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Old 10-09-2017, 12:56 PM   #1
MMricky
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71 burb reduced power

I have 71 c10 suburban with original 350 , rebuilt, sort of. Not confident that it was done correctly as it still has white smoke coming out of tailpipe. Itís been running fine for the 2 years I have had it, recently got the oil changed and topped off trans fluid and now after about30 minutes of run time itís like a switch I get reduced power. The more gas I give it it just wats to stall, oil pressure is good and trans shifts as normal just wonít go. Donít know if it is motor, trans, fuel issues. Just canít figure it out, it always starts, just happens after itís run for a while. I have 700r auto trans with edelbrock 4 barrel, mechanical fuel pump, running no ethanol in gas, spark is electronic being no points, just not sure how to diagnose any help would be much appreciated
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Old 10-09-2017, 03:16 PM   #2
geezer#99
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Re: 71 burb reduced power

First thing to check whenever you have a no power situation is your timing.
Make sure the distributor hasn't moved and you have at least 12 degrees initial timing.

Other things to check is for vacuum leaks.
And it's possible your module in your distributor is starting to die.

Last edited by geezer#99; 10-09-2017 at 03:24 PM.
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Old 10-09-2017, 03:48 PM   #3
MMricky
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Re: 71 burb reduced power

Thanks for the info thatís where I will start
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Old 10-09-2017, 07:24 PM   #4
garyd1961
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Re: 71 burb reduced power

Change all the fuel filters including the one in the carb if it has one. If you shut it off for a minute and start back up what does it do?
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Old 10-10-2017, 10:26 AM   #5
68gmsee
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Re: 71 burb reduced power

Agree with above recommendations.

When you have a sudden loss of power it's always a good thing to start a checklist and do the easiest and cheapest first.

-Timing
-Vacuum leaks
-Filters (including breather and carb inlet filter)
-Bad fuel pump or fuel restriction (fuel pump should produce 1 pint of gas in less than 30 seconds into a plastic container.)

Other things include compression check -maybe a leak down test since you mentioned white smoke out of the tail pipe. If it's not normal condensation it could be sucking in coolant or maybe transmission fluid.

If all the above checks out, carb may need to be checked. On high mileage engines a worn cam would give the same symptoms but it would be gradual.
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Old 10-10-2017, 03:01 PM   #6
kwmech
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Re: 71 burb reduced power

Sounds like it may be constipated if it progressively gets worse. Check for a restricted exhaust system, plugged muffler etc
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Old 10-12-2017, 03:44 PM   #7
MMricky
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Looks like it is a vacuum line, so far running better but I will start going through the list of other suggestions, the guy I bought the vehicle from said he had rebuilt the motor and it had 12k on it, not confident with the work but it has always run. Thanks for all the feedback
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