Stutter, Hesitation on Acceleration

B

ben

New member
Ok im at wits end!
75 Scout II, 304, Holley 2300, Holley dizzy w/pertronix iii and flamethrower iii coil. All new ignition components and firing order verified.
Starts and idles at 600-700rpm perfectly, when gas is applied it hesitates for about 1-2 seconds and recovers. If I put a load on it a great deal of gas is needed to get it moving and if it stalls under load it needs to be choked to get it going again. Ive also inspected the new carb for binding parts, restrictions and plugged venturis, it is gtg.

Help! :(
 
Sounds like the carb is not delivering a good pump shot. Or it has a power valve issue. The no top end could be caused by ignition timing make sure its set at least 10btc. And thats off the #8 plug. Also if this is a brand new outta the box Holley, you will need to probably adjust jet sizes to accomodate the engine. Maybe not. The only way to tell is with a plug check.
I have found that the new Holley carbs are full of casting flash and other little goodies before. Imho, you should disassemble them and verify all passages and ports are clear before installation. Face it the old guys at Holley have been replaced by folks who dont give a flying shizz if it works or not!!!
 
What's the list number of the 2300? Is this issue worse when the engine is cold, hot, or no difference across the board? Have you checked to see that the accelerator pump is giving a healthy and even discharge of fuel the moment the accelerator linkage is actuated? This is best verified with the engine off, filter canister removed, eyeballs peering down into the airhorn, with adequate lighting. If you don't see two good squirts as soon as you blip the throttle, something is wrong with the accel pump. Has the fuel float level in the fuel bowl been verified? Are you able to achieve wot via the accelerator pedal? Those sii pedal arms are notorious for bending and eventually breaking at the pivot point from metal fatigue. Something to check. Have you connected a vacuum gauge to assess manifold vacuum with this engine? You May have a vac leak somewhere.
 
0-7448 model 2300 w/manual choke less than 100 miles and new from Holley. Was running well until stutter issue arose.
Well this May be the wrong forum! So now the truck wont start at all, spark present but no fuel when the accel lever is actuated. Normally a healthy audible squirt of fuel can be heard ( and seen) when working the throttle now I get nothing. I didnt have time tonight to pull the gauges out but I did check the peep hole on the bowl and the fuel is level with the bottom of the hole. I also pulled the fuel line and turned the engine over and a healthy fuel stream came from the line. (I know dangerous and unscientific :nono: ) im lost! Lol
 
The most obvious possibility to my thinking is blockage inside the metering block. Are you running any filtration between the tank and the carb? How's the inside of the fuel tank? You could try removing the idle mixture screws and blasting some carb cleaner chased with compressed air into them. Reset the screws and see if that gets you some flow. Better yet would be to remove the metering block from the carb for a more thorough cleansing. It doesn't take much to block those tiny passages.
Another possibility, but less likely is that the accel pump diaphragm is ruptured to the point that it simply can't force any fuel through the squirters.
 
There is a filter between the tank and carb. The tank is clean to my knowledge. Ill try the metering block route and see what happens!
 
Well I guess next time instead of trying to push someone in the right direction and keep it simple, ill just keep my wag to myself and let ya baffle em with bs that sent him right back to the same place! Just stating the obvious!!!
 
scoutboy74 said:
the most obvious possibility to my thinking is blockage inside the metering block... ...another possibility, but less likely is that the accel pump diaphragm is ruptured to the point that it simply can't force any fuel through the squirters.
Click to expand...

To all: the end result might be an insufficient or no pump shot from the accelerator pump circuit, but a blockage inside the metering block can cause that. Those posts from scoutboy 74 and towpainter3 don't contain *wags*... They are educated diagnoses.

Bottom line: remove the metering block, clean well, inspect/replace accel pump components, re-assemble, adjust/tune accel pump.
 
towpainter3 said:
well I guess next time instead of trying to push someone in the right direction and keep it simple, ill just keep my wag to myself and let ya baffle em with bs that sent him right back to the same place! Just stating the obvious!!!
Click to expand...

Take a deep breath. There was no way for you or anyone to state the obvious at that point because not enough was known about the equipment or the problem to home in on any one possibility. You provided several, as many of us might do in an initial response. I followed your lead by asking the op for more specifics and clarification, which he provided. That additional information has certainly helped narrow the focus. We still don't have a verdict on this thing yet. Your second post just struck me as being nothing more than an out of place attempt at fishing for an atta boy. Forgive me if I misinterpreted.
 
Boy I didnt mean to start anything:nonod:
so disassembled the carb and the fuel was pretty dark and it looked sluggish. Ill know in a while what the result is. Will keep posted!
 
You didn't. Don't worry about it. Dark fuel. Are you trying to burn months old fuel? If so, I'd advise against that. You'd be better off siphoning your tank dry as possible and starting over with fresh gas.
 
No fishing here , never looking for atta boys, possibly I shoulda asked for more specifics, but as eric stated and I shoulda said, take it apart , then let us know. In all my years as a mechanic in my garage and at the tracks working on these carbs, most of them the 500 cfm models on dirt cars, all the symptoms pointed to stopped up passages.
As he stated it was new and I've seen countless fubars from Holley in the past years.
Anyway, we are all in this for the same reason, to keep em running. I'm all for that!
Let us know how it comes out.
 
Ok running well again.
The accelerator pump was shot, sad really brand new factory rebuild less than 50 miles on it :mad5:
went to speed shop and got a Holley trickit kit and rebuilt the carb blowing out all the passages.
Because I did have some other small issues I changed the plugs and installed autolite 85s. Adjusted the timing and it is fine now.
Thanks for the help! :icon_up:
im sure ill have more questions!
 
Good deal. That is disappointing to hear of the slipshod work on the rebuild, but not unheard of these days. Until your last post, I was under the impression that this carb was brand new rather than a refurb.
 
Same here on the new carb part but still the border jumpers building them with the chineeze parts they get what can we expect. Glad to hear its goin now, like scoutboy said I,d still be concerned about the dark colored fuel.
 
You must log in or register to reply here.
Back
Top