Power Loss @ High RPM & High Throttle

[Surfwagon]

Hello,

My van ('89 2.1 manual) has been great for a few months and then on a one hour drive I felt a stutter and then no fuel. I let go of the gas and stepped on it again and good to go. Later that day on the hills at over 3500k rpm and 80-100% throttle the van seems to stop receiving throttle input until I let go and press the throttle. (Note the van doesn't die, just as if I let go of the gas)


What I've done so far:

Checked for vacuum leaks (none found)
New Temp II sensor
New O2 sensor ( didn't have one before, now the rpm fluctuates at idle and sits around 1.1k rpm when before without the O2 sensor it was locked around 850 rpm
Checked Throttle position switch (clicks at 0 and clicks at full throttle checked with the pedal and by hand)
Lucas injector cleaner
AFM has the bluesblog Ben's Place transistor "hack" from PO I have new transistors on the way arriving Friday http://www.benplace.com/vanagon_intermittent_syndrome.htm

Went out again driving for about an hour and same issue persists. Now I can replicate it on command.

What I'm doing today 6.24:

Check fuel filter (if I see anything I'll pick up another one)
Replace the 5 pin fuel pump relay with a 4 pin
Replace the ignition switch (don't think it's this, but its good practice to have a new one)

What I'm on the fence about:

New spark plug cables / rotor / cap (they look like they have been replaced in the previous 5 or so years)

Borrow another ECU to see if its that

Thoughts? Has anyone faced this issue before? I've used my google-fu and been going through the list, but thought it would be good to ask directly as well.

Thanks

[Surfwagon]

Decided to just go ahead with the cap/rotor/cables/spark plugs. Is there anything else I should look into?

[0to60in6min]

Fuel pressure regulator and fuel pump?

[Surfwagon]

[SCM]

Sounds like you're throwing a lot of parts at it without actually diagnosing the problem. I would hold off on that until you get some advice on how to figure out the cause of your issue. Unfortunately, all I can suggest is to remove your fuel pump and see if there's a bunch of crud blocking the inlet. Your problem sounds a bit like a dirty gas tank which is fairly common.

Unless someone modified your fuel system, your fuel filter is downstream of the pump. There is a screen on the pump inlet that can get clogged with rust/sediment in your gas tank causing a lack of fuel to your engine which will be especially noticeable at high speeds because more fuel is needed under those conditions.
_________________
'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[Vanagon Nut]

[Surfwagon]

[Surfwagon]

[crazyvwvanman]

The fuel pump has only one speed and it runs 100% of the time when the engine is turning.
When things are working as intended, the fuel pump sends much more fuel to the engine than is needed.
The excess fuel is returned to the tank through the fuel pressure regulator.
When the engine is working harder, it uses more fuel and less is returned to the tank.
The harder it works the less fuel is returned but always some fuel returns unless there is a problem.

If the engine work load ever exceeds the amount of fuel being pumped, the fuel pressure drops and the engine looses power.
As soon as you let off on the gas pedal the engine again uses less fuel and the fuel pressure returns to normal and the engine again has enough fuel .
This fuel shortage never happens unless something is wrong, typically a plugged filter, but it could be other things.

Mark

[Surfwagon]

[Surfwagon]

SOLVED

For anyone looking in the future I figured out what was happening in my specific case.

The D pillar air duct in my '89 Westy had collapsed. I noticed when I was checking to see if the idle stabilizer was connected properly. I just ripped out the ruined plastic air duct and gave it a spin. Was fine for 120 miles.

Also it looks like my air flow meter was modified to run without the o2 sensor because it runs much too lean with it on.

Best of luck!