Fuel Injection Trouble

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PaducahFrank
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Fuel Injection Trouble

Post by PaducahFrank » Wed Mar 08, 2017 9:24 am

My 78 Bus will not start and I'm thinking it is a fuel injection problem. It will start and run like a banshee on starter fluid, until the fluid runs out. I've sent the ECU to Fuel Injection Corporation twice, the first time they made a repair on it. The second time they just checked it and said it was fine. I spoke with a great guy there and he said told me I have a grounding problem. I can't find it. I work with some VW guys and they say I am a fool for not throwing all the fuel injection stuff away and converting it to a carb. Man I just don't want to do that because my guts tell me that is wrong. I'm looking for some advice.

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Re: Fuel Injection Trouble

Post by Amskeptic » Wed Mar 08, 2017 10:27 am

PaducahFrank wrote:
Wed Mar 08, 2017 9:24 am
My 78 Bus will not start and I'm thinking it is a fuel injection problem. It will start and run like a banshee on starter fluid, until the fluid runs out. I've sent the ECU to Fuel Injection Corporation twice, the first time they made a repair on it. The second time they just checked it and said it was fine. I spoke with a great guy there and he said told me I have a grounding problem. I can't find it. I work with some VW guys and they say I am a fool for not throwing all the fuel injection stuff away and converting it to a carb. Man I just don't want to do that because my guts tell me that is wrong. I'm looking for some advice.

Prise black cover box off of the AFM (you may need to razor the seal around the perimeter)

Turn on the ignition and don't forget that it is on. This is a temporary test..

Move the little wiper inside the black box counterclockwise

Can you hear a click at the double relay mounted on the left side of the firewall and the fuel pump run? Let me know.

If it is not running, check for a black wire off the coil (+) #15 terminal that goes to the left into the reverse lights fuse. There is another black wire that branches from there and goes to the double relay up on the left side of the firewall. With the ignition temporarily on, unplug this wire from the coil and reattach it. Did you hear a click inside the double relay?
Shut off ignition at conclusion of your test.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 203,125 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: Fuel Injection Trouble

Post by PaducahFrank » Wed Mar 08, 2017 10:39 am

Colin,

I think I've already checked this indirectly. When I turn the ignition to run I get 12 V at the #10 pin on the ECU connector. I have a fuel pressure gauge on the fuel header, when I turn the ignition to start the starter runs and I have fuel pressure (whatever the spec is for starting). I found a check sheet in this "A.F.C." manual I found and everything was in spec, with the exception of the grounds on pins 5, 16, and 17. They were showing a small ohms reading but they had good continuity on my multimeter.

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Re: Fuel Injection Trouble

Post by asiab3 » Wed Mar 08, 2017 11:02 am

Hi Frank,

Good to hear you own and know how to use a multimeter. You're at least halfway there! :)

My first check is to make sure the white wire from the ECU is connected to coil terminal #1 (negative.) Without this wire, the ECU can not sense engine speed to dispense the correct amount of fuel. I do not recall if you'll get a hint of starting without the wire, but it won't run well, if at all, without it.

--

So you know your pump circuitry (electrical and pressure) are working, but what about the signal needed to fire the injectors? The current path to fire the fuel injectors comes right out of the double relay, through the series injectors, and into each injector, with the ECU controlling the grounding of the injectors as a group. Because the double relay has quite a few bus bars, contact points, and coils, it is possible that it could be causing issues without total failure.

Colin has an excellent write-up about the double relay here, if you'd like to read more:
viewtopic.php?f=50&t=5459

I think a good step to take now is, temporarily, to bridge terminals 88z to 88b AND 88d while attempting to start. This will bypass the double relay for all critical engine components. Remove your jumper wire after the attempted start and let us know how it goes.

Robbie
1969 bus, "Buddy"
http://theroadtells.com
"I would not do this again on a short time frame, the country is just so vast and beautiful…" - Barb/Elwood

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Re: Fuel Injection Trouble

Post by Amskeptic » Wed Mar 08, 2017 9:26 pm

PaducahFrank wrote:
Wed Mar 08, 2017 10:39 am
Colin,

I think I've already checked this indirectly. When I turn the ignition to run I get 12 V at the #10 pin on the ECU connector. I have a fuel pressure gauge on the fuel header, when I turn the ignition to start the starter runs and I have fuel pressure (whatever the spec is for starting). I found a check sheet in this "A.F.C." manual I found and everything was in spec, with the exception of the grounds on pins 5, 16, and 17. They were showing a small ohms reading but they had good continuity on my multimeter.
If you have real fuel pressure during cranking, then I guess a dumb electrical problem is not allowing the injectors to fire.
Be methodical and careful and exhaustively thorough.

5 16 and 17 are all grounds as you know. They must be continuous to the ECU plug terminal tines, you know this too. But *carefully* check that all terminal tines are at the same elevation inside the mpc connector plastic. Too many times, people do not align the ECU plug and they seat the thing not comprehending that a mis-alignment can cause just one little wire terminal end to rip from its seat in the plastic and sink into the plug in a very subtle way. Check the #1 terminal end in the ECU plug especially.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 203,125 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: Fuel Injection Trouble

Post by vwlover77 » Thu Mar 09, 2017 1:33 pm

Did you send your fuel injectors off to one of the services for cleaning? I had the strange experience with a friend's Bus that the cleaning service somehow ruined the injectors. They were a spare set, luckily. He had a fine running Bus. We swapped out the injectors for the set that had been serviced. The Bus started and ran poorly for a few minutes, then would not restart, period. Put the original injectors back in - bam - started and ran fine. This would be something to investigate after exhausting other possibilities.
Don

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Re: Fuel Injection Trouble

Post by PaducahFrank » Fri Mar 10, 2017 6:17 am

Thanks Don I didn't mess with the injectors other than I verified they would open and spray fuel. I'll put the word out when I figure out this problem.

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Re: Fuel Injection Trouble

Post by Amskeptic » Fri Mar 10, 2017 8:37 pm

PaducahFrank wrote:
Fri Mar 10, 2017 6:17 am
Thanks Don I didn't mess with the injectors other than I verified they would open and spray fuel. I'll put the word out when I figure out this problem.
Or we will be putting out the word on MaybeMay 13th!
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 203,125 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: Fuel Injection Trouble

Post by PaducahFrank » Mon Mar 13, 2017 6:20 am

Finally got a chance to mess with the ole bus this weekend no dice. I have 3 theories. 1. The test rig for L -Jettronic ECUs at Fuel Injection Corporation has something wrong with it. My ECU has been out there twice and they say it is fine. 2. My wiring Harness is bad. or 3. Somehow the ECU is not happy with the signal coming from my coil.

I made a jumper as Robbie suggested and jumped 88z, 88b, and 88d. Fuel pump starts running approx 38 psi fuel pressure bus would not start. I noticed when I engaged the started the fuel pump really seemed to bog down so I replace the battery with a spare battery I happened to have. That seemed to help but still no bus start. Then I took the ecu connector of and rechecked 5, 16, and 17 for ground, checked 1 for continuity to the connection on the coil. All was well. I unplugged temperature sensor 2 and jumped it to ground. I made sure pin 13, the wire that goes to T2 had continuity with ground. Still not starting. I took the ecu out and took the board out of the case, rechecked 1, 5, 16, 17 and 13 (T2 that was grounded) from the ecu side of the connection. All good. Tried to start again NO DICE.

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Re: Fuel Injection Trouble

Post by Amskeptic » Mon Mar 13, 2017 10:24 am

PaducahFrank wrote:
Mon Mar 13, 2017 6:20 am
Finally got a chance to mess with the ole bus this weekend no dice. I have 3 theories. 1. The test rig for L -Jettronic ECUs at Fuel Injection Corporation has something wrong with it. My ECU has been out there twice and they say it is fine. 2. My wiring Harness is bad. or 3. Somehow the ECU is not happy with the signal coming from my coil.

I made a jumper as Robbie suggested and jumped 88z, 88b, and 88d. Fuel pump starts running approx 38 psi fuel pressure bus would not start. I noticed when I engaged the started the fuel pump really seemed to bog down so I replace the battery with a spare battery I happened to have. That seemed to help but still no bus start. Then I took the ecu connector of and rechecked 5, 16, and 17 for ground, checked 1 for continuity to the connection on the coil. All was well. I unplugged temperature sensor 2 and jumped it to ground. I made sure pin 13, the wire that goes to T2 had continuity with ground. Still not starting. I took the ecu out and took the board out of the case, rechecked 1, 5, 16, 17 and 13 (T2 that was grounded) from the ecu side of the connection. All good. Tried to start again NO DICE.
You are sorely tempting me to stop by on my way back from Salt Lake City. This makes no sense.
Colin
( p.s. pull a spark plug after your next attempts. Is it wet? Pull all of them and clean, gap, and dry them. You have ONE CHANCE to get it running if they were wet! )
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 203,125 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: Fuel Injection Trouble

Post by PaducahFrank » Tue Mar 14, 2017 2:37 pm

Haven't had a chance to pull those plugs yet and it's freezing out there tonight. I'm stuck on the possibility of a bad ground somewhere. Is it possible that even though I'm getting good continuity to ground on ECU connectors 5, 16, and 17 the dang thing ain't good enough for the FI ground? I replaced the ground strap from the body to the negative battery post and that really improved the operation of the starter. That strap was getting burning hot you would crank the starter. I'm wondering if maybe that strap between the transaxle and body is offering up enough resistance at low voltage potential, to render the FI system inoperable?

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Re: Fuel Injection Trouble

Post by Amskeptic » Wed Mar 15, 2017 8:20 am

PaducahFrank wrote:
Tue Mar 14, 2017 2:37 pm
Haven't had a chance to pull those plugs yet and it's freezing out there tonight. I'm stuck on the possibility of a bad ground somewhere. Is it possible that even though I'm getting good continuity to ground on ECU connectors 5, 16, and 17 the dang thing ain't good enough for the FI ground? I replaced the ground strap from the body to the negative battery post and that really improved the operation of the starter. That strap was getting burning hot you would crank the starter. I'm wondering if maybe that strap between the transaxle and body is offering up enough resistance at low voltage potential, to render the FI system inoperable?
Stay focused, Luke.

If the plugs are wet, the grounds are good . . .
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 203,125 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: Fuel Injection Trouble

Post by PaducahFrank » Wed Mar 15, 2017 8:36 pm

The plugs were dry Obiwan.

I gapped them and put them back. Just a side note no loss of focus: The plug in #3 cylinder was fouled pretty bad with black debris. I replaced it. Prior to the bus dying it was running really well but a bit rich. I figured it was because my T2 was grounded. Any insight on that?

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asiab3
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Re: Fuel Injection Trouble

Post by asiab3 » Wed Mar 15, 2017 11:12 pm

Ok, so we have confirmed that fuel is not getting into the cylinders, even when you have pressure.

Let's get TS2 plugged back in if it's not. A cold engine appreciates the enrichment it gives during startup and warmup.

Do you have 12v at 86c on the DR when the key is on? When cranking? I don't recall right now the path this wire takes to get to the DR, but I believe it comes off the reverse light fuse from the coil.

Let us know, and we can try more voodoo from here. Your gut feeling to keep the FI will be rewarded soon, I can feel it.
Robbie
1969 bus, "Buddy"
http://theroadtells.com
"I would not do this again on a short time frame, the country is just so vast and beautiful…" - Barb/Elwood

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Re: Fuel Injection Trouble

Post by Amskeptic » Sun Jul 23, 2017 11:07 pm

asiab3 wrote:
Wed Mar 15, 2017 11:12 pm
Ok, so we have confirmed that fuel is not getting into the cylinders, even when you have pressure.

Let's get TS2 plugged back in if it's not. A cold engine appreciates the enrichment it gives during startup and warmup.

Do you have 12v at 86c on the DR when the key is on? When cranking? I don't recall right now the path this wire takes to get to the DR, but I believe it comes off the reverse light fuse from the coil.

Let us know, and we can try more voodoo from here. Your gut feeling to keep the FI will be rewarded soon, I can feel it.
Robbie

You know, there was a conclusion to this saga:

http://www.itinerant-air-cooled.com/vie ... 25#p225261
Sent: Sun Jun 18, 2017 5:15 pm
From: PaducahFrank
Recipient: Amskeptic

Colin the tweaking I did on the AFM has made some nice improvements in starting performance although I still baby it a little when I start it cold by exercising the throttle a bit. Man what a machine. We have been driving around like crazy it is so awesome.
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 203,125 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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