Hesitation Blues

[ktasche1]

Hey volks,

I've been having occasional hesitation/loss of power while cruising along in my 79 westy (FI) after it's warmed up - feels like you are downshifting. Either it passes after a few seconds while still in 4th gear, or I have to downshift to 3rd gear and then it passes. If I put the clutch in when it's hesitating, the engine would die. Fortunately, it would usually start up again and I could go on my way for an hour or so and then it would happen again. That said, once I was unable to start up, the engine seemed pretty hot, so I gave it a 15 minute cool down before she started up again, so....seems to be a strange heating issue that is probably getting worse.

Thoughts?

Much thanks.
_________________
1979 Westy

[aeromech]

How's your fuel filter?
_________________
Lead Mechanic: San Diego Air and Space Museum
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[busdaddy]

And the last full tune up was....????
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[ktasche1]

Tune up <1000 miles ago - new plugs, new filter. Also new fuel pump and coil.
_________________
1979 Westy

[aeromech]

I found a rag inside a gas tank once
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[busdaddy]

How about wires cap and rotor?, anything done to the valves?
_________________
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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[guanella74]

@ktasche1, thanks for posting this. Strangely enough, it sounds like we've got the same problem.

With mine, sometimes it happens in 3rd gear before upshifting, at the higher end of the rpm band (like between 25-30mph. The bus will start bucking, losing then gaining power quickly and then just stops doing it (after 3-5 seconds of the hesitations) and I'm on my merry way. It's down it in 4th too at speed.

I've got an entirely new fuel system (tank to injectors and everything in between), also a new ignition system timed to spec with pertronix for points.

I've been meaning to adjust the [hydraulic] valves. Could it somehow be the valves causing the hesitation/bucking at speed? I'm perplexed on this one. Best guess to this point has been that there's a wire loose somewhere...but which one if so?!

Thanks for any help in advance - hopefully we'll both get this solved!
_________________
- Travis

1974 Westy CampMobile - the OG!
1979 Transporter
1979 Transporter
1977 Transporter
1974 Transporter
1973 Transporter
1971 Westy

[ktasche1]

Yes, it seems like a timing issue, but I would think that would be a constant issue rather than occasional?

I spoke to someone else about this and they thought maybe a faulty alternator could be the cause of the misfiring. Maybe?
_________________
1979 Westy

[Greg in GA]

[guanella74]

bump - would anyone be able to chime in on this one with ideas other than the alternator?
_________________
- Travis

1974 Westy CampMobile - the OG!
1979 Transporter
1979 Transporter
1977 Transporter
1974 Transporter
1973 Transporter
1971 Westy

[aeromech]

Hook up a fuel pressure gauge and go for a ride
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[guanella74]

@Aeromech, thanks for the tip. I've got a new tank, new pump, new fuel filter, newly cleaned injectors (by Cruising perf), new lines, the works. Are you thinking it could be the pump?
_________________
- Travis

1974 Westy CampMobile - the OG!
1979 Transporter
1979 Transporter
1977 Transporter
1974 Transporter
1973 Transporter
1971 Westy

[curtis4085]

[Wildthings]

The only way I see that it could be the alternator is if you have an electronic ignition module installed instead of points. If you have a bad diode in the alternator the electronic ignition might be able to see the voltage pulse from the bad alternator and fire out of time, not very likely though especially if it fixes itself pretty quick.

I would guess that maybe you fuel injection or fuel pump relay is dropping out. They are the two sides of the double relay.

[jtauxe]

I am reviving this hesitation thread because I like the title.

Hesitation Blues sung by Rev Gary Davis:
https://www.youtube.com/watch?v=q_AJifsE2eQ
and where I first heard it played by Jorma Kaukonen: Hot Tuna Live
https://www.youtube.com/watch?v=vMR_1nSPWng

But the real reason is that I am also suffering from a hesitation problem in the 1978 double cab with a 2.0-L Type IV GD fuel injected engine.

It started on my recent 1000-mile trip to Denver and back, to go to the VWs on the Green show. All was running splendidly, but about 700 miles into the trip, I felt it cough. Then again later. On the return trip, it would do this little cough and hesitation occasionally, but it got steadily worse, to the point that it actually stalled at a stop sign (most of the trip was highway driving).

I did manage to get home, and the problem persisted. I started my work, following the advice in the Bentley FI section where it says to eliminate all electrical issues before getting into the FI system.

I started with a valve adjustment just because. The clearances were fine, with only the #1 and #2 exhaust valves being just a teeny bit tight. I also snugged up the alternator pulley belt. The timing was a bit advanced, at about 10° BTDC. Set that 7.5°.

Then I replaced with new, and one at a time (so as to identify the issue)...
- fuel filter (the autopsy on the old one showed no real problems)
- contact points
- spark plugs
- spark plug wires
- rotor and cap
- coil
Test drives between each item were typically fine for a bit (up to a few miles), then it would start in again. On the last one, I got out 30 miles with no issues whatsoever, and then it stalled while I was going full speed, and I had to pull off the road. It did start once or twice, but would not stay running. I had to admit defeat and call AAA for a ride home -- all of 8 miles.

I started again this morning, but made it only about 100 ft down the street before it died again. I coasted backwards back into the driveway, dejected.

Now what? I am out of ideas.

Do I start investigating fuel? I thought that a fuel pump (where I would start) would fail completely. Could it fail gradually, causing hesitation and getting slowly worse?

Any ideas for more diagnostics, folks?
_________________
John
"Travelling in a fried-out Kombi, on a hippie trail, head full of zombie..." - Colin Hay and Ron Strykert
http://vw.tauxe.net
1969 Transporter, 1971 Westfalia, 1976, 1977, 1976, 1977, 1971, 1973, 1977 Westfalias,
1979 Champagne Sunroof, 1974 Westfalia Automatic, 1979 Transporter, 1972 Sportsmobile, 1973 Transporter Wild Westerner, 1974 Westfalia parts bus, 1975 Mexican single cab *FOR SALE*, 1978 Irish 4-door double cab RHD

[aeromech]

Did you consider the condenser? In my experience they have been pretty reliable until recent years. Had a customer tow his bus to me a couple weeks back. Telford Dorr slaved in another condenser and boom. Found the problem.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[heimlich]

[TDCTDI]

Try removing the lead to the temp sensor in the driver side head, next to #3 cylinder (ts2) & ground the lead of the harness to the engine & see if it runs better.
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


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An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[timvw7476]

If it IS the condenser, you get a stoppage of power followed by a hard THUNK through the transaxle mount . It is unmistakable.
Best thing to do is when doing a tune up consider inspection cleaning & tightening the grounds/battery posts. At torsion tube/trans & battery/body by the ECU.
The change-of-seasons really seems to throw a monkey wrench in the works, especially winter to spring. Then here you are in summer wondering what was missed.
There's also an outside chance the 'braid' point plate ground in the distributor is hanging by three threads too. Happened to me once. In 28 years.

[aeromech]

This is why I have a spare distributor for either getting home or troubleshooting. You can eliminate several possible causes by swapping the complete distributor
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound