Fuel delivery issue...am I on the right track?

[wyomingriviera]

Towed home in shame last week; had spark, but not getting gas. Here's what I've found since:

When fuel pump is wired directly to 12v power, she fires right up, but dies immediately. Fuel pressure reads 35 psi, but drops to about 28 when it fires up, and dies shortly after. It's a 2.0 GD motor, stock fuel injection.

Is this a symptom of only the fuel pressure regulator, or is the double relay to blame as well?
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'77 Rivi 2.0 T2 GD
"I tell you, we are here on Earth to fart around, and don't let anybody tell you different."- Kurt Vonnegut

[busdaddy]

Does the pressure continue to read 28 as it dies?
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[wyomingriviera]

It goes back to 35 soon after it dies. Pressure drops when engine fires
_________________
'77 Rivi 2.0 T2 GD
"I tell you, we are here on Earth to fart around, and don't let anybody tell you different."- Kurt Vonnegut

[busdaddy]

It's normal for the pressure to drop when it gets engine vacuum, sounds like it's doing what it's supposed to. If you have the pump wired directly to 12 volts then the double relay is out of the picture so I can't say if it's to blame right now, since fuel pressure maintains it seems the pump is working and the feed from the tank isn't restricted.
So that leaves us with a large vacuum leak or an issue with something electrical as it seems it's only running on the prime the cold start valve provides. Is the black wire laying along the left of the engine with the fuse holder in it connected to terminal #15 on the coil?, is the single whitish wire from the ECU connected to #1 on the coil? When you bypassed the double relay did you unplug it or is the rest still connected?
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[aeromech]

I'm not that good at this but I'd suspect the double relay. As I understand it, when you crank the engine power is supplied from one source to the electric fuel pump. Once you quit cranking the power changes over to another source. Seems to me like when that change happens is when your pump stops and soon the engine will die. I'm sure you can search for a double relay test procedure here somewhere.
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[Wildthings]

This is the classic symptom of a large vacuum hose being off. Could also be something like the plug on the AFM not being fully seated.

[SGKent]

to the OP - all of the above posters are correct on things you will need to check over. There is also the ignition switch which adds another set of contacts in the start position vs the run position.
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[wyomingriviera]

I was hopeful it was the Auxiliary Air valve, but that was seated firmly. I left the double relay attached when I patched power to the fuel pump. I'll check the wires when I can (out of state right now).

Frustrating because it rolled into the campground just fine

Thanks for all the help so far, Sambanistas!
_________________
'77 Rivi 2.0 T2 GD
"I tell you, we are here on Earth to fart around, and don't let anybody tell you different."- Kurt Vonnegut

[Randy in Maine]

I also like the double relay as being the culprit after cleaning and tightening the electrical connections at the battery and the starter.

I trust you have this....

http://www.itinerant-air-cooled.com/viewtopic.php?f=50&t=5459

[SGKent]

where are you now - you say you are camping.
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).

George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[my59]

Take a look at the brown ground wires at the relay. Make sure the one that goes into the relay plug is plugged all the way into the relay. I have one that is loose and has a habit of falling down inside the plastic plug housing if I mess with the relay.

Tighten the ground connection that is under the plenum on the drivers side.

If it just started when you got to your destination....did you hit a bump on the way in that may have jarred something loose?
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my59: Well son, my grandfather died before I got to drive it, so does that answer your question?
our79: sunroof bus w/camper interior and 2.0 FI
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[SGKent]

when you have the time, let's go over the symptoms again. Here is why - you indicate when the fuel pump is wired to 12V the bus starts and dies. Let's discuss what being wired to 12V directly means. Are you running a wire from the battery to the pump for example? Are you running a secondary power source? Is the wire back to the starter still in the circuit? Are you starting it with a screwdriver or the ignition key, remote starter etc.?

Let's carefully explain how we are doing this because I can see lots of ways that the issue can be fuel, vacuum or electrical based on what you have said.
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).

George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[wyomingriviera]

Ok, it's been a while, but better late than never....

When I try to start my bus, no go. No power to the fuel pump. Fuel pressure is at zero.

When I wire the fuel pump to the ignition coil (terminal 15) and I turn the key to position 2, the pump turns on, and fuel pressure goes to ~35psi. I then hit the starter button (came from the PO that way) it fires up for about a second, then dies.

I've done the Bentley tests 4.1 in the fuel injection section. It passed the current supply, but usually fails the test relay function. I say usually because out of the five or six times I've done it, it fired up and stayed running twice.

When the double relay fails, does it usually fail absolutely, or can it work intermittently?
_________________
'77 Rivi 2.0 T2 GD
"I tell you, we are here on Earth to fart around, and don't let anybody tell you different."- Kurt Vonnegut

[busdaddy]

[Tcash]

[Wildthings]

[wyomingriviera]

Word, the AFM flap trick doesn't do anything. When someone cranks the engine, it starts when I hear a click from the double relay. If I don't hear the click, it doesn't start
_________________
'77 Rivi 2.0 T2 GD
"I tell you, we are here on Earth to fart around, and don't let anybody tell you different."- Kurt Vonnegut

[Tcash]

it starts when I hear a click from the double relay.
Does it stay running after it starts?

[Wildthings]

One side of the double relay is the fuel injection relay. You should hear it click whenever you turn the key to the "run" position. The fuel pump relay will not activate if the FI relay doesn't close.

[wyomingriviera]

New double relay, works like a charm!

Thanks for the help!

Looking back, the double relay had been slowly dying, giving me lots of grief over the last few years
_________________
'77 Rivi 2.0 T2 GD
"I tell you, we are here on Earth to fart around, and don't let anybody tell you different."- Kurt Vonnegut