engine troubleshooting help please

[cantwell.colton]

75 dodge dart
it starts up fine and runs well -- but if you push in the accelerator hard to rev it up it bogs down like it want to die -- if you do it slow its fine -- same thing happens when its driven -- as long as you take it nice and slow its fine --

where do i start?

 

[sgtpontiac]

sounds like a weak accelerator pump in the carb..

with the engine shut off, look down the throat of the carb and see if there is a good steady stream of fuel when you crack the throttle....if it dripples or nothing then a carb repair / rebuild is in order.....hope that helps..

 

[Toad]

Sounds like your jets are too small to me. What kind of carb is it?

Toad

 

[donsrods]

Does sound like accelerator pump to me. As sgtpontiac said, look down the throat of the carb and you should see very strong streams when you move the arm.

It is also possible your vacuum advance isn't working right. Put a timing light on it and see if the timing mark moves as you speed it up.

Don

 

[cantwell.colton]

thanks guys - hopefully -
ill check into it all today --
everything ive read said the carb is probably
a holley 1945 single - and is supposed to be
a not so great carburetor and is often recommended
being switched out -

 

[NitroJohnny]

Like Sgt said. I would bet accelerator pump as well. What is happening is when you open the carb fast, you introduce a ton of air and the accelerator pump gives it a shot of gas to mix with the air and it runs. But with the pump not working right, then you introduce the air without fuel and it goes way lean making it bog. Then it might catch up and run, but may just die. My money is on a carb rebuild.

 

[kelseydum]

If it's not the accelerator pump you may check your fuel filters. Check the inline filter (if you have one) and check the filter that's in the carb ( where your fuel line plugs into the carb). It may be getting clogged up a bit and lots of people forget to check the filter in the carb.

 

[rainman]

Acc. pump, filters!!!
Were I would start!!

 

[cantwell.colton]

i got a chance to look at it during the day -- did some little part replacements and connected the linkage up the RIGHT way -- revs up and goes just fine now [ddd
thanks everyone

 

[NitroJohnny]

Yep, that will do it. If the linkage isnt right, then it doesnt hit the accelerator pump when it should if at all. Glad you fixed it.

 

[sgtpontiac]

Good to hear CC...

sometimes it the little details that get ya scratchin your head....[S Just when you think you've checked everything....you find something you missed....

 

[Torch]

Some carbs have a power valve that can stick. it's a piston with needles that go down into the jets. Vacuum holds the piston down where the large end of the needle blocks the jet off more

when vacuum drops the needles rise and the thinner part of the needle blocks off less of the jet allowing more fuel by

the accelerator pump makes the difference when you first drop the vacuum by opening the butterflies.

if the accel pump is working and it's the fuel supply or the power valve, pumping the pedal as you accelerate should run better. same thing with bad gas. the thing getting better as you feed throttle in easy and it running fine under load at stable throttle setting lends me to believe there is nothing wrong with the power valve

the new rubber accelerator pumps pistons get hard and crack when they dry out same with the holley pump diaphragms.
the old leather ones would just swell back up and go back to working when the fuel hit them

 

[LOCCGASSER]

Bogs under acceleration

you have various functions of the carb...idle curcuit, main metering and pushing the accelerator activates the accelerator pump shot...sounds like the accelerator pump is bad...go through the carb, clean a few times and you should be ok....

 

[Old Iron]

And we have another satisfied customer [cl
God I love this forum


Jim