Weird problem with Ford 351 - MasterCraft Pro Star 190
GVB
While test driving the boat would hesitate and backfire when jumping
on the throttle from an idle, but ran fine otherwise. Didn't think
much of it and ended up buying the boat.
Changed oil and filter.
Changed plugs.
Changed water seperator filter.
Changed fuel filter.
* Took it back out in the water and it ran the same.
Installed a breakerless ignition kit (replaces the points and
condenser with a magnetic pickup).
Replaced the distributor advance springs with new ones that came with
the kit.
Replaced cap and rotor.
Replaced ignition coil.
Set timing to 10* before TDC.
* Took it back out in the water and it still backfired, but not as
much. The hesitation problem was still there. But now I couldn't get
it past 4000 rpm (should top out around 4500-4800). And the motor
would stumble at any constant speed below 2000 rpm. It seemed to get
worse as the longer the boat was running. When trying to get it up on
the trailer it kept stalling.
Put the old distributor advance springs back on.
Rebuilt the carberator.
Reset timing.
* Just took it back out on the water today and I am still having the
same problems, although the backfiring is gone.
We rebuilt the carb using lacquer thinner and someone recommended
taking the metering block back out of the carb and soak it in carb
cleaner for a day or so because lacquer thinner doesnt disolve gas
deposits and buildup like carb cleaner does. This person (reputable)
seemed to think that the symptoms still sound like a typical carb
problem.
So the metering block is in the garage soaking. I also had plans to
drop the boat in the water tomorrow and try putting the points
ignition, cap/rotor, and old coil back on and see if that helps.
Can anyone think of anything else I should be looking at to try and
solve this? I havn't measured the resistance of the plug wires, but
they look pretty new. Possible fuel pump problem?
Thanks in advance.
Reg
Dale Coleman
>I bought a 1989 MasterCraft Pro Star 190 w/ Indmar Ford 351 motor.
>While test driving the boat would hesitate and backfire when jumping
>on the throttle from an idle, but ran fine otherwise. Didn't think
>much of it and ended up buying the boat.
>
>Changed oil and filter.
>Changed plugs.
>Changed water seperator filter.
Hi all, whenever I replace the fuel/water separator filter I always
dump the contents into the bottom half of a plastic jug and look at
what was in there. If I find lots of water and a red/pink crappy
looking stuff and I feel there is a carb problem I will replace the
carb with a new one, replace the filter and siphon out the crap from
the gas tank in the boat. I find a clear tube with a hose barb at one
end will find the botton of the tank through the filler on most ski
boats. A floor jack can help lift one side of the trailer so the
filler side is at the lowest point. This should get most of the crap
out of the tank and the new filter will catch the rest.
I have found it a waste of time to try and repair a Holley carb that
has had the pink crap sit in the fuel bowl. You could try pulling the
front float bowl and see how it looks. If there is the pink stuff in
there at least throw the metering block away. You might have success
repairing the carb if you replace the block - about $70 part or so.
Check/replace the gasket under the riser for the carb. This is often
overlooked and I have had many with a hole burnt through. This can
cause a poor idle Ect.
>Changed fuel filter.
>
>* Took it back out in the water and it ran the same.
>
>Installed a breakerless ignition kit (replaces the points and
>condenser with a magnetic pickup).
>Replaced the distributor advance springs with new ones that came with
>the kit.
>Replaced cap and rotor.
>Replaced ignition coil.
>Set timing to 10* before TDC.
I think this might be more then it should be, double check the service
manual. Do not run more timming the manual says! Boat engines are
under a very heavy load and with the crummy gas available today you
are asking for trouble if you bump it up any.
A few more tricks, make sure you check the timing at a low idle speed
and then watch the timing as you slowly speed up the engine. You
should see no movment at first - timing at the bottom of the advance,
then as the speed is increased it should come on up to 28 degrees or
so. A sticky advance can cause lots of trouble.
On different note, I have had some of the old coils cause problems
after switching the old points for a electronic kit. The symptom of
this goes something like, the engine runs fine for 1/2 hour or more
but then starts to cut out. The quick test for this is after the
engine cuts out zip tie a new and cool coil next to the old one and
switch the wires. If the engine runs fine then the coil is bad or
overheating.
I hope this helps, Dale
NetSock
Your running too lean off idle, and thats what causes the stumble, and
subsequent backfire.
You didnt mention what carb you have on it...the idle mixture can be
adjusted on some, but I would be more suspect the the accelerater
pump...asumming you have no vacuum leaks.
Good luck.
"GVB" <news...@abused.com> wrote in message
news:f9d2115.03070...@posting.google.com...
skier
Sounds like a Timing or flooding problem. I would have suggested the
points gap but since you switched ignitions that should take care of
that. Try advancing or retarding the timing some. Not sure exactly how
many degrees that engine runs. My old 1985 PCM 351 used to do the same
thing so I had to adjust points, advance timing, adjust idle, adjust
timing again until I got it running smooth and not backfiring coming
out of the hole.
In the Carb, did you replace the power valve? Also does it run rich at
idle? My floats wouldn't hold after so many years, had to replace.
Engine would load up with gas at idle. Go to Skidim.com for carb
parts. Most Auto parts stores don't stock those floats.
Reed B.
The backfiring/hesitation are typical symptoms of a problem with the
carb's accelerator pump diaphram or adjustment of the carb's
accelerator pump. My boat behaved similarly until I rebuilt the carb
including the pump. It sounds like you took care of the
hesitation/backfire with the re-build, but if you didn't change the
pump diaphram and check/adjust the accelerator pump clearance @ WOT,
do so. That would only address your backfire/hesitation problems as
you come off idle.
I'd look at the other changes you did to the ignition/distributor
since you said it ran fine before you made the changes.
Reed
Jim Thompson
> Rebuilt the carberator.
>
Did you replace power valve in carb rebuild?
GVB
> Hi all, whenever I replace the fuel/water separator filter I always
> dump the contents into the bottom half of a plastic jug and look at
> what was in there. If I find lots of water and a red/pink crappy
> looking stuff and I feel there is a carb problem I will replace the
> carb with a new one, replace the filter and siphon out the crap from
> the gas tank in the boat. I find a clear tube with a hose barb at one
> end will find the botton of the tank through the filler on most ski
> boats. A floor jack can help lift one side of the trailer so the
> filler side is at the lowest point. This should get most of the crap
> out of the tank and the new filter will catch the rest.
When I replaced the water seperator filter there was VERY little water
in it, pretty clean, no red gunk or crap in there.
> I have found it a waste of time to try and repair a Holley carb that
> has had the pink crap sit in the fuel bowl. You could try pulling the
> front float bowl and see how it looks. If there is the pink stuff in
> there at least throw the metering block away. You might have success
> repairing the carb if you replace the block - about $70 part or so.
It was a full rebuild using the kit from skidim.com. I pulled the
metering block and it has been sitting in carb cleaner for about 24
hours now.
> Check/replace the gasket under the riser for the carb. This is often
> overlooked and I have had many with a hole burnt through. This can
> cause a poor idle Ect.
I didn't change the gasket under the riser, but it seems to be still
intac, and the engine paint has made a nice seal :)
> I think this might be more then it should be, double check the service
> manual. Do not run more timming the manual says! Boat engines are
> under a very heavy load and with the crummy gas available today you
> are asking for trouble if you bump it up any.
The manual say "10* at 600rpm". I called Indmar and they said its 10*
BTDC.
> A few more tricks, make sure you check the timing at a low idle speed
> and then watch the timing as you slowly speed up the engine. You
> should see no movment at first - timing at the bottom of the advance,
> then as the speed is increased it should come on up to 28 degrees or
> so. A sticky advance can cause lots of trouble.
I tried that, it seems to be advancing OK.
> On different note, I have had some of the old coils cause problems
> after switching the old points for a electronic kit. The symptom of
> this goes something like, the engine runs fine for 1/2 hour or more
> but then starts to cut out. The quick test for this is after the
> engine cuts out zip tie a new and cool coil next to the old one and
> switch the wires. If the engine runs fine then the coil is bad or
> overheating.
I planned on trying that today. Swapping old parts back in one at a
time if this metering block cleaning doesn't do the trick.
> I hope this helps, Dale
Thanks Dale.
GVB
> Carburation problem.
>
> Your running too lean off idle, and thats what causes the stumble, and
> subsequent backfire.
>
> You didnt mention what carb you have on it...the idle mixture can be
> adjusted on some, but I would be more suspect the the accelerater
> pump...asumming you have no vacuum leaks.
>
> Good luck.
Idle mixture is set perfect. Backfire has been fixed with the carb
rebuild (power valve replacement) and timing set.
Holley 4160. No vacuum leaks that I can find... accelerater pump was
replaced as part of the rebuild.
GVB
metering block didn't fix the problem, it was still stumbling at low
rpm. Tried the easiest thing first, put in the old coil. And it
seems to have fixed the stumbling at low RPM problem!! The old coil
has fluid in it, the new one doesn't. Was the old coil a marine
specific coil or something that prevented overheating? Or did I just
get a bad coil?
There is still a little bit of hesitation upon hard acceleration, but
I am guessing that I can adjust the accelerator pump to push more gas
through? I don't know carb adjustments very well.
And I still can't get it over 4000 rpm.
Any other thoughts on these other two problems?
Timing is still dead on... i readjusted the idle mixture and idle speed.
Thanks everybody.
news...@abused.com (GVB) wrote in message news:<f9d2115.03070...@posting.google.com>...
NetSock
"GVB" <news...@abused.com> wrote in message
news:f9d2115.03070...@posting.google.com...
GVB
Had the boat out this entire weekend... it DID stumble at idle/low rpm
just once or twice. THe problem hasn't completely gone away.
I am also still have a hesitiation problem... the accelerator pump arm
seems to be working ok.
-gvb
"NetSock" <Net...@nospam.com> wrote in message news:<bekdoa$s2q$1...@charm.magnus.acs.ohio-state.edu>...
NetSock
If your tach is correct, and your 13x13 is true, then your down on power.
You might want to take your prop to the shop to confirm it "right".
"GVB" <news...@abused.com> wrote in message
news:f9d2115.03071...@posting.google.com...
GVB
Taking the balast resistor out of the ignition circuit wouldn't effect
the tach would it?
I'll try and hook up a handheld tach on it and see if it's correct,
but I am pretty sure it is.
"NetSock" <Net...@nospam.com> wrote in message news:<beu9lh$odj$1...@charm.magnus.acs.ohio-state.edu>...
Chris & Lorrie
and the acc. pump are probably bad !! Common problem.
Chris
"GVB" <news...@abused.com> wrote in message
news:f9d2115.03070...@posting.google.com...
NetSock
voltage/current thru them.
Wait a minute!? Didn't you say you replaced the ignition with an electronic
unit? If so, where is the ballast located?
I've done quite a few conversions, and the ballast always comes off for
good.
GVB
-gvb
"NetSock" <Net...@nospam.com> wrote in message news:<bf64gm$7bu$1...@charm.magnus.acs.ohio-state.edu>...
NetSock
the accelerator pump, but...
Are you sure the timing is set correctly, and the advance is working? I
presume you know that boats do not use vacuum advances...only mechanical.
Have you tried moving (adjusting the timing) the distributor at full
throttle?