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KoMbI19 Samba Member
Joined: November 15, 2013 Posts: 148 Location: Cincinnati, Ohio
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Posted: Fri Sep 21, 2018 6:13 am Post subject: Fuel Injected Rabbit Slow Start When Hot |
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Hey All,
Just bought my first antique FI VW last month, and its been a blast. 1982 Rabbit convertible with 38k on it, nearly mint condition. Runs like a top on the road with a little bit of a rough/low idle that jumps up and down from 800 to 600 RPM every few seconds. Never stalls out, just fluctuates.
Though lately after sitting after a drive anything over an hour I've noticed it cranking longer and longer before catching and firing. Last night it cranked for at least a minute (on and off), foot fully off or fully on the gas, no start, hardly any firing. New cap, rotor, plugs, and leads. I also swapped out the nasty oil soaked air filter and ran fuel system cleaner through it. I'm about to swap out the ignition coil for a higher rated one, and then the fuel filter. That's my next step. Any tips for diagnosing the FI system to rule that out or make adjustments?
Thanks!
-jd |
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TDCTDI Samba Advocatus Diaboli
Joined: August 31, 2013 Posts: 12815 Location: North Carolina
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Posted: Fri Sep 21, 2018 6:49 am Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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Probably a vacuum leak. Check intake boots at fuel distributor & throttle body, then for any of the small hoses, listen for hissing sounds. If none can easily be found, you might want to have a smoke test done to see where they're at. _________________ Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.
GOFUNDYOURSELF, quit asking everyone to do it for you!
An air cooled VW will make you a hoarder.
Do something, anything, to your project every day, and you will eventually complete it. |
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Butcher Samba Member
Joined: December 05, 2015 Posts: 1285 Location: Right Here
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Posted: Fri Sep 21, 2018 7:24 am Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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I too recommend a smoke test. You'll probably have to pay for that test. I would ask the mechanic to be present when it is done. That way you can see for yourself what needs to be fixed.
Fuel pressure tests should be done too. If you do not know how CIS works, you might as well start reading up. |
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KoMbI19 Samba Member
Joined: November 15, 2013 Posts: 148 Location: Cincinnati, Ohio
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Posted: Fri Sep 21, 2018 7:35 am Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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My old shop has a smoke test machine, I'll hook it up this weekend and test it. Hadn't considered that. _________________ 1972 Karmann Ghia Coupe- all stock
1982 Rabbit Convertible FI- all original
2006 Chevy Colorado Z71- 215k and still kicking! |
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ps2375 Samba Member
Joined: April 24, 2014 Posts: 2471 Location: Meridian,ID
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Posted: Fri Sep 21, 2018 11:01 am Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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Sounds like the WUR is getting old. It is that thing mounted to the front of the block next to the oil filter flange. They do have remans available (or they used to be, but very expensive). That item was the main reason I converted my last Rabbit to MegaSquirt. Never had a hot start issue again. |
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racer23 Samba Member
Joined: May 14, 2014 Posts: 2 Location: Gary In
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Posted: Thu Jan 16, 2020 10:13 pm Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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injectors are leaking when the car sets. look on ebay for a CIS Hot start book. |
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volksworld Samba Member
Joined: November 26, 2011 Posts: 2525 Location: formerly NY currently NC
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Posted: Fri Jan 17, 2020 8:02 am Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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i agree on the warmup regulator...but you need the proper pressure gauge setup to test it...injector seals dry out on these engines and cause vacuum leaks...you can pull the injectors (little puller hook shouldnt be expensive) and raise the plate on the air cleaner housing under the big rubber boot (pump relay jumped) to check your spray pattern and see if they drip when closed( disclaimer...dont set yourself on fire)...the tolerances on CIS stuff is very precise and dirty fuel can really screw things up... iirc there was also a check valve on the nose of the fuel pump that held pressure in the system on shutdown so the fuel wouldnt boil off in the lines and make starting hard...you basically need the same gauge as i mentioned before for the wur....a varying idle speed is usually a lazy oxygen sensor taking too long to react so the idle goes up and down as it makes the mixture too rich, too lean....get a bently book as it has the FI troubleshooting procedures...compression test wouldnt hurt either....iirc thats still a solid lifter engine and since adjustment required a couple special tools and a shim kit it didnt get done by an average owner...you also need a duty cycle meter (some old dwell meters will work) to adjust the idle mixture properly....but if everythings working properly you can pretty much adjust the CO by ear with the 02 sensor disconnected...fixed a ton of these cars but my major problem was that bosch discontinued virtually everything you needed to fix them during the recession and i never found a reliable source for rebuilt stuff |
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Butcher Samba Member
Joined: December 05, 2015 Posts: 1285 Location: Right Here
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Posted: Fri Jan 17, 2020 8:11 am Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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Looking at the OP original post, he's probably got it resolved or sold by now. |
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volksworld Samba Member
Joined: November 26, 2011 Posts: 2525 Location: formerly NY currently NC
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Posted: Fri Jan 17, 2020 7:00 pm Post subject: Re: Fuel Injected Rabbit Slow Start When Hot |
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damn...cant believe some other fool answered a year and a half later and i never noticed the date....i really hate when that happens |
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