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Interesed in a 1985 Caprice...but there is a mystery fuel issue

 
ski_rusk
I love my Chevy Chevette!
Posts: 1
Joined: 09/11
Posted: 09/19/11 03:03 PM

Hi everyone. I came across a 1985 caprice for sale. It has a 305 with Carb, and an auto trans. Mileage is 100k. The car seemed to drive ok, but it did have some sort of fuel delivery issue. It could be something small...or it could be a major problem. I wanted to ask your opinion.

The guy selling the car (small dealer) said he thinks that it's the fuel filter and maybe dirt or bad gas gummed up the filter. What happens when you press the gas is that it basically stalls out. But, if you let off the pedal a little bit it seems to send enough fuel to get you going, but kind of slow. Then, if you press the pedal to accelerate, the bogging down/stalling thing occurs. I did this for a little while and then finally got up to at least 55 mph, but it's very annoying and not really driveable due to the problem.

What do you all think? The car is relatively inexpensive (a bit over $1000) but I'm somewhat cautious. I asked the guy to repair it before looked at it again. Do you agree with the fuel filter theory? Or, does it sound like a bad fuel pump, or worse, a bad carb?


thanks,
sr  

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Ron1973
I have an SS396 tatoo
Posts: 257
Joined: 09/10
Posted: 09/19/11 05:48 PM

Sounds more like a carb problem, The pumper could be bad in it, id check and make sure its spraying fuel.. If its the filter i wonder why the guy selling it didn't just replace it with a new one!  
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Ron1973

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Ron1973
I have an SS396 tatoo
Posts: 257
Joined: 09/10
Posted: 09/19/11 05:50 PM

Check and make sure its pumping gas, look inside the carb and pump it.. Should spray gas in, If i was selling a car i think if i thought the filter was bad, id change it.  
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Ron1973

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 09/19/11 07:45 PM

1985 caprice models with 305 and almost all the engines in the united states were feedback carb equipped..


its going to take a scan tool....  and or a dwell meter..     as the scan tool for that model is OBD1...  and they are NOT easily available.. except used... or the 500 buck and up versions new...  

if you get one of these.. the cartridge needs to be slightly newer than the year model car you are working on..

http://forums.corvettefever.com/70/8585187/c4-corvettes/which-used-scan-tools-for-82-to-94-corvettes-with/index.html


i you have a Dwell meter.. either an analog or a digital version.. set it to six cylinder mode...   find the green test lead near the carb... hook up the dwell meter to that.. and ground the other wire...

see if you get 28 to 35 degrees of dwell.. at idle and if you increase the RPMs slowly to 2500 RPMs..

if the dwell reading is pinned above 50 or below 10..  there are charts for that..

you are also going to need a factory service manual for gm cars and trucks from 82 to 87... the version with the fuel control section..

the mixture control needles have a tendency to stick in the down position...
the Throttle position sensors have failed..
the ground wires get damaged causing computer problems..
the diverter valve and air injection check valves burn out and can leak uncommanded air into the upstream exhaust messing with the oxygen content in the exhaust stream before it passes by the oxygen sensor.. this one weird failure can drive mechanics crazy..


if you are  looking for a car... and the price is right... hmm.

do you have to smog test the car.. or plan on selling it in an area where it needs to be smog tested...

how good are you at reading factory service manuals..  and working on quadra jet carbs...

when these run properly .. you can get on a 305 version over 23 MPG..  when its running right..


that model was also equipped on a few with Throttle body fuel injection..    since it was equipped.. its almost a PLUG and play swap...  you do need most of a donor car to swap... but you can do it from a C10 or even a chevy van..  from up to 92.. there are a few differences in wiring..

or... you can go the route... and take the whole feed back system off.. and replace it with a NON feedback carb.. and a vacuum advance distributer.


there are just so many things to think about.. and so many newer fuel injected models...  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 09/19/11 07:49 PM

the engine of your 1985 Chevrolet Caprice:
   * Available engines
         o 6 Cylinders Z 4.3L TBI
         o 8 Cylinders 6 5.7L 4BL
         o 8 Cylinders H 5.0L 4BL OHV
         o 8 Cylinders N 5.7L MFI Diesel OHV  

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pepsi1
Big Block power for the win
Posts: 940
Joined: 03/11
Posted: 09/20/11 07:42 PM

Make sure the choke isn't flopping closed.

These guys have you covered.

If the carb has a long fuel filter? Some have little popit valves in it see if the filter and/or the poppit valve are clogging the fuel inlet.

It maybe the fuel pump.

Or it mame the accelerator pump!

Last the pickup in the tank has a sock on it. It maybe clogged also. There's not much in the fuel sysytem in that circa Chevy. GOOD LUCK............  

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pepsi1
Big Block power for the win
Posts: 940
Joined: 03/11
Posted: 09/22/11 01:11 AM

wayne let me know if you got my message. It just went blank on me and all was gone.  

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