weird non-start problem

[TDI4evah]

2002 Jetta. Driven by my son, it was running well. He drove to a friends house last weekend, parked it outside overnight. The next morning it would crank over fine, but not catch. He said that with a boost they could almost get it running, but it just wouldn't go.

I got there, replaced the fuel filter, filled it to the top with fresh diesel fuel, then cracked the hard line nuts on the injectors. I cranked it over until fuel started bubbling out several of them, but it didn't really squirt out like usual. Tightened down, it still wouldn't catch. It appeared to not be getting any fuel at all while I was working on it.

I have some diesel starting fluid from a john deere dealer, and used a bit of it sparingly. It would cough and sputter with the starting fluid, but still wouldn't catch.

We had it towed home. Yesterday, wondering whether the injection pump was actually delivering any fuel, I removed the hardlines and had it cranked over while I watched. Plenty of fuel coming out. ***?

I put the hardlines back on, left the injector nuts loose, and cranked it over. This time it squirted all over as usual. I tightened the nuts down and it fired right up. Left it running for a few minutes, tried maybe half an hour later and it started up fine.

I left it overnight. Went out this afternoon and expected it to start right up. It started, but not before cranking it for maybe 30 seconds. It felt like it 'lost prime' and took a while to start drawing fuel from the filter again.

Once running it ran fine. I could turn it off and re-start it. I took it for a spin and it ran fine, though it seemed short on power. It took a long time to get up to 70 in 5'th gear. I'm used to substantially more HP with my VNT17 and bigger nozzles, but it still felt short of stock power.

Ideas?

 

[danny miller]

The fuel pump has a fuel pressure shutoff solenoid on it. Either without 12v or stuck shut, no fuel to the injectors will result.

Check Anti-Shudder Valve.

The clear lines before the fuel pump will show air if it's lost its prime.

The TDI needs a decent cranking speed to catch. Some people have had it turn, but due to a bad starter or low battery, it didn't turn fast enough to catch and they chased around other things.

 

[TDI4evah]

Thanks for the suggestions Danny

I don't think it's the ASV because it chugged with the starting fluid. If that valve was closed it wouldn't have done anything.

I can't say for sure it's not the solenoid, but it seems really strange that it would be an intermittent wire problem that worked when it did, works reliably when driving, but doesn't work only when left overnight.

It's definitely turning fast enough to catch. I've had it start in colder weather turning slower than this.

That leaves it actually losing prime. I'll have someone crank it over for me tomorrow and see if there's fuel in the clear fuel line. If that's dry,
what would be a likely cause?

Thanks Guys!

 

[TDI4evah]

New data point:

It started fine this morning after sitting for a day and a half. The clear line was full of fuel, though what seemed like a lot of bubbles streamed in when running.

 

[BobnOH]

Odd, gotta wonder what happened? Was the car fueled? Was it parked on a real steep hill?

 

[TDI4evah]

Yes, you do have to wonder

The car had a little less than a half tank in it, and it was relatively flat.

It sure seemed like the IP was simply not pulling fuel from the filter. I know the filter was full - I changed it and primed it. It wasn't an out-of-fuel problem, it was a fuel-not-getting-to-the-injectors problem.

Does the vane pump in those get intermittent?

 

[777]

Glow plug and engine light come on when you put the key to the acc position? Specifically when it does not start

 

[TDI4evah]

Yes, the dash looks completely normal. The glow plug cycles normally, engine light is on, ABS light was on for a bit.

The ABS light went off after it started the last time.

 

[Graham Archer]

Have you tried to use a mity vac on the pump (after removing and clamping the line between the filter and the fuel return on the pump)? I'm battling a similar no-start issue right now and I cannot suck fuel out of the pump due to a leaking pump head o-ring. I lose prime after several days. No fuel visible in the return line.

Graham

 

[TDI4evah]

I don't have a mity-vac

Where is this pump head o-ring? I'd be happy to replace it whether it's bad or not, just to see if it fixes the problem.

Thanks!

 

[Graham Archer]

http://www.myturbodiesel.com/wiki/i...eaking-seal-replacement-bosch-ve-vw-audi-tdi/