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The mystery continues

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regularman

regularman

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This is enough to drive me insane. New fuel pump and pressure regulator installed. Drove the car yesterday in the heat up a mountain and plenty of fuel and power and the engine ran cool. Then after about an hour of driving the same old crap started again. I took the car on the interstate and got up to 70 and all at once the engine ran out of gas. I backed off on the pedal and it eventually caught up but I could only go about 45. Any faster and it would hunch and carry on. Also at this time the engine started to overheat again. I think the two are related. Engine starving for fuel and this lean condition causes an overheat. I took the car back home and jacked it up and put the rear on stands. The fuel pump was hot as fire. I turned it one and I could see bubbles in the fuel filter between the tank and the pump. I replaced all the hoses and this still is happening. As I recall with the fuel pumps they should shut off when they reach pressure. This one is running all the time. I got to figure this out.
 
i think mine runs all the time,
but im not sure...
it may vary pump to pump.
sounds like urs might have a problem..
i bought mine at oreillys, u might
wanna try a diferent one......z
 
1977MGMidget said:
If it happens again stop and take the gas cap off. It could be a venting problem.
Click to expand...
You know, I have been thinking through all the possibilities and you might be right. Just watcthing the bubbles in the fuel filter, this is what I think. I think that even though my vent seems to be working, maybe it is not enough and the low pressure vacuum is causing the fuel to boil between the tank and the filter and this vapor is then causing the pump to run all the time. I think I need more fuel vent. Will check this when I can.
 
Put a peice of alm foil over the tank filler, poke a small hole in it and put a rubber band around it to hold it on well.

Time to test again.
 
I drilled 4 1/8 dia holes in the steel piece of my gas cap inside the O ring for venting. Seemed to do the trick.
 
That would work Tim. Glad you found and fixed your prob.
 
If its not venting - it could be vapor lock when the fuel gets too hot...how's your heat shield? how close to exhaust are your fuel lines?
 
tony barnhill said:
If its not venting - it could be vapor lock when the fuel gets too hot...how's your heat shield? how close to exhaust are your fuel lines?
Click to expand...
I have the weber setup. I can see the vapor in the filter so I know its coming before the fuel pump and both are at the back near the tank. Under vacuum gas does boil very quickly. I think it must be the vent. I got work on it some more.
 
seems like a venting prob to me, Jack has a cheap/easy way to check.
 
GeeBee1 said:
seems like a venting prob to me, Jack has a cheap/easy way to check.
Click to expand...
Oh, yes that is definitely part of the plan. First I was gonna jack the car bakc up when cold and see if it does the bubble thing and if so just take the cap off for starters and see how it does. Then, if that works comes the tin foil.
 
One other possibility is that the metal line from the tank has a restriction in it of some sort. I removed the internal strainer when I cleaned and red koted the inside of the tank but there could be some sort of debri in that line and of course I had just topped up the fuel tank so I will have to siphon into a couple of cans to get all the gas out and check.
 
Went for an hour hard ride with the wife pulling long hills and running around town. No gas problem today. I put the old pump back on. The aftermarket type pump ran continuously and got hot and this was boiling the fuel. I put my old one back on and it pumped up and quit. I checked it when I got home and it still pumped up and quit. Yesterday it was hammering away and pumping no fuel and very hot. I was clicking away even when cold and the engine not running yesterday before my ride. I wonder if it was just a loose clamp or tiny hole in the hose. I put on new hoses with the new pump.
 
Could be but my pump ticks all the time as well. The pitch changes a bit when the carb bowl is full but it still ticks a bit. Glad you got to the bottom of it.
JC
 
MG SU pump should tick until the system is pressurized & then not tick again until the system again needs pressurizing...I'd worry about a system/pump that ticks all the time.
 
The new one runs all the time and gets hot. I tested it from one fuel can to another and the pump cooled off immediately, it requires constant fule flow to not get hot I reckon. Since I have the regulator. I been thinking about putting this one in line under the hood as a backup. If the one near the tank acts up. I can flip a switch and use that one for a while. I will hook up a 3 position swith so that either can be powered from the fule pump circuit just for peace of mind.
 
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