Same injection problem...

Hi everyone,

I posted a message last summer. Didn't have time for the follow-up (Thanks speedy Jim for the reply, by the way).

The problem is with a 1982 aircooled westy (Vanagon).

At first, it went so rich that it would lose all power.

Once in the workshop, I had a look on the fuel pressure (looked ok) the fifth injector (which I removed, tested and replaced) and then.... it wouldn't start at all.

Investigating more, I've fouded that the plugs were dry.

12 volts at the injectors, when cranking, but no ground.

So I tested the ground connections, they seem to be ok. The double relay (as far as the tests proposed by Bentleys) found ok too... I Changed the ecu with a supposed-to-be-working used one... no ground to injectors when cranking....

By the way, the #3 cyl head temp sensor looked ok...

Question is, could it be a problem with the signal sent from the coil to th ecu? What kind of signal do the breaker points send to the ecu?

I tested the coil with ohmmetre... it's on specs. only thing is when I put the ohmmetre btween ground and open cicuit of the neg of the coil (i.e. when the breaker points are open), once disconnected with the ecu and the plugs, the ohmmetre shows a resistance. it shows open circuit if I unplug the positive lead of the coil. Is this Normal? or is there a ground somewhere on the positive circuit? Is this might lead to a bad signal to ecu?

Steph

Reply to
Steph
Loading thread data ...

Hi everyone,

I posted a message last summer. Didn't have time for the follow-up (Thanks speedy Jim for the reply, by the way).

The problem is with a 1982 aircooled westy (Vanagon).

At first, it went so rich that it would lose all power.

Once in the workshop, I had a look on the fuel pressure (looked ok) the fifth injector (which I removed, tested and replaced) and then.... it wouldn't start at all.

Investigating more, I've fouded that the plugs were dry.

12 volts at the injectors, when cranking, but no ground.

So I tested the ground connections, they seem to be ok. The double relay (as far as the tests proposed by Bentleys) found ok too... I Changed the ecu with a supposed-to-be-working used one... no ground to injectors when cranking....

By the way, the #3 cyl head temp sensor looked ok...

Question is, could it be a problem with the signal sent from the coil to th ecu? What kind of signal do the breaker points send to the ecu?

I tested the coil with ohmmetre... it's on specs. only thing is when I put the ohmmetre btween ground and open cicuit of the neg of the coil (i.e. when the breaker points are open), once disconnected with the ecu and the plugs, the ohmmetre shows a resistance. it shows open circuit if I unplug the positive lead of the coil. Is this Normal? or is there a ground somewhere on the positive circuit? Is this might lead to a bad signal to ecu?

Steph

Reply to
Steph

Last summer?? HaHa. I can't remember anything from last week.

"At first, it went so rich that it would lose all power." That one immeidately suggests bad cyl head temp sensor to me. It can have a huge effect on the mixture. You can't tell a thing by looking at it. Cold, the Ohms should be 2500 to ground (wire disconnected).

The readings you got on the coil are normal; the meter was reading stuff connected to the positive side of the coil lead.

The ECU is *very* fussy about the trigger signal from the points. Bad condensor, points pitted or wrong gap, bad rotor/cap, coil, all, can affect the signal to the ECU.

Speedy Jim

formatting link

Reply to
Speedy Jim

Reply to
vgonman

Well,

I have worked on many of these vehicles, and what you are describing is not uncommon. As a matter of fact, the local VW dealer refers Vanagons to me for service....at my house! I have bought/sold many of these that were stood up with FI issues. But it truly is a basic system to understand and troubleshoot. May I suggest, first off, to pick up a copy at one of the online auction places of the VW Vanagon/type2 fuel systems. It goes through every component and makes you understand the system. That way you can narrow it down immediately.

If you have 12v at the injectors, something is wrong. That resistor pack (the think that looks like 4 cigarettes in a bundle on the firewall) reduces the voltage. So, thoughts are if that has somehow failed (never heard of this) you would be giving too much fuel. But, seriously, I doubt that is the problem.

To suddenly lose power, may i suggest checking the FI harness grounds that are under the air plenum in the center of the motor. Clean and replace those. Verify spark. If you have spark, then pull a injector out of one cylinder (easier to get to on left side of motor) and have a buddy turn over the motor and verify squirt. No flames please.........have a extinguisher handy, but if you pulse for just a second or two, you are not going to have any issues but please, safety first.

If you have squirt, I suspect a ignition timing issue. Maybe the distributor clamp came loose.

But if you do not have squirt, verify that you hear the fuel pump kick on for a second or two just when you turn the key far enough to have ignition lights on the dash (not cranking the motor). If you hear the pump, that is good. I would then verify pressure in the fuel ring. there is a small 7 mm bolt on the fuel ring right by the cold start sensor. loosen it and see if fuel squirts out. If it does ( or better yet, if you have a gauge put it on that nipple) you know you got pressure.

If you have not replaced head temp sensor in last few years, it is never a bad idea to have a new one installed. Often the threads get corroded, and bad info is given to the ECU. This could be part of your issue. Usually, the FI system will still run the car with a host of shoddy problems, but suddenly stops from an accumulation of issues. Be sure all vacuum connections are tight, if not, zip tie or replace where you can. Any vacuum leak off the huge boot between the AFM and the throttle body will make the car never start in general.

Check this all and get back with any questions.

Reply to
vgonman

.................These CHT sensors go bad with age. My L-Jetronic bug started losing power abruptly at times last fall and I remembered at the time that I had read that the CHT was often the culprit. Someone who had worked at a dealership even told me once that he always kept a good one in his toolbox to use to see if that was all that some customers needed when they brought their bug/bus/vanagon in with a loss opf power problem like this.

..........Anyway, when I replaced my CHT sensor last Oct and my problem went away immediately.

BTW......you say that your vanagon goes rich when it loses power but you also say that the plugs looked clean. Sudden loss of power is usually a too lean phenomena. I run a fuel pressure gauge and an air/fuel ratio gauge on my '77 bug and when my CHT caused my problems, I saw immediately while it was happening that it was going off the scale lean on my A/F ratio gauge and that the fuel pressure was remaining normal.

Reply to
Tim Rogers

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.