Inconsistent hesitation and lunging (UPDATE: problem fixed?)

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Westy78
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Post by Westy78 » Mon Jul 28, 2008 9:06 pm

It's not always the track that's bad. On mine it was higher than spec resistance on the plug pins. Bentley has the specs and which pins to pair up to check the resistance on in the fuel injection section.

I chased a bucking problem for almost a year before doing that simple ten minute test. Of course the very last part to check since it was newer rebuilt AFM.
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chitwnvw
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Post by chitwnvw » Mon Jul 28, 2008 9:29 pm

Loco,

If you can make it down here I can hook you up with a tester/loaner.

Chi'.

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locoqueso
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Post by locoqueso » Tue Jul 29, 2008 3:44 am

chitwnvw wrote: Bentley has the specs and which pins to pair up to check the resistance on in the fuel injection section.
I'll check this out...
chitwnvw wrote: If you can make it down here I can hook you up with a tester/loaner.
I'll take you up on that offer. Thank you sir.
1978 VW Campmobile (P-21) Westfalia - T2 2.0L F.I.- 151,000m
1982 Mercedes-Benz Estate Wagon (300TD-T) - S123 3.0L T.D. - 142,000m
1993 Dodge Maxi Van (190 SLF) InterVec Falcon - B350 Magnum 5.9L F.I. - 70,000m

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Inconsistent hesitation and lunging (UPDATE: symptoms worse)

Post by locoqueso » Sun Oct 05, 2008 11:06 am

“Problems that go away by themselves come back by themselves.”
- (Marcy E. Davis)

Sluggo or Colin, I probably should have started this topic in the “Troubleshooting / Diagnosis” section. Please feel free to move it if I’m in the wrong category.

Well I put off trying to track down this issue for a couple months. I’ve been busy with school and haven’t had much time to drive. I focused on replacing the muffler instead of troubleshooting this problem. When I have been able to take the bus out for a quick drive it seemed to be running fine, that is until today. I planned to take an hour drive up into Wisconsin but about 30 minutes into the trip the bus started chugging in 3rd as I was accelerating past 40mph.

This time the symptoms appear to be much worse than back in July. Now as I was accelerating the RPMs seem to cut and it was as if I wasn’t even pushing on the gas pedal. I slowed down to about 30mph and I tried again but it did the same thing. The engine didn't die. It chugged once or twice and then it acted like I just took my foot off the accelerator even though I hadn’t. I probably had my foot down on the gas for three or four seconds without any effect.

I started over in 3rd again but now I couldn’t go past 30mph so I slowed down even more and dropped to 2nd gear. I’m now having the problem in the lower gear and can’t seem to accelerate. Each time I let off the gas and press down again it tries to go for a second or two but only chugs a couple times and my speed continues to drop. I came to a stop light and the bus died as soon as I stopped. I started the engine and I could get to 2nd gear at 15mph but couldn’t get it past 20mph. This had been going on now for about 5 minutes so I pulled into a parking lot and the bus died again as soon as I came to a stop.

Luckily for me I pulled in right next to a Rosati’s Pizza so I spent the next 45 minutes enjoying an Italian beef sandwich for lunch. When I came out the bus started right up and I was able to drive the remaining 20 minutes home at 45-50mph with no further problems.

I will now make this my next project for the bus before winter hits. I’m hoping the change in symptoms (feeling as if the gas pedal isn’t being pressed, engine dies when it comes to a complete stop, symptom rapidly affects performance at lower MPHs until the engine is allowed to cool down,) might help pinpoint the culprit. If not, then I will continue with my original plan to troubleshoot:

1. Replace fuel filter (needs to be done anyway)
2. Figure out how to check the resistance of the pins per the Bentley manual. (I read it but I’m not sure I understand how it’s done. I'll read it again.)
3. Hit up chitwnvw for the loaner AFM. (if it's not too late)
1978 VW Campmobile (P-21) Westfalia - T2 2.0L F.I.- 151,000m
1982 Mercedes-Benz Estate Wagon (300TD-T) - S123 3.0L T.D. - 142,000m
1993 Dodge Maxi Van (190 SLF) InterVec Falcon - B350 Magnum 5.9L F.I. - 70,000m

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IFBwax
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Post by IFBwax » Sun Oct 05, 2008 12:03 pm

One more thing you can try that may have worked for me, is to remove the plug into the AFM, clean it with electrical cleaner.. both sides. then firmly push the plug back into the AFM. I, as well as many, don't have those little clips on the side that hold the plug firmly into the AFM and when I pushed it on firmly and cleaned the contacts, I haven't had any more problems. We'll see. This is on Charlie by the way, not the Pickle.
The best navigators aren't sure where they're going until they get there. And then they're still not sure.

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http://www.partypickle.blogspot.com

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locoqueso
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Post by locoqueso » Sun Oct 05, 2008 4:30 pm

I think I may have found the problem or at least a problem. I was under the bus getting ready to change the fuel filter and I noticed the fuel pump had greasy/wet residue on the end where the fuel flows out. It looks like fuel may be leaking out and dripping down onto the wire that plugs into that end. I think the oily texture was just from what ever was already on the outside of the pump.

I'm about to create a new topic for a new problem that I'll have to address before I can do anything else with this one. While removing the old fuel filter, the metal fuel pipe that feed into it cracked and it now has a slow drip. I'm taking a break and I'll post more about that later...

:cussing:
1978 VW Campmobile (P-21) Westfalia - T2 2.0L F.I.- 151,000m
1982 Mercedes-Benz Estate Wagon (300TD-T) - S123 3.0L T.D. - 142,000m
1993 Dodge Maxi Van (190 SLF) InterVec Falcon - B350 Magnum 5.9L F.I. - 70,000m

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dtrumbo
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Post by dtrumbo » Sun Oct 05, 2008 5:03 pm

locoqueso wrote:I'm about to create a new topic for a new problem that I'll have to address before I can do anything else with this one. While removing the old fuel filter, the metal fuel pipe that feed into it cracked and it now has a slow drip.
I didn't see your new post yet, so I'll put this here if you need it.

http://germansupply.com/home/customer/p ... at=&page=4
- Dick

1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.

... as it turns out, it was the coil!

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Amskeptic
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Post by Amskeptic » Sun Oct 05, 2008 8:15 pm

This sounds like fuel delivery problem much more than electrical gremlin.
ColinColdInMassachusetts
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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locoqueso
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Post by locoqueso » Sat Oct 11, 2008 11:54 am

I just cut the fuel filter open and a bunch of brown crud fell out. It looked like a dip of chewing tobacco. This stuff is caked all inside of the filter casing. I’m guessing this is the original filter.
1978 VW Campmobile (P-21) Westfalia - T2 2.0L F.I.- 151,000m
1982 Mercedes-Benz Estate Wagon (300TD-T) - S123 3.0L T.D. - 142,000m
1993 Dodge Maxi Van (190 SLF) InterVec Falcon - B350 Magnum 5.9L F.I. - 70,000m

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Amskeptic
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Post by Amskeptic » Tue Oct 14, 2008 7:37 am

locoqueso wrote:I just cut the fuel filter open and a bunch of brown crud fell out. It looked like a dip of chewing tobacco. This stuff is caked all inside of the filter casing. I’m guessing this is the original filter.
So. . . did it help?
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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Randy in Maine
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Post by Randy in Maine » Tue Oct 14, 2008 7:54 am

That crud is likely rust leaving the fuel tank, getting trapped in the fuel filter, and blocking flow when you demand a lot of it.

The bad news is that the fuel is also the pump coolant and there should not be any "whining noises" or "warm to the touch" produced by the fuel pump. A fuel pump for this thing is about $150 so you want to protect it.

Personally I would buy 3 or 4 fuel filters and change it after a while to see if that one also has rust in it also. This could be a message from the fuel tank telling you to fix it correctly, but people have survived for a long time just changing out the filter as needed.

By the way, you should learn how to test the various FI components using your volt ohm meter on the "big plug" that goes into the ECU. Someday it is going to pay off big time. Of course this problem would have required using a fuel pressure gauge on the fuel rail test port.
79 VW Bus

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locoqueso
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Post by locoqueso » Tue Oct 14, 2008 4:50 pm

Amskeptic wrote: So. . . did it help?
Colin
I don't know yet. I cracked the (rusted) steel fuel line that feeds into the filter while trying to remove the old rubber lines. I'm buying a replacement from GermanSupply.
1978 VW Campmobile (P-21) Westfalia - T2 2.0L F.I.- 151,000m
1982 Mercedes-Benz Estate Wagon (300TD-T) - S123 3.0L T.D. - 142,000m
1993 Dodge Maxi Van (190 SLF) InterVec Falcon - B350 Magnum 5.9L F.I. - 70,000m

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locoqueso
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Post by locoqueso » Tue Oct 14, 2008 4:57 pm

Randy in Maine wrote:That crud is likely rust leaving the fuel tank, getting trapped in the fuel filter, and blocking flow when you demand a lot of it.
There was so much of it jammed into the filter it wouldn't surprise me if it blocked the flow of fuel.
Randy in Maine wrote:The bad news is that the fuel is also the pump coolant and there should not be any "whining noises" or "warm to the touch" produced by the fuel pump. A fuel pump for this thing is about $150 so you want to protect it.
I need to take a closer look to see if the fuel leaking from the outlet of the pump is just a leaky rubber line or something else.
Randy in Maine wrote:By the way, you should learn how to test the various FI components using your volt ohm meter on the "big plug" that goes into the ECU. Someday it is going to pay off big time. Of course this problem would have required using a fuel pressure gauge on the fuel rail test port.
Thanks for the advice Randy. I purchased a multimeter but haven't learned how to use it yet.
1978 VW Campmobile (P-21) Westfalia - T2 2.0L F.I.- 151,000m
1982 Mercedes-Benz Estate Wagon (300TD-T) - S123 3.0L T.D. - 142,000m
1993 Dodge Maxi Van (190 SLF) InterVec Falcon - B350 Magnum 5.9L F.I. - 70,000m

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Randy in Maine
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Post by Randy in Maine » Tue Oct 14, 2008 5:26 pm

You might get lucky and just changing out the fuel filter will get you by for a while.

Most of us end up removing the tank to have ti cleaned and resealed up to get rid of the rust. You cannot buy a new FI tank so that is not an option. Not as involved as it sounds and it gives you an opportunity to change out the rest of the fuel fill hoses and the vent hoses on top of the tank. Gas gauge sending unit also if yours doesn't work.

Listen for pump cavitation. That will be the signal for you to change out the filter.

That volt ohm meter will pay off big time down the road. Modern cars have the OBD II diagonostic "check engine" light but we need to use our VOM to do the same thing.
79 VW Bus

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chitwnvw
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Post by chitwnvw » Tue Oct 14, 2008 5:36 pm

Is there a write up anywhere on how to use that voltmeter and what the results mean?

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