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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: scubasteve65 on January 15, 2008, 11:55:02 am

Title: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 15, 2008, 11:55:02 am

Don't know where the vacuum lines go. They are hooked up incorrectly now. The attached pics show all the ports. The question marks are because I'm not sure why one is capped off and the other is joined together with a T. None of the smaller diameter hoses seem to go to the charcoal cannister either.  Your help is greatly appreciated.

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 18, 2008, 09:57:15 am

new /different pictures. Anyone???

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: VileZambonie on January 18, 2008, 10:13:29 am

They look correct. The plugged one that goes to your cannister should go to the bowl vent on the carburetor.

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 20, 2008, 07:30:04 am

I was pointed toward this link (Fig. 15) http://www.autozone.com/az/cds/en_us/0900823d/80/11/24/eb/0900823d801124eb/repairInfoPages.htm
I've got things hooked up accordingly now. My truck doesn't have the DELAY VALVE or DIST TVS in the diagram -does it matter? I can't get the truck to idle at normal operating temp. Cold it's fine. It was suggested I replace the EGR TVS ("ported vacuum switch" at parts place) and my EGR VALVE.  Here's my dumb question...how is the EGR VALVE connected? It has no bolts or no flange to speak of. I see lots of gasket maker oozed out though. Is it a center bolt? Do I twist off the cannister?

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: VileZambonie on January 20, 2008, 08:09:44 am

Did you check for vacuum leaks? Especially at the intake manifold... The only way the EGR will effect the idle is if it's actually opening at idle. There was a non servicable EGR valve. You would need to replace it with a servicable valve if it is removed.

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 20, 2008, 08:19:04 am

I'll go out and check again. I didn't think so though.  2nd one down the page. how is that thing held on?
http://autozone.ro/N,16000214/shopping/partTypeResultSet.htm

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: VileZambonie on January 20, 2008, 08:26:25 am

Your link isn't working. You may have to remove the carburetor. Can you post pix of your EGR?

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 20, 2008, 08:28:56 am

it'll take a minute. try this link
http://autozone.ro/R,APP451056/vehicleId,1307601/initialAction,partProductDetail/store,2965/partType,00214/shopping/partProductDetail.htm

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 20, 2008, 08:41:22 am

EGr pics

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 20, 2008, 08:43:56 am

I'll check back later. going to the outdoor/fishing show at nassau coliseum. heard it really sucked but my fishing buddy is taking his kids to see some flying dogs or some such thing.

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: VileZambonie on January 20, 2008, 08:44:16 am

I haven't had to replace one of those in ages but if I remember correctly the carburetor has to come off.

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: Captkaos on January 20, 2008, 09:42:53 pm

I think you have to remove the carb also.  I think I have still together in the garage I can check on....

Title: Re: Monojet Vacuum Lines. '78 250 6cyl
Post by: scubasteve65 on January 20, 2008, 09:49:05 pm

sorry, I just posted a separate topic on EGR with the same pics.  Thought it might generate an answer