I've got a 92 VW Passat GL 2.0L 16v.
I can't get fuel past the fuel distribution assembly to the injector lines.
Any ideas why? Fuel pump works. I get fuel to the distribution assembly and
back on the return line. I am thinking it's possibly the diaphram fuel pressure regulator,
or the fuel pressure regulator actuator. I know nothing about VWs and finally ordered a
book. I hate this car. I would appreciate any insight.
Thanks guys and gals.
Quote from: VisceralReaction on October 26, 2009, 03:01:15 PM
I've got a 92 VW Passat GL 2.0L 16v.
I can't get fuel past the fuel distribution assembly to the injector lines.
Any ideas why? Fuel pump works. I get fuel to the distribution assembly and
back on the return line. I am thinking it's possibly the diaphram fuel pressure regulator,
or the fuel pressure regulator actuator. I know nothing about VWs and finally ordered a
book. I hate this car. I would appreciate any insight.
Thanks guys and gals.
man you picked a fun one. CIS-E Motronic are about the most difficult to diagnose... luckily I have some experience at it ;)
First I need you to explain to me how your checking for fuel. these systems are very vacuum dependent and if you just removed a injector and started cranking you'll never get any fuel because the air lift plate does not move.
you need to go over the system and insure there are no vacuum leaks. remove the intake boot and inspect it for any cracks. they WILL NOT run with slight vacuum leaks.
I'm guessing this is a crank but no start problem.
The Fuel pressure regulators are pretty fragile and if the've been sitting for years they tend to rust out and stop working, but normally the car will start BUT will run very poor.
the differerntal pressure regulator (on the side of the fuel distributor) will not cause a no start. it is for fine control.
If you lift the plate using pliers while some one is cranking and you get no fuel out the injectors its possible the fuel distributor is failed...
give me a better idea of what you've done and I can steer you closer to the problem.
Yes that's correct. Crank but no start. It fires with ether and I know I have spark.
I pulled the pump apart and cranked and I have fuel moving at that point.
I pulled the fuel return hose from the back of the diaphram pressure regulator
and I get fuel there on the return.
Where and what is the lift plate?
There are miles of vacuum lines!!
air lift plate is under the intake boot.
go over the vacuum lines and make sure they are all at least plugged in.
what happened that it no longer runs? did it stop while driving? just not start one day?
It sat over the summer, it ran, albeit rough.
Then won't start in the fall.
You also may have to bypass the fuel pump relay to get the pump to run more than a few seconds if the engine is not running, a safety to shut off the fuel in case of a crash. Those systems are very high pressure, which also means caution when disconnecting any lines on the high pressure side. Do not take the fuel distributor or pressure regulator apart. Most likely they will leak on reassembly. The system works a lot like a CV carburetor. Air flow lifts the plate acalles is talking about. As air flow increases (more load on the engine) the plate lifts higher. As the plate lifts, more fuel to the injectors. The easiest way to lift the plate is with a magnet. Do not do this long or lift the plate very high if the injectors are left in the manifold. It doesn't take long to inject enough fuel to hydro lock a cylinder. Inspect the boot very carefully. They like to crack in the folds and it can be hard to see.
When I worked on CIS injection we would pull the injectors and place the injectors in a rack with the appropriate number of test tubes so we could capture and measure the fuel. If you choose to pull the injectors on your almost 20 year old car expect the injector seals to crack. Oh, those seals are a common cause of rough running.
I pulled the injectors and will try cranking the while raising the lift plate.
The injector ring seals actually look pretty good suprisingly.
I noticed the bottom of the fuel distributor has a piston that pushes the
lift plate closed when I crank on it. possible problem?
Thanks Howie and Acalles for the insights.
Quote from: VisceralReaction on October 27, 2009, 10:07:29 AM
I pulled the injectors and will try cranking the while raising the lift plate.
The injector ring seals actually look pretty good suprisingly.
I noticed the bottom of the fuel distributor has a piston that pushes the
lift plate closed when I crank on it. possible problem?
Thanks Howie and Acalles for the insights.
that is fuel pressure pushing down against the air lift plate, its a fairly good sign that you have adequate fuel pressure.
I do not suggest jumping the fuel pump relay. If your experienced its OK but I don't suggest it for everyone. if you happen to get fuel in your eyes and the pump is stuck on it could suck. with some one helping you by cranking when your ready to test something you'll get it figured out.
when air lifts the plate it moves that piston in the fuel distributor which allows more fuel to flow to the injectors.
I cannot stress checking for vacuum leaks enough. you see how much force it takes to lift that plate against the fuel pressure you need all the vacuum you can get to move it.
I'm working from memory here and its been, probably 2 years since I've seriously diagnosed one of these. getting them running perfect is a science, but it shouldn't be too big a deal to get it started and running OK.
when removing and installing the injectors always lubricate the seals. also buy a set of seals and plan on replacing them. I've owned CIS-E cars in the past and I had to replace mine about every two years. I could always tell when they were starting to go because it would lose power after about 5500..
It's been probably about 15 years since I touched a CIS vehicle. I guess my long term memory ain't so bad. Just to give you an idea of how sensitive the system is to vacuum leaks, an oil dipstick not replaced properly is enough to make the car run like poo. Acalles suggestion to have someone crank the engine is an excellent suggestion, much safer. Like I said, you can push a lot of fuel through the injectors.