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Fuel pressure
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wingman
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PostPosted: Fri Jul 11, 2014 9:14 pm    Post subject: Fuel pressure Reply with quote

Can anyone tell me how to check the fuel pressure and what the number should be? I got the gauge but do not know how and where to plug it.

Thanks,
Michael
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PostPosted: Fri Jul 11, 2014 9:49 pm    Post subject: Reply with quote

I'm a Type 3 guy but I bet its the same. Between two injectors is a tee with a small screw/metal gasket sealing a hole. Unscrew and save the screw and gasket, and connect your gauge hose there. Use a clamp of course. Set to 28-30 psi. Then unhook the gauge (to a likely small spray of gas from residual pressure) and carefully put the screw back but don't strip it.
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wingman
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PostPosted: Sat Jul 12, 2014 9:04 pm    Post subject: Reply with quote

Thanks! I am able to check the fuel pressure following your instruction. The pressure looks good. Now I have to figure why it runs only 15 mpg with good fuel pressure and MPS Sad
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raygreenwood
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PostPosted: Sun Jul 13, 2014 7:01 am    Post subject: Reply with quote

There are a lot of potential issues behind what you just said. If you can give us a bit better information we can probably help find out why the milage is so bad. To start with....check these items:

1. There can be "0" vacuum leaks no matter how minor. A vacuum leak causes the mps to read any leak as a throttle opening. Following is a list of items that must be checked all hoses and lines must be clamped including runner boots.

Vacuum advance lines at tb
Tb to plenum o-ring
Runner to plenum boots
Runner to phenolic block joint
Phenolic block to head joint
Injector o-rings (the stock injector seals suck. Use CIS injector seals)
Mps vacuum line to plenum joint
Mps vacuum line to mps
Deceleration valve vacuum lines (if you have one)
Deceleration valve adjustment
Oil breather chimney gasket
Oil filler funnel gasket
Valve cover gaskets
Pushrod tube o-rings (a serious oil leak in pushrod tubes can create a vacuum leak)
Plenum vacuum line to throttle dashpot to transmission modulator valve (if you have an automatic transmission)
Vacuum advance unit and vacuum lines to tb
Auxiliary air regulator operation, vacuum lines, specialty 3 way rubber boot to plenum (which iz usually cracked and must be clamped as it commonly leaks)
The vacuum hoses from each head rocker box to the flame trap (the three way connector) and its hose to the air cleaner

Very importantly.....check the 12mm hose from the oil chimney to the plenum. It has a 90 degree elbow at the plenum that must be clamped. Also the nipple it connects to at the oil breather chimney is actually a pcv valve. It has a nylon ring nut on the outside and removes via a D-shaped plug from the inside. These valves are almost always cracked and leaking....and were defective in design. They dump case gas into the plenum right at the mps hoz ed area causing out of sync enrichment. Many of us have found that pulling the sealing disc out of the pcv valve and putting a 3-4mm fixed orifice in line works much better and allows closer adjustment of the mps.

There are other mechanical things to check but all of the above must be checked and fixed first.
Also...you note that mps is "good".....I assume you mean it has correct resistance and no vacuum leaks.....but is it adjusted properly?...and doez it still have the aluminum adjusting plug in the back?
Ray
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wingman
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PostPosted: Sun Jul 13, 2014 4:58 pm    Post subject: Reply with quote

Hi Ray,

Thanks! Is there a place I can get the diagram of the vacuum lines listed below? I have no idea about what those lines are and the correct size to get.

There are some problems may be worth mentioning:

1. The pushrod tubes do leak oil which I plan to fix next.
2. There was no pressure in the fuel line when I opened the test outlet yesterday. Not sure whether it is normal.
3. There are oil residues (maybe leaks) on the hose from oil breather chimney to the plenum.

And yes, I am only able to check that MPS hold the vacuum. I have no idea how to adjust it and could use some pointers here.

Thanks,
Michael
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wingman
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PostPosted: Sun Jul 13, 2014 5:08 pm    Post subject: Reply with quote

Forgot to mention that I have a leaky injector to be replaced when I get one. Can I replace it without pulling the manifold as Haynes suggested?

Thanks,
Michael
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raygreenwood
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PostPosted: Sun Jul 13, 2014 9:41 pm    Post subject: Reply with quote

There are probably posted diagrams somewhere on the Samba.....time to buy a book. The best one to start with is the Haynes green manual for 411 and 412 for 1968-74 and includes the 1.7 and 1.8 engines. Its manual # 091. You can find them on amazon and ebay for less than $20 usually.

You listed your problem already. A leaking cylinder injector or cold start valve will cut your milage in half....and yes thats where your fuel pressure is bleeding off to. Quit drivi g or running the engine until you have that fixed.....it WILL wreck your engine by putting fuel in the oil, carbon on the valves, washing lubricant off the cylinder wall....and will burn up the muffler in a couple thousand miles or less.

As for which hoses to clamp .....if its a hose in a 411 or 412....it does one of two things...carry fuel or vacuum. You are allowed 0 leak of either. Clamp them all.
The rule of thumb with hoses and fuel lines....and this is dead serious.....if you did not replace any hose or tube yourself within the last two years....or have specific receipts for specific hosez being replacex by the previous owner within that time period.....replace them.
We havnt even started on the hoses coming crom the gas tank and fuel filler that commonly leak and will lose gallons of fuel and rust out the front end.

Trust me......if you have just aquired this car and are trying to piecemeal things while you drive it......it will eat your lunch. Awesome cars.....very high maintenance with age....and uncorgiving if you let it go too far.
Ray
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wingman
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PostPosted: Mon Jul 14, 2014 7:48 pm    Post subject: Reply with quote

Hi Ray,

Thanks again. I do have the Haynes manual but cannot find a clear diagram there. I will read more in case I missed anything.

Can you please let me know whether I need to pull the manifold to replace the injectors per the manual? It seems I can get them out with the manifold in place.

Thanks,
Michael
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raygreenwood
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PostPosted: Mon Jul 14, 2014 9:24 pm    Post subject: Reply with quote

No you do not need to pull the manifolds. It takes a bit to get around on these cars.
Its a little harder with a wagon because the surrounding sheet metal is so tight......but I generally use a 10mm wrench or a 1/4 ratchet with a short 10mm socket to remove the 10mm nut holding the injector retainer. Its easiest to take boyh injectors loose on the side you are working on. If the injectors have never had new lines.....rare after 40 years....you should have about 3" of fuel line connecting each injector to the main fuel line.....with a screw clamp at the injector and at the main. If either end has a crimp clamp, worm drive clamp....or if the injector end has a metal band/collar.....it is far past time to remove the jnjector...cut off the collar (called a ferrule) put new line on and proper fuel injection clamps.
Check all of your injectors. Pull them out and put new grommets and tip seals on and check for leaks.

If your car is a four door or two door sedan.....remove the two philips screws that hold the big plastic intake mouth jn, remove the plastic screen, disconnect the two wires and two hoses to the blower, peel the bellows loose and lift yhe plastic intake out. Disconnect the air cleaner trunk as well. Then you can lean into the bay to reach the injectors. Ray
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wingman
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PostPosted: Tue Jul 15, 2014 9:30 pm    Post subject: Reply with quote

Hi Ray,

Thank you so much for the detail instructions. Now is time for me to score some good injectors! Will update after I get it fixed.

Thanks,
Michael
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PostPosted: Wed Jul 16, 2014 7:54 pm    Post subject: Reply with quote

No to crash the thread but I have injectors (used) if you need some. What is the part # on yours?
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wingman
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PostPosted: Sat Jul 26, 2014 5:28 pm    Post subject: Reply with quote

Thanks. I am able to find a good injector and put it in today. No leak so far and let's see whether this helps with the mileage.

Is there a way I can check whether the cold start injector is leaking without take it out? I found the bottom screw is impossible to reach without taking out the distributor.

Thanks,
Michael
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raygreenwood
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PostPosted: Sat Jul 26, 2014 6:07 pm    Post subject: Reply with quote

Really....you can only, test whether its leaking without taking it out...... after for sure knowing all is is not leaking....meaning pump check valve, regulator and all four injectors must be sound.

This is actually pretty easy. Do not loosen the distributor clamp that allows you to adjust timing. In fact make sure its tight. Instead remove the 13mm nut and washer that se urea the clamp to the engine block. Unclio the cap and the 3 wire trigger plug and the power wire to yhe distributor and just pull it out and lay it to the side.

DO NOT turn the engine while you are doing this. Have some gasket paper, an e, acto knife and some gasket shellac like indian head handy.

Pull the injector and hot wire the pump and see if it leaks.

Just put the distributor clamp back on the stud....and you are done wiyhout disturbi g timing.

Or alternately....I think I have removed that screw becore with an offset ratchet and a 1/4" drive bit but its been a while. Cant remember if it was succesful. But typically I pill the distributor at the drop of a hat. Its no big deal. Ray
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wingman
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PostPosted: Sat Jul 26, 2014 10:29 pm    Post subject: Reply with quote

Hi Ray,

How do I hot wire the pump? I thought I can just turn on the ignition and the pump should work?

Thanks,
Michael
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raygreenwood
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PostPosted: Sun Jul 27, 2014 6:45 am    Post subject: Reply with quote

If you turn ok n the ignition. ...it only charges the pump for 3 seconds. If you are leaking in the system....typically there will not be much pressure for long this way. Yes...there will be enough to see if the cold start knje tor tip is wet or dripping.....but not much else. Yes...you can cycle the key again when you finally get the injector out and positioned.....but the risk of developing is that you accidentally turn the key all the way and turn the engine over and disturb timing.
There is another thread here that notes to hot wire at the fuel pump relay to a hot point on the fuse block.....but to those who dont know their way around the fuse block and relayw well yet.....its easiest to get two 8' lengths of wire with gator clips on on ne end and female connectors on the other. Pull the plug out of the pump and note that it is marked + and -.
Connect the clips to the battery first and one connector to the pump first.
Then connect the other wire and the pump will run constant without turning the key.

I noted to connect the wires to the battery first....because there will be a spark when connect the last wire. You should have all of your injectors out....might as well check them all and replace seals if you are checking for leaks. Might as well check injector spray patterns at the same time.

Do this outdoors! Keep a fire extinguisher handy. Wait until any expended fuel has evaporated before c pulling wires. You can get a $1.00 lamp cord switch to put into one of the wires up near the fuel pump that keeps sparking low and safe. Ray
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wingman
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PostPosted: Mon Jul 28, 2014 10:23 pm    Post subject: Reply with quote

Wow, that sounds really complicated. How can i get to the 13mm nut that holds the distributor? Mine is hidden under the vacuum unit and I cannot figure out the way to reach it.

Thanks,
Michael
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PostPosted: Tue Jul 29, 2014 7:54 am    Post subject: Reply with quote

As you will find working on these cars....the term hidden nut....is a relative term Laughing
There are a few contortional bits and pieces you must master.

Typically you can remove that nut with a little p atience and a short 13mm wrench or a long ratcheting 13mm wrench. If memory serves the wrench handle will be roughly laid out towarfs the front of the vehicle.

Actually.....if you have a timing light to retime the vehicle you can do this even easier. Pull the distributor cap off and make a mark on the center of the rotor tip with a sharpie marker and then make a corresponding mark on the distributor housing so you can get it close enough to start and run so you can retime it when you get the distributor back in.

The fuel pump jumper is simple. You need 2 lengths of about 8 feet of wire as noted with crimped on female connectors. Just pull the plug from the fuel pump and plug in the jumper wires ...mind the polarity marked on the female plug of the pump....and connect to the battery. At that point you pump should run constant.

As for removing the screws that hold the cold start injector in.....even with the distributor out...an offset 90° ratecheting screwdriver still helps. Stanley makes one for about $5 that is adequate and can be had at many hardware stores or Home Depot. ..but even better for a little more money for future use is a 1/4" ratchet with a phillips bit.

Once you get the distributor out...plug the hole with a paper towel...NOT a rag. You dont want rag lint in the hole. The screws from the cold start injector are just too prone in their location of being dropped in the distributor bore. Keep a magnetic pick up handy just in case.
Once you have the screws out and are finished with the test.....go to the hardware store and get new screws.....and dont get phillips head. Get hex head screws. This way you can remove them with a simple ratchet and metric socket bit usually without removing the distributor in the future. Ray
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wingman
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PostPosted: Sat Aug 02, 2014 11:41 pm    Post subject: Reply with quote

Thanks. It has been a busy week and I did not have the chance to work on the car. Refueled today and found the mileage only improve a little bit (~17 mpg) after replacing the leaky injector Crying or Very sad . I have done more freeway driving so there are definitely other causes.

Now the engine always dies when starting from cold for the first time. Then it starts right up afterward. But it still likes to stall before warming up. Sounds like I do have problem with the cold start valve but it should not be leaking?

Thanks,
Michael
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PostPosted: Sun Aug 03, 2014 7:57 am    Post subject: Reply with quote

VW's don't run good when they are cold. Just feather the throttle to keep it running for the first 5 miles & don't expect perfection. I'm installing a Fuel Primer Button from Jim Adney to stop having to cycle & wear out the key/ignition switch!
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raygreenwood
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PostPosted: Sun Aug 03, 2014 9:07 am    Post subject: Reply with quote

Mike Fisher wrote:
VW's don't run good when they are cold. Just feather the throttle to keep it running for the first 5 miles & don't expect perfection. I'm installing a Fuel Primer Button from Jim Adney to stop having to cycle & wear out the key/ignition switch!


Mike I know where you are coming from. ....but I dont agree with that unless it's qualified a little bet
The qualification is that OLD VW's with lots of small parts worn don't run well when cold.

If your engine is moderate to high miles ...about 70k miles and up...yes its common that the throttle may need some feathering right after start up. Stalling....no.

These cars when new had no issues starting all the down to below 0. I'll try not to turn this into a rant.
As these engines age....lower compression, worn valves etc....the vacuum signature changes. On D-jet this is especially critical because you will need to carefully adjust the mps to compensate for this. On L-jet...not so much but as compression drops....initial starting takes a lot more cranking due to the flap switch issue and the changes caused to inutal flap movement.

But the biggest group of issues on old vw's..which is a whole pile of small but significant items....is the harness connectors, distributor wear, vacuum leaks around tb runner boots etc., tvs wear, high trigger points resistance, leaky FPR, leaky fuel pump check valve, old or non linear TS 1&2, poor valve adjustment and leaky valves, worn and out of calibration AAR bi-metall8c coils on early type 3 and dead heater coils in later type 3 and 4 AAR's...and the two largest issues of
the group......the lack of will to properly adjust the MPS to the current vacuum condition and the insistance on keeping on using 40+ year old fuel pumps with poor efficiency which causes unstable fuel pressure due to volume issues.

I can assure you that if you are willing to take the time to do EVERYTHING required.....and its not really Expensive. ...just time consuming and tedious. .....your type 3 and 4...especially with D-jet.....will fire on the first 360° revolution (one of the few carw capable of soing so due to paired injection)......and will run and idle flawlessly like it did when new...right down to 0F. Yes...it wont have full power until it warms up some...but feathering yhe throttle...no...it whould not be necessary if its adjusted right and everything else is tight. Just sayin..... Ray
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