carb got really gummed up, even though I fan fuel w/ sta-bil through it before winterizing?

Any suggestions?
Thanks!

 

[insttech1]

Re: VP 3.0 GSPWTR starts, wont' run; fuel filter, bad gas; post winterizing issue?

So I went thru last year's notes about my carb tuning. Both mixture screws had been turned about 3/4 turn out. I backed them out to 1.5, and I could get it to run, and stay running.

I backed them out further to 2 turns, and I can keep it running indefinitely. However, I can not get it down to idle speed. If I approach 1000 RPM, I get a misfire from one of the cylinders. It does not sound good at all....

I think I'll mess with it more tomorrow....not sure if it's all tuning, or if something bad has happened to a rod/piston, or a valve? Would it still run at higher RPM's with a catastrophic condition? Otherwise, I think it's to pull the valve cover and/or carb....

Thanks!

 

[insttech1]

Re: VP 3.0 GSPWTR starts, wont' run; fuel filter, bad gas; post winterizing issue?

Got a hold of a compression tester:
150, 150, 160, 125

Not too happy w/ the 125, but it's within spec'.

Also tested spark; all 4 wires fire, but the spark is orange, and not blue, so I will pursue new wires, and maybe a new coil and pickup. The cap and rotor are new from last year and still look that way.

Any input would be appreciated.
Thanks!

 

[Don S]

Re: VP 3.0 GSPWTR starts, wont' run; fuel filter, bad gas; post winterizing issue?

Sounds to me like you need to rebuild the carb. Passages are probably plugged up.
Do a leakdown test to find if the low compression on the one cylinder to find out where the problem is.

 

[insttech1]

Re: VP 3.0 GSPWTR starts, wont' run; fuel filter, bad gas; post winterizing issue?

Thanks Don!
I did a full rebuild on the carb last year, but if that fuel went funky, then yeah, the passages can definitely be bad.

If a full leakdown test points to valves or piston rings, can it still be run with these numbers, after carb/ignition wires are addressed?

One other thing: plugs (brand new) are black on cyl 1, gas-wet on cyl 2, black on cyl 3, and white-ish on cyl 4 (which is the low comp' cylinder).

Thanks!

 

[insttech1]

Re: VP 3.0 GSPWTR starts, wont' run; fuel filter, bad gas; post winterizing issue?

OK it RUNS!

I'll eat a little crow here....somehow I swapped plug 1/2 wires, apparently last year during winterization.
I will have to address cylinder 4, and timing, but at least it now RUNS!!

Thanks!