high speed death

[wdkingery]

 
My route home from school changed 2 weeks ago, forcing me to take a longer path that has a 70 mph speed limit. Usually I do a static 54 mph, but Considering I spend so little on fuel, I have decided to hold the skinny pedal to the floor for increasingly long stretches, sometimes for 5-7 minutes at a time. Top speed around 80 (it gets quieter then??)
I normally run my fuel filters until the car won't go anymore, or struggles to. But the other day, at only 50 mph, the car just stopped running. Coasted off the road, changed the fuel filter.. Seemed fine. Awful strange how the fuel filter cut out like a light tho.. Normally they die a slow death. Well, the next day, same thing. So I changed the fuel filter again today, and went for a drive.

Final verdict is: if I go more than 60 mph for more than 5 minutes, the gas pedal slowly does less and less, until it struggles. If I pull over, it will shut off immediately. Let it sit, crank and crank, and it will run fine again. It's almost as if the pump cannot get the fuel fast enough. The pump doesn't have to draw its own fuel, as I have an electric lift pump off a diesel v8 Chevy.
Clogged return line or something?  It is slowly getting worse it seems. I had the smoke screw turned down for the summer; i just turned it back up today, but haven't had a test drive since.

On a lighter note: before I started doggin it, I was getting just under 40 mpg on a 50/50 blend of motor oil to diesel, for an average of  77-85 miles-per-paid-gallon, for a cost per mile of between 4.5-5.1 cents, depending on diesel prices and mppg. I have now gone thru 3 fuel filters (I converted to the spin on kind gas stations use,) 2 1-micron bag filters, and about 200 gallons of motor oil. 200 gallons times $3.86 per gallon = $772 saved, minus the 5 filters and about $50 in fuel collecting the motor oil. Have had to pull my injectors three times to clean them. Injection pump timing is at 1.41 mm now.. Seems to like the timing more and more. Have been about 10k miles now.

[CrazyAndy]

Sounds like something's gummed up.  If you have access to one, hook a mityvac up and see if you can pull fuel through the supply and return lines (I forget if the return just has a dump on the top of the tank or an actual pick up).  If they pull/push fine, try running this tank down and filling up on straight diesel w/ some diesel cleaner and stabilizer and see if that cleans it out.  If they don't, get something to clean the hard lines like a speedo cable on the end of a drill, and replace the soft lines.  One last thing I'd ask is if your lift pump is worn, causing it to slow down or stop after heating up which would cause enough of a restriction.

[745 turbogreasel]

If you have to change your filter even once in 10,000 miles, you should be running  a restriction gauge or light.
Just to eliminate eazy stuff, try a run with the fuel cap loose/off, and maybe the same at the muffler.

Can you drain a sample form the bottom of your fuel tank?

[theman53]

These pumps use fuel to cool themselves...just like every in tank push pump on a gasser. If you are doing this repeatedly it is not going to have a positive result on the wear characteristics of the pump. I would spend more on filters and change it faster. The lift side of the pump is probably getting weaker everytime you run it short. Yes there is a pusher pump, but the lift pump is for internal pump pressure. The more pressure the more advance it has...probably why you keep adding more advance and it likes it. Just some observations, as I am not the final authority, but I would think I am not far off. I bet if you add that savings on fuel for a pump rebuild you will be right at 0.00 saved and ready to start again.

[theman53]

There is this too.
http://forums.vwvortex.com/showthread.php?5856741-Volkswagon-Diesel-Injection-Pump

[Dakotakid]

When this engine totally craps out, I hope you will pull the head and show us photos of the piston tops so we can see how much etching has occurred in this "experiment."

[mtrans]

You need fuel as you see.50/50 is nothing on warm wether.
Much better is 1m static(hidro filter) than bag filter.Do you check in tank mash?Try only D for some time to see.Put clear lines from IP to see if is air in.

[wdkingery]

One last thing I'd ask is if your lift pump is worn, causing it to slow down or stop after heating up which would cause enough of a restriction.

looks like my lift pump was gettin hot and poopin out on me .. just threw it in the ditch at the bank at the corner of hell and nowhere today so.. we'll see on the way home if it was the problem

[fatmobile]

'85 Jetta?
 Do you still have the water seperator and check valve?
 Where was the fuel pump located?
 
 Throwing it in the ditch was littering. I hope you kept it and realised it might be getting hot because it had to pull so hard due to a restriction.
 I hope you go back and pick up your mess.
 
 Vacuum gauge on the fuel line!

[wdkingery]

'85 Jetta?
 Do you still have the water seperator and check valve?
 Where was the fuel pump located?
 
 Throwing it in the ditch was littering. I hope you kept it and realised it might be getting hot because it had to pull so hard due to a restriction.
 I hope you go back and pick up your mess.
 
 Vacuum gauge on the fuel line!

ok i didn't really throw it in the ditch.. it was added for emphasis. it's in the trunk.
but yes i do have the water separator thing, and it no longer spits out water since i started on wmo; in fact it doesn't release any liquid any more. and i'm not adverse to getting rid of it. would you get rid of it? how to do this?

[Dakotakid]

Nah, picking up litter makes the local civics groups feel important!

Pull your in-trunk tin plate and inspect your lines entering and exitting the sender for cracks or mouse bites. Then, pull the sender, carefully pop off the little bottom-cover cap, and use carb cleaner or gas to clean the minute nylon screen located there. I had to do the same on my 85 last winter.

If ambitious, use a little electric pump to drain the tank and then use a bunch of lint-free clothes to wipe the inside of the tank clean (while it is still in the car). There is no baffle in these plastic tanks and wiping it clean is not bad. Reaching in there to clean it is a lot like helping a cow have a calf....although you urban dudes wouldn't know squat about THAT!

Less time in front of the keyboard and more real work will have you up and running.
The water seperator? You get rid of it by going back and reading the sentence immediately preceding this one.

[wdkingery]

Nah, picking up litter makes the local civics groups feel important!

i so wanted to say that, but i didn't actually litter..

got any advice on a water separator? i'd like to have one.

i didn't see how your info shows how to delete the separator, but i'm sure i'll see it when i get home

[R.O.R-2.0]

Nah, picking up litter makes the local civics groups feel important!

i so wanted to say that, but i didn't actually litter..

got any advice on a water separator? i'd like to have one.

i didn't see how your info shows how to delete the separator, but i'm sure i'll see it when i get home

i would delete the mk2 water separator AND filter..

i would UPGRADE to a mk1 filter/separator, and a racor if you can afford it.. they are about $100 for a base and element..

ive got no dedicated water separator on my car, just the built in separators in the mk1, and racor filters.. my Racor has a clear bowl on the bottom.. makes it easy to check for water..

[wdkingery]

i would delete the mk2 water separator AND filter..

i would UPGRADE to a mk1 filter/separator, and a racor if you can afford it.. they are about $100 for a base and element..

ive got no dedicated water separator on my car, just the built in separators in the mk1, and racor filters.. my Racor has a clear bowl on the bottom.. makes it easy to check for water..

you say the water separator also has a filter on it, or you refer to the filter up near the IP?

[burn_your_money]

Just delete that white box under the car by the rear passenger seat. I think there is 2 lines, one in an one out. Cut and splice and then throw that white box in the ditch.