Idles great, dies on street: distrib or carb or ???

[MorToy]

Hey Folks,

Thought St6fan and I had same issue, but thinking it may be something else (mine idles fine unlike St6fan) and I did not want to hijack his thread.

So here's the scoop: After full rebuild the car was running like a champ. Got 250 trouble free miles. In town, highway, etc. Then one day I was driving along about 35 MPH and the car seemed to buck and stutter. Thought clutch went out, but realised the engine died. Coasted to curb and tried restarting. It would catch, but I had to goose the gas pedal. Ran for maybe a block at a time before losing power, bucking, and dying. Let it set overnight and tried next day. Fired right up and idled perfectly. Let it idle until it got to operating temp and the thermostat kicked open. Felt pretty pleased, ran it into street, got up to speed and it drove great...for the first three blocks, then it died. Could get it to catch after several tries and by giving it gas. Would only run for a block. Would die no matter what speed or gear.

I was pretty sure it might be distributor, (and why I was on St6fan's thread) but now not so sure. The distributor had been the one thing giving me grief on the rebuild and was the last obstacle before I got the engine running. As it stands now, I have to turn it counter clockwise all the way until it hits the end of the curved groove for the set bolt for it to register 5*. Tested the distributor with multimeter using the FSM method. Within spec.

My dad is convinced it is sediment in the fuel system fouling the carb. I added 5 gallons of premium gas and replaced fuel filter--there was rust grit (looked like sand) in the filter. Would fouled carb idle fine and conk out at cruising speed? Secondary jet clogged, maybe? Or...anyone think it is distributor? Fuel, air or timing...

[Petros]

I agree with dad, it sounds like you have a partially plugged fuel system. Low fuel flows runs okay, and than with higher demand it cuts out. Parking it overnight allows some of the blockage to fall away from the inlet and than gets sucked back into it after it runs for a while.

IF filter is working there should be nothing getting to carb. Take the hatch off the fuel tank cover in the rear area (under the carpet next to the spare). Than remove the sender unit and with a flash light inspect the inside of the tank. There is a plastic screen on the end of the fuel pick up if I remember correctly and it could get partially blocked. If the tank as a lot of loose crud in it you would be best to drain it from the plug, filter it and wash out the tank several times. If you filter the fuel you can reuse it, or use it for lawn mowers, chainsaws, etc.

It is still possible it could be a marginal electrical component that works okay cold, but as it warms up and the demand on it increases it breaks down. That is less common however, they usually just fail. Check the fuel system first especially since you found crud in the fuel filter already.

It is possible to remove the top of the carb with it still in the car, but you have to be VERY careful with the tiny clips, springs, check valves and other small parts (much better to remove the carb and disassemble it on clean sheets of paters on a large table). Than you can inspect/clean out the bowl and all the jets and passages, and reassemble it. Save that for a complete carb rebuild if you need it later.

Good luck.

[Lil Beast]

I would do as described above first, it does sound like fuel starvation! Just had a similar problem for a different reason! Petros made me think about the fuel tank, mine was clean but I still blew in the line to make sure nothing is stuck in it! You could unplug the gas line before the filter plug a longer misc. one and blow air in it, listen for bubbling in the tank! Could do it from the carb both you'll have to blow thru pump and filter might be hard! Start I try to see if solved it, might be just temporary but if it re occur further down the line you know you're tank is too dirty in a way!
Did it work better after you put a new filter and gas? If yes it's a sign if not it's another sign! Try pouring gas in the throat of carb, the pump most likely leaks out when toast! You can unplug the gas line of carb and ask someone to crank the engine with the dist wires unplugged(so it doesn't fire) and using a bottle to eveluate flow , put the line in it and watched it fill up, should be fairly quick to fill a liter(dunno 5 second maybe) if takes way longer something obstruct the line or pump could be worn out(like a say they usaully leak)! if all those pass it's not fuel related unless you're dirty filter broke inside and let some stuff in the carb! Chose the order you may like!

[MorToy]

As always, your help is appreciated, thanks guys,

Well, my dad will be pleased to hear your analysis! And...guess I'd take dirty tank/plugged lines over distributor.

I'll check out the tank and blow out the lines with a compressor. Probably be a day or two until I get some time, but I will post the results for other folks.

Petros, yep, I've lost more than one spring rebuilding a carb. Just found a small clip in my driveway the other day, in fact!

Take care, and happy motoring.

[rer233]

best way i've found to diagnose a fuel tank/ supply line problem is to rig up an aux fuel tank under the hood (antifreeze jug works good.) fill it 3/4 full of known good gas, connect hoses to fuel pump inlet and return nipples, drive the car & see how it runs! if still bad, problem's somewhere else. good luck.

[MorToy]

Took the fuel sender gauge off and peered into the tank. Looks pretty darn clean in there. The plastic intake screen appears intact as well. I will move onto blowing out the lines.

[Lil Beast]

How is the pump? New or reused the old one? Have you tested the flow by disconnecting the line by the carb! Maybe try a clear one to test(replace the hose that goes from pump to carb with a clear one) so you can see a little what is goin on, maybe some bubbling!
Check all the connection where there is rubber hoses, make sure all the clamps are tight! Make sure the fuel lines are not close to any heat source! Just mentioning cause you mention full rebuild, maybe some stuff as been rerouted! I just went thru something similar! My fuel pump failed, so bought an electric one cause I need it for my swap! Got me 1 step closer in a way, and after the install in ran fine for a while until Buck and Stutter showed up to the party! So start looking for the problem! So had to go by elimination! Started with a new filter, ran great for an hour until Buck and is friend came back to ruin it all, brand new filter and pump couldn't be that! So start lookin in the tank for crudes nothing not even a grain of sand! Close it back, undo the line blow in it, hear the bubbles goin! Try again went fine for 15 min! Buck came back, got so pissed I undid everything! Told myself Buck wants a fight he found one! Had to see what was goin on in the fuel system, so went and bought 2 clear filter slightly bigger, install them, one before the pump and in the hood(original spot) turn the pump on, looked at the filters the 1 before was lookin good, then lookked in the hood, it was bubbling, I was a little confuse! So went by the pump and saw a tiny tiny little leak(a drip every 5 second) try to clamp it better no luck, keep drippin, change the rubber for a new one same thing! Decide to take the fitting off it breaks in the pump, PITA, good thing I'm equipped so start drilling the brass to get to the thread of the pump and start clening them! BTW at a shop, a new pump would been cheaper, crazy! Put in a bigger brasse fitting and new hose hook it back up! Start the engine and runs fine since, almost 2 week now! So it turn out that brass fitting was creating an air lock in the line! Go figure, very odd it was the 1st time I've dealt with a problem like that! I thought of that cause when I bleed brakes if the hose is not. Well clamp on my vacuum pump it draws air bubble and makes it hard to know when to stop bleeding the brakes or clutch! So it could be as stupid as that! Even ask some of my mechanic friends when it happen and 1 came and said vapor lock right away! Does your carb has been rebuilded? Maybe wrongly adjusted! Me I was thinking it had something to do with flow or pressure, but no as I didn't finish installing my fuel pressure regulator yet! Got lazy and worked fine after the bubbling was gone!

[MorToy]

Lil Beast: Interesting. So you think your issue (buck and die) was the result of a bad connector on the fuel pump? Sounds like air was being sucked in with the fuel. I put a brand new OE pump on after the engine rebuild, but will check the fittings for a leak. Our troubles do sound quite similar...

The carb is a new factory rebuilt (National).

[Lil Beast]

Only thing I can think of so far, was a small crack in my brass fitting! The only thing I did was to replace my fitting and the 2 filters, I can't see the slightly bigger filter being the cure! Cause it was bubbling before I change the fitting and ran like crap, after with the new fitting no bubbling and runs just like it should! I'm not saying that is your problem but cost nothing to check it's worth it! Especially if you're dealing with pretty much all new stuff! Which was my case! I does sound very similar, it pissed me off for a week not understanding what went wrong! I did everything from removing evrything I did rewired differently and the fitting did solved it! And usually when there's a problem and you find it, there is something to see, sometime small, like that puny crack! Start from the beginning and work you're way up! You looked in the tank, so next I would blow in it at the tank and work my way up the line, etc...

[MorToy]

I disconnected the main fuel intake line from both the fuel filter and tank ends and blew it out with about 40 PSI. Bunch of grit came out. After this I drove it around and it did fine for 20-30 miles, then same issue.

So I dropped the entire gas tank (fun!) and took out the intake connection from the top of the tank. The plastic screen was intact--not clogged up at all...but the main fuel intake line was rusty and had flakes of crude in it. Looked like plague clogged artery. I reamed it out with a wire and let carb cleaner soak in it for 3o minutes. Bunch of rust came out. Put it all back together and it seems to be running OK...cross my fingers!

Thanks to Petros, rer233, and Lil Beast!

[Lil Beast]

CHEERS!