VW Type 3 EFI fuel pumps

[jaywithtype3]

Need expert on fuel pumps for VW Type 3 squareback fuel injected (EFI).
I got 2 fuel pumps, one Bosch & one after-market (no id), & neither makes pressure from center=output port. Bosch(#0580463005 long-listed for my cars 1968 & later) makes up to 40 psi from relief port (next to cap) & good flow. Other pump same until it froze in half minute & wouldnt turn (why?). On both pumps, air pressure will trip internal valve to blow air from both ports. But fuel wont come out center port even if block relief.
Have dissembled old pump to study all internals & discovered these normally have fuel inside motor, somehow brushes work without blowup (so why would it stop running?). Have several books covering EFI system. A past replacement pump of same shape & structure worked with original hose hookups. Original VW pump had different shape & maybe valve structure. Has order of ports been reversed without notice? Can i run car on relief-port fuel reliably, & block center port or return it to tank? This BOsch fuel system is same as used on Porsche 911 (& later?). Pump is shown on ebay.
Can a 2-port pump (in & out) be used reliably on this system, which normally regulates pressure & returns overflow to tank? JC Whitney lists some. What alternatives to expensive, unavailable, or fast-failing 3-port pumps have people found and used reliably?
Excuse length & my problems typing. Have much system info to trade. Can be week or more before i can check for response by forum or email.

[Jadewombat]

Not sure if this helps answer your question.

[Marc]

The recirc passage is there to ensure that the pump is always cooled & lubricated by fuel. You should never run a roller-cell pump "dry" as it will be destroyed in short order - always hook up some houses routed to a fuel can when bench-testing. A quart of gas is plenty (and of course you'll do this outdoors with an extinguisher handy).

The "mixture" inside is too rich to burn - the only time there's any risk of internal combustion is when the pump is nearly dry.

[jaywithtype3]

thanks to jade & marc from jaywithtype 3; yes i noticed internal fuel passage in old pump. But i have worked well beyond what you covered, & still mystified. Anyone else dealt with above mysteries?

[raygreenwood]

Need expert on fuel pumps for VW Type 3 squareback fuel injected (EFI).
I got 2 fuel pumps, one Bosch & one after-market (no id), & neither makes pressure from center=output port. Bosch(#0580463005 long-listed for my cars 1968 & later) makes up to 40 psi from relief port (next to cap) & good flow. Other pump same until it froze in half minute & wouldnt turn (why?). On both pumps, air pressure will trip internal valve to blow air from both ports. But fuel wont come out center port even if block relief.
Have dissembled old pump to study all internals & discovered these normally have fuel inside motor, somehow brushes work without blowup (so why would it stop running?). Have several books covering EFI system. A past replacement pump of same shape & structure worked with original hose hookups. Original VW pump had different shape & maybe valve structure. Has order of ports been reversed without notice? Can i run car on relief-port fuel reliably, & block center port or return it to tank? This BOsch fuel system is same as used on Porsche 911 (& later?). Pump is shown on ebay.
Can a 2-port pump (in & out) be used reliably on this system, which normally regulates pressure & returns overflow to tank? JC Whitney lists some. What alternatives to expensive, unavailable, or fast-failing 3-port pumps have people found and used reliably?
Excuse length & my problems typing. Have much system info to trade. Can be week or more before i can check for response by forum or email.

The type 3/type 4 (and others) three port D-jet pump is phenomenally reliable. If its kept clean and rust free 30 years is no problem. A few things to bear in mind when testing

1. The polarity of power (+/-) must be strictly observed. What you are seeing can happen when the pump runs in reverse.
2. If there is no flow of any kind and no pressure from the D (center port) and you have it from the other ports...and the pump is running in the correct direction/polarity.....then a.) you either have a restriction in the D port or .b) you have a damaged relief valve at the "R" port. This is very common. The relief valve port should NEVER be open or flowing any fuel when you are just running the pump with open hose ports. It should open at approximately 65-70 psi and bypass to return lines to keep from damaging the pressure head o-ring.

If there is fuel flowing from the R port when all else is well.....then you have at the minimum a leaking check ball/bad port/ broken spring. Very common as rust can destroy the ball, seat or spring.

One giveaway is the fuel flowing from the S port and the R port...but none out of the D port. Again...if there is no restriction or plugged port coming from the roller cell chamber to the D port.....and polarity is correct......this generally means that bot only do you have the bad relief valve as mentioned above....your main roller cell chamber is shot. If the cell has surface rusted or been run dry for considerable amount of time...it wears metal away making pressure leak from cell to cell across the chamber...thus going out the larger holes (paths of least resistance) of S and R (which can only happen at R with a bad relief valve).

When you opened the pump....if there was even light surface rusting the pump can be shot.

Also a word about testing. These must be tested with the proper D-jet regulator or similar with a real fuel loop. If you attempt to dead head these pumps to a closed line with a gauge attached for test purposes...they will almost instantly give nearly "0" flow out the D port and pop the R valve and bypass fuel...and the excessive pressure across the chamber may even push fluid out the S port.....and....if the pump was healthy...it invariably blows past the o-rings at the pressure head....and usually may never seal again if the o-ring was aged....requiring new (and very specific) o-rings.

So....if you are testing with a deadheaded pump it can very well give you the same symptoms you have....no real pressure at D, bypass at S and R. Ray

[jaywithtype3]

thanks ray. Read my story carefully: those are two NEW pumps, one real Bosch, one unmarked. Used proper test loop with all needed parts, for 28 psi & return, & no dry runs. Used soft start & full 12v battery starts. Mystery remains: no fuel from D under any conditions. Note air moves the valve, fuel wont, and pump does move fuel out R.
Please dont confuse with old pump, on which i would like guidance reclosing, resealing with what, and reclamping, unless hopeless. no rust but valve was sticky, not a reason why motor would not take current and turn. Studying its inner functions showed clearly that valve is shut, allowing no fuel out D (unless pressure pushes open), else goes out R.
Note all pumps have configuration as Marc showed above. Original 1968 pump was somewhat different in valve structure. No valves are working as you say, but maybe should be.
More later, week or so, if you are anyone has more answers.

[raygreenwood]

In the next few days I will take one of mine apart and take pictures. On the pump that is not pushing anything out of the D port but is pushing out the R port.....it sounds like it was probably a rebuild and they got either the rotor or cells in the wrong position...or they are very out of spec. It sounds like there is pressure across the whole roller cell system internally.... in other words...bleeding across the rotor. Its also possible that the pump head was installed out of position...but I would think that would be easily seen. Ray

[jaywithtype3]

raygreenwood, see general type 3 forum for my replies on your valuable observations.
thanks from jaywith type3 with fuel pump mysteries