CIS-E 16v won't start (1991 Passat)

[cra2y86]

This car was my daily, parked 8 months ago for a 5-speed swap and some floor repair.

I put some gas in it the other day to see if she would fire up. And she did, but only for a second. Repeatedly.

I jumpered the fuel pump relay, pulled the injectors, and saw no fuel when I lifted the metering plate. I went as far as taking the top part of the dizzy off and manually moving the plunger. It wasn't stuck.

I cracked the bolt on the 5th injector and took some fuel to the face, so that's getting fuel. It seems the car turns over and runs for as long as the 5th injector fires.

Also, when I turn the key to start, the main fuel pump buzzes for about 2 seconds and then goes quiet. When jumpered, it stays on. Is this an area I should be concerned with?

Why aren't I getting fuel to the injectors?

[WaterWheels]

. . . I jumpered the fuel pump relay, pulled the injectors, and saw no fuel when I lifted the metering plate. I went as far as taking the top part of the dizzy off and manually moving the plunger. It wasn't stuck.

I cracked the bolt on the 5th injector and took some fuel to the face, so that's getting fuel.

Also, when I turn the key to start, the main fuel pump buzzes for about 2 seconds and then goes quiet. When jumpered, it stays on. Is this an area I should be concerned with?

First the fuel pump running for a few seconds and then stopping. This is normal and correct. Some like to say it is "priming" the system but it is really just running as normal and stopping because the pump realy "sees" no engine rotation. The relay receives a signal from the ignition coil negative terminal, call it a tachometer signal if you wish, and if that pulse is not at least something like 300 per/min it opens the relay again. So yeah, it is acting correctly.


That you are getting fuel at the cold start injector indicates that it is reaching the fuel distributor. The cold start injector gets system pressure through the fuel distributor, but not through the chambers inside. So the fuel distributor itself "could" have a clog. With your car the diferential pressure regulator (DPR) is the governing factor in fuel being sent to the injectors. If it is bad it is "possible" that it has shut-down fuel delivery by staying/sticking closed inside (it is a valve of sorts). The injectors themself require a min opening pressure, crack-open pressure, and even if you were sprayed in the face at the cold start valve, the pressure still can be too low. The injectors need about 3+ bar pressure to pop open. One or two bar pressure would be more than enough to get you a face full of gas but still not be enough to poen the injectors.

I think a fuel pressure test should be done at least for a first step.

[cra2y86]

First the fuel pump running for a few seconds and then stopping. This is normal and correct. Some like to say it is "priming" the system but it is really just running as normal and stopping because the pump realy "sees" no engine rotation. The relay receives a signal from the ignition coil negative terminal, call it a tachometer signal if you wish, and if that pulse is not at least something like 300 per/min it opens the relay again. So yeah, it is acting correctly.


That you are getting fuel at the cold start injector indicates that it is reaching the fuel distributor. The cold start injector gets system pressure through the fuel distributor, but not through the chambers inside. So the fuel distributor itself "could" have a clog. With your car the diferential pressure regulator (DPR) is the governing factor in fuel being sent to the injectors. If it is bad it is "possible" that it has shut-down fuel delivery by staying/sticking closed inside (it is a valve of sorts). The injectors themself require a min opening pressure, crack-open pressure, and even if you were sprayed in the face at the cold start valve, the pressure still can be too low. The injectors need about 3+ bar pressure to pop open. One or two bar pressure would be more than enough to get you a face full of gas but still not be enough to poen the injectors.

I think a fuel pressure test should be done at least for a first step.

Thank you so much for this info. I should have access to a pressure tester this weekend.

In the meantime I swapped in a known-to-be-good DPR. Still nothing at the injectors.

[cra2y86]

Update:

Added more fuel to the ~1/4 tank and jumpered the fuel pump relay. The pump ran noisily, then I heard swishing, and the pump grew quieter.

Started right up! I guess the main pump wasn't being fully primed and some extra gas put it where it needed to be.

[WaterWheels]

Added more fuel to the ~1/4 tank and jumpered the fuel pump relay. The pump ran noisily, then . . . Started right up!

The 1/4 tank might have been a good bit of information to throw in at the beginning. This is rather typical of a bad trasnfer pump (in tank pump). The main pump is not designed to draw (suck) fuel from the tank, it has to be feed by the small transfer pump. Over a 1/4 tank or so the pressure in the tank is enough to push the fuel to the under car pump, but when the tank starts to get low the fuel can't push it up and out to the main pump. I would test or just replace the transfer pump before it kills the main pump.

[cra2y86]

This car (wagon) came with a non-op fuel gauge. When I pulled the transfer pump/sender I discovered the p.o. repaired the connections with bare speaker wire. I sourced a used transfer pump from a running sedan part out, installed it, and found out later that sedan and wagon transfer pumps are different.

Could this be that difference showing itself?

[ellocolindo]

I am at the same point now. I swaped out my fuel dizzy because i sold it to a fellow member here; and now i put one that has been off a car for a few years. Now i have fuel to the 5th injector but nothing on the other 4 injectors.

I will try and check my fuel level

[WaterWheels]

I sourced a used transfer pump from a running sedan part out, installed it, and found out later that sedan and wagon transfer pumps are different.

Could this be that difference showing itself?

The units are different between the two cars but so are the shape of the fuel tank itself. The transfer pump itself is the same item and I think the difference lies with the tank shape and how far up or down the reach difference is or the positioning of the hose nipples. Using a "used" pump is OK but have you tested it first to be sure it is working and providing the required volume? If you maintain at least a half tank of fue,l or more, does it seem to work OK? If so then it really could be that the pump you got is bad.

[cra2y86]

The more I think about it the more I'm beginning to agree that the transfer pump is at fault.

I admit that I didn't test the used transfer pump before swapping it in (at the point I didn't know that the pump/sender assembly was splittable. I came from the land of single-fuel-pump EFI.)

The car is running fine now, but I think I'm going to replace the transfer pump (it's cheap enough and I wanted to do the filter anyways) for peace of mind.