Ok so I had the Qjet reputably rebuilt with all fresh internals - there were some issues found with the accelerator pump circuit and even a small crack in the carb body near the lever... It's back on now and :rant: car still stumbles on acceleration and stalls when coming to stop thereafter. Once it stalls, it takes a few minutes to restart. Initial start up is fine, but within a minute or so while warming at high idle, the engine stumbles and stalls out - takes a few minutes to restart thereafter. So I guess at this point, I can't tell if it's getting not enough fuel or too much... I tuned the carb with a vacuum gauge, finding the highest amounts (20+ lbs) with each mixture screw turned out approx. 3.5 turns. Neutral idle is set for approx 600rpm. Watching the fuel flow at idle thru the glass filter element, the element seems to alternate between staying full and emptying to a near trickle (then pumping rapidly to capacity again) - giving it gas in idle fills the element up sometimes rapidly, sometimes after brief delay. the motor doesn't stall at idle regardless of the fuel level in the element but does stumble and stall coming off acceleration in gear after driving a short distance. Engine timing seem stable and I couldn't find any vacuum leaks under the hood. Fuel tank, sender and rubber lines coming from tank are new. I'm thinking of changing out the fuel pump even though I don't suspect it, but have few other thoughts. anyone have other ideas?
I agree with Jim. Be sure to check the rubber line that connects the gas tank to the steel line on the frame too. A lot of people miss them and they can collaspe when the fuel pump draws a strong suction. Next bet would be the fuel pump. I think new ones are like $20 or so from either rockauto.com or northernautoparts.com.
"It's back on now and :rant: car still stumbles on acceleration and stalls when coming to stop thereafter. Once it stalls, it takes a few minutes to restart. Initial start up is fine, but within a minute or so while warming at high idle, the engine stumbles and stalls out - takes a few minutes to restart thereafter." Sounds like a flooding condition. Taking a few minutes to re-start after stalling out? The carb is either dumping a lot of fuel into the engine (flooding), or it isn't getting enough fuel. I'd vote for too much fuel. Have you removed the air cleaner and taken a look when it stalls to see if there is a lot of vapor coming up out of the carburetor, indicating fuel is dumping in?.....Cliff
I've pulled the air cleaner a couple times after the motor stalled following initial start up - no excessive fuel odor or vapors. I haven't checked the body-mounted fuel line yet but will do that - if it's accessible, I'll replace it anyway. I went ahead and ordered a new Carter fuel pump in the meantime. $17.50 shipped is worth it in any case. If I really wanted to overthink this I'd wonder if maybe the cam lobe driving the pump might be worn, causing erratic pump operation... :idea2:
I'm going to guess fuel line issues. Even with a good pump, it can't suck the fuel up the line due to a collapse of the old rubber lines, or obstruction in the tank sock. Or air getting in from cracked vent lines. The lines are easy to see above the rear differential in front of the tank. The rubber segments connect your hard lines, just make sure they are all ok. And you have some small sections of rubber on driver side about midway up the frame rail connecting the hard lines. If you still loose pressure, then you probably need to pull the tank and pull the pickup and check for debris in the tank. Your fuel pickup sock could be picking up a bunch of debris and blocking it, then when it stalls, its falling back off and you have to refill the fuel line to get it started. Make sure you have a good quality fuel filter in the line before it gets to the carburator. Don't trust the filter in the carb, and the glass ones you described don't have a good reputation for cleaning. Good luck.
Next up on the checklist are the mid-body rubber lines, already did the rear sections when I installed the new tank and sender. Collapse in the mid line may be an issue given the erratic flow I've observed going thru the glass.
Just a quick question, you said idle was set at 600 in neutral, but you meant 600 in Drive, right? Just wanting to check.
Re: still falling flat after rebuild - UPDATE - think I got it! I set neutral idle to 600rpm as per the specs - drive idle settled in at 500. Since last update earlier this a.m. I've reset the idle to about 650 neutral and changed out the mid-line hose running from the pump. It was a bit soft and I noticed a decent improvement on the subsequent test drive. It wasn't until I readjusted the tank line that I think I solved the problem though. Tank line must have shifted after I installed the tank 'cuz it was partially kinked. Fixed that and BAM! I hammered her on all 4 barrels for as long as I could hold it and no problem. I'll be driving her more this week to see if I truly got this figured out.
