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Classic/Antique Car Repair/Lincoln Mark V starving for fuel


Ray wrote at 2008-06-12 04:03:58
Check the gas cap.  If air can't get into the tank, the fuel pump can't pump gas out.  Take the top off of the carb and inspect/clean the float and inlet valve; perhaps it is sticking shut.  If you are careful, you can do this with the carb installed on the engine.  Another (unlikely) possibility is a loose camshaft sprocket bolt.  The two piece fuel-pump eccentric is clamped to the front of the camshaft sprocket with a single bolt.  If it loosens, the eccentric spins on the bolt instead of pushing on the pump.   Finally, one last thing that hit me between the eyes with my 400 once.  Check all of the low voltage wiring in the ignition system.  Wiggle it while the car is running.  Once mine would run fine for days, then suddenly stall for no reason. Turned out to be an  intermittent connection at the distributor; I just stumbled on it by dumb luck. I had ruled out electrical, because everything was new.  Too bad it was also defective!  Good Luck!

rd62rdstr wrote at 2008-06-13 05:53:14
Yeah, vapor lock has been my guess as well. I am on my third fuel pump in the last week. I changed it again to make sure the first new one was working. When the car is running fine, gas comes through the pump. As I said when it stalls out, it appears to be from fuel starvation.

dchgomag wrote at 2008-06-29 20:54:30
I have a 79 Mark V, 400 cid. 56k original miles, in near mint cond. I am experiencing the very same condition. However, after trouble shooting and installing a new fuel pump, new rubber fuel hoses, pulled sending unit to inspect the sock, tank etc, blowing compressed air both directions of the line, etc., wanted to monitor the fuel deliver as I don't think this is a charging/volts. problem. So, I installed a clear inline fuel filter. From cold and/or after a cool down period of norm. op temps., find the fuel in the in-line fuel filter runs dry. At first, the filter is full and remains full for about 20/30 minutes. After that, you can watch over a 5 minute period, the filter drain dry. I do see bubbling as it drains giving me the thought is could be an air leak. I've yet to reinstall the sending unit so I don't know if anything I've done has remedied the condition.

Good though to know I'm not the only one out here with this problem.

I've yet purchased a new gas cap so we shall see here too. God, I hope it's not the cam bolt mentioned!

dchgomag wrote at 2008-07-20 02:19:36
Well, it really doesn't appear to be a fuel delivery, at least up to the gas filter. I installed a clear in-line filter for monitoring purposes. It remains full even when the car dies out. Side note: the alt. continues to put out a constant 14, with the gas filter remaining full, even when the car dies out once it reaches norm. op. temp. It can be primed by pouring gas down the throat of the carb., and the car will remain running for a short period of time.

Guess I'm going to pull the top of the carb. to see if there is an obious visual problem with the float, jets, etc.

More after that.

1979 Mark V Givenchy wrote at 2013-10-20 23:07:06
Any updates on this concern? My 1979 has the exact same symptoms. Everyone says go electric fuel pump but I find it hard to believe all of these Mark V's now need electric fuel pumps?  Help!  I have already replaced distributor, carbuertor, fuel pump twice, new 3 row radiator with electric fan (original fan still functioning) ignition module, fuel filter, EGR valve, new catalytics and muffler and a A/C compressor in the process.  It runs good cold, when hot, it starves out from vapor lock.  Fuel pump ticks when hot then goes away, so I bought another pump to see if it will help. Just crazy to me that some Lincoln's have this issue while others do not.  

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Vern Bullock


I can answer most questions about autos built in the 1920 through 1990. Mechanical issues and technical questions are my expertise. I also have a general knowledge of most older automobiles. Keep in mind, I can only provide answers if the questions are very specific and complete. Without details, I can only speculate and that's not good for solving your problem.


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