Help! '87 Jetta no start

Fuel filter?

Got to determine what system the fault is in. Ignition, or fuel to begin with.

Easiest way is to spray some starting fluid in the intake and see if it runs for a little longer. Don't spray it while running. If the starting fluid makes it run longer you know you have a fuel problem.

Are you sure the fuel filter is letting fuel by?

Start with this and let us know-it is likely something easy.

I'm pretty sure ignition is OK. I get a fat spark on all plug wires. And it does run strong for a few seconds. Fuel filter is relatively new. I guess a slug of something could have dislodged and wound up there, but I bet there is no more than 300 miles on the filter, with the last 50-60 on the racetrack.

I get plenty of fuel from the cold start valve, which is obviously why it runs for a few seconds. I pulled the #1 injector and cranked it the injector in ajar, and got only a weak squirt. That's when I started testing the fuel pumps. At any rate, it's pretty obvious to me it's not getting fuel through the main system.

But filters are cheap, I'll pick one up before I head to the shop tonight.

As I understand this system, it's basically a mechanical system. All the electronics are there to modify the mixture. If they were totally dead the car should still run, albeit rich. Can anyone confirm that?

Distributor runs right off the rear cam, so side thrust is nonexistent. At any rate, there is no discernible play in the shaft. Grounds have been kept clean and tight since I've had it. I did run a jumper from negative battery to block to see if it made a difference, and it didn't.

I don't know about the CIS-E, but on my digifant with those symptoms I'd check the wires to the O2 sensor.

'luck - Chris

Rex B wrote:

Yeah, I know what you mean, but that's why I suggested checking the wiring. If I disconnect the O2 sensor on my 89 Jetta the car runs great, too. But one time I was cruising along and suddenly lost power. When the car stopped, it had the same symptoms as yours. Took about an hour of fooling around and thinking, but when I unclipped the O2 sensor harness the car ran fine.

What was happening was that one of the wires was shorting to ground giving a wierd signal to the ignition computer, causing the car to die a few seconds after starting up. A real pain. I fixed the problem and haven't looked back since.

But - that being said - yours is a CIS-E, and I don't know if the symptoms would be the same.

h> Digifant is total electronic, so I'd agree.

I agree. As a simple test, you can disconnect the wire to the differential pressure regulator

This willessentially make the CIS-e into a CIS running at full enrichment. A few years ago I had symptoms very similar to yours. I could start the car and it would run for a few seconds (I guess until the thermo time switch turned off the cold start injector), then stall. I first suspected the transfer pump (on my 4th in 8 years) but it was fine. I disconnected the return hose from the pressure regulator, and found that there was plenty of fuel flow. I did not have a pressure gauge. Needing transportation since I had my parents visiting from overseas, I took the car to a mechanic who said the there was insufficient pressure from the main fuel pump. He replaced it with a scavenged pump, and 3 years later the car is still running fine.

I believe you said you replaced the main fuel pump already. Have you tried measuring what fuel pressure it deliveres? Could it be a problem with the fuel pressure regulator?

I did replace the pump. I re-measured fuel flow last night per Bentley, from the fuel return hose. It was far short of spec, only a few ounces. I could not figure out a way to check the pressure. Where can I attach a gauge? Right now it's looking like a blockage of some sort. Good tip on disconnecting DPR. I'll give it another shot tomorrow night.

Thanks

If you have a working 02 sensor in there measure the voltage. If it's below

0.4 V then you know that the mixture is very lean. Lift the disc up to see if you get more fuel out of the injectors.

SFC

"Rex B" schreef in bericht news: snipped-for-privacy@corp.supernews.com...

It's a new sensor, but it doesn't get hot enough to work. I've been driving it that way occasionally. It hasn't run as it should, but it ran pretty well.

So check me out:

Remove to rubber intake boot to get at the disc Turn key on (optional?) Jumper fuel pump relay Pull injector and stick it in a container Lift disc to check fuel flow.

I had a light bulb idea today-if it did indeed backfore coming off the track it is possible it messed up the air flow sensor plate. Have a look-see in this area.

Possible(not likely) with coolant temp sensor. Check wiring etc.

Check for poor grounds.

Best of luck!

I did look at the plate, moved it up and down a few times. Doesn't bind, and no visual issues. Pretty sure the backfire was out the tailpipe. Also, the plugs I pulled out where black with soot.

Can you elaborate a bit on the coolant temp sensor?

I was reading the troubleshooting section for CIS-E for a no start condition when cold and that was a possibility.

The job of the CTS is to tell the ECU the temp of the coolant. In turn the ECU alters the mixture level. The warmer the coolant then less fuel. The cooler the coolant then more.

Conceivably if the CTS was reading wrong the ECU would not send enough fuel.

Easiest way to find out if it is bad is to unplug it and then start it up. I can tell you for sure the engine will run with the CTS unplugged. If you unplug it and it runs you likely have a bad sensor.

I have not done this, but one place to do it would be in line with the supply line to the pressure regulator, using some sort of adapter. If the blockage is in the fuel pressure regulator, the pressure you measure should be the max. the pump can supply, i.e. higher than normal operating pressure. Random thoughts on my part, no factual knowledge claimed.

Jim B.

If that's all it takes to make it run, I'm going to be pretty ticked!

LOL Thanks, I'll try that in the morning.