Add me to the list of bucking, hesitation, now no start

[ivwshane]

Good times!

So my bus has been experiencing some bad hesitation and bucking. I thought it was only happening during cold weather but I drove today in 70°+ weather. It drove fine for about 15 minutes and bucked and hesitated a few times before making it to my destination, towards the end of the drive I also began to stall.. The drive was mostly non stop back roads with an average speed of 65mph. On the way back home I decided to take the freeway. About ten minutes into the drive I started getting some hesitation and bucking. A few minutes later it for really bad. Luckily I was near my exit and I almost made it home. Unfortunately it continued to buck and hesitate bad. At a stop sign it stalled and would not start again. The engine would turn over with no problems but it wouldn't start.

My initial research led me to believe it is the temp sensor, which at first made sense since that was one of the only parts I replaced in my last engine refresh (as opposed to refurbishing parts).

So now I need to check to see if I'm getting spark (how can I test the distributor and the coil).

I'll need to check the fuel pump (how?).

What else do I need to check and how?


Here is my engine background/history:

Its a 2.0 FI that was "rebuilt" in 2012 due to low compression.
I replaced the points for an electronic ignition and have been running it that way since with an original black coil.
I dropped the engine a couple of years ago to fix an oil leak and replaced every fuel hose and air vacuum hoses with a geebee hose where available.
All fuel injectors were replaced with new ones.
Every seal and gasket was replaced except the oil pump which I didn't touch.
Throttle body was refurbished by whip here on the samba.
New plugs and wires were used (ngk bp6et).
Temp sensor II.
Oil pressure switch.
The EGR was “refurbished" but probably should be disabled.
New Bosch cold start valve.
New FI harness and alternator harness.
Valves adjusted several months ago.
Fuel filter was replaced.
Fuel tank was cleaned (only minor surface rust was in it).
The transmission was rebuilt by Eric laundrie at transworks in el cajone ca.
Passed smog in January with flying colors.

The following parts I believe are original:
Distributor
Black coil
Alternator
Starter/solenoid
AAR
AFM
Fuel pressure regulator.
Voltage regulator.

If there is a way to test things we without needing a helper?
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77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab

[brownbus2]

i had almost the same issue off and on for a while. It turned out (i hope that fixed it) to be a rusty fuel tank.

Check your filter for rust or brown crud. Mine was bad.
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formerly known as Brown_Bus
1976 FI Marino Yellow Westy

[busdaddy]

Ignition issues can present much like fuel issues sometimes. I'd start with a replacement condenser, preferably used since new ones suck. Aside from that a fuel pressure gauge can tell you plenty, especially if it's on a long enough hose to see while driving in a mirror.
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Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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Слава Україні!

[ImAddicted]

What brand electronic ignition?
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1979 Transporter (sold)
KC1MUR

[Wildthings]

To test the ignition, just place the coil wire so that its metal terminal is about 1/4" from the metal of the engine case, fan shroud, or tin. Have someone else crank the engine while you watch for spark. If you have spark there, insert a spare spark plug into the end of the #1 wire, set the body of the plug against a ground and crank the engine, check the other wires in turn.

You can also clip your timing light onto each of the plug wires and see if the light fires.

[cmonSTART]

My first thoughts would be to check the fuel pressure as suggested, but also a visual inspection of the contacts on the inside of the distributor cap, a visual inspection of the rotor, and the plugs.

I had a similar issue a couple years ago which turned out to be bad plugs and some really worn and pitted distributor cap contacts (probably related.) Heating the engine up seemed to make it worse.
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'78 Bus 2.0FI
de K1IGS

[Abscate]

Cap and rotor. Replace annually.
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.ssS!

[Whaanga]

I recently went through a similar scenario. https://www.thesamba.com/vw/forum/viewtopic.php?t=752836&highlight=

I realize you’re running FI, I have a crappy single mount carb.

But - I started by evaluating the fuel system (filter), hoses, tank, etc.
I moved on to ignition/timing and replaced/gapped the points, new condenser, checked valves, etc.

Finally I pulled the carb and did a thorough cleaning and replaced the gaskets, etc. I also checked the Jets etc.

It wasn’t until I did the carb work and finally got good results and a well running engine. I can’t speak about FI and its maintenance, but your symptoms are just like mine and doing the carb work made the difference.
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Late 1973 Bay w/a transplanted 914 Engine

[raygreenwood]

The others are spot on.

It sounds like one of two things to me....ignition or fuel tank.
Go all the way through the ignition. Pay close attention to grounding or arc to ground issues and connection issues for the wires.

Check the voltage to the coil. Check the ground wire on the points plate (yes I know you have a module). Completely go through the ignition.

If its not ignition.....first check fuel pressure. Then check fuel volume. (trying to keep you out from under the bus until you need to be there )....then tell us about your in-tank sock filter. I would get rid of it and put an external one one. Then check the filter.

Check all of the main EFI system grounds and also the grounding of the main relay to the system. Ray

[ImAddicted]

Can skip the sock filter, FI bus won’t have one. My gut says coil or modulle
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1979 Transporter (sold)
KC1MUR

[raygreenwood]

[69BahamaYellow]

Ivwshane, if you have a Pertronix electronic ignition, that could be your problem. I have a 2.0 FI bus and It was causing the same issues you are seeing. Pertronix is now recommending to use wound or mag core spark plug wires instead of the traditional solid copper wires and you also need a 3 ohm coil max. Apparently they found that if you don’t follow this advice, it damages the ignition over time and it will fail intermittently instead of “it either works or it don’t”. I still love the no maintenance, easy starting these units provide so much better than points/condenser, and still use them today.

[cmonSTART]

[ImAddicted]

[ivwshane]

[ImAddicted]

[69BahamaYellow]

The recommendations from Pertronix regarding wound/mag core spark plug wires and a coil with no more than 3 Ohm primary resistance was right on the installation instructions for the new Pertronix ignition I bought last month. This was not on the instructions for the one I bought back in 2016 that eventually failed causing bucking, hesitating, and the same symptoms as the OP

Pertronix wire set I used was part number 704101. The 2,4 spark plug connectors were a little short for a type 4 motor, but I just drilled out the center of a couple old connectors and slipped them onto the new ones to give some extra length, otherwise they fit fine.

I used the 40511 flame thrower coil, since my Bosch blue one measured almost 4 ohms. I put the same Pertronix coil and wires on a friends bus recently. The coil was a little small for the factory clamp so I made a spacer to make it work

Here’s the installed Pertronix wire set

Use caution when removing boots and grommets from these wire sets as the crimped on ends that fit into the distributor cap are very sharp

[vwmaniaman]

Do you have 12v at the coil. ignition switch maybe?
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Working on a VW is like fun with a friend!
65 Beetle
75 Westy "Pumpkin Van"
86 Westy "Brown Betty"
87 Cabrio

[vwmaniaman]

I had a 74 Westy that did as yours. It was the condenser that was causing this issue. Buy an old distributor at the next swap ,eet and use the condenser off of it. Sad but true, they don't makem like they used to.
_________________
Working on a VW is like fun with a friend!
65 Beetle
75 Westy "Pumpkin Van"
86 Westy "Brown Betty"
87 Cabrio

[ivwshane]