fuel in cylinder - hydraulic lock

Folks,

I have a '94 Honda VFR750 with about 10,000 miles. I bought it recently
from someone who hadn't ridden it for a few years, rustproofed the tank
with POR-15 (great stuff!), thoroughly tore down and cleaned the
carburetors and replaced the fuel filter. I've been riding it for a
couple of months now, and about a week ago noticed some drops of fuel
on the garage floor, dripping from the fuel pump. Closer investigation
reveals that it seems to be coming from the plastic housing around the
fuel pump itself. Not sure if it's related to my problem, but it may
be.

Anyway, I tried to start it yesterday morning, and it went
whirr-whirr-BAM! Wouldn't crank when I tried again, so I put it in
gear, rocked bike back and forth a couple of times, put it in neutral,
and it then turned over and started, but had a misfire.

Checked the oil when I got home from work, and it's overfull - bad
sign. Try to start it again, and another whirr-whirr-BAM episode. The
BAM sounded like knocking two hammers together. I pull the plugs and
see that cylinder #1 plug is wet, and the top of the piston is shiny,
unlike the other three which are dark with carbon. Put it in 6th gear
and rotate the wheel. Piston #1 reaches top of stroke and sprays liquid
gas out the spark plug hole. Continuing to move wheel, more resistance
is felt at piston #1 bottom dead center.

Removed tank and cranked with starter this morning. Seems smooth as gas
continues to spray out cylinder 1 for a while.

I assume the next step is to pull the carbs, open the float bowl for
#1, look for debris and thoroughly clean it.

Questions:

Should I go ahead and replace the fuel pump? Do they leak when they go
bad?

My current theory is that I'll find a piece of rubber from the fuel
pump diaphragm jamming the float needle. Does this make sense?

How do I know whether or not I bent something from my starting
attempts?

Lastly, what should I have known or done to discover this issue
earlier? I think I'm going to start checking the oil on at least a
weekly basis from now on.

Thanks in advance for your help.

Regards,

John R. Allen
Bainbridge Island, Washington, USA

 

First thing I'd do is change the oil. I can't believe you cranked it
again a second time after you discovered the diluted oil and
hydraulic lockup. Well yeah, I can and I might have done it
myself if I was upset by the problem but I suspect this was not a
good thing to do.

If it were me, I think I'd change the oil, get rid of the leak, check
the compression, listen for disturbing noises then if I thought it
was OK, try to run it and see what happened.

If it was running badly or making new noises I'd shut it down again.
If it ran OK, I'd run it a while then change the oil and filter and
look for any metal bits or powder in the old oil and filter.

Not sure that's the right course of action, but after I finished
cursing myself, the bike and the world in general it's probably
the course I'd take.

 

Sounds like the intake was full of gas, the cylinder was empty, you
tried starting it the valve opened, cylinder filled with gas then locked.

any gasoline leak is bad, if the fuel pump is cracked then replace it.

or a piece of por15

when the engine seizes or starts sounding like an old threshing machine
you'll know.

don't you have a fuel shut off valve/petcock on this bike? It is supposed
to have one I thought. Get in the habit of turning it off when you park
the bike.

Ted

 

Before doing to much, I would remove any concern over that BAM you described
as sounding like 2 hammers - may be something more serious than a backfire
although you may have already determined the cause. (as I read the message
my first thought was a broken rod or piston or bent valve but you say the
piston is moving ok, so I scrapped most of that thought).

In any case, you may want to try pulling the spark plugs and use the starter
to turn it over - do all the mechanical movements sound smooth - no banging,
grinding, odd sounding scratching or other odd noises. Then try it turning
it using the rear wheel to eliminate the starter noise itself. If you have a
compression gauge, I would get a reading from each cylinder. If the engine
components sound correct, and the compression is good, then I'd start work
on the carbs / fuel pump / gas leak issue.

 

Yeah, well, I can't believe I did it either. A case of overactive
wishful thinking.

 

I've done worse in moments of frustration. Hope it works out OK.
I'd change the crapped up oil before I did more experiments.

 

I think you ought to check the oil every time you run the machine. If
the crancase is too full (as when the bottom end fills with gas), you
can blow all the engine seals.

Jim

 

I know someone who had a bent con rod caused by hydraulic lock. He had
to strip the engine and replace it.

Leon