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Old 04-22-2017, 04:01 PM   #1
Backpayne
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250 bogs down when pedal goes to the floor

I don't go WOT much with my 250 but if I do while I am already moving it bogs down/stumbles. I let off of the pedal and it runs fine. This is the only issue I have with the engine.

Is this a carb (newish Weber 32/36) issue? Or do I need to look at the fuel pump?

Thanks!
-Jeff
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Old 04-22-2017, 04:42 PM   #2
geezer#99
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Re: 250 bogs down when pedal goes to the floor

Fuel pump or timing. Check fuel pump by putting fuel line in a clear quart jar. Should fill it in 20 to 30 seconds of cranking.
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Old 04-22-2017, 11:58 PM   #3
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Re: 250 bogs down when pedal goes to the floor

Didn't think about timing. Does this mean I need to back it off a little?
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Old 04-23-2017, 12:05 AM   #4
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Re: 250 bogs down when pedal goes to the floor

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Didn't think about timing. Does this mean I need to back it off a little?
No!
Advance it more.
What's your initial timing now?
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Old 04-23-2017, 12:30 AM   #5
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Re: 250 bogs down when pedal goes to the floor

Whew! Good thing I asked! *I'm 36 and this is my first vehicle with a carb and I have a LOT to learn.

I will check tomorrow but I believe I set it in the 8-10 range.
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Old 04-23-2017, 12:45 AM   #6
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Re: 250 bogs down when pedal goes to the floor

Make sure you check and set it with the vac advance plugged off.
And try 14 degrees too.
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Old 04-23-2017, 01:02 AM   #7
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Re: 250 bogs down when pedal goes to the floor

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Make sure you check and set it with the vac advance plugged off.
And try 14 degrees too.
Will do! If I advance it too much I will experience pinging, correct?
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Old 04-23-2017, 01:04 AM   #8
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Re: 250 bogs down when pedal goes to the floor

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Will do! If I advance it too much I will experience pinging, correct?
Likely and hard to crank over.
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Old 04-23-2017, 01:05 AM   #9
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Re: 250 bogs down when pedal goes to the floor

You'll experience detonation which you will hear. I successfully ran my 292 at 16 initial for the longest time. The Bogging could also mean it's running to rich. Have you checked the plugs to see if they are black from too much fuel?
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Old 04-23-2017, 01:09 AM   #10
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Re: 250 bogs down when pedal goes to the floor

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You'll experience detonation which you will hear. I successfully ran my 292 at 16 initial for the longest time. The Bogging could also mean it's running to rich. Have you checked the plugs to see if they are black from too much fuel?
I just replaced the head with a rebuilt head and put in new plugs. I've put roughly 30 miles on it since the head swap; would there be any evidence of running too rich on the plugs in 30 miles?
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Old 04-23-2017, 11:06 AM   #11
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Re: 250 bogs down when pedal goes to the floor

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I just replaced the head with a rebuilt head and put in new plugs. I've put roughly 30 miles on it since the head swap; would there be any evidence of running too rich on the plugs in 30 miles?
If it's that rich then yes, The guys here that have run webers have said they are a bit of a pain to tune in.
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Old 04-23-2017, 04:40 PM   #12
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Re: 250 bogs down when pedal goes to the floor

Additional things to check.

Carb fuel bowl fuel level, carb accelerator pump and vacuum advance.

Fuel pump: When you check the fuel pump remove the line where it connects to the carb and place it in a plastic container. You should get at least one pint of fuel in less than 30 seconds.

To check vacuum advance remove the distributor top and observe while you put suction on the end of the advance tube. It should move and hold the vacuum. If you don't have a vacuum pump, use mouth suction. It's not that hard to make it move.

Accelerator pump: With a flashlight look inside the carb throat when actuating the throttle lever. You should see fuel squirting into the carb. If you don't the accelerator pump may be bad.

Only way to check the carb fuel bowl level is to remove the top of the carb.
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Old 04-23-2017, 05:52 PM   #13
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Re: 250 bogs down when pedal goes to the floor

Thanks, Guys. I'll go through all of the above. The timing was at 10 so I moved it to 12. I'll drive it like this for a bit and will adjust as needed.

I think I need to really work on the carb adjustment, too. My 250 goes through gas quite rapidly! I'm estimating 12-14 mpg; maybe that is typical?
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Old 04-23-2017, 08:33 PM   #14
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Re: 250 bogs down when pedal goes to the floor

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...
I think I need to really work on the carb adjustment, too. My 250 goes through gas quite rapidly! I'm estimating 12-14 mpg; maybe that is typical?
Yo, backpayne, you didn't say if the mileage is city or highway or both or if your truck has A/C, is automatic or manual. Depending on what you have it may be about right. My 68 with a 250 with no A/C and three speed manual gets about 12-14 in town and 15-16 on the highway. No up and down hills, just flat country.

These old trucks were made mostly for farm and ranch work as opposed to today's trucks which have become every day family vehicles. Good gas mileage was not that important back then.
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Old 04-23-2017, 09:34 PM   #15
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Re: 250 bogs down when pedal goes to the floor

Hills and nothing over 50 for my driving, so it sounds like I am in the typical range.
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Old 04-24-2017, 09:10 AM   #16
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Re: 250 bogs down when pedal goes to the floor

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Hills and nothing over 50 for my driving, so it sounds like I am in the typical range.
I'm not familiar with your carburetor but as you mentioned, tweaking it might improve your miles per gallon slightly. Certainly worth trying.
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Old 04-24-2017, 11:06 AM   #17
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Re: 250 bogs down when pedal goes to the floor

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Hills and nothing over 50 for my driving, so it sounds like I am in the typical range.
That sounds about right for a 250 with a 2 barrel. Tuning it more might help though as weber's have been known to increase mileage nicely. I forget which member it is now that did a 32/36 and spent quite some time tuning it....he got 18 mpg outta that 250.
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