Mercury Cougar Owners banner

1 - 9 of 9 Posts

·
Registered
Joined
·
380 Posts
Discussion Starter #1
Edelbrock 1405 Performer on my '70 351W. not many issues there, although i did just find one of the floats out of whack and fixed that.

just today, i noticed the engine was stumbling if i got my foot into it fairly good. seemed pump related, so i tried all three adjustment holes in the linkage. it was still acting like it was getting overwhelmed with too much fuel at once.

so i disconnected the linkage totally and it performed great. so.......

do i need the pump hooked up? i think i understand its purpose, but the car didn't seem to miss it at all.

is the pump bad or did i damage something there when i fixed the one float?

appreciate your ideas-

billy
 

·
Premium Member
Joined
·
2,142 Posts
Something is wrong if the car worked with it off! The accel pump is needed when you accelerate hard -- the carburetor venturis do not have time to react so the carb must squirt more gas into the manifold via the accel pump.
When you are cruising a check-valve typically overrides and prevents excess squirting -- which sounds like how you tested. Try a 0-60 and see if it doesn't backfire through the carb :)
 

·
Registered
Joined
·
380 Posts
Discussion Starter #3
Something is wrong if the car worked with it off! The accel pump is needed when you accelerate hard -- the carburetor venturis do not have time to react so the carb must squirt more gas into the manifold via the accel pump.
When you are cruising a check-valve typically overrides and prevents excess squirting -- which sounds like how you tested. Try a 0-60 and see if it doesn't backfire through the carb :)
i did zero to 90, and it worked great in all regimes except it started to break down a bit above 85 mph. not that i'm ever there, but when i trouble shoot, i try to put it through some hoops. anyway no backfire, no nothing.

if what you say is true, it would indicate the pump is stuck in a perpetual state/position to send extra fuel when the venturi action calls for it. any other checks i can do? is it time to take the top half of the carb off again?
 

·
Registered
Joined
·
380 Posts
Discussion Starter #4
i did zero to 90, and it worked great in all regimes except it started to break down a bit above 85 mph. not that i'm ever there, but when i trouble shoot, i try to put it through some hoops. anyway no backfire, no nothing.

if what you say is true, it would indicate the pump is stuck in a perpetual state/position to send extra fuel when the venturi action calls for it. any other checks i can do? is it time to take the top half of the carb off again?
even my own post didn't make a lot of sense. it is, of course, the linkage that pushes the pump down to deliver the raw fuel to the venturi. when the linkage is disconnected like mine is, there is nothing to push the pump down. so unless the car is running incredibly rich to start with (it's not), you would think acceleration performance would suffer greatly with the pump linkage disconnected.

but it didn't. ????
 

·
Premium Member
Joined
·
2,142 Posts
No clue unless the throttle linkage is severely limiting throttle travel in which case you won't need the accel pump :)
 

·
Registered
Joined
·
380 Posts
Discussion Starter #6
No clue unless the throttle linkage is severely limiting throttle travel in which case you won't need the accel pump :)
linkage is fine. i know it doesn't make any sense, but it works great with the accel pump disconnected. i will call Edelbrock tech line in the morning and see what they say-
 

·
Registered
Joined
·
380 Posts
Discussion Starter #7
linkage is fine. i know it doesn't make any sense, but it works great with the accel pump disconnected. i will call Edelbrock tech line in the morning and see what they say-
called Edelbrock. at first the tech said if it runs fine without it, then my set up doesn't need it. then he went off the line for a minute to consult a more experienced tech. that guy said if the check ball and weight in the accel pump circuit was left out after the rebuild, the venturi effect is strong enough to suck the fuel out of the circuit and into the air horn. that would make for a rich mixture cruising along, and so he said to look out the back end and check for black smoke indicating a rich mixture.

does this sound plausible to you guys? guess it's time to take the carb off and check for the little ball and weight.
 

·
Registered
Joined
·
992 Posts
That explanation sounds like the only real possibility (I wouldn't have known that/news to me) good thing you called tech.

I think you would've really missed that accelerator pump the 1st time you tried to start your car cold. how the heck could you start it? I guess you'd have to do full-throttle cranking for a long time? You'd have to prime it manually with a squirt can from the top or spray starting fluid down the carb (which by the way is very effective at getting a stored vehicle to start fast after sitting for a long time).

Kevin
 

·
Registered
Joined
·
380 Posts
Discussion Starter #9
That explanation sounds like the only real possibility (I wouldn't have known that/news to me) good thing you called tech.

I think you would've really missed that accelerator pump the 1st time you tried to start your car cold. how the heck could you start it? I guess you'd have to do full-throttle cranking for a long time? You'd have to prime it manually with a squirt can from the top or spray starting fluid down the carb (which by the way is very effective at getting a stored vehicle to start fast after sitting for a long time).

Kevin
nope. starts great. runs great. i watched the nozzles, car running, and opened the throttle. no fuel came out. then i physically pushed the plunger down and witness fuel coming out of the nozzles, and the car almost stalling from getting flooded with gas. no black smoke coming out of the back end cruising.

it does not appear my car set up needs the accel pump to run and accelerate. it may do better with a working pump circuit, but it does fine without. if the weight is missing, that might allow too much fuel to enter the air horn and flood the carb. just have to take it apart and see.
 
1 - 9 of 9 Posts
Top