Bad Fuel Pump

RonLiv · Apr 16, 2019

The car was acting strange. It would run along fine and if I tried to accelerate it would hesitate. If I really got on it, the carburetor would backfire and the engine would near cut out and I had to take my foot all the way off the gas. I was thinking the ignition, or the carb were either bad or needed adjusted, possibly a timing thing. It is an old AVS 4682 Carter that was rebuilt and I did put a new ignition box in, as that was a former problem. One of the wires was sliding off the distributor at one point as well but solved that issue. Knocked myself out on this and decided I had exceeded my pay grade, finally brought it in to a real mechanic, one who specializes in Mopar and the guy who did the heavy lifting on my rebuild. On the way over, it died, wouldn't restart. Had to have it towed the last mile.
Diagnosis-Bad Fuel Pump, never in a million years woulda guessed.
This is why I shouldn't touch stuff, sigh...………..

69hemibeep · Apr 16, 2019

Happy ending. If the new one acts up in a short period of time check the rod behind the pump for length, they do wear out.

RonLiv · Apr 16, 2019

69hemibeep said:
Happy ending. If the new one acts up in a short period of time check the rod behind the pump for length, they do wear out.

Thanks for that, would not have known.

Russ69Runner · Apr 16, 2019

Did the fuel pump leak out the drain hole. That is a what I look for on them. Yes the pump rod will wear down also like Bob said. Glad you found it plus you have a lot of new part's.

Big John · Apr 22, 2019

Check the rod length while the pump is out. Should be 3.22" long.

RonLiv · Apr 23, 2019

Well, that didn't work. Picked up the car today and after about 30 minutes of clear sailing, same thing happens, loss of power, carb backfires, car shuts down.

These are the steps taken:
Checked for spark - has good spark
Check for fuel - Carb was dry
Removed fuel line from carb and crank - no fuel.
Checked the fuel lines - no problems
Removed line to pump - fuel flows freely
Remove line from pump to carb and blow out - no blockage
Check rod that rides on cam - OK
Replaced fuel pump and tested it - OK / Test drive OK.

Very well could be the rod though as you guys suggested, I don't know if it was specifically measured for wear. I've asked that question and have shared the measurement advice.

Sigh...…….. Drove the crap out of this last summer without a hitch. Now this.

Russ69Runner · Apr 23, 2019

Now what type carb are you using. May be a filter at the carb. Some have a small screen at the inlet. The holey has a small filter at inlet. Just a thought. Man nothing worst than fuel problem's or electrical can drive a man crazy. Hope you just had a vapor lock. Check gas tank vent pipe to see if it is plugged. Hope you find the problem. Russ.

69hemibeep · Apr 23, 2019

You measured the rod?

RonLiv · Apr 23, 2019

69hemibeep said:
You measured the rod?

Not that I'm aware, they said they "checked it" so I don't know what that means. I asked the question about the measurement. Thanks!

RonLiv · Apr 23, 2019

Russ69Runner said:
Now what type carb are you using. May be a filter at the carb. Some have a small screen at the inlet. The holey has a small filter at inlet. Just a thought. Man nothing worst than fuel problem's or electrical can drive a man crazy. Hope you just had a vapor lock. Check gas tank vent pipe to see if it is plugged. Hope you find the problem. Russ.

That's something I didn't think of, I'll check that as well. Thanks

RonLiv · Apr 23, 2019

They measured it, it was exact.

Checked it and after it gets hot it is losing pressure, I put a gauge on it to verify
6 psi cold and less than a hot
I ordered different pump and new push rod

RonLiv · Apr 23, 2019

Russ69Runner said:
Now what type carb are you using. May be a filter at the carb. Some have a small screen at the inlet. The holey has a small filter at inlet. Just a thought. Man nothing worst than fuel problem's or electrical can drive a man crazy. Hope you just had a vapor lock. Check gas tank vent pipe to see if it is plugged. Hope you find the problem. Russ.

I have the original Carter 4682 AVS.

Russ69Runner · Apr 25, 2019

Well sounds like is has something to do with the pump or the pump push rod. I know this is a stupid question but the sending unit in the tank is new I take it and you have a new tank. Maybe a faulty fuel pump brand new. Wish you the best of luck and the problem gets fixed quick. Russ. :thumbsup2:

RonLiv · Apr 25, 2019

Russ69Runner said:
Well sounds like is has something to do with the pump or the pump push rod. I know this is a stupid question but the sending unit in the tank is new I take it and you have a new tank. Maybe a faulty fuel pump brand new. Wish you the best of luck and the problem gets fixed quick. Russ.

Thanks Russ, yah the tank and sending unit is new, well new last summer. Thing is I drove the crap out of this thing last summer, I guess about 1K miles or so including a trip to Carlisle for Nats and back, never a problem.

droptop · Apr 26, 2019

Sounds like classic vapor lock to me. Is the metal fuel line from the pump to carb touching the engine anywhere? If it is, the fuel line acts line a heat sink and will cause it to vapor lock.

RonLiv · Apr 26, 2019

droptop said:
Sounds like classic vapor lock to me. Is the metal fuel line from the pump to carb touching the engine anywhere? If it is, the fuel line acts line a heat sink and will cause it to vapor lock.

Thank you, I will pass this along, good advice. I turned this over to the garage.

RonLiv · Apr 27, 2019

New "Hemi" fuel pump. Does this mean I can say "I got a hemi" LOL.
New push rod
Blew out the lines and checked vents.
Checked metal fuel line at carb.
Test drove
We should be good!

RonLiv · Apr 27, 2019

Thanks everyone for the input! Greatly appreciated.

69hemibeep · Apr 27, 2019

Now what kind of oil do you run to protect the rod?

droptop · Apr 27, 2019

69hemibeep said:
Now what kind of oil do you run to protect the rod?

Kind of a personal question there Bob.

Bad Fuel Pump

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