need help w/ 72 suburban - engine issues, etc. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

capev86 · 07-16-2009, 04:44 PM

1st) anyone have trouble with the idle control unit? i put a new one on my rochester 2 barrel and for some reason it won't retract all the way and let the engine idle gently when it is warmed up. it seems to stick and i have to manually push it back down. i just rebuilt the carb and decided to change it at the same time. should i throw the old one back on and see if that clears it up or could there be some other issue causing this. i don't have a manual on these era trucks (yet) so i have yet to go poking about for a sensor or something that triggers it to close.

2nd) the truck is still bucking ever so slightly except when accelerating. new air and fuel filter, electronic ignition, cap & rotor, wires, etc. haven't put in the new plugs (yet) and was thinking maybe a new fuel pump might make a difference as the old one is probably 37 years old like the truck (only 73,000 original miles). it is running about the same as before the carb rebuild except that it no longer stumbles when you first start moving. anyone got any bright ideas what it needs to get it the last little bit to running perfect. it is 95% already and good enough to take on my long trip this weekend, but want it the best it can be.

3rd) the right side "custom/20" decal just fell off. any way to repair these or do i have to replace the whole emblem. it looks like the bolts that go through the fender came off the back of the emblem. can i temp fix it with glue or do they have to be welded or soldered on?

those are my big issues for now. any advice would be great!

JimKshortstep4x4 · 07-16-2009, 07:47 PM

Here is a schematic that hopefully will help you on the carb idle problem.

The spark plugs can make a big difference so you may want to install them soon.

On your emblem, replacing it is the best solution but if you can get the double sided automotive tape made for emblems you can use it. I don't know if the tape is still available but 3M made it and it is good tape.

Jim

capev86 · 07-16-2009, 08:25 PM

hmmmm.....

my unit on my truck looks a lot like that (with the little piston that pushes on the throttle arm on the carb) but it only has a single wire lead going to it and no vaccuum connections.

i am planning to spend the day tomorrow (friday) tinkering with it as much as i can. but then i'm headed north after 6pm. spark plugs and changing the rear gear oil (H052 axle) are high on the list. i don't know what was done to this truck as they never drove it but i have been methodically changing stuff out to make sure everything is up to snuff. thanks for the help!

JimKshortstep4x4 · 07-17-2009, 05:23 AM

If you only have a single wire then I suspect that you have AC and the solenoid is controlled by the AC switch.

Jim

capev86 · 07-17-2009, 08:01 AM

sorry.....no air conditioning on my rig.....

Muleman100 · 07-17-2009, 08:55 AM

3M makes an emblem adhesive that worked on my Blazer and has held on for 4 years.

JimKshortstep4x4 · 07-17-2009, 06:54 PM

Does your Burb have a TCS system on it, (probably not)? Also, does the solenoid operate with the ignition switch? (Does the plunger extend with the switch on and retract with the switch off?).

Jim

07-16-2009, 04:44 PM	#1
capev86 Registered User Join Date: May 2009 Location: Eliot, Maine Posts: 1,314	need help w/ 72 suburban - engine issues, etc. 1st) anyone have trouble with the idle control unit? i put a new one on my rochester 2 barrel and for some reason it won't retract all the way and let the engine idle gently when it is warmed up. it seems to stick and i have to manually push it back down. i just rebuilt the carb and decided to change it at the same time. should i throw the old one back on and see if that clears it up or could there be some other issue causing this. i don't have a manual on these era trucks (yet) so i have yet to go poking about for a sensor or something that triggers it to close. 2nd) the truck is still bucking ever so slightly except when accelerating. new air and fuel filter, electronic ignition, cap & rotor, wires, etc. haven't put in the new plugs (yet) and was thinking maybe a new fuel pump might make a difference as the old one is probably 37 years old like the truck (only 73,000 original miles). it is running about the same as before the carb rebuild except that it no longer stumbles when you first start moving. anyone got any bright ideas what it needs to get it the last little bit to running perfect. it is 95% already and good enough to take on my long trip this weekend, but want it the best it can be. 3rd) the right side "custom/20" decal just fell off. any way to repair these or do i have to replace the whole emblem. it looks like the bolts that go through the fender came off the back of the emblem. can i temp fix it with glue or do they have to be welded or soldered on? those are my big issues for now. any advice would be great!

07-16-2009, 07:47 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: need help w/ 72 suburban - engine issues, etc. Here is a schematic that hopefully will help you on the carb idle problem. The spark plugs can make a big difference so you may want to install them soon. On your emblem, replacing it is the best solution but if you can get the double sided automotive tape made for emblems you can use it. I don't know if the tape is still available but 3M made it and it is good tape. Jim Attached Images __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC Last edited by JimKshortstep4x4; 07-16-2009 at 07:48 PM. Reason: spelling

07-16-2009, 08:25 PM	#3
capev86 Registered User Join Date: May 2009 Location: Eliot, Maine Posts: 1,314	Re: need help w/ 72 suburban - engine issues, etc. hmmmm..... my unit on my truck looks a lot like that (with the little piston that pushes on the throttle arm on the carb) but it only has a single wire lead going to it and no vaccuum connections. i am planning to spend the day tomorrow (friday) tinkering with it as much as i can. but then i'm headed north after 6pm. spark plugs and changing the rear gear oil (H052 axle) are high on the list. i don't know what was done to this truck as they never drove it but i have been methodically changing stuff out to make sure everything is up to snuff. thanks for the help!

07-17-2009, 05:23 AM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: need help w/ 72 suburban - engine issues, etc. If you only have a single wire then I suspect that you have AC and the solenoid is controlled by the AC switch. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

07-17-2009, 08:01 AM	#5
capev86 Registered User Join Date: May 2009 Location: Eliot, Maine Posts: 1,314	Re: need help w/ 72 suburban - engine issues, etc. sorry.....no air conditioning on my rig.....

07-17-2009, 08:55 AM	#6
Muleman100 Registered User Join Date: Nov 2008 Location: Crosby, Texas Posts: 377	Re: need help w/ 72 suburban - engine issues, etc. 3M makes an emblem adhesive that worked on my Blazer and has held on for 4 years.

07-17-2009, 06:54 PM	#7
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: need help w/ 72 suburban - engine issues, etc. Does your Burb have a TCS system on it, (probably not)? Also, does the solenoid operate with the ignition switch? (Does the plunger extend with the switch on and retract with the switch off?). Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC Last edited by JimKshortstep4x4; 07-18-2009 at 05:16 AM. Reason: added wording



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