hard start / poor MPG - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 01-04-2008, 02:06 PM   #1
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Default hard start / poor MPG

Help I have a 1985 buick Park Ave. It has HEI ignition si is different than most cars on this forum. It is hard starting after the initial morning start.
History i\ : it has 41 k mile was a 1 owner. I have done the following plugs wires cap rotor o2 sensor fuel filter air filter clean IAC clean throttle body clean maf checked timing
2 treatments of seafoam thru the intake and it was driven 900 mile to my house with 3 cans of techron fuel additive. I have also changed the transmission fluid and filter.
It has a poor idle like a miss but it is not missing. around town mileage is 13.5. The mileage over the 900 mile trip was 20 mpg
After having fixed all of the above the MPG is no better and the miss/ poor idle and hard start is still the same. I also cheched for vacuum leaks with a guage and checked for gas at the regulator on the fuel rail > I also checked the egr valve and changed the pcv valve. I have no codes and have checked and cleaned grounds and battery cables,
I also took a new coil and tried it with no change.
help what next ?

JOHN
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Old 01-04-2008, 04:09 PM   #2
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Default 1985

Seeing you have a classic RWD your problem may be better served in that section.
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Old 01-04-2008, 04:23 PM   #3
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Moved accordingly.
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Old 01-04-2008, 07:54 PM   #4
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The 1985 Buick Park was a FWD and the first year for the C Body iirc.... But still a classic

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Old 01-04-2008, 11:36 PM   #5
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Have you checked the timing with a timing light?
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Old 01-06-2008, 12:57 PM   #6
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This is a FWD car and more like the 87 to 91
can it go back to that forum please
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Old 01-06-2008, 01:10 PM   #7
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Quote:
Originally Posted by madsen
This is a FWD car and more like the 87 to 91
can it go back to that forum please
being a 307 old engine, its more related to the rwd engines.

have you checked your fuel pump pressure?
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Old 01-06-2008, 08:13 PM   #8
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I think we are all a little off topic on this one.... But lets see what we can straighten out...

The 307 FWD would have been the Buick Rivera with the Longitudinal FWD set up...

The 85 Park Ave was all new and was one of the first FWD C Bodies made...

So this would be a FWD Park Avenue, with a 3.8 V6, the old style oil pump, rocker shafts and the Distributor parked on the front of the engine as its the old style Buick 3.8.. These days this car is few and far between... I haven't seen one in about 6 or 7 years...



Ok I am at this point not completely sure what to tell you to check on this car.... These cars are very picky about the MAF sensor and the Failure rate on them was really high..

Do you have any codes at all stored in the ECM?

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Old 01-07-2008, 12:19 AM   #9
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for some reason i swear he had a riviera, oops.

after re-reading ur original post, i see you have already checked for fuel, but did you check the pressure? or just the presence.

but what was the mileage before. it doesnt really seem that bad. 20 mpg in a car that has 23 year old technology, doesnt seem that bad to me. plus cold weather will always hurt ur mpg.
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Old 01-07-2008, 01:45 AM   #10
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I am wondering whats making it chew fuel like that tho... Its an old set up, and doesn't have the Serpentine belt system... It has 3 belts I believe...

But it is an SFI system...

A lot of things make that set up very picky...

But its hard to say what issue it may be having..

I'd love to see pics of the car.... Its been a long time... It would be cool to see the engine

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