Non DeLorean issue. (VW)

[thirdmanj]

A new acquaintance of ours, a fellow VW owner, has a 1979 VW Wesfalia. It runs, but not for extended periods. I know it's got a Bosch EFI "L-Jet" maybe? It starts ok, I detected a little back fire when he pulled it out, but it was minor and the engine sounded strong besides that. Anyway, he says that it will make it arround the block, but that "after it gets hot a little while it dies". I'm guessing something electrical, but my tech manual doesn't have one of those handy TS sections in the Fuel Injection part. So I figured I'd keep looking and post here just to see if anyone can help out. VWs owners have a site called the "Samba" but word is that they can be a bit rude when a question gets asked more than once. Well, I'm off to keep poking arround. Thanks again!

-James

[Squall67584]

Don't know much about the pancake-style engines, but if its shutting off while it gets hot it could be the cooling tins. Either they've got some junk between them and the cooling fins or the tins are bent. Not sure if that helps out any.

[thirdmanj]

Hmm, that's a thought! We'll take a look!

[Ron]

Does it start right back up or does it have to sit a while.

Check for spark and/or give it a shot of starting fluid...
...It could simply be the fuel filter packing up.
Need more info...

[vwdmc16]

start by checking if its the fuel or ignition system that is failing when it gets hot. It could just as easily be a overheated coil.

[EarlHickey]

I agree that you need to confirm if it's fuel or ignition. A handy clamp on calibrated spark tester makes short work of this.

If the ignition is ok, check fuel pressure and delivery. If 'runs but not for extended periods' means it is dormant most of the time... fuel is likely.

When it gets warm and dies, does it black smoke and die with a hard bucking and jerking indicating excessive fuel or just suffocate softly indicating inadequate fuel?

A faulty pressure regulator, or vacuum missing to it, could be the culprit if it smokes black. Easily tested if removing the vacuum to it does not change it's running.

Vac drops the regulated pressure and no vac bumps it upwards towards 50 psi.

The main pump should dead head at around 90 psi, test dead head by pinching the return line coming off the regulator, with your gauge "t'd" in the supply line unless you have a schrade valve on your injector fuel bar and you don't care to contaminate some used R12 AC gauges. You can clean them afterwards.


Don't overlook all the simple maintenance items and it's easy enough to remove the fuel filter and pour it's contents out the inlet hole into a clean glass.

Ignition secondary items, air and fuel filters, valve adjustment (critical especially if a neanderthal ever did a valve job that has no clue about rocker geometry or good seats) which could indeed cause a loss of compression with a warmed up engine. Do the valves make their even and rhythmic musical cadence when cold...... no wait.... that engine has hydraulic tappets, never mind that!

Does the fuel smells like shellac or look like your urine after a hard week of doing things you shouldn't? It could get expensive unless you get lucky and are timely enough with some fresh fuel and additives (I like anything with Techron and use some Marvel Mystery Oil) for the fuel.


Just in case it happens to be a flow meter problem, you can insert the nipple of your blow gun and pop the top on it to access the stationary foil strips and moveable contact arm for cleaning with contact solvent.

Reseal with RTV, or your favorite gorilla glue, and pop it back on.

Now this is assuming L-jet and for some reason, I was thinking the 79 still had CIS/K-Jet.

If it has electrically pulsed fuel injectors, that would be L-Jet and it's a very simple system.

The temp sensor has a negative coefficient and this means as the temp rises, it's resistance decreases. Disconnect it, full rich within that sensors affect on the system, but it will start and run just fine until warm. Black smoke, eight stroking and then dies. Short it's wire to ground and it goes full lean.

Typically the rich black smoke problems often foul plugs unless you are running a good coil and Iridium plugs, gold cores resist fouling well too.

Good luck.

I am sure I still have good manuals from both Bosch and VW for it.

[thirdmanj]

Yeah, it isn't my bus, and I haven't actually been in it, so I can't be more detailed. I'll talk to the owner over the weekend and see if we can see what's up. But thanks again so much for the ideas. It was a shot in the dark, but there is some great stuff to think about! Much thanks!

[EarlHickey]

Yeah, it isn't my bus, and I haven't actually been in it, so I can't be more detailed. I'll talk to the owner over the weekend and see if we can see what's up. But thanks again so much for the ideas. It was a shot in the dark, but there is some great stuff to think about! Much thanks!

To get that square black cover off the l-jet flowmeter you have to pop a little hole in it (cafefully) to insert the blow gun tip and it will pop right off. They aren't cheap or easy to find good and used... and many that are bad simply need a little cleaning.

Again, good luck.