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Frustrated, irritated and ready to start throwing wrenches

Dedles1

Dedles1

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Oct 20, 2011
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Location
Motherlode, California
I’ve been trouble shooting my 350 for a couple of months now and just can’t get it running right
Background: stock GM350 crate engine with about 12k miles on it. Q-jet carb.
I’ve only got to drive this blazer one time… and that was when I picked it up and drove it home last fall. It was given to me by family, the body was in great shape, and the engine had low miles on it. It was off the road for about 3 years, but was started up frequently to keep things lubed up.
On my drive home it lacked power and just wasn’t running right. When I have it in neutral or park, I can rev the engine easily, but then I put it in drive and have a load on the engine, it stumbles and acts like it has no power.
I found several bad vac lines and replaced them. I checked the timing and its spot on at 4*BTDC. I changed the spark plugs, wires, fuel filter and coil. What else should I do?
 
I'm thinking EGR valve.
 
I'd give her a bit more timing too. I usually ran mine around 10 or 12 degrees iirc. Also look for vacuum leaks (internal and external, intake gasket?) put a vac gauge on it and see what the vacuum looks like
 
Fordum: Is there a way to test the EGR? I'll check that after work or this weekend.

Russell: I'll have to pick up a vac gauge then i'll check that too and i'll advance the timing a little more to see if that helps.

black dawg: Yes i pulled the vac advance and plugged the line when i timed it.

I Just need to cool off a little and gather myself before i go back under the hood... its irritating when you fix 5 things and still find nothing is better.... guess i should get used to it, kinda like being married
 
I do mostly Ford stuff, but its a fairly common problem around here. The quick test is to watch the shaft while putting vacuum to it and see if it moves.
However, I understand that sometimes even if it moves it might need to be pulled off and cleaned.
I think most folks here have fiddled with this once or twice, so someone should be able to pass along more info.
 
Instead of replacing parts, I'd recommend you pick up a shop manual and learn how to diagnose the real problem through testing of components. Sure, you can spend $200 and replace everything under the hood, but what if you find out it's a bad fuel pump or coil which you could have tested in 10 minutes?

Testing is far more cost & time efficient and ultimately more effective than throwing parts at a problem! :thumb:
 
I agree, testing parts is more effective... I dont just throw parts at it... i replace the things that are damaged or not working properly (cracked vac lines, dead coil, cracked spark wires) and replace the worn things (spark plugs, fuel filters) i generally test as much as i am able to because i dont have a whole lot of money to throw at this project. I've got the chiltons manual, but if there is a more detailed "shop" manual. that would be worth having to me.
 
Yes, there is, and it's GREAT. I got mine on eBay. What year is your truck?

EDIT: If you have a 1987, for example, I think this is the manual:

http://www.ebay.com/itm/1987-Chevy-...ors_Manuals_Literature&vxp=mtr#ht_1303wt_1039

But before you buy, be VERY CAREFUL and ASK THE SELLER to tell you the contents. There is a wiring diagram manual, a service manual, a S-10 manual, an emissions manual, a TBI emissions manual, and then the shop manual.

In your case, you MAY want the emissions manual, because it goes over all the engine controls and engine problems. However, ask the seller if it covers engine troubleshooting. I have one for the 1991 but that's only helpful if you have TBI...
 
How much have you driven it?? I've had a few vehicles that would start right up and idle fine, but acted like yours did. I kept driving it, and after a bit it got better. I guess you can say, "blowing the cobwebs out". Maybe it was carboned up, or just had stale gas in it.

I also had one car where the 4 barrel's wouldn't open. Car drove fine, but mash it and would fall on it's face. Timing was off just a little. Advanced it, then started going thru tires with the new found power....
 
Mine is a 79 K5. I'm deffinitly going to have to get myself one of these... I have just enough knowlegde and experience to get myself into a lot of trouble ... but i'm pretty handy with a wrench and learn fast. so some detailed manuals would be just what i need.
 
b454rat: I've seriously only driven it about 30 miles, but i do start it up at least every 2 days and bring it up to temp. when it wasnt running right, i parked it and started working. then dove into the interior over the winter when it was raining and i didnt want to be stuck with my back in the rain all night (no garage) but now that the weather is great again, i've been under the hood every chance i get again.
 
Cybrfire: I don't know what the pressure is. I don't have the tools to check that or the vacuum pull. That's a good suggestion though. I'll see if I can borrow those tools or rent them around here this weekend. If not I'll go pick some up next payday and post up my findings
 
My vote goes to needing a carb rebuild. If it starts up and idles good but runs like poop once off the idle circuit, im guessing there is a float problem or perhaps clogged primary or something to that effect.
 
Do some inspection. Look at the cap and rotor, make sure the mechanical advance isn't stuck. Pull the plugs and look at them and inspect the wires for black spots or cracks. See if the throttle linkage is moving correctly, that the choke is releasing, that fuel is not running over the bowl and the bowl is not empty, etc. Replace the fuel filter. The list goes on and on, but the point is that you familiarize yourself with the vehicle and the state of maintenance, while eliminating things from the list. You could also try some fuel additive to clean the carb, but I don't know what to recommend.

How old is the gas in it?
 
thanks to all for the advice. I know this is something i can fix, even if i have to do a whole rebuild...hope it doesnt come to that at this point, because funds would make that a very slow opperation.... my whole idea when i got this truck was to learn everything as i go. I've worked on my trucks before, but it was always installing aftermarket stuff and replacing things here and there... plus i always had a computer that diagnosed the problems for me... this "all mechanical" machine is kinda new teritory to me. But i can do it, just have to learn it all... This whole thread started because i got so fed up with not being able to figure this out quickly... guess i threw a tantrum like my 3 year old. But i have come to realize that if i am going to do this right, i'm going to need to have patience. I'm going to get some more tools and attempt to diagnose this by finding more defined symptoms. and if i buy some tools that i end up not needing right now, i'll have them for the future. 'Cause knowing me, i'll keep this rig till either it or i die... hopefully i go first.

By the way... this site is the best thing i could have ever found. Thanks to all.
 
Fordum said:
I do mostly Ford stuff, but its a fairly common problem around here. The quick test is to watch the shaft while putting vacuum to it and see if it moves.
However, I understand that sometimes even if it moves it might need to be pulled off and cleaned.
I think most folks here have fiddled with this once or twice, so someone should be able to pass along more info.
Click to expand...

I know a lot of people will buy block off plates. I think I would first try just unhooking the vacuum. If its stuck open not sure how you would test for that since it could still hold a vacuum.

You could take it off and apply vacuum to it see if it opens and closes.
 
One night I had my dad's '68 Chevelle wagon ,I was on a date,and it started feeling like the carb was clogging up or the exhaust was restricted--it would rev right up in neutral,but in drive it'd either feel gutless as heck,or I'd have to feather the gas pedal and pump it,in order to accelerate from a stop--or else it would snuff out,sputter,and stall....it got worse as the night went on,until the point it would only start in park or neutral,and run fine,until I shifted into drive,when it would stall immediately.........................................................................................I knew how to check for spark,and it seemed to have nice blue spark,so I figured it wasn't ignition related--but it also had plenty of gas and I saw fuel get squirted out of the carb's venturi when I opened the throttle,so it was not a lack of fuel problem either.................................................................................................I'd seen cars with clogged catalitic converters have this problem,but this car didn't HAVE one!....and the pipes and muffler were not crushed or damaged,I looked (as I had been on a few dirt roads with it "parking" earlier with the girl I was with!)...As I was standing there stumped staring at it,a guy I knew pulled up to us in his '65 Impala,,and I showed him what the car was doing..he said "dude,you probably need a distributor cap or rotor--let me look in my trunk,I might have the old ones off my car ,I always like to keep spares on hand,I never toss old parts or things like fan belts,etc...he found them in his trunk,and he helped me put the rotor on,the cap looked OK,so we tried it with just the "new used" rotor..the car fired up,and when I put it in gear and tried booting it--it smoked the right rear tire!---felt like it had 150 more HP than before...........................................................................................................................................................................................................I put a new cap and rotor on it the next day,gave my friend his old one back...I noticed when I inspected the rotor closely,it had a dark carbon spot under the spring tab,a hole had been punched thru the plastic there,and evidently,the spark would jump to ground instead of firing the plugs under a load--electricity always takes the path of least resistance I was taught,so I guess at idle,it was ok,but once you opened the throttle up,the increased load made the resistance higher than jumping to the distributor shaft was...
 
Got a buddy who said I can use any of his tools I need, and he's got it all. But said to check the timing again before I go pick them up. I hadn't tuched the blazer in about a week due to lack of time, money, and the need for more tools... so I just went out and hooked up the timing gun... still at 4*BTDC... hdnt done it yet, so I retaarded it to 8*... got a little better but still not right... took it to 10* and found a world of difference. Tightened it all down. Hooked up the vac advance and it wasn't quite right again... unhooked vac and aall was good... so I'm back to feeling that timing is the issue again, and I'm actuually happy about that. Now I just need to know if I'm either a little off on timing or if my vac advance is no good... any suggestions? This is new teritory for me?
 
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