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Narch22 Samba Member
Joined: August 30, 2017 Posts: 7 Location: Illinois
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Posted: Wed Aug 30, 2017 5:33 pm Post subject: Re: Official Fuel injection questions thread |
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I have a 1978 super with fuel injection. We believe the AFM/MAS needs replacing, but we cannot find a place to purchase one. I realize most, if not all, will be a re-manufactured unit, but it's better than a non-functioning original. See my recent post for pictures and the full story.
https://www.thesamba.com/vw/forum/viewtopic.php?t=685702 |
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garyt Samba Member
Joined: June 14, 2015 Posts: 763 Location: Burgundy
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Posted: Thu Aug 31, 2017 3:45 am Post subject: Re: Official Fuel injection questions thread |
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It may need replacing but they are quite robust. For instance I assumed because of wear to the track by the wiper arm mine was no good, but actually it was fine. My problem was a bad connection where the arm in the potentiometer switches off and on, so the car assumed it was at idle all the time (causing low power).
If this is not it, it could either be running too rich or too lean.
You should try leaning it out by turning the toothed gear. See if that helps. Then enrich it by going the other way. Paint a white dot on the gear so you know where it was at the start. You might also clean the whole AFM shebang, it helps a lot.
You must have no vacuum leaks for any of this to work. |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51057 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Thu Aug 31, 2017 7:22 am Post subject: Re: Official Fuel injection questions thread |
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garyt wrote: |
You should try leaning it out by turning the toothed gear. See if that helps. Then enrich it by going the other way. Paint a white dot on the gear so you know where it was at the start. You might also clean the whole AFM shebang, it helps a lot. |
I don't recommend messing with the AFM cog or any other adjustments, it ran fine before so find what other component caused it to change suddenly first. AFM adjustment should only be performed as a last effort and the results must be checked with a AFR meter as you go, poking at it blindly can burn valves and cause other permanent engine damage. _________________ 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
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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garyt Samba Member
Joined: June 14, 2015 Posts: 763 Location: Burgundy
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Posted: Thu Aug 31, 2017 8:58 am Post subject: Re: Official Fuel injection questions thread |
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From reading the other thread I assumed they had boiled it down to the AFM being the problem.
Apart from the circuit board it is a mechanical device and simple to adjust, or at least it is better than buying a new recon one that also does not work (as I have read on here). |
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garyt Samba Member
Joined: June 14, 2015 Posts: 763 Location: Burgundy
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Posted: Thu Aug 31, 2017 9:46 am Post subject: Re: Official Fuel injection questions thread |
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By the way, I read (on a Morgan blog, which have the same AFM) that the little wiper arm should be set at the first pointy bit on the circuit board. Yours does not seem to be set there. Maybe someone else already tinkered with it. Who knows, I don't know if this is correct but it works for me and gives the correct fast idle on cold start up. |
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garyt Samba Member
Joined: June 14, 2015 Posts: 763 Location: Burgundy
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Posted: Thu Aug 31, 2017 9:56 am Post subject: Re: Official Fuel injection questions thread |
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Busdaddy:-
The poster said -
"When purchased, the car did not start, but previously ran. The previous owner said he could not get the car over 10mph, even when at full throttle."
So apparently it was not ok before (unless you know other info) and suddenly changed. |
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cuzzinit Samba Member
Joined: August 31, 2012 Posts: 158 Location: Berea KY
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Posted: Thu Sep 14, 2017 3:49 pm Post subject: Re: Official Fuel injection questions thread |
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Bought a 78 vert in NorthDakota. Driven few times in three or four years. Ran good when i started, great with fresh gas. I ran out of gas, and not far after idle got rough eventually not at all. I replaced fuel filter and still no idlebut ran good all way home. Now its hard starting.... i'm going to replace fuel filter again and some of vaccum hoses look old, so i'll replace
Where should i start digging next to find out whats wrong ? |
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unclewede Samba Member
Joined: May 01, 2015 Posts: 374 Location: Oxnard, CA
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Posted: Fri Sep 15, 2017 8:04 am Post subject: Re: Official Fuel injection questions thread |
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cuzzinit wrote: |
Bought a 78 vert in NorthDakota. Driven few times in three or four years. Ran good when i started, great with fresh gas. I ran out of gas, and not far after idle got rough eventually not at all. I replaced fuel filter and still no idlebut ran good all way home. Now its hard starting.... i'm going to replace fuel filter again and some of vaccum hoses look old, so i'll replace
Where should i start digging next to find out whats wrong ? |
You ran it dry and now it's rough? Injector(s) plugged. |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51057 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sat Sep 16, 2017 9:25 am Post subject: Re: Official Fuel injection questions thread |
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A car that's only been driven 3-4 times in the last few years could have bad gas and crap in the tank, modern gas doesn't store longer than 6 months.
You could have damaged the fuel pump when it went dry, the filters on the injectors may be plugging up, there could be crap in the pickup in the tank or stuck in something like the pressure regulator, a fuel pressure test might tell you a few things.
Good idea starting with vacuum hoses and seals, it could just be a coincedence, but if it's been running on old gas sending the injectors out to Cruzin performance, Witchhunter or you local Bosch injection service dealer for a cleaning and test can't make it any worse. _________________ 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
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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cuzzinit Samba Member
Joined: August 31, 2012 Posts: 158 Location: Berea KY
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Posted: Sat Sep 16, 2017 3:41 pm Post subject: Re: Official Fuel injection questions thread |
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unclewede wrote: |
cuzzinit wrote: |
Bought a 78 vert in NorthDakota. Driven few times in three or four years. Ran good when i started, great with fresh gas. I ran out of gas, and not far after idle got rough eventually not at all. I replaced fuel filter and still no idlebut ran good all way home. Now its hard starting.... i'm going to replace fuel filter again and some of vaccum hoses look old, so i'll replace
Where should i start digging next to find out whats wrong ? |
You ran it dry and now it's rough? Injector(s) plugged. |
doesnt want to idle, seems to run good since i changed fuel filter..... |
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cuzzinit Samba Member
Joined: August 31, 2012 Posts: 158 Location: Berea KY
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Posted: Sat Sep 16, 2017 3:54 pm Post subject: Re: Official Fuel injection questions thread |
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busdaddy wrote: |
A car that's only been driven 3-4 times in the last few years could have bad gas and crap in the tank, modern gas doesn't store longer than 6 months.
You could have damaged the fuel pump when it went dry, the filters on the injectors may be plugging up, there could be crap in the pickup in the tank or stuck in something like the pressure regulator, a fuel pressure test might tell you a few things.
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it was given fresh gas everytime driven. And ran good when i started, fuel gauge read 1/4 tank when i ran out and the problems began not long after.
The gas tank looks recent, however the filler hose is not and fuel pump doesnt look as new as tank, but considering the location..... i might replace it anyway just to do it. |
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garyt Samba Member
Joined: June 14, 2015 Posts: 763 Location: Burgundy
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Posted: Sun Sep 17, 2017 1:50 am Post subject: Re: Official Fuel injection questions thread |
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Suggest clean everything and replace all hoses that look/feel old.
When you run them dry, any crap in the tank goes into the pipes and filter (if lucky), but I have had stuff that gets past the filter, also stuff stuck in the bend of the tube as it comes out of the tank. There is an outflow and an inflow tube. Get some plastic fuel cut off pliers, they are great for stopping the fuel for checking the tank outlets, which is not hard, you need to lift up the tank a bit and support it. However, in order to check it propeerly you may need to take it out completely, which is not so hard either. Label everything and be careful for safety of course.
If you suspect, after all this, that it's the injectors, you can try to clean them yourself before sending them off, the bosch manual says they get buildup of varnish on the pintle tips that curves around, and this can be gently got off with carb cleaner as a DIY job. Also what solved my problem was doing this plus tapping them each on a hard surface, with the protection caps on of course and not too hard. This can dislodge a sticking injector with a bit of luck. |
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cuzzinit Samba Member
Joined: August 31, 2012 Posts: 158 Location: Berea KY
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Posted: Mon Sep 18, 2017 6:05 pm Post subject: Re: Official Fuel injection questions thread |
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Thx, for the replies. Next time i can work on it, i intend on changing vac lines, fuel filter and possibly pump as well as some hoses. If i dont order new fuel pump, can i get by with spraying cleaner through or would that just be a wasted effort..... |
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garyt Samba Member
Joined: June 14, 2015 Posts: 763 Location: Burgundy
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Posted: Mon Sep 25, 2017 11:25 am Post subject: Re: Official Fuel injection questions thread |
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Well I would change the filter, see what's in it, and then try the car. Spraying stuff in the pump probably wont do much. You can shake it while its off, see if anything falls out. There are tests you can do reported on here, try a search. I read somewhere that running the car with a little bit of two stroke oil in the fuel can clean the injection system. Best thing is change all old hoses and the filter first I reckon. |
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cuzzinit Samba Member
Joined: August 31, 2012 Posts: 158 Location: Berea KY
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Posted: Sat Oct 14, 2017 9:37 am Post subject: Re: Official Fuel injection questions thread |
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I drained the fuel tank to see what, if any thing was in there. Changed filter and ck pump for debris.
It still doesn't idle, but runs.
Not sure what to do next. But going to look at plugs and valve adj while i'm at it....
Suggestions ? |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51057 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sat Oct 14, 2017 9:43 am Post subject: Re: Official Fuel injection questions thread |
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cuzzinit wrote: |
I drained the fuel tank to see what, if any thing was in there. Changed filter and ck pump for debris.
It still doesn't idle, but runs.
Not sure what to do next. But going to look at plugs and valve adj while i'm at it....
Suggestions ? |
A full tune up including a valve adjustment and compression test is always time well spent, after that find the vacuum leak with this: https://www.thesamba.com/vw/forum/viewtopic.php?t=620083&highlight=smoke+tester _________________ 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
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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cuzzinit Samba Member
Joined: August 31, 2012 Posts: 158 Location: Berea KY
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Posted: Sat Oct 14, 2017 9:54 am Post subject: Re: Official Fuel injection questions thread |
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I drained the fuel tank to see what, if any thing was in there. Changed filter and ck pump for debris.
It still doesn't idle, but runs.
Not sure what to do next. But going to look at plugs and valve adj while i'm at it....
Suggestions ? |
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VW_Jimbo Samba Member
Joined: May 22, 2016 Posts: 9879 Location: Huntington Beach, CA
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Posted: Sat Oct 14, 2017 10:09 am Post subject: Re: Official Fuel injection questions thread |
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Can you do a volume check on the injectors? Maybe one of them is clogged. _________________ Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
TDCTDI wrote: |
Basically, a whole bunch of fuckery to achieve a look. |
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
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Root_Werks Samba Member
Joined: December 31, 2007 Posts: 784 Location: San Juan Islands
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Posted: Tue Oct 17, 2017 8:59 am Post subject: Re: Official Fuel injection questions thread |
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1976 Std Bug - Large crankcase breather hose:
The original one crumbled and leaked. I've tried a few different hoses, but they all kink. I even purchased one with one 90 degree bend molded which helped, but still kinked as it rounds the alternator.
This causes the crank to build up pressure and spit oil from the pulley.
Anyone have a good source for a proper, molded breather hose? _________________ When I set my timing, why do I flush, then take a pee? |
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cuzzinit Samba Member
Joined: August 31, 2012 Posts: 158 Location: Berea KY
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Posted: Wed Oct 18, 2017 4:27 pm Post subject: Re: Official Fuel injection questions thread |
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VW_Jimbo wrote: |
Can you do a volume check on the injectors? Maybe one of them is clogged. |
i guess not since i not sure what a volume check is....
and now that i took the plastic tube off going from the plenum ? to throttle body, i'm not sure how it works and having trouble finding diagram or video
to show what things are. |
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