yet another problem:( fuel/carb related...

J

John Barbieri

True Classic
car was running fine today, stopped somewhere for a minute, started the car back up first thing I noticed was my idle went from 900rpm where it normally is, down to 500 rpm and almost immediately, as soon as I was on the road and I hit the gas, the car started bucking like a mule... I remember these same symptoms before, years ago when I was using this car a daily driver, before it was rebuilt. I took it to a mechanic who discovered my jets were getting clogged from old coked up oil coming from the crankcase breather... these days I don't run the crankcase breather into the carb so I tried cleaning the jets anyways, I get about a 1/8 mile down the road and it bucks like a mule all over again or just bogs down/hesitates and I limp it back home to try another remedy...

I have tried two different fuel pumps:

moving the check valve from the fuel return line to the line coming from the fuel pump into the carb,:

tried a new fuel filter:

tried pulling the pick up from the tank and cleaning the filter bag;

checked for vacuum leaks, none to be found...

short of rebuilding the carb I don't know what else to do and if that doesn't work, replace the whole fuel system carb, fuel pump, check valve and fuel tank pick up with brand new replacements?

man, these cars are nothing but problems, barely fix one minor problem and get stuck with two more... f*** me...
 
John Barbieri said:
s soon as I was on the road and I hit the gas, the car started bucking like a mule
Click to expand...

Was that sometime soon after you bought gas?

That sounds a lot like a bit of water in the carb. The idle and transition circuits in a DMTRA/DATRA draw from the middle of the emulsion tube wells so will work fine even if there's water in the carb - but as soon as you open the throttle enough to need the main circuit you're sucking water.

If you have access to an air compressor, try removing each jet one at a time and blasting compressed air down through the jet's well. You'll end spraying liquid every which way through every orifice in the carb, but you'll also get any water in there out of the carb.
 
put Sea Foam in the gas.
There's lots to sort out but no worse than any other old cool car. Mine is finally dialed in, I loved it running an errand this morning and commuting all week. It's worth it.
 
EricH said:
Was that sometime soon after you bought gas?

That sounds a lot like a bit of water in the carb. The idle and transition circuits in a DMTRA/DATRA draw from the middle of the emulsion tube wells so will work fine even if there's water in the carb - but as soon as you open the throttle enough to need the main circuit you're sucking water.

If you have access to an air compressor, try removing each jet one at a time and blasting compressed air down through the jet's well. You'll end spraying liquid every which way through every orifice in the carb, but you'll also get any water in there out of the carb.
Click to expand...

can't be water, was filled up with the best gas available and it drove fine til it got down to 1/4 tank... something else too, it has done this before as it gets down to around 1\4 tank a couple of times in the last three weeks, filling up the tank, pulling the jets and blasting them with compressed air fixed it before but now nothing is remedying this issue...
 
John Barbieri said:
can't be water, was filled up with the best gas available and it drove fine til it got down to 1/4 tank... something else too, it has done this before as it gets down to around 1\4 tank a couple of times in the last three weeks
Click to expand...

That sounds Iike crud and water in the bottom of the tank. The easy workaround is to never let it go below half full, but that's a fairly unsatisfactory answer.:no:

Assuming that you have a mechanical fuel pump (because it's a carbed car).... Disconnect the fuel line at the fuel pump inlet, connect it to a cheapie electric fuel pump powered from your battery, and drain the tank. Use the gas in something that doesn't have a carb. Refill with known-good gas and a bottle of Seafoam. Repeat the air-compressor blast.

If modern cars still used carbs, we wouldn't be putting ethanol in gasoline.
 
EricH said:
That sounds Iike crud and water in the bottom of the tank. The easy workaround is to never let it go below half full, but that's a fairly unsatisfactory answer.:no:

Assuming that you have a mechanical fuel pump (because it's a carbed car).... Disconnect the fuel line at the fuel pump inlet, connect it to a cheapie electric fuel pump powered from your battery, and drain the tank. Use the gas in something that doesn't have a carb. Refill with known-good gas and a bottle of Seafoam. Repeat the air-compressor blast.

If modern cars still used carbs, we wouldn't be putting ethanol in gasoline.
Click to expand...


nope nope nope... figured I'd start with a carb rebuild since its the only thing I hadn't checked... sure enough, when I pulled the carb off the manifold there was gas all over the gaskets, upon further inspection, I noticed that the insulator plate has a bit of a bow in it, doubled the gaskets with new gaskets. Also, when I tore the carb apart and checked the floats, they were way out of spec. Car runs fine now. Knock on wood til it gets down to a quarter tank again.
 
If this happens consistently at 1/4 tank, take another look at the pickup tube on the level sender assembly. There could be a hole in it that sucks air when the fuel level gets low.
 
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