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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: Mikeymike383 on February 27, 2016, 04:32:34 pm
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Idles fine but when I put it n gear it's dies even if I try to give it gas 1978 gmc Jimmy 2wd with org sbc 350 and th350 tranny. Just put a new vac advance on it. I've let it warm up 4 like 5 mins and it still dies
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i would think an improper tune due to a vacuum leak. do you have all your vacuum hoses still hooked up?
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P.o put a different carb and intake but most stuff is still hooked up or capped off
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Well, it's a 78 so no lockup converter......... so that's out.
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Condition of the exhaust.?
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Well, it's a 78 so no lockup converter......... so that's out.
but couldnt it be a sign of a bad converter?
was it running just fine beforehand?
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i dont think it would cause that much of a problem with being a small vacuum line but unplug the vacuum advance line right at the distributor with the engine running. does the engine speed change?
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I'll check it in the morning it was running fine and I realized that the vac advance didn't work so I put in a new 1 but didn't drive it. And now it turns off when put in gear. It's a after market dual exhaust system. The guy that put it on did junky welds so I can feel exhaust coming out of a few lil spots. Could it b anything with the carb. The p.o gave me papers with the truck saying it was rebuilt sep 15th 2015. My buddy keeps saying its vapor lock but if it was vapor lock would it idle fine then just die when put in gear. I have a 1976 all org caprice that use 2 do this but it needed the carb rebuilt
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Problem started when u messed with the distributor.
That's where I'd be looking.
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Bone basic on a 78
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Ya maybe it was tune with the non working vac adv
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I was thinking I actual drove the Jimmy around my apartment complex after I changed it but that was a few days after I changed the vac adv
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I'd reset my base timing to 8 to 10 deg and go from there. If this was a running driver.
If not fuel filter first.
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Ya I'm going 2 change the fuel filter tomorrow anyway. This is gonna b my daily driver once I'm done fixing the lil problem and doing a full service on it
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You haven't given any history other the vac advance
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What kind of other history are u looking 4
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The vacuum advance could be leaking. Where do you have it plugged into? Did you unplug it and see if the rpms change?
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Did you set the timing after the vacuum cange? Is it a new distributor ?
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It was running fine, changed the vac can and the problem started.
Really doesn't make any sense to me.
How long have you had it?
What was/is the idle rpm neutral and in gear?
Advance hooked to manifold or ported.
Only thing that comes to mind is mechanical advance coming in too soon at idle and when placed in gear mechanical advance drops out causing idle to go to low and stall.
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I had it 4 3weeks. And I was going threw fixing the lil problems& doing a tune up when I realized the vac adv didn't work at all so I changed it out with a new one and my buddy said we needed to retard the timing on the dizzy. It's plugged in the carb. It's a 1973 Buick quadrajet. If the mech adv is dropping causing it to stall how do I go about fixing this problem?
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And no it's the same dizzy that was in it when I got it
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whats youre base timing at now?
most of us op for 12° and do manifold vacuum (manifold vacuum isnt limited to just the manifold, the carb should have a port on it for manifold vacuum also)
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I don't know off hand what my base timing it at now. The Buick quadrajet only has 2 vac ports on it 1 on the side net 2 the choke(left) and on on the bottom or base of the carb. We have it hooked up 2 the one on the left side. I can't find a vacuum diagram 4 that carb so I can know where it goes
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You need a port that has constant vacuum at idle. (Manifold vacuum)
When idling in neutral pull the hose off going to the dizzy And you idle speed should lower.
Put you finger on the port and see if there is vacuum. Use a vac gauge if you have one.
No vacuum means ported vacuum (no vac at idle) This is assuming your at a normal idle speed range.
Any idea what your idle speed is in neutral fully warmed up engine with choke full open.
You should be able to change idle speed by applying vac or sucking on the hose to the vac advance can.
This may be carb issue also but basics first.
Get some one else to help and partially hold the choke flap closed and see if it runs that way. BE super careful and stand to the side.
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Ok I'll check this out tonight when I get home. So the vac adv needs 2 b hooked up 2 manifold vacuum
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I prefer it that way
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Ported came along with emissions.
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not that it "has" to but for emissions it should be but for performance we all prefer manifold
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Now let me ask this if it's a carb problem what could it be
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vacuum leak/improper tune
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My 85 had the same issue it turned out to be gunk in the fuel lines clogging them up. So it would have enough to idle but would die after a little driving maybe a few feet. Try the fuel filter but if that don't work drop the tank and shove an air compressor in the line from the tank to the pump and blow it out backward.