I have searched the no start threads but have not found a solution. My ALH 01 Jetta sedan will start when cold but after driving 1/2 hour has trouble starting or will not start. Changed relay 109 and found contacts slightly pitted. Found when car is hot a large air bubble in the fuel line after shutdown. When engine cools 2-3 hours or over night bubble disappears. Shutter valve tested and works fine. New fuel filter with blue and black O rings installed in proper order. Problem existed prior to fuel filter replacement. Any ideas on where the leak is comming and why it clears up on its own?
01 ALH Hard/No start after running for 1/2 hr
- Thread starter FredGard
- Start date
Further testing found the following. If the fuel filter T connection was moved there seemed to be more bubbles in the fuel line. I placed a vac pump on the supply line to the fuel pump. Was able to draw fuel but not at a rate I would have expected and it stopped as soon as I stopped pumping. However if I connected to the supply side of the filter NTF. I also was able to pinch off the fuel return from the pump to the filter and draw fuel thru the filter as I would expect. So I suspected the fuel pump check valve. Then I read a post that someone had on hard starting and after many fixs that were not 100% they finally tested the fuel for gas. Knowing, somehow, off road diesel had been put in this vehicle I decided to test if a match to a small amount of fuel pored onto a rock would light. Surprise it lit. Double checking the internet and diesel will not light like gas unless it is heated before lighting. Retest of my fuel found it easily lit and burned. So will be draining as much fuel as possible, thankfully less than 1/4 tank, then filling up with fresh road diesel. I will probably also replace the return lines from the injectors. They are cloth covered and seemed awfully dry and stiff. Remember having this same type of fuel lines on an old VW 410 and 411 I owned. With similar trouble telling when they got old brittle and hairline cracks. Will keep you all posted. But anyone with more Ideas please feel free to chime in.
Since your car still run's and you are down to 1/4, I would run it until you start to feel uncomfortable going any further and then fill up with a few gallons of fresh fuel. Continue to only add a few gallons, until the car begins to run normally then fill her all the way up.
Drained the fuel using the line from the tank into the fuel filter, about 2 hrs. Then mityvac'ed the fuel out of the filter. Put in 9 gal of new diesel and sucked it to the filter then thru the filter. dumping the first 3-4 oz coming out of the filter. Car started right up and seems to start much easier and few if any bubbles. Think the issue is solved if it returns I will post within the week. Otherwise consider this post closed.