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  • August 19, 2018, 01:41:16 PM

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Author Topic: Intermittent lack of fuel flow?  (Read 3793 times)

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Online Draekon

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Intermittent lack of fuel flow?
« on: August 20, 2015, 10:48:14 AM »
I have a weird fueling problem that I cannot track down.

Car starts right up as it should. Idles fine in my driveway. If I take it for a drive, it'll work fine for a few miles and then stumble and sometimes stall.
I looked down the carb after it stalled a couple times and activated the the throttle, and there was only enough gas to squirt out the first time.  So it seems as if the fuel bowl is emptying.

I have a new fuel pump and new fuel filter.  I have also tried another carb, with mostly the same results.  The pickup filter in the tank is not clogged, and I could not see anything floating around in the tank that would cause a random but temporary clogging.  Everything that I have tried has made the problem less severe but still persistent.  I also tried driving around without my fuel tank cap on, still had the problem, so its not a venting issue.  The return line is not clogged, there is plenty of gas flowing back into the tank.

Any ideas on what it could be?
« Last Edit: August 20, 2015, 10:52:49 AM by Draekon »

Online amcfool1

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Re: Intermittent lack of fuel flow?
« Reply #1 on: August 20, 2015, 10:53:55 AM »
ignition module could be failing, check ICM, coil,  wires, etc good luck, gz

Online Draekon

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Re: Intermittent lack of fuel flow?
« Reply #2 on: August 20, 2015, 11:21:44 AM »
I replaced the ignition module over the winter, along with the spark plugs.  Ignition coil is new since the problem started.  Spark plug wires should still have plenty of life.

Online amcfool1

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Re: Intermittent lack of fuel flow?
« Reply #3 on: August 20, 2015, 12:03:37 PM »
there was a guy just recently on theamcforum that went through the exact same problem. never did pinpoint the EXACT failed part, but it was somewhere in the ignition, maybe distributor pickup. Long story short, he ended up scrapping the entire electronic ignition setup, and installed an old school points distributor. Problem solved, car runs great. good luck, gz

Offline eaglefreek

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Re: Intermittent lack of fuel flow?
« Reply #4 on: August 20, 2015, 02:30:46 PM »
Maybe install a clear fuel filter so you can verify for sure there is a no fuel issue. If so, what is the condition of the fuel lines at the tank? Does this happen when the tank is full and less than full? Sometimes there can be a hole in the pickup. Also, never rule out a part just because it is "new". Many new parts are substandard nowadays and fail prematurely.
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Online Draekon

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Re: Intermittent lack of fuel flow?
« Reply #5 on: August 20, 2015, 02:51:33 PM »
The fuel lines look fine, although I don't think I'd be able to tell if there was a pinhole or something.  The ignition module is the only new part that I haven't tried replacing since the problem started.

All of this has been with about 1/8-1/4 tank of fuel.  I'm hesitant to fill it up in case I need to drop the tank.

I'll try the clear fuel filter to try to verify whether or not its a fueling issue.  Where would you recommend installing it?

Offline eaglefreek

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Re: Intermittent lack of fuel flow?
« Reply #6 on: August 20, 2015, 03:26:12 PM »
Anywhere after the pump and before the carb.
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

"I know he'd be a poorer man, if he never saw an eagle fly,
Rocky mountain high"  John Denver
Click for Fayetteville,TN Forecast" border="0" height="100" width="150

Offline eaglefreek

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Re: Intermittent lack of fuel flow?
« Reply #7 on: August 20, 2015, 08:43:10 PM »
Another option is to install an inline fuel pressure gauge, after the pump and before the filter. http://www.summitracing.com/parts/mrg-1564
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

"I know he'd be a poorer man, if he never saw an eagle fly,
Rocky mountain high"  John Denver
Click for Fayetteville,TN Forecast" border="0" height="100" width="150

Offline Billman

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Re: Intermittent lack of fuel flow?
« Reply #8 on: August 21, 2015, 12:12:36 PM »
I had the same symptoms and replaced a lot of the ignition parts as you have. My car would run fine up to 45 mph and then wouldn't go any faster. I would replace one part and then test drive it then go change another all to no help. I finally dropped the tank and pulled the sending unit, since there are no direct replacements available I just cleaned the pickup screen and put it back in. The problem hasn't returned since.
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Online amcfool1

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Re: Intermittent lack of fuel flow?
« Reply #9 on: August 21, 2015, 12:14:20 PM »
hi sending units/socks available from Blasers. gz

Offline eaglefreek

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Re: Intermittent lack of fuel flow?
« Reply #10 on: August 21, 2015, 02:21:15 PM »
hi sending units/socks available from Blasers. gz
For SX4's? I know wagon ones are available, but I'm not too sure the SX4 ones are.
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

"I know he'd be a poorer man, if he never saw an eagle fly,
Rocky mountain high"  John Denver
Click for Fayetteville,TN Forecast" border="0" height="100" width="150

Offline macdude443

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Re: Intermittent lack of fuel flow?
« Reply #11 on: August 21, 2015, 02:49:03 PM »
SX/4 units aren't available from what I've read.  Only wagon.  Different tank.

I had a faulty, brand new ignition module that would often stumble and cut out pretty violently.  I thought I was running out of gas.  Replaced the filters and all.  No change.  Put another module in and never had the problem again.  I installed a Motorcraft module direct from Ford.  The one that was bad was from Standard Motor Products.  Usually I've had good luck with them.
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Online Draekon

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Re: Intermittent lack of fuel flow?
« Reply #12 on: August 21, 2015, 03:10:59 PM »
I'm going to try to a clear filter first to try to narrow it down between ignition and fuel.  I'm pretty certain that it is fuel since none squirts out the second time I hit the throttle with the car off after it stalls.  But I've been wrong plenty of other times about whats causing a certain issue.

I replaced the pickup sock around 4 years ago, it looked fine when I pulled it, so I don't think that its the issue.

Offline Amc1320

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Re: Intermittent lack of fuel flow?
« Reply #13 on: August 21, 2015, 09:38:04 PM »
I had to remove the sock, it was ruined

I added a clear filter before the fuel pump.

I agree with that Eaglefreek said, I like to see the gas flowing to I can figure out whats going on.

Might be a longshot but my dad had a heck of a time with his concord cutting out like that, it was his float in his carb had gotten stuck somehow. it would literally run out of gas then fill back up and so on, took us forever to figure it out
Rob c
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Online Draekon

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Re: Intermittent lack of fuel flow?
« Reply #14 on: August 28, 2015, 01:04:36 PM »
I put on a clear fuel filter inbetween the carb and the regular filter. When it dies, there is still fuel in the clear filter. So its starting to look like its not a fuel issue.

I also tried replacing the ignition module, still has the same issue.

So here's my list of what is NOT the issue so far:
-Carb
-Fuel filter
-Fuel pump
-Fuel pickup sock
-Fuel return line
-Fuel vent
-Coil
-Ignition module
-Spark Plugs

Anyone have any other ideas?