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

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sergitin32
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1983 volvo 240DL B21A (Carb) gas mileage very low

Post by sergitin32 »

I tried this post yesterday, not sure why it doesn't show as posted,
Here we go again.
After two years not running. The car went to the shop, they put back the old distributor and claimed the warm start valve was not working properly. Bypassed the wire to the valve and the car is running. But this time is running with twice the gas it is supposed to use, average 12 mpg or so, 5.5 km/L. Once made 8.8 and i did some highway driving.

Here is the pattern, first it is winter cold out, although nothing like under zero, actually a pretty good winter with 8 degrees or so, some times close to 2 celciums. The car does not go full warm, ever, the temp readings are always 2 to 3 mm from the cold line. It used to be more like a quarter or a third from the whole spectrum.
Then another thing in a pattern comes like it "runs off gas" always when starting dead cold then it runs for a little while, lets say a few blocks from home. But the colder it starts the shorter the little ride...
For example my car has a heated underground parkade. So most of the times it stalled like 4 to 7 blocks away, yesterday it was parked in a big forest like park. It stalled one block away. .. Then it wont start at all, unless I put some gas in the tank. Then I don't want to give it too much choke cuz it is doing sooo poor mileage.

This last sentence throws me to it is running too rich and spending too much gas. But then why always when cold, never giving me this when warm at all. I am not sure at all if it is running out of gass or just flooded with gas, when I opened the carb last week to setup the needle high it was (as always) super wet with gas on the bottom of the piston that holds the needle (Zenith Stromberg CV carb).

Could a super cold engine make things that un-efficient? Bad sensor?
Could a cold carb have the bi-fold metal cold start valve been reacting to temperature and making the car run rich forever?

Here are the readings on my last 4 runs with a 10L jerry can every time.
1- 55 km
2- 44 km (change the needle height to lower <more into the main jet>)
3- 88 km (great I think it is going better than before, this day I did a half and half highway/city driving) But also the car didn't get too cold during the whole driving period as most of the times.)\
4- 45 km (BUMMER! I had my girls in the car in some park festival at night and it was cold, they got some nice adventure I was just eating my guts worried.)

"Needles" to say I am looking for answers.
Today I am going to check:
Vacuum
Temp issues (sensor vs thermostat)
Take off all the gas emission thingys, most of them not in great shape.
Check tranny fluid levels, (my transmission is leaking so I need to source a gasket for it and repair it, until then I keep topping it with anti leak fluid and transmission fluid)
Check coolant (I guess All I can do is add some? Maybe flush and refill?)
Check wire harness for any wire issues
Check PCV system for any dirt / plugged.

I do know, my trunk is empty all of the time, took the roof rack off, the tires are in good pressure for sure. The gas test gave me back twice this mileage, but I am not sure if they get this from the gases or just a data log of the car model and year. meaning it said 19 mpg. Even when still poor I can work with that since it is the nature of this beast.

Any advise will be golden at this point, I am willing to take it to the shop again, but I cant really afford it. But then I need the car for my work and can not afford another one with more unknown issues.

Thanks for reading and happy Santa-mas. :mrgreen:

Sergitin.
1989 Volvo 240DL , 1995 Volvo 960 Sedan , 1995 VW Rialta , 1987 VW Cabriolet

lummert
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Post by lummert »

Is there a warm air source from the exhaust manifold to the air cleaner? If no longer present then the cold air could be freezing up in the carb. This would cause poor running and excessive fuel usage. The temperature gauge reading is more likely a thermostat that is either rated too cold or is stuck open.
1988 Volvo 760 Turbo Wagon

sergitin32
Posts: 176
Joined: 11 February 2007
Year and Model: 1989 240 DL , 1995 9
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Post by sergitin32 »

Thanks for your reply, but as I said, it is not super cold here,
no freezing temperatures.
The thermostat is the stock one and this car is a canadian build so I am sure it should be the right rating, which leaves me with a thermostat continuously open, and thats what I am reading about in haynes right now.
Cheers.

Sergio.
1989 Volvo 240DL , 1995 Volvo 960 Sedan , 1995 VW Rialta , 1987 VW Cabriolet

sergitin32
Posts: 176
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Location: Vancouver, BC, Canada
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Post by sergitin32 »

Does anyone has an idea on how to trouble shoot the temperature sensor in this car?
Since there is no computer or codes to compile from it. I would believe there should be a resistance value for it? I know if I shoot the cable to ground that would make the gauge go all the way hot, Haynes explain... hence if the gauge is OK the sensor might be faulty, but then it could be the thermostat, I want to differentiate between the sensor and the thermostat. In order to know which one to change.

Thanks in advance

Sergitin.
1989 Volvo 240DL , 1995 Volvo 960 Sedan , 1995 VW Rialta , 1987 VW Cabriolet

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93Regina
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Post by 93Regina »

sergitin32 wrote:temperature sensor in this car?
Infrared temperature gun, pointed at thermostat housing. Otherwise, install new 195°F thermostat with new gasket. On older vehicles, when it is unknown when thermostat was last changed, then change it out.
warm start valve
I would have to know what's "feeding" intake side. I've look thru parts book, and there could be an
EGR system, along with crankcase ventilation system. And either one could cause issues.

I'm familiar with various systems installed, but I need to know your specifics. Got diagrams of what's on your system?

Warm Start Valve - Have you got a photo of that valve? Your carb sits on intake/exhaust manifold, and there should be enough heat there to vaporize fuel.

Your carb may or may not be the issue...but carbs do need to be overhauled....

sergitin32
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Post by sergitin32 »

My carb was rebuilt two years ago and not used till now, it should be in good conditions unless some gunk built up. But overall should be sound.
Warm start valve just redirect the fumes from gas in the carb bowl into the intake air chamber where the air filter is. then shuts closed when the switch is turned on,
EGR is removed and plugged, Pulsair removed and plugged, PCV still there I need to check it for plugged junk, but I have done it before ans it shouldn't be that bad in the little driving I have done since then, maybe 5k km.

I do think heat there is, but the prob is not whether fuel gets vaporized or not, but whether the COLD start valve keeps open or not since this is a folded metal valve in the carb that acts based on temp. If the thermostat is stuck open, in the warm up time and stays like that, then the engine is running rich for a longer period of time, if on top it is cold outside, then it is worst... also having in mind cold air drags more fuel etc.

Anyways, I thought tomorrow I will go to a auto cooling shop here to get it flushed and change the thermostat just because, also ask them to take a look at the sensor and make sure it is working properly.

Then I assume I would have to readjust the carb needle maybe? We'll see.

Thanks for your answer, I spent all day today working on it and reading the manuals: haynes chilton and Bentley, only Haynes has info on Canadian built volvos with carbs, the rest is all FI.

Happy holidays.

Sergitin
1989 Volvo 240DL , 1995 Volvo 960 Sedan , 1995 VW Rialta , 1987 VW Cabriolet

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93Regina
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Post by 93Regina »

sergitin32 wrote:Warm start valve just redirect the fumes from gas in the carb bowl into the intake air chamber where the air filter is.
You got a pic? Is this a Stromberg 175 CDT (ECE-Version)? Can you explain the parts?

Image

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93Regina
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Post by 93Regina »

Or does it look like this? I'd like to see these items mentioned

Image

sergitin32
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Post by sergitin32 »

The second one it mine, zenith stromberg 175 CD.
I thin the temperature compensator is the thing I am talking about, but not completely sure (it compensates with more gas for low temperatures, maybe?), the warm start valve is outside the carburetor thou, located close to the ignition coil, it connects by two hoses to two inlets in the plastic plate that hooks up to the inlet flange at the carb.

As I said my carb was rebuilt / overhauled to factory specs and other than the needle setup, which I have played with I don't want to alter anything else. Also I do have A LOT of literature about it so I will be reading it when I find time.

Today I talked to the shop that specializes in cooling problems in my area and they will be changing the thermostat, and renewing the coolant sometime next week.
Then I will think about anything else to be done to the carb to compensate for a warmer engine, or not.

Thanks a lot.

Sergitin
1989 Volvo 240DL , 1995 Volvo 960 Sedan , 1995 VW Rialta , 1987 VW Cabriolet

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93Regina
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Post by 93Regina »

sergitin32 wrote:temperature compensator...carb was rebuilt / overhauled to factory specs
If carb was overhauled correctly, then the issue lies elsewhere. I found the shop manual for this carburetor, and it explains the warm-start valve, etc.

You have a simple system to trouble-shoot...

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