Topic: More Carb problems - please help (Read 2238 times)

IrishCJ6 · « **on:** March 11, 2012, 07:32:17 PM »

So the Jeep had its first outing today, started off fine but by lunch time (after a lot of stop/start driving and sub 1500 RPM driving) the Jeep did a massive backfire, flooded itself and then ran really rich, I pulled the air cleaner off and found a lot of what looked like steam/fuel vapour and a bubbling noise from within (as if the fule was boiling). I took the top off the carb (Motorcraft 2100 on an AMC 360) and found that at the float needle opening it was bubbling almost like air bubbles trapped in the fuel also the float chamber was really full. I drained the fuel, removed the float and needle and cleaned everything, I then bent the tab down a little on the float to try and reduce the fuel intake ( I had previously set the float level to the setting in the workshop manual). It seemed to solve the problem for about 10 mins and then did the same again, I again pulled the thing apart and again bent the tab a little further. At this point I decided it was no point in continuing and headed home, 45 min drive at 90-100kph and it was fine no problems. Got back to the garage and stopped to open the gate and the same thing as before happened.

It seems to only do it at idle or low RPM, and hasn't done this before during my road testing phases or not that I have noticed.

As for engine temp 80 deg C MAX and fuel line is away from exhaust etc etc, running standard mechanical fuel pump.

Has anyone seen this before or got any idea what is going on here, any suggestions welcomed.

Panic mechanic! · « **Reply #1 on:** March 11, 2012, 08:17:51 PM »

are you running the standard 2 outlet fuel filter between the carb and pump?

IrishCJ6 · « **Reply #2 on:** March 11, 2012, 08:32:20 PM »

No fuel filter between pump and carb, my filter is at the tank?

Nosebolt · « **Reply #3 on:** March 11, 2012, 08:37:39 PM »

didn't we chat about this before?

Bubba · « **Reply #4 on:** March 11, 2012, 08:39:04 PM »

you need a jeep filter as it has an overflow return to tank you are overpowering the float needles by the sounds

Panic mechanic! · « **Reply #5 on:** March 11, 2012, 08:49:32 PM »

its a common mistake people do

IrishCJ6 · « **Reply #6 on:** March 11, 2012, 08:56:02 PM »

Thats cool, if thats what it is, but why is it only doing it now and not when I was testing the Jeep on the road. I don't have a return outlet/inlet on the tank, can I tee this into the fuel line at the tank end?

Panic mechanic! · « **Reply #7 on:** March 11, 2012, 08:59:46 PM »

when your engine is revving it uses all the fuel in the feed, sending very little down the return line, when idling the pump builds up a steady pressure and eventually overpowers the float valve in the carb. you should have a return line to the tank its normally alongside the main fuel line unless it has been removed.

Bubba · « **Reply #8 on:** March 11, 2012, 09:00:02 PM »

replaced the tank ?

IrishCJ6 · « **Reply #9 on:** March 11, 2012, 09:06:03 PM »

Quote from: Panic mechanic! on March 11, 2012, 08:59:46 PM

when your engine is revving it uses all the fuel in the feed, sending very little down the return line, when idling the pump builds up a steady pressure and eventually overpowers the float valve in the carb. you should have a return line to the tank its normally alongside the main fuel line unless it has been removed.

Mine had a different engine previously (diesel) so never had one, so I just put in what I thought was correct,

The tank in mine is the one I made myself,

Panic mechanic! · « **Reply #10 on:** March 11, 2012, 09:08:45 PM »

that explains it, you will need to put in a return line, you could run it back into the filler neck to save you ripping the tank out.

IrishCJ6 · « **Reply #11 on:** March 11, 2012, 09:13:26 PM »

Ok, I'll try that, is there any specific fuel filter that I need or is it just a 3 outlet universal filter

IrishCJ6 · « **Reply #12 on:** March 11, 2012, 09:16:36 PM »

would this one work?

http://www.ebay.de/itm/Kraftstoffilter-Fuel-Filter-Jeep-Wrangler-YJ-4-2-L-/300565865229?pt=DE_Autoteile&hash=item45fb1f230d

Nosebolt · « **Reply #13 on:** March 11, 2012, 09:18:42 PM »

Quote from: IrishCJ6 on March 11, 2012, 09:16:36 PM

would this one work?

http://www.ebay.de/itm/Kraftstoffilter-Fuel-Filter-Jeep-Wrangler-YJ-4-2-L-/300565865229?pt=DE_Autoteile&hash=item45fb1f230d

yes

IrishCJ6 · « **Reply #14 on:** March 12, 2012, 10:42:56 AM »

I take it that the return line is 1/4" / 6mm ? and the inlet/outlet is /16" / 8mm ?

IrishCJ6 · « **Reply #15 on:** March 20, 2012, 07:17:49 PM »

Think I have fixed the problem, installed the filter and return line today, ran the engine up at idle and got it to running temp, turned on and off a few times, seems ok

dieselj20 · « **Reply #16 on:** March 20, 2012, 08:10:32 PM »

http://howellefi.com/tbi-kit-1972-93-304-360-401-v-8-jeep-amc-offroad.html

IrishCJ6 · « **Reply #17 on:** March 25, 2012, 08:36:10 PM »

Well had a good day out today, whilst I seem to have resolved the overfueling issue I now have another, the thing won't idle, it will maybe run for 10-15 sec once off the gas then just dies, no probs restarting etc, any ideas

Bubba · « **Reply #18 on:** March 25, 2012, 08:39:05 PM »

does it idle if you bring the tickover up

IrishCJ6 · « **Reply #19 on:** March 25, 2012, 09:26:07 PM »

Haven't tried that, will do next time I'm at the Jeep

Author Topic: More Carb problems - please help (Read 2238 times)

Panic mechanic!

Nosebolt

Panic mechanic!

Panic mechanic!

Panic mechanic!

Nosebolt

dieselj20