Quote:
Originally Posted by TrailerWorks
Hey Folks,
Waking up a '73 280SE 4.5 after a 13 year slumber. First step was making sure there was spark - cleaned the points and installed a new battery. Starts and runs briefly on starter fluid, so compression/spark are at least present.
Fuel on the other hand...
First stop was fuel pump (doa) and filter (very old and full of some very sticky shellac). The fuel tank was (thankfully) empty with just a little buildup in the bottom. Flushed with a couple of gallons of gas and it ran clear and strong. Small victory. Could not get compressed air through the fuel line, so I bypassed it.
Cleaned the pump and bench tested it. Didn't do much so on a whim I tried CarQuest - they have a fuel pump that lists as a replacement for the 280SE. For $50 it was worth a try. Seems to work OK, but I have yet to verify the pressure is in the 30 psig range.
Which brings me to the point - the fuel pressure regulator. There are two regulators on the 4.5 - I believe the first is simply a damper of sorts, and the other (one inlet and two outlets) sets the actual pressure. At this point, I have fuel pressure up to the second regulator but not through it. I took it off and cleaned it. You can feel the spring pressure inside by pressing with a small screwdriver. It seems to me that the amount of pressure it would take to pass fuel through it would be extreme. I bypassed the first regulator and tried to get fuel through it straight from the pump, but still no luck. The fuel backpressure when I removed the line was quite strong.
So, the question is have I got too weak a fuel pump or is it when the regulator fails it does so in the closed position? I might try putting 30 psi of air through it tomorrow and see what happens.
Once I get fuel through it, we'll see if I can get some through the injectors...
Thoughts?
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First of all, the carquest pump maybe OK for a test, but not long term.
Check this thread out
D-jet fuel pump acting up
Fuel enters the fuel rails at the front and the flows down both sides. The flows come together again at the fuel pressure regulator - It has two inlets and one outlet. this one outlet connects to the fuel damper and from there fuel flows back to the tank. From your post, it sounded like you may have thought the fuel flowed the other way? I have never tried it, but I doubt you could get reverse flow through the regulator.
Maybe try soaking the pump, regulator and damper in carb cleaner or similar. Try blowing through them the proper way. Dismantle and have a look at the pump internals and check that there is resistance across the terminals. Try hooking 12v to pump with head off and see if the spindle rotates. You may be able to bring the pump back to life!
To test the pump, reinstall it and run the discharge line into a container. Pressure should be about 30 psig and low 2L/min.
You will probably need to get the injectors cleaned - there are places that will do it for under $20/injector. But for a start, try soaking them in carb cleaner or an injector cleaner.
Have fun
