I am at such a complete loss right now. When I accelerate very slowly without much load on the engine Im fine. If I give it any real gas, or accelerate when in 4th gear, I get a bogging, almost feels like detonation. I've replaced the cap,rotor, wires, fuel pump, fuel pressure regulator, changed the springs and jets in the carb, checked the float level,changed the timing both high and low, re-wired the fuel pump to include a relay, and still the problem is there. WTF is happening? Like I said it idles fine, accelerates very slowly fine, and even cruises fine no matter what the RPM. The plugs look perfect, the exhaust smells normal/rich, and fuel pressure is a steady 6psi any time I pull over and pop the hood to check. Ideas???
STILL can't find the problem with my bogging
bored&stroked
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I am at such a complete loss right now. When I accelerate very slowly without much load on the engine Im fine. If I give it any real gas, or accelerate when in 4th gear, I get a bogging, almost feels like detonation. I've replaced the cap,rotor, wires, fuel pump, fuel pressure regulator, changed the springs and jets in the carb, checked the float level,changed the timing both high and low, re-wired the fuel pump to include a relay, and still the problem is there. WTF is happening? Like I said it idles fine, accelerates very slowly fine, and even cruises fine no matter what the RPM. The plugs look perfect, the exhaust smells normal/rich, and fuel pressure is a steady 6psi any time I pull over and pop the hood to check. Ideas???
B&S,
Just a suggestion, try dropping back the timing to a lower value and see if you still have the problem. If you have maybe 36 Total timing, try 27 just for a test, to see what happens. If the problem goes away, then you have a solid starting point. If not, you can start looking at other areas.
Fred.
Just a suggestion, try dropping back the timing to a lower value and see if you still have the problem. If you have maybe 36 Total timing, try 27 just for a test, to see what happens. If the problem goes away, then you have a solid starting point. If not, you can start looking at other areas.
Fred.
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I have backed the timing down, it didn't seem to help. I have tested the accelerator pump in all three holes [its an edelbrock 1405, about 6-7 months old]. It seems like the richer I go mixture wise the better it gets, but its getting way rich. This is a stock vortec 350 from a 99 pickup with a RPM intake, 1 5/8" headers, 600cfm carb, and msd 6a and blaster 2 coil.
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Does a failing blaster 2 ignition coil cause this? How about a 6a box? I think Im about to give on this one and pay someone to figure out whats wrong if that is possable, seeing as I've adressed just about everything on the truck.
I'm not a expert but have some Edelbrock experience. How does it run when cold? Have you checked the float drop? What Hg spring are you using? What jets and metering rods? You say richer makes it better,do this test, close the choke some and take it for a short drive, this will make it a bunch richer across the board. If it gets better or goes away then you will know its lean somewhere. Your symptoms sound like a lean spot between the pump shot and the power mode staging. Bring the power mode staging in earlier "stronger spring" and richen the power mode. For other areas, do a compression test to make sure there are no sick cylinders, check for vacuum leaks, close the plug gaps, try a colder range plug, slow the advance curve, use a lower thermostat, use higher octane fuel. Heavy truck, stick shift, economy gearing = detonation can become a problem.
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I chased a problem like this for a long time once. Changed every thing with no help. Do you know what your fuel pressure is while accelerating? Here is why I ask. I went to put fuel in my car one day and as I opened the cap there was a large sucking noise. I replaced the cap and solved the problem. I had this happen again on another Chevelle after that. Did not waste time tracking it down.
Look down your carb while moving the throttle, you must see a steady stream of fuel discharging from the booster area near the top of the carb. If not, your accelerator pump is bad or not adjusted properly. It is normal for the idle and steady cruise speed to be good even if your accelerator pump is bad. When you open the throttle blades of a carb your vacuum drops and demands more fuel to mix with the additional air from the open throttle. Jets are mostly affecting the engine at or near more open throttle conditions. If your engine stumbles, and seems to loose power it is usually because it is not getting the additional fuel from the accelerator pump, richining up the mixture. Six psi should be good for street. Also you can get a smooth transition between idle and open throttle if you ease into the pedal....but this is not what we want to live with! Check for the stream of gas when moving the throttle.
Sam
Sam
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79 Posts
Thanks for the replys-
Yes the accelerator pump shoots a stream of fuel the moment the throttle is touched even a little. I tried to go really rich last night, 107 front and 100 rear with the heaviest [quickest opening] springs and 70/42 rods. The problem because MUCH worse, even light throttle misses, which is now making me think ignition somewhere? My normal mix is 104/100 jets and 70/42 rods with the heavy springs, still on the rich side for a stockish motor like this. The truck has 3.73's, not exactly a load inducing gear when this same entire engine setup was in front of a .67 overdrive and 3.07 gears before with no problems. Thermostat is a 160, and the plugs are R42LTS's compared to R44LTS's stock
No I cannot tell what my pressure is while accelerating. If all else fails then by tonight I will have somone drive with the hood open while I sit in the engine bay and watch the pressure. Dangerous? Sure. Do I have any other choice? Not anymore. 2 weeks is long enough without a vehicle.
Yes the accelerator pump shoots a stream of fuel the moment the throttle is touched even a little. I tried to go really rich last night, 107 front and 100 rear with the heaviest [quickest opening] springs and 70/42 rods. The problem because MUCH worse, even light throttle misses, which is now making me think ignition somewhere? My normal mix is 104/100 jets and 70/42 rods with the heavy springs, still on the rich side for a stockish motor like this. The truck has 3.73's, not exactly a load inducing gear when this same entire engine setup was in front of a .67 overdrive and 3.07 gears before with no problems. Thermostat is a 160, and the plugs are R42LTS's compared to R44LTS's stock
No I cannot tell what my pressure is while accelerating. If all else fails then by tonight I will have somone drive with the hood open while I sit in the engine bay and watch the pressure. Dangerous? Sure. Do I have any other choice? Not anymore. 2 weeks is long enough without a vehicle.
What I don't understand is why everyone is so quick to say "not enough gas", when too much gas can also cause a bog. How do I know this? Simple. I had a bone stock 73 Elky back in high school, and like all the other high schoolers, I wanted to have the coolest looking engine on the planet, which of course meant a Holley Dbl Pmpr. Massive bog 
Finally wised up and put a simple little 600 CFM vac secondary on. No more bog. Too much fuel too soon can be just as problematic as too little. But that's just MHO.
Finally wised up and put a simple little 600 CFM vac secondary on. No more bog. Too much fuel too soon can be just as problematic as too little. But that's just MHO.
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Holy crap, you guys wont belive this.
Thanks to the continued support from you guys and my fellow truckers I kept attacking the truck every night, checking anything and everything. I even replaced/re-set some things two/three times. Today was the LAST day I could be without it as dad is now home and needs his car back tomorrow. I had already changed the wires twice, so I thought why not the plugs once? They looked great, and are only 6months old but what else is left to change? While I was at it I also put the original jets in [104's] and tried a q-tip in the accelerator pump. My test drive made me laugh and almost cry at the same time. Everything is perfect once again. It runs with no problems at all, no matter how heavy the throttle gets or what RPM Im trying it at.
THANK YOU to all who helped, I know I pleaded quite loudly. I also hope everyone knows I did that because you all are the only real gearheads on the net who actually take the time to give helpfull, insightfull answers, with REAL world knowalge to back up those ideas.
Thanks to the continued support from you guys and my fellow truckers I kept attacking the truck every night, checking anything and everything. I even replaced/re-set some things two/three times. Today was the LAST day I could be without it as dad is now home and needs his car back tomorrow. I had already changed the wires twice, so I thought why not the plugs once? They looked great, and are only 6months old but what else is left to change? While I was at it I also put the original jets in [104's] and tried a q-tip in the accelerator pump. My test drive made me laugh and almost cry at the same time. Everything is perfect once again. It runs with no problems at all, no matter how heavy the throttle gets or what RPM Im trying it at.
THANK YOU to all who helped, I know I pleaded quite loudly. I also hope everyone knows I did that because you all are the only real gearheads on the net who actually take the time to give helpfull, insightfull answers, with REAL world knowalge to back up those ideas.
B&S,
I know your problems solve, but here is just a misc item on your statement:
"If all else fails then by tonight I will have somone drive with the hood open while I sit in the engine bay and watch the pressure. Dangerous? Sure. Do I have any other choice? Not anymore."
We had the same problem, we wanted to watch the Fuel gauge above 5K rpm. We also wanted to watch the engine, in fourth gear, but didn't want to sit on the front fenders. So we grabbed the Laptop, hooked up the Cadcam to an extender USB cable and put the Cadcam in front of the engine with some ty-raps. It was a cheap Cadcam, and it had to be manually focused. We did some recording of what the Cadcam was viewing. We even did this at night, to see if we could see any problems with the plug wires. Just having fun and getting carried away, we watched the rear axle, the exhaust, and just about anything that moved on the car. All in all, it told us exactly what we needed to know as we moved the cadcam around. So if you ever decided you need to watch your engine, this is the easy way to do it.
Fred.
I know your problems solve, but here is just a misc item on your statement:
"If all else fails then by tonight I will have somone drive with the hood open while I sit in the engine bay and watch the pressure. Dangerous? Sure. Do I have any other choice? Not anymore."
We had the same problem, we wanted to watch the Fuel gauge above 5K rpm. We also wanted to watch the engine, in fourth gear, but didn't want to sit on the front fenders. So we grabbed the Laptop, hooked up the Cadcam to an extender USB cable and put the Cadcam in front of the engine with some ty-raps. It was a cheap Cadcam, and it had to be manually focused. We did some recording of what the Cadcam was viewing. We even did this at night, to see if we could see any problems with the plug wires. Just having fun and getting carried away, we watched the rear axle, the exhaust, and just about anything that moved on the car. All in all, it told us exactly what we needed to know as we moved the cadcam around. So if you ever decided you need to watch your engine, this is the easy way to do it.
Fred.
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121 Posts
Dang, Bubba's been sittin' on my fender for a week now. Geuss I can call him in for dinner.
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