77 FI Bus Fuel Leak at Heads

[EZ Gruv]

Try applying 'mouth vacuum" -extra piece of hose to the vac port on regulator, and...uh...suck. This can be done with the engine off using the afm wiper to turn on the pump

Does the pressure change?

I have one of those hand-pump MightyVac things that I use to bleed the brakes; that should work, right?
So if I hook this pump up to the pressure regulator, when I increase vacuum, pressure should go down?

[vwlover77]

Yes.

[EZ Gruv]

OK, some test results here.

I ran the pump by moving the flap in the AFM. Pressure went up to 38. When I let go of the flap it settled at 35. Attached the vacuum and gave it a few pumps. When I got to about 8ish psi, the fuel pressure gauge read about 30.
I released the pressure and went to retest. Again with the AFM flap open - 38, but it did not settle at 35 as before. It dropped to 10 and held.
A third test revealed teh same results.
Onto the fourth test. Moved the AFM flap, went up to 38 while open. When I let go - down to zero.
Repeat.

[vwlover77]

When you say "Let go of the flap", do you mean you allowed it to return to rest and the fuel pump to shut off?

When you applied vacuum to the pressure regulator was the pump running? It needs to be for the test to be valid.

Is there more gas leaking out of the exhaust after doing these tests?

[EZ Gruv]

When you say "Let go of the flap", do you mean you allowed it to return to rest and the fuel pump to shut off?

When you applied vacuum to the pressure regulator was the pump running? It needs to be for the test to be valid.

Is there more gas leaking out of the exhaust after doing these tests?

I did not realize I needed to hold the flap open during the test, sorry.
I just went out and did it again, holding the flap open while I applied vacuum.
At the begining it went up to 38 again. As I applied vacuum the fuel pressure came down. I got up to about 12 psi on the vacuum gauge and the fuel pressure was down to about 31. It took me about 30-45 seconds to accomplish this test.
That is when I started smelling fuel again. A look under the bus revealed fuel dripping again. A close look topside showed some fuel on BOTH sides under the injectors. Could the injector seals all have failed at the same time? Seems reasonably unlikely. Did the test take so long that the heads just filled up with fuel and 'overflowed' back through the injector ports?

Ugh.

[Gypsie]

oooh oooh were getting warmer.

Now I'm curious to know if you have fuel squirting into the cylinders when you do this test. Fuel this side of the injectors does indicate seal leakage or maybe fuel line to injector/rail weakness.





Uh I have to sign off now cause my wife is reading over my shoulder and is seeing all this tight injector squirting stuff and is busting a gut and suggesting some very lewd responses....

I'll check in later....

[vwlover77]

With the engine off, even with the fuel pump running, the fuel injectors should NOT be spraying fuel.

Humor me here...... Unplug the big connector from the ECU (or unplug the electrical connectors from all 4 fuel injectors) and run the fuel pump again via the AFM wiper for the 45 seconds or minute it took to run the previous test. Don't worry about the pressure regulator.

Do you still get fuel leakage?

[EZ Gruv]

With the engine off, even with the fuel pump running, the fuel injectors should NOT be spraying fuel.

Humor me here...... Unplug the big connector from the ECU (or unplug the electrical connectors from all 4 fuel injectors) and run the fuel pump again via the AFM wiper for the 45 seconds or minute it took to run the previous test. Don't worry about the pressure regulator.

Do you still get fuel leakage?

I unplugged the ECU and retested; did not see/smell fuel at all.
Then, to try to replicate the previous results, I plugged the ECU back in and tested, didn't see/smell fuel this time. Weird.

[EZ Gruv]

I pulled the injectors on the 1-2 side. I ran the fuel pump with the AFM flap - no spray. I unplugged the injectors themsleves - no spray.
The small inner seal fell apart though, so I ran to the store for a new set.

[EZ Gruv]

Alrighty, I changed all the old, cracking, broken, dry injector seals (all 8 ). Replaced the 35mm long fuel lines on the 1/2 side (I replaced the 3/4 side just over a week ago).
I tested the CSV per Bentley, it checked out fine.
Finally decided to install the fuel pressure regulator, since I had it anyway.

Crank, crank, crank..put, put, put..VROOOM! Lot of white gassy smelling smoke coming out of the tailpipe.

I cut it off and changed the oil.



Over a gallon of oil/gas mixture!

I just took the bus around the block and it ran just fine.
Thanks to all for your assistance!

[chitwnvw]

Is it in the Bentley on how to change out the injector seals?

[EZ Gruv]

Is it in the Bentley on how to change out the injector seals?

Not sure, but it is pretty self-explanatory. Take the injectors out. Remove the old seals. Clean them up externally, put the new seals on.

[bretski]

Great news, Eric!

[chitwnvw]

Is it in the Bentley on how to change out the injector seals?

Not sure, but it is pretty self-explanatory. Take the injectors out. Remove the old seals. Clean them up externally, put the new seals on.

Hmmm, maybe I am being retarded. I couldn't figure out how to get the injectors out. Maybe I should take another pass at this.

[Bleyseng]

remove 2 nuts and pull! =D>