Oldsmobile cutlass supreme 1980, cant go over 15mph

New spark plugs and wires surely can't hurt. What about fuel? Did you empty the tank and put new fuel in it? Bad gas could be an issue. Causes weird problems and gunk could clog filters, etc.

Start with the basics mentioned above.

rough when you rev it? yeah, go thru everything as mentioned above. fuel delivery, spark, timing, filters

If your motor has a carburetor and I think so " take the breather ( air filter ) off and look around the chock arrange ment ....when familiar with its opening and closing movement then start the engine and try closing the choke more or less then giving ing it gas ( move throtle by hand open?) See what this produces ( does) with motor running ( closing choke by hand more or less) if the engine is then producing more power ,smoothly ,interpit the results with more choke better ? means it needs more fuel.. when if Opening chock some means improves running? it's flooding needs less gas.. a list for needing more gas follows 0. Look at new plugs see if there getting black tips already..? (If so proceed to TOO MUCH GAS below)1 fuel filter s one in carb front one under the car in the gas line...2. Bad vacuume leaks like the pvc hose or maybe a bad break booster A try plugging them off with plugsin the hose ect...3. Check the gasoline try replacing it with new. 4. Check for enough fuel pressure at the carb and color ( condition)of gas ect...5 have carb cleaned and or rebuilt...TOO MUCH GAS SUGGESTIONS...1 check is chock set to tightclosed then adjust it more open or temporarily wire it open somewhat...( for test)...is choke pullout working ?..2..carburetor may be letting to much gas inside it through a hanging or scotched float or bad float itself " if so get carb serviced or replaced. After checking the possible fuel issues its a good idea to check and see it your motor has jumped time a tooth or 2 this can cause a lose of power but Check tge stuff mentioned in previouse posts and anytime spark plug wires are 9 years old there just to old ...but may not fix other issues..if you find rust on yhe filters you probly need to take tank off and check to see how much is inside...or it could clog a new filter and it can stop a fuel pump too...if it helps to set your idle screw up ( while testing) ther on the left near the throttle bellcrank.. text back if you have a question ..post and pics like of what the spark plugs look like if your cars flooding youl see some black smoke useualy..hope this helps

mickeypowa said:

Hi guys !!

thanks for your help and time !

I changed the spark plugs, I had ngk ur5 which were black (see the photo) I replaced by ngk ur4ix (irridium and a bit hotter). I Started again but the problem is the same as before.

When I close the choke the engine stalls. Is it normal ? When I rev the engine, I see gasoline only in secondary barrel (where there is the choke blade) not in the primary. Is it normal ?

It seems I have gas pressure as we can see on the gauge. I am going to clean the gasoline filter but it seems already pretty clean.

I took some videos :

Video1
Video2

Edit :

I cleaned the little gas filter.
and here is a bottle of my gasoline coming from before filter, it seems perfectly clear.


thanks again

Mickey

Click to expand...

when was the last time you rebuilt your carburetor?

I was starting to write this whole dissertation on how a carburetor works but decided to just throw in a few comments after watching the 2 videos...

Once the engine reaches it's fully operating temperature, typically you would leave the choke wide open, so yes closing the choke could make it stall. Looks like you have a manual choke setup. Closed on those cold mornings, open once warmed up. and left closed when you forget. Looks like you got it flopping somewhere of partly open but not fully open.

Looks like a double pumper. The front barrels with the choke are the primaries. Between the primary and secondary actuation, it's progressive meaning the primaries will start to open first then at some point probably midway of the primaries opening the secondaries will start to open so you won't see any fuel being fed out of the rear secondary barrels because you didn't rotate the throttle far enough.

The accelerator pump shot is the 2 solid streams you see coming from the nozzle. Looks okay but not great. Secondary not squirting bc read previous^^^

The booster which is the cylindrical object in the smack middle of each barrel. I believe once the idle transfer slots are uncovered you should see fuel emitting out bottomof the booster. Yours looks like it's trickling out of the passenger side primary booster and very little to nothing out of the ds primary booster. If you hold the throttle open long enough for the boosters to feed the engine, it should be a nice cone shape.

Did you check float levels? How's the idle air mixture screws? Do they respond to adjustment or do nothing when turned? The latter will point to a suspected blown power valve. You could benefit from rebuilding the carb but a can of carb cleaner might help. Looks like the gaskets on the float bowls are all dried up so at the very least get the ones that can be reused. Blast all the air bleeds. You probably need the bowl off to clear up the ds primary booster. Inspect the jets for any obstructions when you have the bowl off.

You mention engine dyeing when you close choke good when it's closed all the way it should ..And if( when) it's cold then say somewhere between 1/8 " to 1/4" is fair for and old Holly carb...when it's hit it should be open if you have to wire it shut halfway then you have stoped hets or a big vacuume leak..or something more significant...I suppose you have tried looseing abd adjusting distributor timing while it's running set it somewhere like 10 degrees back from the highest idle point ( when turning) that should get you in the ball park 10 degrees is like 5/8" inch turn measured at the distributor body.. back is couterclockwise...gas is OK I do seem to see fine rust inside filter sooo ...plug is turning black from short trips ect...personally I would use ac r44 or r45ts instead of j* plugs in a chevy but that's next time .the plugs can be cleaned with spray starting fluid just spray it on the plug tip like carb cleaner...yes either clean a plug...while I don't useit fir starting engines...next question do you hear any tappets clicking ? Lots of them ? No then good it's getting oil pressure...you could do some more tests with your carb get a gasket set and check front jets what size is your engine a 305 ?..post the numbers on the carb please... it's possible carbs to big and normally these gm cars have a quadrajet or 2 barrel rochestor..Have you got anextra carb to switch onto the motor might be a way to check how it behaves I don't suppose it's cold temp where you at ? Check the secondary throttle see it it's closed now and also see it moves freely if you can do that by opening choke and pushing the throttle all the way open move any auxiliaries flap valves open and push the secondary vacuum pod rod up ..while looking down the back barrels notice if it hangs up it should go back closed as it works off of vacumme and when motors off it should close by the spring in the secondary pod it's proubly ok but not impossible to malfunction