: 1973 Coupe DeVille Fuel Pump Question!



Coogan 1031
11-01-08, 01:20 AM
hello,
i dont know if i am in the right thread but any help would be appreciated.
every once in awhile when i am driving if i go to a wide open throttle at about 15-20 mph my coupe with the 472 will literally fall on its face! no power and it sounds like it is bogging down? if i let up a second it will take off real qwik like it should? i NEVER go full throttle from a dead stop, it is when i am rolling down the road around 20 mph? could it be a fuel pump and fuel filter? maybe a distributor? it idles a bit rough and loads up with fuel cause you can smell it. do you think i should just have the edelbrock carb adjusted? i apologize for all the questions but you guys have always helped me out in the past! i have no clue when the fuel pump was changed last or if ever was because i bought this used? this happens when the car is warmed up not from a cold start?

thanx
Coogan 1031

deVille33
11-01-08, 11:25 AM
What manifold are you using with that Edelbrock? What carb is it? Are you using an adaptor on a stock manifold? It sounds like you have a mismatch here somewhere in the fuel delivery system. Stock Cam? Check your carb and assessories for vacuum leaks. Need more info to diagnose this situation.

Coogan 1031
11-02-08, 01:01 AM
it has the stock manifold with a 750 4 barrel edelbrock carb with a 2 inch adapter.
i changed out the fuel filter today and it's still not any better. it has the stock cam in it and i checked no vacuum leaks as i can see. thanx for helping me with this. i am leaning towards the fuel pump being on its way out, but i am no way even close to being a mechanic!! do you think it could be the distributor not advancing the timing? bad fuel? timing needs to be advanced?



thanx again
Coogan 1031

Coogan 1031
11-02-08, 08:59 PM
i just replaced the coil on my coupe and it seems a little more responsive. when i was looking over the wires to make sure they were all tight on the plugs and distributor cap i seen that my coil had two 1 inch cracks in it? it starts a lot quicker but still has that bog every once in awhile? i did notice that it seems to happen when the car isnt totally warmed up to temp. any help on this would be really appreciated.



thanx
Coogan 1031

Superjim
11-03-08, 11:38 AM
It sounds to me like it may be the accelerator pump in the carb.

Either that or the secondarys are opening too quick and dumping more air in at low RPM then it can handle. Thats why ... when you let up a little...it takes off like it should.

Does the carb have vacuum or mechanical secondarys?

Texas Jim

Coogan 1031
11-04-08, 12:16 AM
hello,
thanx alot for helping me with this cadillac issue. i have a 750 edelbrock with an electric choke on it and i think they are mechanical secondaries? i just spoke to a guy who said i should check the resistor or capacitor by or under the distributor? i had no clue what he was talking about? i told him i had no clue what he was sayin and he kept on goin so who know if that makes any sense at all? i had the point system upgraded to the pertronix about 7 months ago. i still have the point style distributor with cap, rotor and wires. it seems to get worse after the car gets to proper operating temp?


thanx
Coogan 1031

cadillac_al
11-04-08, 09:23 AM
It sounds to me like it may be the accelerator pump in the carb.

Either that or the secondarys are opening too quick and dumping more air in at low RPM then it can handle. Thats why ... when you let up a little...it takes off like it should.

Does the carb have vacuum or mechanical secondarys?

Texas Jim


Superjim nailed it. I doubt the Edelbrock carb will ever work as good as the stock Qjet. Edelbrock prints an in depth manual that comes with the carb expaining how to tune it. If you don't have it maybe you can look for one somewhere or Edelbrock must sell replacements. It could be a vacuum advance problem too. With the engine warm and air breather removed, you should be able to stab the throttle and watch the secondaries open. If they flop open too fast then there is the problem. You should be able to look down the carb with the engine OFF and move the throttle and see the accelerator pump squirting. If no squirting then there is another problem. Good luck and I would watch Ebay for a decent Qjet.

Superjim
11-04-08, 03:07 PM
One of the problems with the Edelbrock carb is... the spring that controls the top airvalve for the secondaries loses its tension over time and must be readjusted.

When the spring gets weak.. it allows the SUDDEN opening of the secondaries, and the intake loses all vacuum and the car falls on it's face for a few seconds till everything can catch up.

Another problem is the little STOP CAM on the side of the card, built into the linkage, that prevents the secondaries from opening when engine is cold, gets bent and the secondaries open too soon and basically flood the engine for a few seconds with both fuel AND air.

Get it all adjusted RIGHT, and I think your problem will go away.
Or replace it with a Quadrajet, like came on it. But they also have to be adjusted RIGHT.

Texas Jim

Coogan 1031
11-04-08, 11:00 PM
thanx alot everyone for helping me with the fuel pump issue on my caddy. i had a new pump installed today and it runs out great! it idles better and it starts right up with a turn of the key! prior to the new pump it would take 3-5 seconds before it would turn over? once again many thanx to all for taking the time out to help out a fellow caddy man!



Coogan 1031