TheSamba.com :: View topic

Sat Jul 18, 2020 10:38 am

1988 Westy.
Vans been sitting for awhile.
30+ psi fuel pressure
160 psi on all 4 cylinders

Van starts and idles fine but when trying to accelerate it feels like your trying to startout in 3rd gear but know I'm in 1st.
Clutch is faily new

When sitting still engine revs great and RPMs jump right up but we'll only seeing the problem once put into grear and trying to move.

Any ideas?

Sat Jul 18, 2020 12:05 pm

Maybe a clogged Cat or Exhaust?

Sat Jul 18, 2020 12:45 pm

Fuel filter.

Sat Jul 18, 2020 2:46 pm

If its been sitting for a while dump a bottle of Techron into the fuel tank and see what that does for you. Ethanol laced fuel doesn't age well and will quickly clog the injectors when you try to put a vehicle that has been sitting back in service.

Sun Jul 26, 2020 11:51 am

This is becoming Frustrating..

Van will Start and Rev quickly with no Hesitation.

But when trying to go forward in 1st Gear it feels like I'm in 3rd or 4th. And engine drops.

Compression is 150+ in all 4 Cylinders.
Replaced Fuel Pump
Replaced Fuel Filter.
Replaced all 4 Fuel Injectors new

So WTF would cause this Van to fall Flat on her face with such loss of power.

It's a Manual Trans, Clutch is fairly new, and grabs about 2" off the floor
Any Ideas.. ?

Sun Jul 26, 2020 11:58 am

Idle stabilizer relay? Behind rear passenger taillight. About size of a cigarette box. Unplug that and try to start the car. Will require a bit more fuel to get it started.

Drive it around and see if it still hesitates.

MAMY people drive without this relay (expensive part) and adjust their rpm a little higher to account for rpm drops while clutching

Sun Jul 26, 2020 12:20 pm

Brake stuck? eg, can you move it in neutral?
Does taking off from 2nd gear work any better?
Any unusual noises while taking off?

Sun Jul 26, 2020 1:07 pm

What is your fuel pressure once you put a load on the engine? Have you checked your timing?

Sun Jul 26, 2020 1:48 pm

vacuum leak in the intake manifold. check the 4 pipe couplers in the center. then the rubber seals under the injectors.. even the seals @ the intake to the head..
the Throttle body seal and the rubber S_shaped hose and all hoses connected to it..
essentially anything after the AFM will suck in unmetered air when under 'load' but not really impact idle or basic hand revving as there's no work/load
I've also had the AFM plug be unplugged and idle but no go. so unplug it and reconnect that too.

you can also have the above fueling issues as mentioned.. ie. clogged injectors with bad spray patterns from sitting with bad gas.. fuel pump not delivering the rated pressures either from age, bad wiring, clogged filter, water in the gas or such..

possibly mouse nest in the air cleaner as well... idles/revs but no power.

many times it's a combination of minor nags that creates a major headache.
same in marriage.

Sun Jul 26, 2020 2:02 pm

Maybe the throttle cable adjusted way way loose.

Sun Jul 26, 2020 3:22 pm

danfromsyr wrote: vacuum leak in the intake manifold. check the 4 pipe couplers in the center. then the rubber seals under the injectors.. even the seals @ the intake to the head..
the Throttle body seal and the rubber S_shaped hose and all hoses connected to it..
essentially anything after the AFM will suck in unmetered air when under 'load' but not really impact idle or basic hand revving as there's no work/load
I've also had the AFM plug be unplugged and idle but no go. so unplug it and reconnect that too.

you can also have the above fueling issues as mentioned.. ie. clogged injectors with bad spray patterns from sitting with bad gas.. fuel pump not delivering the rated pressures either from age, bad wiring, clogged filter, water in the gas or such..

possibly mouse nest in the air cleaner as well... idles/revs but no power.

many times it's a combination of minor nags that creates a major headache.
same in marriage.

Dan has hit all the main causes of these symptoms above. One odd thing about the Vanagon is that the corrugated rubber hose connecting the Air Flow Meter (AFM) to the throttle body can crack in a way not visible when it is installed and the movement between the engine and the body-mounted air-filter-AFM assembly can cause the crack to open and admit unmetered air into the intake tract. This causes a lean, weak mixture. Realistically, that corrugated hose has to be removed to properly inspect it.

Assuming there are no air leaks, then the main influence in the Digifant system on transient throttle response (the situation when you open the throttle and a temporary enrichment is required) is the AFM. The wiring to it can be compromised, or the carbon traces in the potentiometer section of the AFM, or the flap mechanism itself can be compromised. The carbon traces are the most common type of faliure.

Neither the Digifant (1986 to 1991) nor the Digijet systems use a throttle position sensor, like more modern EFI systems, as an input to determine transient throttle enrichment - - they both rely on the AFM for this important function.