QuestionQUESTION: I recently bought a 1977 Lincoln Mark V. It has the 400 motor in it. I drove it back to my hometown 300 miles with no problems. The very next day, I was driving it and it stalled out on me. It acted like it was running out of fuel, bogging down and no power. I pumped the gas pedal and while still moving and it lunged and tried to stay running but eventually stalled out. Once I pulled over, I tried to restart it, no such luck. I had a buddy come by and we looked to see if the car was getting gas in the carb, it did not appear to have any.I cracked the fuel line, no pressure or gas spillage. I blew through the fuel filter, it wasn't too bad. Replaced everything and it started. A few miles later it stalled out again. Over the course of the last two weeks, I have dropped the gas tank and made sure it was clean inside with no sediment or blockages. I have replaced the sending unit (first 1 appeared to be fine). I ran compressed air through the hard fuel line. I replaced the rubber fuel lines going from the sending unit to the hard line and from the hard line to the fuel pump. I replaced the fuel pump 3 times. I rerouted the gas line from the fuel pump to the carb so that it does not go anywhere near anything hot. It now runs up behind the power steering pump around the back of the AC compressor and then to the carb. I made sure to blow compressed air through that hard line as well and replaced the rubber portion. I once again replaced the fuel filter and rebuilt the carb. The car continues to stall out on me once I have driven it a bit. I can spray Starter spray into the carb and it will run. If I continue to spray and keep the car running, it eventually will run on it's own, which allows me to get a few more miles down the road. After buying the car I also replaced the rotor, distributor cap, ECM, spark plug wires, spark plugs, thermostat, and flushed the radiator. I do not believe the problem to be electrical, because it starts when I spray the starter fluid into the carb. Any ideas?
ANSWER: Hi Sal:
Sounds like you have ruled out most areas that would cause this kind of problem. The fact that it runs for awhile before stalling, tells me something stops working in the process of driving. So, let's examine what mechanical parts (other than the ones you have replaced) are at play when driving. Also, I am assuming that after changing out and cleaning the fuel system, you are now getting fuel to the Carbs? However, if you are not, then it
There are a couple of things that you didn't mention.
First is the automatic choke. Could it possibly be sticking or broke? Secondly, is the air intake. If you have air leaks in the intake, it would run rough at idle and stall when driven. This would also cause her to run very rich and flood out. Are you seeing these symptoms?
Check these two items and let me know what you find.
---------- FOLLOW-UP ----------
QUESTION: "Hi Sal:
Sounds like you have ruled out most areas that would cause this kind of problem. The fact that it runs for awhile before stalling, tells me something stops working in the process of driving. So, let's examine what mechanical parts (other than the ones you have replaced) are at play when driving. Also, I am assuming that after changing out and cleaning the fuel system, you are now getting fuel to the Carbs? However, if you are not, then it
There are a couple of things that you didn't mention.
First is the automatic choke. Could it possibly be sticking or broke? Secondly, is the air intake. If you have air leaks in the intake, it would run rough at idle and stall when driven. This would also cause her to run very rich and flood out. Are you seeing these symptoms?
Check these two items and let me know what you find."
After cleaning out and replacing the fuel system, I have the exact same results. The car idles fine no smoke. When it stalls out, I pull the fuel line off of the carb and try to crank the motor and there is no gas coming through the hose. I can immediately spray starter fluid into the carb and it will start and run whike I continue to spray. I had felt that it was vapor lock, but when I crack the line open, there is no pressure or fuel. I am at a loss because it definitely seems to be a fuel delivery problem. If it were electrical, it would stand to reason that the spray would have no effect. I am not noticing anything weird in the choke. It appears to me that if the choke or flapper were in the wrong position, the spray would not have any effect. The car drives great for the first 5-15 miles depending on how warm the weather is, which is why I suspected vapor lock. It seems to do better in the evenings once it has cooled down. I picked up an electric fuel pump, but wont have a chance to install it until Friday evening. I plan on running this together with the mechanical one to see if it will help. I sprayed the starter spray around the vacuum hoses and intake, but I did not notice a change in the rpms.
AnswerHi Sal:
Thanks for the follow-up.
I am now suspicious of your fuel pump. If you have the fuel pump connected to the camshaft, when the engine turns over, fuel should pour out of the hose (when disconnected). You mentioned, no fuel at all is coming from the hose. That tells me the pump is not pumping. If so, the pump must be failing at some point. Also, you mentioned that you can drive it for 5-15 miles before it stops. Where is the fuel coming from to drive it at all? I'm a bit confused on about that.
However, if you can run the car until it heats up, you could be getting vapor lock. How much heat is the car generating at the location of the fuel pump? If it is hot enough to boil the fuel, it will create vapors and cause the pump not to work any more.
An electric pump would work better, but you will have to now wire the electric pump and place in a good location away from heat.
You could try heat insulation around the pump to keep it cool, if you think this is what's causing the problem.
