1983 volvo 240DL B21A (Carb) gas mileage very low

[sergitin32]

It does look simple, but in quest for complications we could count on the fuel evaporative system, which I never even care to know what does, and might as well take of as soon as possible as well as the rest of the emission control systems. I am all about the environment but prefer to put some gas there than the whole car in the wreck yard.

Thanks for keeping up with my thread.

[lummert]

Is your car's evap system non-functional? I once had an Olds Cutlass with an incorrect fuel pump installed (return line plugged) that would stall because of no fuel tank vent.

[sergitin32]

I am not sure of that. What is it suppose to do? What are the symptoms of a miss functional evaporative system? I will need to look into that for sure, or just eliminate it and let the thing just breath with a hose to the front of the car, not sure... need to research that system, thanks for the hint, since that one is the one I have never touched.

Sergitin

[jimmy57]

Have you checked to see if the cold start lever is going back to off position? It has been years since I worked on a carburetted 240 but I recall the "choke" cable leading to the handle on left of dash below headlight switch. It attaches to the front of the carb. If this is not adjusted or it hangs it stands a very good chance of killing MPG as it adds fuel.

How does it run? Seems like it has normal power? Runs smooth and idles smooth?

Does the vacuum advance hose have vacuum when the throttle is opened? There could be a temp vacuum switch that does not allow advance vacuum until coolant is hot.
The cooler running temp will not make that car rich since it uses manual choke and needs no coolant heat to turn off the cold enrichment valve ("choke"). An engine with 60C coolant instead of 90C doesn't use more fuel unless there is a reason like the vacuum advance or an enrichment device involved.
I ask about performance since the distributor was out and I am curious if timing was set properly.

[JDS60R]

Hey Sergitin,

Where are you located? Perhaps one of us is close enough to help?

I too am concerned that the car is not getting up to temperature, might be overfueled by way of the carburetor settings, and may need some timing adjustment.

Lets see what the new thermostat brings for results?

[sergitin32]

Yes the choke is going to the flat (not contact) position no prob. I will check again for the mark and the 2500rpm I think it should be.

It runs badly, idles badly, hunts quite a bit. power wise it is hard for me to say, it feels poorish.

I expect timing was set properly on the shop before it went for the gas emission test, it does go when under throttle, it is idle what suffers more.

I will need some time to read the literature on the stromberg carb to get beck to you about whether it does have a temperature based enrichener or just the choke. I do believe there is one but now I am uncertain. I do know these carbs come with a temp isolator plate between the manifold and the carb for some reason, so at some point they do want to keep a temp range at the carb side. I do believe (and the carb specialist told me) they do this for warmer climates to help with the cold start. I will read some today.

I know there is a wax actuator some where in the vacuum system, but can not remember either where or what it does. I do have Idp heavy duty vacuum hoses all around, and last time I measure vacuum it from a non ported inlet (I think the break booster) it was around 20 mm Hg so not bad.

For now I know it is not reading the right temp in the dashboard and I wonder if it is working cold or the sensor or gauge is giving the wrong reading.

It feels like running the car cold without the choke on, it sucks. And it is literally sucking gas, for some reason still above my understanding.

Thanks

Sergitin.

[sergitin32]

quote from haynes manual: " The carburetor is equipped with a temperature compensator , which allows more air in the idle circuit in relation to temperature. As the compensator warms up, more air is admitted. This reduces the variation in idle speed relative to temperature. There is also a warm
start valve, which offsets the effects of fuel vapor from the float bowl during high under the hood temperatures, which can lead to difficulty in starting."

I will keep reading and keep you guys posted.

Sergio.

[sergitin32]

Hi guys,
I would appreciate if someone could give me an answer as to what is the right temperature range my car is supposed to be working when warm? And what would be the thermostat "temperature" that is would suit my car for this cold but not freezing climate?
I will change the thermostat and flush and change all my coolant. then see how does the car go.
Thanks.

Sergitin.

[sergitin32]

I would also like to inquire where does the temperature needle is supposed to be seating in my gauge?
I remember since I got the car it has been seating between the first and the second third of the full scale. Lets say around 8 o'clock, then this time the thing is seating pretty much just 2 mm over the cold mark. Never moves from there.

I do believe now that the cooling system are way overlooked in maintenance, and I will be way more proactive towards it in the future for sure.
You guys enjoy the holidays.

Sergitin.

[lummert]

I'm running 87*C thermostat in my 1988 Volvo 760 Turbo. This is in Indiana.