75 elsorado hesitation and poss misfire?

[Doug Spingelt]

I just replaced the fuel pump and and spark plugs and the car is running pretty well.  there is still an issue on accelleration.  if I hit the gas hard at all the car has a strong hesitation.  Also whe idoling, it seems like it is misfiring or someting. it is smooth, but has a blib in it that you can feel anb hear.  It is hard to explain.  I am wondering if it could be timing? Carb adjustment?  I have never worked on a carb before.  Thank for your advice.   

[TJ Hopland]

How well does it start?   I wonder if the accelerator pump is working.   If you look down the carb ( you will have to hold the choke open if its cold) and stroke the throttle you should see a squirt of gas coming out each side going down the throat of the carb.  How long has it been since the carb has been gone through?   About 10 years is the max I have seemed to get out of any of mine before there starts to be issues even under the best conditions.   5 years is more average before they seem to benifit from a good cleaning and some new soft parts.

Have a look at the distributor.  If you remove the cap and rotor (you can leave the wires hooked up, just swing it away) you will see some little fly weights and springs.  Make sure everything there is able to move freely and that it always springs back.  Next have a look at the vacuum can.  Hook it to a a hand vacuum pump (they can be had cheap now days, you can even get one that bleeds brakes) and see if it operates and holds.  They usually wont hold forever but as long as they hold for 30 seconds to a minute they should be fine.  This would be a good time for a new cap and rotor if its due anyway.   Put it all back together and see how it runs.  Try unhooking and plugging the vacuum line to the dizzy and go for a test see if it still has that hesitation, it should be more sluggish but no worse for hesitation.   If that solves your hesitation problem try hooking you vacuum pump and operate the advance with the engine running to see if that makes it hesitate.  It was a common problem with age on these to have the fine wires inside the distributor crack.  When the vacuum operates the wires flex and maybe loose connection.  If thats all good then start tracing vacuum lines to see if the vacuum advance is operating properly.  If that all looks good then you are back to carb issues. 

[J]

I Just replaced my cap,rotor,coil wires and plugs i had the same problem before it eventully stopped (would not start) i had two brittle wires that just fell apart   and my rotor was just barely on 2 bolts were loose that holds this in place so it was wobbling  so i think changing everything was a good choice what a difference i have quick response on Acceleration where as before it was hesitant i always thought it was a carb problem........

[Doug Spingelt]

After driving it today it seems a liibtle better and I have isolated the hesitation. It is only upon hard acceleration; otherwise it is super smooth. It is when the "second stage throttle" engages in the carb when the hesitation occurres.  I plan on replacing cap and rotar as well as adjust timing but that is another project.  Thanks as always. 

[mgbeda]

What you describe is a common quadrajet problem, and it is caused by the carb getting gummed up inside.  It is more common on cars that don't get driven much.  You might be able to get those secondaries freed up by squirting carb cleaner into the carb and revving it until it revs smoothly.  More likely that carb will need to be taken apart and cleaned, at which point you might as well rebuild it.

-mB

[Doug Spingelt]

I will try that tonight withbthe carb cleaner.  I was suspecting that could be the case, as it sems to have gotten a bit better with use.  This car has been sitting (outside in the woods) with virtually no use in about 4 years.  Thank you for your help.  On a good note, the new heated glass is being delivered today for the top.  (Old one broken)  Cant wait to get the car water tight or water resistant again. 

[Richard Pope]

If this is not an EFI car, you might want to check the plate that holds the condensor & points inside the distributor. The center of my plate was slowly being 'ream' which allowed the whole plate to shift upon acceleration. I replaced the whole distributor and my hesitation issue- which sounds very similar to yours - went away. If your plate is loose you will see some small shavings when you pull the cap.

[TJ Hopland]

If this is not an EFI car, you might want to check the plate that holds the condensor & points inside the distributor.

All 75's (and up) had the HEI distributor so no points.  Biggest slightly unusual issue with them was the pickup coil wires cracking over time.  The rest of the problems are the same as any other dizzy,  worn bound up weights, non functioning vacuum advance, cap and rotor wear and corrosion.

I would say after sitting for 4 years that taking the carb apart will do a lot of good.  Some of the 75's had pretty funky carbs with a few extra metering rods and jets.  Kits are still available.

["Cadillac Kid" Greg Surfas 15364]

Doug,
Just a diumb question. You say the car was sitting out in the woods for 4 years.  How much gas was in the tank? Did you drain the tank before you started the car?
Water in the gas, say nothing of the Shellac that old gasoline can turn into will certainly not help the performance.
Greg

[Otto Skorzeny]

Shellac ...

Actually it turns to varnish, not shellac. Shellac is made from the crushed shells of certain insects.

The candy, Skittles, is made from shellac.

[Chris Conklin]

The candy, Skittles, is made from shellac.

And margarine is only one molecule away from being latex.