My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Davy

Davy wrote:
My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Davy


Never anything remotely like it.

Its not shorting a wire or summat is it?

"Davy" wrote in message
...
My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Gotta be a blocked jet somwhere or a gasket covering a hole.

"R" wrote in message
...

"Davy" wrote in message
...
My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Gotta be a blocked jet somwhere or a gasket covering a hole.

I second that opinion. I suggest that you dismantle that carburetter again,
and clean it thoroughly in clean petrol (having thoroughly cleaned the
outside first with Gunk, paraffin, or petrol). Preferrably, blow through all
the jets with compressed air. As as been suggested; some gaskets can be
fitted the wrong way round, thus covering a fuel or air jet.
BTW, I have no experience of that particular carburetter.

Sylvain.

That's an oldie but a goodie. My first sense is that you have the
mixture screws out too far, and it's running rich. Turn in
(clockwise) till very lightly seated, and back them out 1 1/2
complete revolutions.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

"Davy" wrote in message
...
: My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with
two fuel
: pickup tubes) will not start unless I remove the air filter;
nor will it
: start with just the air cleaner bolt installed without the air
filter.
: I have serviced the carb and replaced the gasket. I have
checked and am
: certain that the bolt is not interfering with the movement of
the manual
: choke.
:
: Anyone experienced this problem?
:
: Davy
:
:

"Davy" wrote in message
...
My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Davy


Pure guesswork here. A very rich mixture needing lots of air to start.
Removal of filter allows more air. Does the bolt also allow even more air
when removed?
Presumably when you can start it it subsequently stalls when it gets hot?
Phil

Christopher,

you might have a point about being too rich. Looking again at the carb, the
filter retaining bolt goes through the centre of the choke butterfly. When
the bolt is removed then it leaves a hole in the middle of the choke and the
engine is less choked.
I was on the wrong lines, as in "what does the bolt interfere with"; rather
I should have been thinking "what is different with the bolt removed"
thanks

Davy

"Stormin Mormon" wrote in message
...
That's an oldie but a goodie. My first sense is that you have the
mixture screws out too far, and it's running rich. Turn in
(clockwise) till very lightly seated, and back them out 1 1/2
complete revolutions.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
.

"Davy" wrote in message
...
: My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with
two fuel
: pickup tubes) will not start unless I remove the air filter;
nor will it
: start with just the air cleaner bolt installed without the air
filter.
: I have serviced the carb and replaced the gasket. I have
checked and am
: certain that the bolt is not interfering with the movement of
the manual
: choke.
:
: Anyone experienced this problem?
:
: Davy
:
:

Phil,

I will try to start it with the filter and bolt in place and not full choke.
thanks for the ideas.
Davy

"Phil B" wrote in message
...

"Davy" wrote in message
...
My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Davy


Pure guesswork here. A very rich mixture needing lots of air to start.
Removal of filter allows more air. Does the bolt also allow even more air
when removed?
Presumably when you can start it it subsequently stalls when it gets hot?
Phil

Following on from the theories mentioned in this thread, I tried to start it
with the air filter attachment bolt in place but with less choke - no
success.
Incidentally I now find that I can start the engine with the air filter box
attached provided I remove the attachment bolt - then starts first pull.
Davy
"Davy" wrote in message
...
My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Davy

"Davy" wrote in message
...
Following on from the theories mentioned in this thread, I tried to start
it
with the air filter attachment bolt in place but with less choke - no
success.
Incidentally I now find that I can start the engine with the air filter
box
attached provided I remove the attachment bolt - then starts first pull.

That's what is known as a BODGE.
You should take the advice given to you by two of us (a blocked jet, or a
wrongly fitted gasket blocking a fuel/air jet).
But then, it's _your_ lawnmower engine; so who cares.

Sylvain.

Davy
"Davy" wrote in message
...
My 1968 B&S 3.5 HP lawnmower engine (92902, pulsajet carb with two fuel
pickup tubes) will not start unless I remove the air filter; nor will it
start with just the air cleaner bolt installed without the air filter.
I have serviced the carb and replaced the gasket. I have checked and am
certain that the bolt is not interfering with the movement of the manual
choke.

Anyone experienced this problem?

Davy

Sylvain VAN DER WALDE wrote:
"Davy" wrote in message
...
Following on from the theories mentioned in this thread, I tried to start
it
with the air filter attachment bolt in place but with less choke - no
success.
Incidentally I now find that I can start the engine with the air filter
box
attached provided I remove the attachment bolt - then starts first pull.

That's what is known as a BODGE.
You should take the advice given to you by two of us (a blocked jet, or a
wrongly fitted gasket blocking a fuel/air jet).
But then, it's _your_ lawnmower engine; so who cares.

Thats the sort of state I got my wifes peugot handed to me in, after it
packed up halfway up the A1..it was obvious it was running way too rich.
I looke for the airbleed adjustment, and discovered it had been removed
in order to try and fix it.

I left it a a garage who wanted me to replace the airbox and the computer.

Then I phoned a friend, talked it over, he sent me a spare airbleed
screw, and we decided to change the water stemp sensor.

Its resiatnce never varied in a pot of boiling water, from cold. So I
spent £7.50 on a new one and screwed it in. Problem solved.

Exact same problem-you adjusted your fuel mixture with air filter bolt removed. Adjust left lean- start with throttle held on low - insets air cleaner bolt-adjust throttle mixture

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