TheSamba.com :: View topic - 77 FI bus. I cannot get this thing to run.

Sat Feb 18, 2017 5:29 pm

This is a long story, I am going to try to make it simple. I bought this bus non running. It failed a compression test on cyl 3. I determined the head was cracked around the exhaust valve. I replaced the head, adjusted all valves, inspected and gapped all spark plugs. All of this was done in accordance with the maintenance manual. I also installed a new distributor with petronix electronic ignition. I started the bus, let it warm up, and drove it around the block. It was missing a little, so I pulled all the injectors and inspected the spray pattern. One injector was bad, so I replaced it. The spray pattern on all injectors are now acceptable based on the fuel injection manual. After this, the bus has gradually degraded in a 2 day period to the point that it won't start. As a result, I have spent months troubleshooting. The following is what I have done. Replaced fuel pump/filter after finding rusty tank. Fuel is now clear./pressure @ rail. Performed troubleshooting of fuel pump relay/verified power to pump while cranking. Verified blue spark by grounding spark plugs/ignition timing is correct. To the best I can tell all vacuum routing is correct.

Sat Feb 18, 2017 5:31 pm

In addition, I found the ground wire from the frame to engine to be broken. I cleaned the grounding points and installed a new bonding braid(aka ground wire)

Sat Feb 18, 2017 5:49 pm

Assuming you do actually have both spark and fuel, I am going to guess that the timing has drifted for some reason. Either the distributor body is slowly turning or you didn't get the tang on the distributor shaft aligned with the slot in the drive and it is slowly drifting as a result.

Sat Feb 18, 2017 6:26 pm

I'd still suspect bad fuel. You said the tank was rusted and you didn't pull it and clean it out. It ran okay and slowly went bad. Sounds like something is plugging up with crap to me. You can't take shortcuts

Tue Feb 21, 2017 12:51 am

Before, the van quit completely, I rechecked timing with a light while holding the throttle open to keep the engine running. While a completely accurate reading wasn't obtainable due to variable rpm, I was able to obtain readings close to what was specified IAW the maintenance manual. I just went out and checked, and as far as I can tell, the distributor is fully seated and the distributor is tight. Are you saying that there are still ways that the slot can possibly drift? Also, I did take a shortcut by not removing and sealing the tank after I discovered the rust. Initially I wasnt aware of the rust, as the van did have fresh fuel when I purchased it. I did however drain the tank and change the filter and pump after I discovered the rust. As I said before, I do have pressure at the rail, I suppose I need to verify what pressure actually is. I intend to clean the tank now, however I am afraid that that the fuel system, or possibly the cold start injector may be clogged. I am not aware of a way to accurately determine if the fuel system is clogged besides looking at the spray pattern on the injectors. I have checked the spray pattern on all 4 injectors, they are consistent with the pattern on the one new injector I recently installed. As far as I can tell, the pattern looks like the hand drawn picture in the fuel injection manual. I am sorry for the slow response, but thank you for the replys. Bouncing ideas with experienced people helps.

Tue Feb 21, 2017 1:53 am

Put a gauge on the fuel rail so you will know what the pressure is doing.

If the pressure drops off you may have clogged the fuel filter. What happens when you remove the fuel filler cap? Does air suck into the tank.

Replacement tanks are available.

Dump some FI cleaner into the tank and see if that improves things. If the engine will not run then you can cycle the pump by pushing open the flap in the AFM.

Edit: Sorry my original answer was for a Vanagon and not a Bay.

Tue Feb 21, 2017 7:30 am

You have crap in your tank, still. You have to drop the tank and clean/reseal it. I had the same problem...twice, so I speak from experience. Take your filter off and cut it open. If there is a pound of rust in there, you know what to do. And the filter likely blocked all the rust from getting into the injectors and pump, so you prolly didn't do any damage to anything.

Tue Feb 21, 2017 6:17 pm

kangaboy wrote: You have crap in your tank, still. You have to drop the tank and clean/reseal it. I had the same problem...twice, so I speak from experience. Take your filter off and cut it open. If there is a pound of rust in there, you know what to do. And the filter likely blocked all the rust from getting into the injectors and pump, so you prolly didn't do any damage to anything.
X2. I just went through that with my 75 Chevrolet. If the tank is rusty, there is no fixing it and the battle will continue. I had to replace the whole system.

Wed Feb 22, 2017 1:15 am

One of the problems with the L-Jetronic fuel injection system is that all the players demand total respect. What does that mean?

Every F.I. component that you will find outlined in the Fuel Injection (chapter 10) of your Bentley manual will need to be functioning as intended. The only rational way to verify this is to perform all of the test/inspect procedures for each component in that chapter ensuring they are all playing nicely with each other. When someone in that orchestra is being an idiot, the audience walks.

Thankfully, the tests can be done with average hand tools, a multimeter and a pressure gauge attached to fuel injection rated hose.

:arrow: You can test your fuel supply by following procedure 4.4 on page 10-11 and 4.10 on page 10-20

Obviously, you should have re-inspected your fuel filter by now for additional crap that may be causing you repeated grief.

You can also rig up... albeit with some thought, expense and effort... a 'stand-alone' fuel supply to your fuel pump. This will completely bypass your questionable fuel tank. Don't forget to have the return line re-routed to your temporary fuel supply.

8) Don't give up! A nicely tuned fuel injected bus is a real novelty on the freeway.

Wed Feb 22, 2017 12:11 pm

Wasted youth wrote: 8) Don't give up! A nicely tuned fuel injected bus is a real novelty on the freeway.

And in the mountains and rain and cold and heat and at car shows and…………………

Wed Feb 22, 2017 6:29 pm

Agreed. I need to determine a fuel pressure reading. I have replaced the filter and pump..although I'm certain the original pump is still good. The fuel flow directly from the pump is clean (verified by manually closing the contacts on the AFM). Prior to any other work, I intend to remove and seal the tank (or replace if required). As suggested, I will then troubleshoot in accordance with the fuel injection manual if I can still not get it to run. I agree that fuel injection is the way to go. I do not want to abandon it, but the wife wants to camp..soon. Unfortunately, I have been called out of town for work. When I get back, I will provide updates of my troubles or success for others that may have the same problem in the future.

Wed Feb 22, 2017 11:55 pm

Cool! Keep us posted, as often these threads help someone in the future resolve their side-of-the-road dilemmas.

Judging by your tag line, you will be able to handle this.

By the way, the pressure gauge needs to be nothing special. 0-50 PSIG is perfect. When you remove the fuel rail test port, the cap should have a very small aluminum sealing washer. Very easily lost!

Put a thick rag under it before you take the cap off, and wear safety glasses. If your regulator, fuel pump and injectors are doing their job, there should be about 30+ PSI of fuel pressure in there.