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Engine suddenly runs terrible
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Drzdirtbag
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PostPosted: Tue Jun 06, 2017 8:33 am    Post subject: Engine suddenly runs terrible Reply with quote

Hay all,
I have a 76 2l fi van, she has been running like a top su i rebuilt her last year.. If put 15k miles on her with no issues.. I pulled into the driveway at home last night, shut it off, then 5 minutes later went to start her up to move her, and she didn't want to start, I could get her to run but very rough and wouldn't idle. Almost like the timing was way off... I haven't had a chance to investigate yet.. Anyone else had this issue?? Any thoughts?? I know it's had to suggest anything without hearing it..
Thanks, randy.
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williamM
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PostPosted: Tue Jun 06, 2017 9:28 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

Well- you can throw parts at it -- or get the free trouble shooting tech manual here and do a "Robbie" style investigation to replace the faulty part.

Because FI is essentially a vacuum controlled fuel pressure system, a cold start system , an air flow control for fuel enrichment n fuel pump safety- not to mention the double relay, then power supply-

You can see why a few readings from components are needed to peak interest here.

your essentialy asking "what pellet hit the duck"
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AB westy nut
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PostPosted: Tue Jun 06, 2017 9:33 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

Start with the easy stuff like looking for a massive vacuum leak. Maybe one of the larger hoses split or popped off. The fact you can get to start means it's getting spark and fuel.
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busdaddy
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PostPosted: Tue Jun 06, 2017 9:38 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

A broken rubbing block on the points often produces a similar symptom.
As already mentioned get systematic with it and don't just start poking things or replacing parts, it was running fine and then it wasn't, what broke or came off suddenly?
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ROCKOROD71
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PostPosted: Tue Jun 06, 2017 10:53 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

My 77 did this on Sunday. Couldn't get it to start. Made all manner of terrible noises, then started and would only stay alive with the pedal floored, eventually came out of it (running like shit for ~ 2 mins)
Then ran fine.
Ran fine today.
Sweet, "reliable" FI
My engine was gone through extensively last year, lots of hoses and clamps and stock tid-bits replaced to specs.
Feel like mine is the temp sensor but do those go intermittent before actually failing or do they just fail?
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79SuperVert wrote:

30 years from now, the next guy may not want your girlfriend, but he may want your classic car, depending on how nice you were to it.


asiab3 wrote:

Careful guys, a petulant child can grow up to be president these days.


**winter drivers: no survivors!**rust warrior**#keepbodyshopsbusy**
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Tcash
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PostPosted: Tue Jun 06, 2017 11:12 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

Look for any hoses that may have popped off.
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Drzdirtbag
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PostPosted: Tue Jun 06, 2017 12:49 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

Thanks for all the help fellas.. When I get home from work tonight I'm going to have a look.. It's the first time she has given me any problems and she waited till we where home first.. I love my van..
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curtp07
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PostPosted: Tue Jun 06, 2017 1:37 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

Smoke tester is invaluable..
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PostPosted: Tue Jun 06, 2017 11:13 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

ROCKOROD71 wrote:

Feel like mine is the temp sensor but do those go intermittent before actually failing or do they just fail?


TS2 holes and connectors can build corrosion from sitting. Part of the fuel injection troubleshooting manual should say "unplug it and plug it back in." That will let you know if anything is loose or corroded, which can happen intermittently and pass the resistance test but give problems on the road.

Everyone with a FI bug or bus should have this somewhere handy.

https://www.thesamba.com/vw/archives/manuals/afc_fi_training_troubleshooting_manual.php

After a multimeter, I find the sense of smell to be helpful with a fuel injected car. If you smell gas, you have a rich condition or a misfire. If you don't smell gas, you probably have a fuel delivery problem.

Let us know how you do with the multimeter, and if you find any hoses disconnected, or if you just flat out ran out of gas or anything silly. It happens to all of us.

Robbie
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ROCKOROD71
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PostPosted: Wed Jun 07, 2017 5:12 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

Thanks for the response Robbie. This morning The bus would start and rev up quickly and die, after a long-ish drive last night and being parked. I popped the engine hatch- sure as shit there was a hose just blown off completely disconnected. Must have been coming loose for a while with a slight vacuum leak. Right now I couldn't tell you what hose it is, but it connects up to a plastic T or Y connection where the hose has a metal pipe it clamps to that also goes into the connector with a clamp on it. Can't get it super tight but it is in there, I will have to take a more in depth look at it when I have the Bus at home. At least it is running "ok" for now.
I do have that manual and a multi-meter, I really need to start using them!
I do have a slight gas smell normally, but I think I have a weep (not a leak exactly) at the fuel rail LH side, where that little outlet for a fuel pressure tester goes. There is a bolt with a seal under it that I need to replace.

Thanks for the suggestions everyone, sorry to hi-jack...
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1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI
79SuperVert wrote:

30 years from now, the next guy may not want your girlfriend, but he may want your classic car, depending on how nice you were to it.


asiab3 wrote:

Careful guys, a petulant child can grow up to be president these days.


**winter drivers: no survivors!**rust warrior**#keepbodyshopsbusy**
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Drzdirtbag
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PostPosted: Wed Jun 07, 2017 10:49 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

Well, it's unfortunately nothing obvious.. It flashes up right away like she is supposed too, but dies a second later.. If I'm on the gas, I could keep her running but it's super rough.. I'll keep looking..
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Tumbledown76
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PostPosted: Wed Jun 07, 2017 11:58 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

I had this problem a couple of months ago. Started right up, dies right down unless I pump the throttle...a lot. In the end, tt was a combination of vacuum leaks first (found them with smoke), and then realizing my AFM was shot. The Bentley and AFC tests served me very well.

Drzdirtbag, what happens when you unplug your AFM unit? Will your bus idle.

ROCKOROD71, looks like your somewhat local. If you need to borrow a smoke tester or a hand, lemme know.
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Drzdirtbag
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PostPosted: Wed Jun 07, 2017 12:31 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

Thanks tumbled
When I unplug the aim, it starts right up and keeps running game at a higher rpm...
Randy
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Abscate Premium Member
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PostPosted: Wed Jun 07, 2017 12:37 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

Quote:
do have a slight gas smell normally, but I think I have a weep (not a leak exactly) at the fuel rail LH side,


If it will help you park this until you get this fixed, please rename the "weep"......... "flamethrower"

Posted with love - there is no such thing as a small fuel leak.
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Drzdirtbag
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PostPosted: Wed Jun 07, 2017 12:53 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

Well... Crisis averted.. As most of you thought, it was a vacuum hose off.. I just couldn't see it till I removed the cover to inspect the AFM.. Thank you all so much.. Again!! Haha
Cheers to all, and time to go for a drive..
Peace, randy..
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airschooled Premium Member
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PostPosted: Wed Jun 07, 2017 1:54 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

Woooo two for two in this thread for disconnected hoses?

Remember that VW didn't use hose clamps on the intake vacuum system anywhere- this allows hoses to pop off in the event of an intake backfire to soften the blow to the AFM flap. Leave the hose clamps in the tool box for emergencies.

(Remember when BigEmma's AFM flap was jammed shut, and it required a tow that ended up destroying their entire brake system? Embarassed )

Robbie
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curtp07
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PostPosted: Wed Jun 07, 2017 7:42 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

A poor mans "pop off valve" just like my old 911 with the early CIS that would backfire and blow the air box to bits before the "modification"...
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Wildthings
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PostPosted: Wed Jun 07, 2017 11:12 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

Yeap, the engine likely rocked backwards on shut off momentarily pressurizing the intake manifold and a loose hoses blew off. VW originally used hoses that matched the ID of the fittings they went on, i.e. a 12mm ID hose went onto a 12mm ID/13mm OD fitting offering a nice tight fit. However once the rubber of the hoses ages the fit is no longer tight and the hose may blow or even just plain fall off. Replacing all the hoses, elbows, and boots periodically when the rubbers gets hard will save endless headaches.
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ROCKOROD71
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PostPosted: Thu Jun 08, 2017 6:04 am    Post subject: Re: Engine suddenly runs terrible Reply with quote

All my hoses were replaced last year. This particular one that blew off, I will have to get a picture of, seems like the ID is the same on the hose as where it goes, there is a metal "connector" pipe used to join them, hose clamp on the hose end as well as the plastic fitting. Can on;y "tighten" a clamp around the plastic fitting so much before it breaks or cracks, which I do not want. Was wondering if it would be ok to wrap this metal pipe in electric or plumbers tape to get a tighter fit or use a mandrel or something to widen the pipe a hair> I feel like getting it in snug should help with potential vacuum leaks at that spot. Will get a picture as soon as possible.
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1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI
79SuperVert wrote:

30 years from now, the next guy may not want your girlfriend, but he may want your classic car, depending on how nice you were to it.


asiab3 wrote:

Careful guys, a petulant child can grow up to be president these days.


**winter drivers: no survivors!**rust warrior**#keepbodyshopsbusy**
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ROCKOROD71
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PostPosted: Sat Jun 10, 2017 2:29 pm    Post subject: Re: Engine suddenly runs terrible Reply with quote

So here are some pics of my hose in question:
Image may have been reduced in size. Click image to view fullscreen.


Above you can see the braided hose in my hand with a metal pipe in the end, and a hose clamp. This hose goes to my decel valve, and connects to the open plastic T fitting you see in the pic.
Image may have been reduced in size. Click image to view fullscreen.

Above you see the braided hose and pipe plugged into the T fitting. It goes in and out with not much effort, which leads me to believe air leaks here easily. Note there is a hose clamp on the plastic T fitting as well. I am hesitant to crank down on that because if the plastic cracks, thats a whole other can of worms.

Image may have been reduced in size. Click image to view fullscreen.


Another shot from the rear hatch of the hose plugged in place. The T fitting goes to the LH side of the plenum and to the LH side of the engine bay, where it exits. I take it this is for the vacuum booster brake servo? It is a hard plastic type line, not rubber.

How can I secure this hose and prevent leaks? Can I use electric tape around the metal pipe junction so I have to really twist it in lace, then tighten the clamp on the plastic T fitting? Should I widen the pipe somehow? It needs to be a more snug fit, for sure.
Thanks for any suggestions...
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1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI
79SuperVert wrote:

30 years from now, the next guy may not want your girlfriend, but he may want your classic car, depending on how nice you were to it.


asiab3 wrote:

Careful guys, a petulant child can grow up to be president these days.


**winter drivers: no survivors!**rust warrior**#keepbodyshopsbusy**
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View user's profile Send private message Gallery Classifieds Feedback
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