Fuel Pressure Readings

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fomanchu
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Fuel Pressure Readings

Post by fomanchu »

I'm testing the fp on my 86 Cabby and need some help. I have done the initial fp test (jumped fp relay) with the tester valve closed and came up 5 bar for the test. Then I removed the jumper an the fp dropped by to 1 bar in 6 min. Bentley says should be 2.5 bar in 10 min.

Next test, jumper relay and open valve and system pressure is around 1 bar. Is this telling me my Fuel Pump is bad or I do need to do add'l testing? Oh..the car is also cold.

Thanks
fomanchu 86 Cabby
fomanchu
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Re: Fuel Pressure Readings

Post by fomanchu »

DOH!! Nevermind.. found a leaky near a banjo fittin'. Gonna put a new washer on and retest.. sorry :D
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Briano1234
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Re: Fuel Pressure Readings

Post by Briano1234 »

I have had good luck over the years on my diesel by taking the copper washer off, sanding it smooth a wee bit, then polishing both sides of the fitting. Holding the washer over the flame of a torch till it changes color, take about 10 seconds or so, and re-using them.
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fomanchu
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Re: Fuel Pressure Readings

Post by fomanchu »

Thanks BrianO, I bought a hole bag of new washers and just forgot to put them on. Im fighting a hard start, hesitation on the 86 cabby I bought in dec. I've replaced plugs (ngk), wires (bosch), cap/rotor (duralast...yes i know .. i know), static check timing, replace valve cover gasket, installed new ground wires from coil to valve cover, alt to frame, hood to fender and cleaned grounds in engine from battery to tranny. I've also replaced fuel filter, cold start injector w/used, new thermoe time, all fuses with new and added a new intake fuel pump and techron fuel injector cleaner. Ive also checked for vacuum leaks around all hoses and injectors.

The car takes 3-6 cranks to start..sometimes I prime it w/the ignition switch...i can hear fp running. Once it starts it slowly creeps from like 400 rpm to 1500..PO set idle too high. Once its running, its fine until it settles down and sounds like its starved for gas. FP is not loud when running...but I can hear a slight hum. FP readings looked ok with the valve closed. Warm starts are fine.

Once I check the fuel pressure..next check is to check injector flow and replace o'rings..might as well clean them while they are out.
Was thinking of cleaning wur and fuel distributor..am I heading in right direction?

fomanchu
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Briano1234
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Re: Fuel Pressure Readings

Post by Briano1234 »

Well I will add, you never clean the grounds from frame to engine/tranny.. Just replace it and know it is good to go for a few years. I have seen more flaky issues resolved over the years by replacing the battery to frame, and the frame to engine/ground.... Keeping them clean is one thing but the intergrainular corrosion that can get in the copper after 20 years is totally amazing.
Briano

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Calimus
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Re: Fuel Pressure Readings

Post by Calimus »

Yup, first thing I do on the MK1's is make a new set of grounding cables. I get the once from Advance auto, they are twisted copper in a clear insulator. I use that for the battery to the trans and the same from the trans to the body or even something a bit smaller will work. Free the electrons and you would be amazed at home much easier trouble shooting can be.
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fomanchu
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Re: Fuel Pressure Readings

Post by fomanchu »

Ok..i guess I'll replace the ground cables from the battery to frame and frame trans. I'll keep this thread updated. Thanks for the help.
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kamzcab86
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Re: Fuel Pressure Readings

Post by kamzcab86 »

Replacing grounds is always a grand idea and you should do it regardless. However, I doubt the ground cables are the issue here because:
fomanchu wrote:The car takes 3-6 cranks to start... Once it starts it slowly creeps from like 400 rpm to 1500..PO set idle too high. Once its running, its fine until it settles down and sounds like its starved for gas... Warm starts are fine.
If the car is starting with no issues when warm, then we're dealing with a cold start and cold running problem.

Things to check/test:
Cold control pressure
Auxiliary air regulator (might not be opening)
Injectors
Cold start system (valve, relay, wiring)
Air-flow sensor plate

Also, have you gone to http://www.cabby-info.com/cis.htm and performed all procedures outlined there (including testing the OXS components)? If not, do it.
fomanchu wrote:Once I check the fuel pressure..next check is to check injector flow and replace o'rings..might as well clean them while they are out.
Was thinking of cleaning wur and fuel distributor..am I heading in right direction?
Most definitely wouldn't hurt to do all of the above. :wink:
fomanchu
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Re: Fuel Pressure Readings

Post by fomanchu »

Thanks all,

But now im dealing w/a NO start issue! :rmad: So, I have the fuel pressure gauge setup and ready to do a warm pressure test and the car wont start. It just turns over but doenst catch. I remove the gauge and put all everything back together and try again. No go! Im stumped. So I check for spark from coil..nada! Also my battery is getting weak from cranking so I put it on a charger to charge up.
Uggh!!

After charging..still no spark. So I replace coil and STILL NO SPARK! Im stumped...

:banghead:
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Briano1234
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Re: Fuel Pressure Readings

Post by Briano1234 »

Static time the thing, that is make sure that it is in time.......
Check the tests for the Hall sender.

On Cabby-info.com there are links to a static test of the Hall circuit.
Briano

Yes as matter of fact, I have the Luck o'the Irish...everything I touch turns to fertilizer of the bovine variety.
You can lead a user to a link, but you can't make him Click.... :screwy:
fomanchu
Posts: 13
Joined: Tue Jan 10, 2012 8:44 am
What year is your cabby?: 1986
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Re: Fuel Pressure Readings

Post by fomanchu »

Thanks Briano..will check Hall sender and recheck static timing..
fomanchu
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Re: Fuel Pressure Readings

Post by fomanchu »

Hmm..just finished testing switch unit, control unit and half of hall sender I get 7.33 volts from connector, but need led light to test. While im sitting thinking about what started this..the coil.
So im double checking my wiring w/bentley.. terminal 1 is negative and 15 is positive. I have the following green/black to term 1 and red/black to term 15.
Bentley looks like both black to 15 and grn/blk and red/blk to terminal 1
fomanchu
Posts: 13
Joined: Tue Jan 10, 2012 8:44 am
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Re: Fuel Pressure Readings

Post by fomanchu »

Ok...got her running again, i mixed up the wiring on the coil. So back to square one with fuel pressure testing.
So far my readings are as follows: system pressure cold 4.9 to 5 bar, control pressure cold 1 bar.
I'll get warm readings tomorrow. Im done for the day. Thanks for all your help.

PS car starts good w/new coil , but still suffers from hesitation and ruff idle.

fomanchu
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Re: Fuel Pressure Readings (UPDATE)

Post by fomanchu »

I'd like to at least post a resolution to this thread. I rarely post on forums but I really hate when only problems are posted by not resolutions. So I bought the cabby in dec with a ruff idle/cold start (crank like 10-15 times)/warm start problem (crank at least twice). I immediately got it home and replace oil, plugs, wires, cap/rotor and later the ignition coil, fp relay, and replaced all fuses. Also replaced tranny fluid as it is an automatic. Cold starting problems still exist but car ran better once it warmed up and warm start problems went away. I also had to replace return feed lines from car to tank as previous owner(s) put a botch job in.

Since I had a good baseline on ignition components I moved on to fuel. I replaced fuel filter and looked at 26 years of crude and rust on the fuel accumulator, leaky fuel lines and rusty fuel intake pipe..which means rust in the fuel system :shock: . After thinking about this I read someplace where someone suggested starting from the rear to the front w/fuel. My thoughts are always that you never know what a PO did or replace, especially w/o records. So u might as well start from new/used.

So off to ebay where i purchase a used fuel accumulator, used filler neck (these are hard to find), autohausaz (im not affiliated) for in tank fuel pump, germanautoparts (again not affiliated) for fuel pump. I drained the gas out of the tank, took a good peak and could see rust flakes and dirt on the tank bottom. So I drain the gas and clean the tank the best I can from the top. Then I replace the intank pump/fuel filler neck and give her a start. Still same symptoms, but she's not hesitating as much after the warm start.

So i take a break from fuel and install a new radiator and replace all hoses, thermostat and flush too. The old radiator was leaking and the car temp light would flash occasionally. Now the gauge barely goes to the half mark.

So the weather gets surprisingly warm here for Chicago burbs and I decide to return to fuel and check fuel injectors. I have been reading they can be cleaned. I take my fuel injector puller and pull one. I decided to try to clean using the instructions listed below, but no go..they were clogged too bad. I tried 3 cans of carb cleaner and 1 berrymans b12..still no go. So i know I have to bite the bullet and buy a set. So I cross reference the number to a Mercedes part number that matches (Mercedes 0437502047). I order injectors and o-rings and they arrive 1 week later. Of course I ended up getting sick so all work was paused...until yesterday. I install new fuel pump/used fuel distributor/replaced all fuel lines below/ also replaced fuel carrier w/one from ebay as the old one was too rusty. I also installed the new injectors, which was surprisingly very easy.

I started the car which i had to crank 5-6 times to prime the system, but once it started it hesitated still (WTH!!). I looked under the car for leaks, none, then looked in the engine and I forgot to tighten two injectors, which were leaking gas. DOH!!
I take my time tighten them all and recheck all my work, take the car of the jack stands.....and the car cranks and runs smooth!!

I know this is long, but I just want to say it wouldn't be possible w/o this site or the people who take the time to post how-to's. During my research I used the following sites, plus a Bentley Manual..

Fuel Pressure
http://www.mikegabriel.net/vw/badhabitr ... ssure.html

How to change in-tank and fuel pump (used the sealant recommended and no leaks!)
http://forums.vwvortex.com/showthread.p ... fuel-pumps

Cleaning Injectors..
http://alabbasi.com/injectors.html
http://reflectionsandshadows.com/cis-injector-cleaning/

And of course last but not least..the one site that gave me the courage to buy this car
http://www.cabby-info.com/

thanks all...still got plenty of work to do, but im enjoying it!
86 vw cabby
fomanchu
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Calimus
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Re: Fuel Pressure Readings

Post by Calimus »

Wow, thats some work. Thanks for posting up the resolution. It's always nice to know the whole process and not be left hanging. Hope to see you post more in the future and good luck with the rest of your project.
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