No start condition

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Ronin10
Getting Hooked!
Location: Columbia City, Seattle, WA
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No start condition

Post by Ronin10 » Thu Aug 08, 2019 7:18 pm

I've scratched my head thoroughly on this one and came up empty so I thought I'd try the big guns.

BACKGROUND: At the end of June on the way back from Kettle Falls, WA the bus started bucking/misfiring. I was able to limp home and did some diagnosing once there. The problem seemed to be a hot coil issue. The engine would run fine while cool, then buck once hot. I swapped in my spare coil and the issue seemed to go away. This past weekend while on the way to Cle Elum, WA the problem reemerged. Again, I was able to limp home, but the problem was no longer confined to when the engine was hot. I swapped back to the original coil and was able to get too and from work on Mon, Tues, and Wed. On Sunday, I had ordered a pair of Brazilian Bosch Blue coils. They arrived tonight, but this morning the bus wouldn't start at all. I swapped in a new coil, but no luck on the start.

SYMPTOMS: The engine turns over just fine and will seem to catch just once, but once I release the key, it dies. After that, it won't even catch. If I let it rest for a while, I'll get the catch-once behavior again, but still won't run.

DIAGNOSTICS SO FAR:
  • I swapped in my spare, known to be good, double relay. No effect
  • I checked the wiring at the starter, ignition switch, headlight switch, and hazard switch for loose wires or connectors. All looked good.
  • I checked the various vacuum hoses for anything loose or blown off by misfires. Nothing out of place.
  • I checked the distributor to see if the timing clamp was loose. Nope.
  • I pulled the air cleaner assembly and checked to see if the flap in the AFM was wedged in the open position. Nope.
  • I pulled the cable going into the AFM as it sometimes works loose. Looking at the connector, pin 6 of 7 was recessed a bit. I tried to pull it back into place, but couldn't get it properly seated. No change.
  • I confirmed spark at each of the ends of the spark plug cables. All looked good.
  • I verified the fuel pump worked when operated at the AFM.
  • The fuel pressure maintains 28 psi and jumps to 38 psi while cranking.
  • I verified the FI grounds were connected.
Air, fuel, and spark are all there. A solution escapes me though.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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satchmo
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Location: Crosby, MN
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Re: No start condition

Post by satchmo » Thu Aug 08, 2019 8:20 pm

Condenser? Points? Or Pertronix? How are they?

I don't get the number six bullet point. Why would anything change if you couldn't effect a remedy for the recessed pin?

Check all the pins on the double relay to make sure they aren't backing out of the connector block. Recheck that recessed pin on the AFM connector.

Satchmo
By three methods we may learn wisdom:
First, by reflection, which is noblest;
second, by immitation, which is easiest;
and third, by experience, which is bitterest. -Confucius

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asiab3
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Location: San Diego, CA
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Re: No start condition

Post by asiab3 » Thu Aug 08, 2019 8:33 pm

It sounds like the CSV is firing but the injectors are not. Do you have a noid light? I find them useful for diagnosing issues like these. (Bosch 2 is the name of the plug, if you were to purchase one online.)

If you dribble a little gas into the plenum via the S-boot or brake booster Y, does the engine run a little longer?

Verify TS2 is not malfunctioning and flooding the engine?

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Ronin10
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Location: Columbia City, Seattle, WA
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Re: No start condition

Post by Ronin10 » Fri Aug 09, 2019 9:12 am

I apologize for the delayed reply. Weirdly, I didn't get a notification of the response. I could've addressed a lot of this last night.
satchmo wrote:
Thu Aug 08, 2019 8:20 pm
Condenser? Points? Or Pertronix? How are they?
Condenser and points. Both are new, but I haven't tested them individually. Only tested the system via spark at the cylinders. I did leave part of my initial troubleshooting out when I first experienced this at the end of June...I swapped out my old, tired distributor with my spare unit rebuilt by Bill Fowler. No change in behavior and part of what let me to think this was a hot coil issue.
I don't get the number six bullet point. Why would anything change if you couldn't effect a remedy for the recessed pin?
Sorry, my explanation was poor. The pin itself on the AFM wasn't recessed. it was the corresponding cable-side connector that was recessed. I was able to work it out some, where I felt it was enough to engage the pin on the AFM, but not enough to locked into position.
asiab3 wrote:
Thu Aug 08, 2019 8:33 pm
Do you have a noid light?
I don't. Hadn't even heard of them, but did a little searching and ordered one. That seems really handy to have in the tool box.

I'll verify the double relay connector blocks, TS2, and add a little fuel to the plenum manually and report back. Incidentally, my TS2 failed several months ago. I replaced it with a new one I had gotten from Bus Depot. I'm going to be really annoyed if it failed already. Guess I should be used to that now with the dearth of quality in our collective parts inventory.

My wife and I are going away for the weekend to celebrate our anniversary so I probably won't get a chance to investigate this further until Sunday afternoon or Monday. Sit tight folks.
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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Ronin10
Getting Hooked!
Location: Columbia City, Seattle, WA
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Re: No start condition

Post by Ronin10 » Sun Aug 11, 2019 5:01 pm

ISSUE RESOLVED.

I got back from the weekend away with the wife and set to further diagnosis. I first checked the TS2 and it was reading 3500 ohms at ambient temperature. I swapped in my Bus Depot spare that was reading 2500 ohms. No change.

I then removed the rear half of the air filter box and sprayed carb spray down the outlet to the AFM while my wife tried to start the engine. It wanted to crank over more so than without the hydrocarbon assist, so I thought Robbie was onto the right path by calling out my injectors.

So without a NOID light in hand, I turned my test light into one by clipping a test lead in the alligator clip end of my test light and inserting the other end of the lead into the harness-side plug for the injector. I then poked the spike end of the test light into the other opening in the injector plug and had my wife try to start the engine. On the 3/4 side, I got some anemic flashing, but on the 1/2 side nothing discernible. Issue with the injectors, indeed!

So I consulted the troubleshooting chapter in my Bosch FI guide and came across a sentence that read something to the effect of: the fuel injection components don't cause issues so much as the things them connect them, namely the harness, grounds, and plugs. In going through those connections, I found the ECU connector loose at the top of the ECU, but still latched at the bottom. Turns out the hook on my ECU connector is worse for the wear. Reseating the connector fixed the issue. I still need to do a long test drive to verify the hot condition misfiring is no longer occuring with the new coil, but the no start condition is resolved.

Thanks for the help!
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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asiab3
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Location: San Diego, CA
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Re: No start condition

Post by asiab3 » Sun Aug 11, 2019 5:29 pm

Glad you're making progress. I'm sure if you e-mailed Kyle Automotive Specialities he could help you find the new ECU plugs he is using on his new FI harnesses (which are excellent.) IF you wanted to go that route…

Noid lights are too cheap not to order off Amazon and keep in the glove box. But I did not diagnose your injectors per se; maybe just the whole system involved in supplying ground pulses to the injectors which are receiving a constant ~5v, correct? :pirate:

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Amskeptic
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Re: No start condition

Post by Amskeptic » Mon Aug 12, 2019 9:37 pm

Ronin10 wrote:
Sun Aug 11, 2019 5:01 pm
ISSUE RESOLVED.
ECU connector loose at the top of the ECU, but still latched at the bottom.
Dang ... into my little black book goes this one ...
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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asiab3
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Location: San Diego, CA
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Re: No start condition

Post by asiab3 » Tue Aug 13, 2019 5:34 pm

Amskeptic wrote:
Mon Aug 12, 2019 9:37 pm
Ronin10 wrote:
Sun Aug 11, 2019 5:01 pm
ISSUE RESOLVED.
ECU connector loose at the top of the ECU, but still latched at the bottom.
Dang ... into my little black book goes this one ...
Colin
Oh boy… Wait until the ECU plug #1 wire looks good up close, but then retracts as you get the plug into position, and then looks great pulled up close, and then retracts……

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Amskeptic
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Re: No start condition

Post by Amskeptic » Wed Aug 14, 2019 7:41 am

asiab3 wrote:
Tue Aug 13, 2019 5:34 pm

Oh boy… Wait until the ECU plug #1 wire looks good up close, but then retracts as you get the plug into position, and then looks great pulled up close, and then retracts……

Robbie
Good practice for the discerning. There is some whack stuff out there these days ...
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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