odd stalling and stuttering.

[Lance-ftw]

Ok, new issue..

a week or so ago I noticed a little stutter when I was running down the highway. not on accel or anything just rolling along it sort of lurched a little... barely perceptable really.

A few days later it felt like it was running out of gas, sputtered and almost stalled. I pumped the gas and it lurched and picked back up and ran fine, I knew I had gas so I figured maybe I blew something through the filter or whatever, didn't think twice about it.

A few days ago it started stuttering bad. Not consistently or in any way that I can create a pattern and make it do it. Sometimes when I'm sitting at a light it'll stutter and stall out, sometimes going down the road it'll start to lose power and the engine almost sounds like it's about to shut off. It'll sputter a bit then start running fine again. Happens more in drive or reverse than neutral or park but it still happens in nuetral and park as well.

I took it to my mechanic and he thinks the carb is jacked up, floats sticking or something but I'm not 100% sure. We pulled some fuel out and checked it for water and didn't see anything.

The carb is an aftermarket edelbrock, truck is a 70 cst10, engine is a late 80s early 90s 350 (bolts in the middle of the valve covers)

At idle in park or nuetral its around 1k rpm and in gear it's just over 500. I'm not set up for 'performance' even though the previous owner put some mild cam in it.

Any ideas on what I should check?

Oh, there's no smoke and aside from me flooding it once tryin to start it up I'm not noticing any gas smell or seeing any fuel overflow around the carb.

thanks in advance for any ideas. because of labor costs I might just buy a new carb and stick it on if I can't find anything viable to troubleshoot.

[Lance-ftw]

oh, forgot to add, the fuel pump appears to be working fine according to the mechanic, not sure what he based that on but there ya go.

[Longhorn Man]

when was the plugs and wires, cap and rotor done last? Sounds like a plug not doing its job all the time to me

[68gmsee]

Yeah, go over the ignition real good. Check for loose wires, bad spark plug cables, leaking vacuum advance, etc. If you have an HEI check for any play on the shaft.

Another thing you may want to check is the condition of the spark plugs. See if they're carboned up or seem wet with oil/fuel.

It is possible your carb is flooding out as you're cruising. You may want to have someone follow you as you drive it to see if they see any puffs of smoke either gray or bluish.

Is the engine burning any oil?

[ChevLoRay]

I don't know which Edelbrock carb you have, but when I got my truck it had a 1405 (manual choke/.100 main jets) on it. It ran rich and the exhaust gasses would make my eyes water. The carb sat on an adapter on a stock Q-Jet intake. The rich fuel mixture caused plugs to foul and also made sure the cylinder walls were cleaned periodically.

Without knowing that there would be an improvement, I opted for a new Edelbrock 2101 intake and an Edelbrock 1901 Q-Jet carburetor. That combo led to a much leaner mixture and better performance, even thought there was a need for a heat shield on the starter solenoid to prevent heat soak.

My thinking is that your issue is with carburation and that a rebuild may be in order. Go to www.edelbrock.com and check out their tech section for carbs.

[NoNeck]

If you have checked out the other great suggestions, and still have the stumbling:

1. Check the fuel filter (you do have a fuel filter, right?). It could be partially clogged with trash. Or, if you are using a cheapo plastic filter it could look like the one in the photo below (notice the inlet nipple).

2. Try filling up with Non-Ethanol gasoline. My son's 4.3 V-6 S-10 ran exactly as your truck until he switched fuels. His check engine light would immediately come on and the engine would barely come up to speed when he went back to the 10% Ethanol gasoline.

3. The sock on my fuel sender was partially collapsed on my '68, and at cruising speed the engine would sometimes literally run out of gas because of the obstruction. It's fairly simple to remove and inspect it without removing your tank.

Good luck!

NoNeck

[Lance-ftw]

it doesn't jsut do it at cruising though, I could be idled at a light and it'll do it. I checked my fuel filter and it was clean and clear.

I'll check the plugs and what not tomorrow. I just had the head gasket replaced a while ago, it ran great for a month or so then started this up. not sure if they replaced plugs and stuff back then. Maybe it's time for new plugs either way.

I also do have a HEI, the carb has an electronic choke and I'm deffinitely not spitting smoke. I can leave it in park and it'll idle fine for a while then it'll sputter a bit, usually go back to normal then sputter and die. I watched the exhaust while it was sitting there and never saw even a hint of smoke.

[68gmsee]

Weird... The engine will idle and run good for a period of time and then without touching anything it just sputters and dies on it's own. Still could be fuel related. Maybe a weak fuel pump.

To check fuel pump output disconnect the dis to coil cable and place the fuel pump line to the carb in a plastic jug. You should get app 1 pint of gas in 30 sec or less. Fuel pump psi should be around 3.5 to 5.

[ZombieWeinerDog]

are you burning any oil?

[68gmsee]

Originally Posted by ZombieWeinerDog

are you burning any oil?

Already asked... He said no.

[ujsf01]

Like 68 gmsee said, do a volume and pressure test on the pump. One way you could tell if it's the pump as well would be when it dies, remove the breather and use a light to look down the carb throat while opening the throttle by hand. If no fuel squirts out the accelerator pump discharge nozzles, the bowl is dry due to a weak pump or restricted supply line/tank strainer. I had a pump fail on my 66 Impala and prior to it totally giving up the ghost, it acted just as you are describing.

[1972RedNeck]

My brother has had 3 floats go bad on his 1406 Edelbrock.

[Longhorn Man]

a bad float wouldn't give off and on poor running.
A bad fuel pump and/or clogged filter generally only does this on the freeway, not at idle. (this does not compair to a modern vehicle which won't even start with a bad/weak pump.

it is not likely to be a fuel issue.

[DesertCat]

Lance, there are a lot of suggestions here. To keep this on track maybe update your post listing what you have checked (and please don't just say yeah it's good... give specifics). Often times something subtle like this is a couple of things (that might seem okay) working in synergy.

I'm with 68gmsee... check the HEI end play. Been there, still have the scars

[kevmic28]

Heat soak/ vapor lock???? It could be related to the recent heat wave here in Texas. I know in the summer I have to deal with vapor lock with mine.

[lil hoodlum]

since you said it will do it while sitting at a light and while driving, I think you may have some trash in your carb. You say it mostly does it going forward and in reverse. Sounds like some debris is in the carb and is sloshing around while the truck is in motion covering up the inlets. It really isn't hard to remove a edelbrock carb and open it up for inspection. Might as well hit it with some carb cleaner inside and out.

My truck used to do the same thing you are describing when I still had the old fuel tank and lines. Rust was getting into the carb and the motor would start to act up. Some of the rust was so fine it looks like real fine sand. I could actually see it move around when I had the carb off and opened up for inspection.

Good luck.

Keith

[lil hoodlum]

Originally Posted by kevmic28

Heat soak/ vapor lock???? It could be related to the recent heat wave here in Texas. I know in the summer I have to deal with vapor lock with mine.

I used to dread driving in the summer for the same reason. Heat soak/ vapor lock when leave my engine just barely running. I have a clear fuel filter just so I could actually see how the fuel situation was going.

I installed a plastic spacer, I can't remember what size it is maybe 1/2". I also bump up the fuel/air ratio for the summer. Lower it for the winter. I discovered that my air/fuel ratio was kinda lean causing the engine to run hot. You should try turning out the fuel metering rods out a little bit to see how it runs. If you don't see any improvements you can allways turn them back in to where you had them.

Good luck!

Keith

[ChevLoRay]

Originally Posted by lil hoodlum

......You say it mostly does it going forward and in reverse...... Keith

If it does it going sideways.....hold on tight!!!!

[Lance-ftw]

I havn't had time to check anything out yet. I really appreciate the info here, I will update with details on what I do check when I get the time (most likely tomorrow during the day) Thanks again for the info so far, I will respond with details soon

[kevmic28]

Originally Posted by lil hoodlum

I used to dread driving in the summer for the same reason. Heat soak/ vapor lock when leave my engine just barely running. I have a clear fuel filter just so I could actually see how the fuel situation was going.

I installed a plastic spacer, I can't remember what size it is maybe 1/2". I also bump up the fuel/air ratio for the summer. Lower it for the winter. I discovered that my air/fuel ratio was kinda lean causing the engine to run hot. You should try turning out the fuel metering rods out a little bit to see how it runs. If you don't see any improvements you can allways turn them back in to where you had them.

Good luck!

Keith

Thanks Ill give that try when it cools off. I have an aluminum spacer adapter between the stock intake and my Edelbrock carb.

[rico7769]

I had the same issues with a reman holley carb. Had trash in the fuel tank that got in the carb somehow. Ruined the guts and caused it to flood. I was able to see a small trail of gas running down the high rise manifold that gave it away. Not sure if that helps but worked for me when I replaced the carb and tuned it up.

[Lance-ftw]

I looked for overflowing gas from the carb but can't find any. I do have significantly worse gas mileage right now though I'm noticing... maybe it is flooding it out.

[Lance-ftw]

Ok, sorry for the late update but I just found it and you may or may not believe what the hell it was...

I took the breather off in preparation of taking the carb off to look into it. I already knew my fuel pump and filter were working good and my plugs,while not perfect looked fine.

So I've got the truck idling with the breather off and it's running like a champ, I sit there for 10 minutes (counting the dollars burning up in the motor because gas is too expensive) and nothing... just chugs on like the little beast it is.

So, i start to shake the truck by bouncing on it and it starts to sputter and stop. sputters when I jump on it, stop when it comes to rest... out of the corner of my eye I see a tiny little spark in the back of the motor by the HEI. So i focus in on the spot and bounce again and sure enough theres a red wire coming from the HEI rubbing against what looks like a little metal pipe, like super tiny pipe and everytime I bounce it sparks on that little pipe.

2 minutes later and a little electrical tape and the problem is gone. I obviously need to redo the wiring in the truck for a variety of reasons (i.e. the AC blows a fuse everytime I turn it on and I've got no less than 7 wires just taped off at the end hanging in various places in the motor and countless under the dash) but I'm sure glad I was able to fix the issue with 2 cents in electrical tape instead of 200+ dollars in parts.

Thank you all for the info, it told me where to look and without that I wouldn't have found it. Ironically the most problems I've had with the truck have been electrical which is ironic because I've got a little bit of a facination with electricity and my tags on the truck are "BZZZT" :P