Author Topic: Start issues: AAZ in 92 Jetta (Read 7548 times)

Patrick · « **on:** June 16, 2007, 10:11:51 am »

A little history. Been running the car for 2 1/2 years, put on about 100,000 km in that time. Always been a good starter, even at 25 below and windy.
Noticed a little tough to start a couple of weeks ago, found bubbles in teh fuel line, replaced filter. Still tough to start, checked glow plugs and found power, wound up replacing 2. One was bad, one I broke taking out. Slow start still in evidence. Car runs great once it starts, will start right away if it's just been shut off (about 1 rev like it should/did before) but has to crank if it's been shut off any length of time. Acts like there's a check valve somewhere that's not holding?

I'm seeing air in the line that feeds the pump when I shut it off, but not when it's running. Any ideas?

burn_your_money · « **Reply #1 on:** June 16, 2007, 01:18:17 pm »

It sounds as if your pump may be loosing it's prime, or the GP relay or sensor (temp sensor) are not working properly.

Darth Garry · « **Reply #2 on:** June 16, 2007, 01:25:07 pm »

I had the same problem, I actually had a leak in one of the fuel lines near the tank. I would have to crank for 20 seconds to get it going, and it would skip for a minute or so after started. After I fixed the leak, it ran great.

Garry

Patrick · « **Reply #3 on:** June 16, 2007, 05:32:34 pm »

1) Glow plugs, relay, temp sensor, etc. all are working fine.
2) been watching for leaks, haven't found any yet
3) feels like it's losing it's prime, but that doesn't make sense to me(barring leaks at the pump I'd expect to see) when both the feed line and the return line go higher than the pump before they drop under the body. Once it's shut off, where's it going to go?
4) the other thing I forgot to mention is that I checked my water separator when I changed the fuel filter, found a small amount of water. Found a little in the fuel filter too. Went looking there first because I had a major water problem in another vehicle, my perkins powered truck. Don't know where the water came from, pulled the plug on my tank at home and got only good fuel, only fill at reputable high volume stations. Don't think the start problem is due to water, car runs too strong. I'm leaning towards a leak somewhere, but I still don't see any fuel anywhere.

commuter boy · « **Reply #4 on:** June 16, 2007, 10:37:24 pm »

Could be a check valve. The one on my Passat went, so instead of digging around the tank to replace the old one, I just put one on the return line by the fuel filter.

I had a pump losing prime before, there was no drips of diesel at first, just a bit of dampness around the split between the pump and the head, but that was enough.

The best way I've found to test the glow plugs was to pull the injectors and watch them heat up through the injector holes. Way easier than ammeter testing, only costs you four heat shields and 15 minutes of time.

Patrick · « **Reply #5 on:** June 17, 2007, 06:03:52 am »

Didn't realize there's a check valve in the tank, thanks. Should still start though, there's fuel in the pump and at the filter (higher) that won't drain back, right? No visible leaks at teh injection pump yet, or under the car.

QuickTD · « **Reply #6 on:** June 17, 2007, 08:08:06 am »

AAZ's are very sensitive to timing, particularly with regard to starting. If the timing suddenly is out of whack for no apparent reason I would strongly suspect the crank pulley. If it just starts hard with no other running problems then you may have caught it soon enough.

Patrick · « **Reply #7 on:** June 17, 2007, 05:37:22 pm »

Thanks, I'll check that. Maybe better drive my truck until I can? Don't know the age of the engine, might have the old style pulley. Really feels like fuel though.

Patrick · « **Reply #8 on:** June 17, 2007, 06:08:18 pm »

MIght have found the problem. Went out to check the pulley, seems to be tight (without pulling anything apart). Started the car to look for a wobble (was running 20 minutes ago), same slow start. Went back to the front and watched major air being sucked into the pump. some bubbles out the other end too. Shut the car off, watched air bubbles coming back up from the pump to the filter (in line, not return) for several minutes. Front corner of timing cover is wet, wasn't last time I was under the hood. Would a leaky seal on the front of the pump cause this?

Just for reference, I'm assuming this is a standard AAZ pump?

Worst part is I was really close to you with this car today Quick!

burn_your_money · « **Reply #9 on:** June 17, 2007, 06:15:33 pm »

Timing belts aren't a big fan of diesel fuel. I'd look into getting that fixed asap.

That looks like a normal AAZ pump

QuickTD · « **Reply #10 on:** June 17, 2007, 07:55:45 pm »

That could very well be your problem. It can be a relatively easy fix or kind of a difficult one, depends on the year of the motor. Early AAZ's have a conventional injection pump pulley with a key, you just pull it off, replace the seal and stick it back on. Later pumps have a 2 piece pulley, the pulley bolts to the hub with 3 bolts. The hub has no key, so the indexing to the pump shaft is lost if it is removed. With some careful screwing around it is possible to remove it and re-index it, just want to warn you before you pull it apart...

Patrick · « **Reply #11 on:** June 18, 2007, 02:37:20 am »

Thanks Quick. You wouldn't happen to have a part number or size for the seal would you? I'll get a belt and seal before I pull it apart....

I know the local injection shop is one of the ones that wants everyone to think pumps are black majic, not to be touched by mere mortals......... might be tough to get a seal from them.

QuickTD · « **Reply #12 on:** June 18, 2007, 08:08:18 am »

I'll get back to you on the seal size, I might have one at the shop. Joe (Joe's diesel) might also have one around. The ones from bosch are the best, proper fit and meant to run in hot fuel. I can get most anything from my local injection shop, he's learned not to ask...

Patrick · « **Reply #13 on:** June 18, 2007, 07:55:55 pm »

Got a seal from the local guy, got the story first (wasting your time, need to do the whole pump, etc. Ultra low sulpher fuel wrecking pumps) He claims they're all the same, 17mm. Got an actual Bosch seal, going to write down the part number AND take all the numbers off the seal. Chaged me 23 bucks plus taxes, pretty sure the local bearing place can match the seal , don't know if it will be any cheaper but I'm going to check. Took the day off tomorrow to tackle this (and a bunch of other) projects.

Patrick · « **Reply #14 on:** June 19, 2007, 06:53:36 am »

Just for reference, Bosch number is 1 460 283 312.000
seal measures 17mm x 28.1mm x 7.3mm
Numbers on seal are DF17 28 7.3