heard this one yet???? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

stevenfromtexas · 07-30-2018, 07:22 PM

ok, i've been tweaking on my pickup for the last few months. when i'm out driving it, it will die when down shifting from 3rd to 2nd. this is a huge problem when i go to turn onto my street and down shift to turn left. it will die. not cool when there are cars heading toward me. most of the time i have enough momentum to pop the clutch and get it going again.
Also, it is making a "sucking" noise around 40MPH. i can ease into the accelerator and it goes away. just seems like it's starving for either air or fuel

so....why do you guys think this is happening.

250
3OTT
single barrel rochester
10* initial timing
RPM's approx: 550
Petronix ignition
full tank of gas

let me now if there is another info y'all need

firedemon · 07-30-2018, 08:40 PM

check for vacume leaks turn idle up to 700 fuel filter

ryans69chevy · 07-30-2018, 11:29 PM

I've had my hose from the hard line to the fuel pump kink.

**special-K** · 07-31-2018, 08:06 AM

Air filter, fuel filter... is that the only time it stalls at idle? Does it start w/o a whole lot of cranking? Just wondering if the fuel pump is weak.

stevenfromtexas · 07-31-2018, 08:29 AM

Quote:

Originally Posted by special-K

Air filter, fuel filter... is that the only time it stalls at idle? Does it start w/o a whole lot of cranking? Just wondering if the fuel pump is weak.

it starts great, idles great, runs very well. only time it wants to AND does die is slowing down for stop lights/signs and waiting to turn.

stevenfromtexas · 07-31-2018, 08:35 AM

Quote:

Originally Posted by firedemon

check for vacume leaks turn idle up to 700 fuel filter

ok, ill set it up a little more on the idle speed.

bill3rail · 07-31-2018, 11:31 AM

Partially plugged fuel filter?

davepl · 07-31-2018, 11:42 AM

Loose neutral safety being nudged by the shift? Sorry, I don't even know if the safety is on the pedal or trans, just a random thought...

And I think you'll need to be more like 750 rpm. My Dad could get his old 307 to idle down to zero, pretty much, but my 402 needs to be 700 and it'll still be stall prone if the AC kicks in, so...

stevenfromtexas · 07-31-2018, 12:30 PM

Quote:

Originally Posted by davepl

Loose neutral safety being nudged by the shift? Sorry, I don't even know if the safety is on the pedal or trans, just a random thought...

And I think you'll need to be more like 750 rpm. My Dad could get his old 307 to idle down to zero, pretty much, but my 402 needs to be 700 and it'll still be stall prone if the AC kicks in, so...

ok!!!! that sounds perfect with the rpm adjustment suggestion. ill try that. i got a new fuel filter earlier and fixing to put it on.

no neutral switch on this guy. never had one from when dad taught me to drive it 30 years ago.. "make darn sure you push the clutch in before you start it!!!!" i can still hear him saying it every time i get in

stevenfromtexas · 07-31-2018, 02:18 PM

ok....new fuel filter and turned up the RPM's to 750
still stumbles when i'm slowing down. and died on me once a little bit ago turning left.

ncpetersc · 07-31-2018, 03:14 PM

Quote:

Originally Posted by stevenfromtexas

Also, it is making a "sucking" noise around 40MPH. i can ease into the accelerator and it goes away.

This bit still sounds like a vacuum leak.

I'm too new to this stuff to know what happens to vacuum levels during downshifting. But easing into the accelerator making it go away makes sense for a vacuum leak.

**Steeveedee** · 07-31-2018, 03:23 PM

Could be high or low float level. Does it do it on right turns?

I had a '64 Malibu SS that I beefed up the suspension enough that I could corner it hard enough to starve it for fuel. It would have been a good candidate for fuel injection. But I'd probably corner even faster and would have ended up dead. I used to mountain race it; not many could stay with me in the corners, but they had me on cubic inches (it had a 283, everybody else had no less than a 327) and could catch or pass me on the straightaways.

72velle · 07-31-2018, 03:39 PM

Check your vacuum lines.

stevenfromtexas · 07-31-2018, 03:50 PM

Quote:

Originally Posted by Steeveedee

Could be high or low float level. Does it do it on right turns?

I had a '64 Malibu SS that I beefed up the suspension enough that I could corner it hard enough to starve it for fuel. It would have been a good candidate for fuel injection. But I'd probably corner even faster and would have ended up dead. I used to mountain race it; not many could stay with me in the corners, but they had me on cubic inches (it had a 283, everybody else had no less than a 327) and could catch or pass me on the straightaways.

yes sir, stumbles a little to the right also.

stevenfromtexas · 07-31-2018, 03:53 PM

Quote:

Originally Posted by 72velle

Check your vacuum lines.

ok....

i sprayed around the line from distributor advance can and at the base of the carburetor also around the PCV in the valve cover, no difference in RPM's.

that's will happen right? a little jump in RPM's? if there is a leak?

stevenfromtexas · 07-31-2018, 03:55 PM

Quote:

Originally Posted by ncpetersc

This bit still sounds like a vacuum leak.

I'm too new to this stuff to know what happens to vacuum levels during downshifting. But easing into the accelerator making it go away makes sense for a vacuum leak.

ok....i'll do some more looking. i did get a bigger air cleaner but i'm waiting on an adapter for the single barrel. curious of what difference that'll make

bw46 · 07-31-2018, 06:54 PM

maybe check to make sure your choke isn't malfunctioning/closing

hjewell2 · 07-31-2018, 07:01 PM

Quote:

Originally Posted by stevenfromtexas

it starts great, idles great, runs very well. only time it wants to AND does die is slowing down for stop lights/signs and waiting to turn.

float level to high????

**70STOVEBOLT** · 07-31-2018, 08:34 PM

My $ is on incorrect float level

stevenfromtexas · 07-31-2018, 09:56 PM

ok

i'll try looking at the float again. confirming too high means the tab is spread open too much? not allowing enough fuel?

**Steeveedee** · 07-31-2018, 11:20 PM

Do you still have the instructions from the kit? Float level and float drop are both specified there. You can look those specs up in the manuals that are posted here.

BRL · 07-31-2018, 11:29 PM

Movie: "Lawn Mower Man."

Billy Bob Thornton...

"Have you checked the float level?" ...

BRL · 07-31-2018, 11:33 PM

Quote:

Originally Posted by stevenfromtexas

ok

i'll try looking at the float again. confirming too high means the tab is spread open too much? not allowing enough fuel?

...oh

Missourimark · 07-31-2018, 11:40 PM

Does it have power with wide open throttle, if so probably not fuel filter or obstruction. Sucking sound at 40 mph , if its got power it may be a vacuume leak, do you have power brakes ? If so, do they feel normal, timing ok , distributor bolt tight ? Timing could be retarded. So many things it could be.

stevenfromtexas · 07-31-2018, 11:48 PM

Quote:

Originally Posted by Missourimark

Does it have power with wide open throttle, if so probably not fuel filter or obstruction. Sucking sound at 40 mph , if its got power it may be a vacuume leak, do you have power brakes ? If so, do they feel normal, timing ok , distributor bolt tight ? Timing could be retarded. So many things it could be.

yes sir, accelerates great!!
no power brakes
Distributer bolt is tight

07-30-2018, 07:22 PM	#1
stevenfromtexas Registered User Join Date: Mar 2013 Location: Hewitt, Texas Posts: 444	heard this one yet???? ok, i've been tweaking on my pickup for the last few months. when i'm out driving it, it will die when down shifting from 3rd to 2nd. this is a huge problem when i go to turn onto my street and down shift to turn left. it will die. not cool when there are cars heading toward me. most of the time i have enough momentum to pop the clutch and get it going again. Also, it is making a "sucking" noise around 40MPH. i can ease into the accelerator and it goes away. just seems like it's starving for either air or fuel so....why do you guys think this is happening. 250 3OTT single barrel rochester 10* initial timing RPM's approx: 550 Petronix ignition full tank of gas let me now if there is another info y'all need __________________ Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71"

07-30-2018, 08:40 PM	#2
firedemon Registered User Join Date: Jun 2015 Location: @ Posts: 890	Re: heard this one yet???? check for vacume leaks turn idle up to 700 fuel filter

07-30-2018, 11:29 PM	#3
ryans69chevy Registered User Join Date: Sep 2010 Location: Casselton, North Dakota 58012 Posts: 1,082	Re: heard this one yet???? I've had my hose from the hard line to the fuel pump kink.

07-31-2018, 08:06 AM	#4
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,852	Re: heard this one yet???? Air filter, fuel filter... is that the only time it stalls at idle? Does it start w/o a whole lot of cranking? Just wondering if the fuel pump is weak. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

07-31-2018, 11:31 AM	#7
bill3rail Registered User Join Date: Jul 2013 Location: LI, NY 11801 Posts: 1,140	Re: heard this one yet???? Partially plugged fuel filter? __________________ 1970 C10 8' Fleetside, L6 250, 3 on the Tree. The most basic of pickup trucks!

07-31-2018, 11:42 AM	#8
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: heard this one yet???? Loose neutral safety being nudged by the shift? Sorry, I don't even know if the safety is on the pedal or trans, just a random thought... And I think you'll need to be more like 750 rpm. My Dad could get his old 307 to idle down to zero, pretty much, but my 402 needs to be 700 and it'll still be stall prone if the AC kicks in, so... __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

07-31-2018, 02:18 PM	#10
stevenfromtexas Registered User Join Date: Mar 2013 Location: Hewitt, Texas Posts: 444	Re: heard this one yet???? ok....new fuel filter and turned up the RPM's to 750 still stumbles when i'm slowing down. and died on me once a little bit ago turning left. __________________ Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71"

07-31-2018, 03:23 PM	#12
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,589	Re: heard this one yet???? Could be high or low float level. Does it do it on right turns? I had a '64 Malibu SS that I beefed up the suspension enough that I could corner it hard enough to starve it for fuel. It would have been a good candidate for fuel injection. But I'd probably corner even faster and would have ended up dead. I used to mountain race it; not many could stay with me in the corners, but they had me on cubic inches (it had a 283, everybody else had no less than a 327) and could catch or pass me on the straightaways. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

07-31-2018, 03:39 PM	#13
72velle Registered User Join Date: Jul 2018 Location: Bluffton, SC Posts: 59	Re: heard this one yet???? Check your vacuum lines.

07-31-2018, 06:54 PM	#17
bw46 Registered User Join Date: Sep 2015 Location: portland, OR Posts: 48	Re: heard this one yet???? maybe check to make sure your choke isn't malfunctioning/closing

07-31-2018, 08:34 PM	#19
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,355	Re: heard this one yet???? My $ is on incorrect float level __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear

07-31-2018, 09:56 PM	#20
stevenfromtexas Registered User Join Date: Mar 2013 Location: Hewitt, Texas Posts: 444	Re: heard this one yet???? ok i'll try looking at the float again. confirming too high means the tab is spread open too much? not allowing enough fuel? __________________ Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" Last edited by stevenfromtexas; 07-31-2018 at 10:02 PM.

07-31-2018, 11:20 PM	#21
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,589	Re: heard this one yet???? Do you still have the instructions from the kit? Float level and float drop are both specified there. You can look those specs up in the manuals that are posted here. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

07-31-2018, 11:29 PM	#22
BRL Registered User Join Date: Jun 2014 Location: Tahuya WA Posts: 607	Re: heard this one yet???? Movie: "Lawn Mower Man." Billy Bob Thornton... "Have you checked the float level?" ...

07-31-2018, 11:40 PM	#24
Missourimark Registered User Join Date: Nov 2017 Location: Mound City Missouri Posts: 24	Re: heard this one yet???? Does it have power with wide open throttle, if so probably not fuel filter or obstruction. Sucking sound at 40 mph , if its got power it may be a vacuume leak, do you have power brakes ? If so, do they feel normal, timing ok , distributor bolt tight ? Timing could be retarded. So many things it could be. __________________ Mark, 1969 custom camper, 454,th400,373posi



Register or Log In To remove these advertisements.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Register or Log In To remove these advertisements.