Bogging even when engine is warm

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tercle
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Posts: 222
Joined: Sat Aug 27, 2011 9:57 am
My tercel:: 1985 SR5
Location: Seattle

Bogging even when engine is warm

Post by tercle »

Last night, the car ran fine. Drove 80-100 miles on freeway during the day with no problems.
On the way home, spent an hour and a half in stop and go traffic, then 10 minutes of 60 mph freeway driving, then 10 minutes of city driving - all with no problems. Temp was always good.

This morning, it bogged badly in second gear as soon as I tried to get up to 25 mph.
I bucked and bogged home.

Checked the timing - good.
Replaced the fuel filter - no change.
Tried to clean out the carb with a 1/2 can of carb cleaner - no change.

With the air cleaner top off and operating the throttle by hand, I got it to start bogging.
I trickled in a little gasoline, and the bogging ceased and it revved up.
I was able to maintain whatever rpm I wanted, as long as I added gas from the little plastic bottle.
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dlb
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Joined: Mon Jul 06, 2009 9:03 pm
My tercel:: '87 sr5, '83 dlx parts car
Location: bc, canada

Re: Bogging even when engine is warm

Post by dlb »

that sounds like fuel starvation. take the air filter housing off, plug the vac hoses, start the car, and watch the fuel level through the sight glass. rev it up and see if the float level drops below the 'ok' point. if it does, there's something besides the fuel filter causing fuel starvation. could be crud in the fuel line between the tank and filter, the fuel pump could be dying, could be crud in the filter screen of the carb's fuel inlet.
tercle
Top Notch Member
Posts: 222
Joined: Sat Aug 27, 2011 9:57 am
My tercel:: 1985 SR5
Location: Seattle

Re: Bogging even when engine is warm

Post by tercle »

That's a good idea.
I used the day's last light to do that.
After cleaning the window, I saw that the fuel level was at minimum.
I started it up, and it idled fine and the level went up to the mid point.
I revved it up and there was no bogging.

I am happier, but more confused.
Maybe I need a new vacuum hose or cut it back so it's tighter?
I just buttoned it up - maybe I will drive it tonight.
Have to help with Thanksgiving stuff now.
Happy thanksgiving, dlb and everyone!
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dlb
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Posts: 7447
Joined: Mon Jul 06, 2009 9:03 pm
My tercel:: '87 sr5, '83 dlx parts car
Location: bc, canada

Re: Bogging even when engine is warm

Post by dlb »

that's frustrating. i hate intermittent problems. oh well, just keep an eye on it and watch the fuel level the next time it does it.
tercle wrote:Maybe I need a new vacuum hose or cut it back so it's tighter?
i'm not sure which vac hose are you referring to. what are you thinking of?

i'm canadian so we already had thanksgiving back in october, but happy thanksgiving to you and every other american forum member too!
tercle
Top Notch Member
Posts: 222
Joined: Sat Aug 27, 2011 9:57 am
My tercel:: 1985 SR5
Location: Seattle

Re: Bogging even when engine is warm

Post by tercle »

Not 100 percent sure.
It connects to a gizmo on the underside of the air cleaner.
It looks like it is the hose to the HIC valve on page EC-43.
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Bogging even when engine is warm

Post by Petros »

That could be be weak fuel pump, so check fuel delivery and pressure of the fuel pump per FSM. Also, check the condition of the fuel line between the fuel tank and the fuel pump. there are four sections of rubber fuel line between the tank and the fuel pump, if it has a leak in any of them it will suck air rather than fuel and result in fuel starvation. It will not necessarily leak fuel since this is the low pressure side of the pump, if there is a crack or pin hole leak it will suck in air along with the fuel. Most likely location is the sections of fuel line in the engine compartment between the pump and the metal line, or at the fuel filter. There is also a short length of rubber line from the top of the fuel tank to the metal fuel line, but that one rarely cracks, but it is possible it could be that one too. If you pump check out I test by running a fuel line from a gas can into the fuel pump, if the problem goes away, it almost certainly is in the fuel line.

Also, could be plugged or partially sticking needle valve in the carb. So if the fuel pump checks out, and you have no leaks on the fuel lines, check the condition of the needle valve in the carb.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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