fuel system help...

[harvey]

I'm at a loss.

She's a '79 diesel rabbit. 1.6L engine, supposedly replaced around 1990. I've been running on B-100 for 3 or 4 months...

About a month ago; driving at about 10mph, just passed through an intersection, the engine shuts off and we coast to the side of the road. I pop the hood, poke around, don't find anything obviously wrong. All the accessories are working, even both headlights, for a change. I crank the engine. Crank some more. nothing. I let it sit for about 45min while I go into the grocery store we so conveniently stopped next to. I try again, and manage to get her started. We make it through the next intersection (maybe 1/2 mile) and the same thing; the engine just shuts off. This time we call the tow truck.

Vacation time.

2 weeks later. I check the fuel stop solenoid on the pump. It clicks very nicely. I change the fuel filter. I check around for leaks, no puddles to be found. Time for a joyride. She cranks, and fires right up with the standard cloud of white smoke. We cruise out of the parking lot and down the road. 1/2 mile later... another ride in the towtruck.

Has the biofuel eaten away the innards of the injection pump? why would it start up after sitting for awhile? I'm not sure where to go from here.

any suggestions?[/img]

[tylernt]

I still suspect the fuel stop solenoid. It may click but maybe internally, it isn't staying open, or there is a break in the wire somewhere that gets jiggled when you go over a bump and this kills the engine.

The other possibility could be fuel starvation -- do you see bubbles in the fuel line from the filter to the pump when it dies?

[tawney]

If you don't have a clear fuel line from the filter to the pump, get one and look for those air bubbles. I would suspect that first, then the stop solenoid; never had one that would click, and not work properly. You could run a jumper wire from the positive battery terminal straight to the solenoid if you thought it might be a bad connection, but it seems that the problem only crops up after running a short while, so it doesn't sound like a bad connection.

If there's no air in the line, run it again till it quits, (in the driveway, maybe,) then loosen one of the injection lines at the injector and crank the engine while looking for fuel to squirt out at the loose fitting. That would confirm it's a lack of fuel, and the stop solenoid would be the next suspect.

Have you checked to see that the vent line back to the tank is unobstructed? You can blow through it to find out; it's in the engine compartment to the left of the engine not too far back of the passenger side headlight. If it's clogged it would allow a vacuum to build up in the tank making it more likely that the pump would pull air into the fuel line. The problem could also be a clogged pick-up filter in the tank. All that assumes you have air in the line. If not, replace the stop solenoid.

[Fatmobile]

yep, get a clear fuel line from filter to pump,.. and another stretch on pump output.
1/4" vinyl will work for all the lines but you'll have to slide a tapered punch or something into the end of hose going to the metal line returning fuel to tank.... to stretch it to 5/16".
I predict the biodiesel loosened grime in the tank and clogged the intank screen.
I just posted pictures of the tank insides.
A vacuum gauge on the fuel line would always let you know ahead of time when your fuel line has a restriction.

[harvey]

biodiesel won't melt the vinyl? I guess it won't be any worse than what i have now...

i checked for the screen in the fuel tank, turns out it's already been removed (awesome pics by the way, it's hard to see what's going on in there)

i'm off to check out the vent line. and find some clear tubing.

thanks for the advice.

i'll let you know how it goes.

[Fatmobile]

Someone probably used compressed air to clear a restricted fuel line and blew the screen off it's perch.
It could be rolling around inside the tank but you'd have to drain fuel to see it.
If the screen isn't in place, all the junk got pulled into the fuel line.
I use an electric fuel pump, a clear plastic fuel filter with 3/8" ins and outs and a good stretch of fuel line.
Pickup fuel from the tank through the sender hole and run it through the filter and pump, through the fuel line all the way to the engine bay and pump the fuel backward through fuel supply line with filtered fuel.
It'll push all the crap back to the tank where it gets picked up and run through the filter and pump again.
I normamlly only have to do this to the tank area. I pull the screen and clean it off then pump fuel out of the tank area, through a filter and back into the tank. It "vacuums" all the crap out of the tank.
A friend and I spent 7 hours trying to backflush the fuel line in a gasser converted to diesel, that didn't have an intank screen.