VW type 3 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.

[aircooledtechguy]

I would highly recommend updating to a modern 2 port in/out style pump and leave that OEM style d-jet pump for those who feel a need to bang their head against a wall. As long as the pump you install can make about 40psi, you're good as the regulator will regulate it down to the proper 28-30psi. DO NOT however go to a wrecking yard and plumb in a pump from a CIS (K-jetronic) car and expect the d-jet regulator to handle that. That is a recipe for a fire in a big way since the CIS pumps put out over 90+ psi!!

You will need to remove the "Y" and associated hose that connects the "R" and "S" ports on the d-jet pump.

[jaywithtype3]

thanks to nate from jaywithtype3; still need best ideas on what 2-port pump; should use about 2 amps, not be one of those performance jobs with heat-fins all over. Also need check-valve on output?
For others: i meant to add that Bosch pump taking about 4 amps, twice too much, as it flows thru relief port (only). Also want to know how to reseal old open pump (sealant, clamping, etc) (yes i know big gamble unless all works perfect). Besides any more answers to mysteries i described above.
For those reading this far, i have solved many many other EFI problems way beyond what books cover, but not this one so far. 2-port pump feels like best long-term solution, but lacking type, & certainty.

[aircooledtechguy]

You can go onto eBay and do a search for Walbro EFI pumps. I don't know how many amps they use, but honestly, you have a lot more to worry about than electrical consumption if your car won't run without a pump. . . I'm running a Walbro on my Squareback with MS injection and it's been flawless. I think they are around $80-90 and it'll run D-jet perfectly.

[jaywithtype3]

thanks again to nate from jaywithtype3. I see Amazon has same Walbro pumps as ebay, none stated as EFI, but despite your experience, am still concerned that e.g. #GSS342 rated for 255 lph is way over needs. VW has regulated loop, but small tubes & hoses mean VERY strong back pressure & return flow, maybe fast erosion of hoses. I can do testing and reduce voltage to pump to see if moderate this. Do i need a checkvalve to avoid partial emptying of fuel loop? Also on third look that seems to be in-tank pump, not wanted, cant tell if any Walbro are not. What number are you using, & are you using it out of tank? Before sending more direct message, am responding this way in case you have more to add. Old VWs use like 2 gal/hr = 8 lph.

[aircooledtechguy]

Umm,. . . 2gal/hr would not feed a 1600cc carbed motor for 1 hour @ 60mph. . . Think about it. You are confusing PSI for flow rates. True that the carbed cars only needed about 2 PSI, but I can tell you that the old mechanical fuel pumps will pump WAY over 2 gal/hr. . . Ever had a fuel hose burst?? In a nano-second you have a cup or fuel all over everything.

You are WAY over thinking this, which is common with these cars. In order to build pressure you must have flow. No additional check valve is needed since your dual relay that runs the pump is designed to allow the pump to prime the system with fuel. Again, you're over thinking this. The stock EFI fuel pump is going to pump 10s of gallons p/hr. Ever used one to siphon a tank?? You can move 10 gallons in about 5-7 minutes.

The Walbro 255L p/hr external pump is what I run pumping through the stock fuel line from the tank to the rear loop on my car. I use the German EFI hose on all rubber hoses. I cannot tell you how many folks use this Walbro pump with great success using stock regulators and hoses. Again, you're over thinking this. Anyone who goes over 2 years on rubber hoses with today's ethanol-rich fuels without changing the hose is asking for problems anyway.

[jaywithtype3]

thanks nate on more hints. havent confused anything but okay with raising theoretical fuel flow to somewhere between say 20 lph & 255 lph. assume you are confirming that Walbro GSS342 is external & what you are using. Other walbro pumps also do 255 lph & may be internal. some regular fuel hose has lasted 20+ yrs at 28 psi, but wont go forever. i use copper tube for long runs.
Anyone else have some final words on solution recommended above, before i spend $ & test it?

[raygreenwood]

The walbro pump listed is correct for you. It will work fine. The requirement for almost all of the ACVW's for fuel injection (D-jet) is 28-30 psi @ 1 liter per minute. For tehL-jet vehicles its about 42 psi max at 1 liter per minute.

As aircooledtechguy correctly noted.....pumps are rated by volume. They create pressure by pushing volume against a constant restriction (either spring loaded gate or restricting orifice).

The Walbro does indeed make 255L per hour...but that flow level is largely unsrestricted. When you restrict it with say....a low pressure check valve (which is what your fuel pressure regulator is)....you get that regulated pressure plus a reduced liter/hr flow. from what I have found the Walbro pump in question....with D-jet will give you your 30 psi at about 160Lhr flow at that pressure. Thats about 2.66L/min...very respetcable.

By comparison....the stock D-jet pump puts out 28-32 psi at between .9 and 1.1l/min on average......with a max pressure of about 70 psi. But...unrestricted...it puts out about 160-180L/hr

I highlighted that last part because its important to the understanding of these pumps. The D-jet three port pump has a ball check style relief valve. If you pinch a line or get a restriction....it vents to the return line at about 70 psi to keep from blowing the head seals on the pump or the hoses in the car and causing a fire. Right as it vents to 70 psi...the Liter per minute drop to about .3-.4 lpm.....so..do you see how volume works?

It also matters how the pump is built and check valved. For instance.....the CIS pump that aircooledtechguy mentioned....killer pump by the way......is only a little larger in flow volume than the D-jet three port pump. (the BoscH 044 CIS pump is 200L per hour)...bit it maintains this pressure against a restriction....at 5 bars of pressure and requires 16 amps to do so. Its next in line bretherin is the Bosch 040 pump...whcih is the same exact pump that is check valved differently and so puts out 6.5 bars of pressure at a constant 102 liters per hour...and draws 11 amps to do so.

These pumps CAN be used we D-jet....and teh regulator can handle it...but if you just hook one up without adjusting it you get a constant 50-60+ psi of pressure. You can adjust the D-jet regulator down....but you are perilously close to the end of teh adjustment of that regulator. Its not reccomended. If you are crafty though....you can use twin regulators (two orificies relieveing one line )and it makes a very dependable pump system but should be used with a feeder pump. Lots of plumbing.

I cannot remember if the walbro pump has an internal relief check valve like this. But....it should have like most two port inline pumps....an upstream output end ball check valve. If it did not.....it would be a very inefficient pump.

The way it works is that one compression cycle of the roller cels in the pump raises pressure above the level needed to crack open the check valve on the output side of the pump. The fuel passes through and then cannot come back. This is required or else the pressure head would span the entire roller cell chamber and make it virtually impossible to draw new fuel into the cell chamber.

This check valve system is also required to keep fuel pressure from bleeding off immediately duringshutdown...or else hot starts would be very difficult. As it is....high pressure injected cars like CIS...had such bleed down issues that they required a bladder style fuel pressure accumulator to make sure they could readily start.

The walbro pump listed will be just fine for D-jet.

by the way...the three port D-jet pump had a build quality and tolerances that far exceed that of the walbro pump...because they had to. They were early designs and did not have the volume to create the efficiency needed. They can last 30-40 years easily. But...the price is just far too high. I can buy three Walbro pumps...one every 5-7 years or more....for the cost of a new original d-jet pump.....and it will function perfectly. Ray

[supaninja]

I too am using a Walbro 255, it will have zero problems feeding a Djet system. In fact I'm on year 4 in my daily, got about 70,000 miles on the Walbro. One thing I do want to warn you about, there is a bunch of bootlegged walbro's floating around out there, http://www.evans-tuning.com/blog/2010/0 ... knock-off/ normal price is around $100, if the pump is much less it should raise a flag, I only buy mine from a reputable sellers (not ebay or amazon).

[jaywithtype3]

thanks to raygreenwood for interesting observations & confirmation on Walbro pump. worrissome that supaninja above says fake walbros on amazon, my only easy source.
On specialty forum you raise possibility of a stamped Bosch pump being a bad rebuild. On one hand, that pump looked clean, no flaws outside, but on other hand, it did have slight drip of fuel from case, not under pressure. Other obvious rebuild had stamped numbering ground off & sloppy ports. Both came from Fuelpumpking, one 2010, one 2012. suppposedly can return latest.
I did not stress on 31 Dec to you that blowing with mouth or airpressure into D port finds no flow, & examination of dissembled once-working pump shows one cannot blow that valve open that direction. Thus fuel pressure is needed from inside to open it, & if pump assembled wrong (two in two different years?), then you have provided an answer, but only partial. see next:
Walbro inline pump aside, i am likely also to use above pump thru its R port as inline pump, unless someone knows serious oversight/problem. This works in full simulation, 28 Psi regulated, good flow, so rollers are grabbing fuel. But no check valve for start up?.

[raygreenwood]

I beleive it has an anti-backflow check valve which is all that is required to keep line pressure from dropping past minimum regulator pressure. Virtually all inline two port pumps have a check valve at the outlet end. Ray

[aircooledtechguy]

Jaywithtype3: Are you some sort of engineer?? Mechanical engineer, electrical engineer, structural engineer???? The reason I ask is this: you ASK for peoples HELP and then you question every bit of help from the stand point of "I have over-educated goggles on and think too deeply on EVERYTHING"

VWs are s-i-m-p-l-e and must be approached with that frame of mind or you will over-think the simplest of problems. You're coming at this fuel pump swap like the car has OBD2 computer on-board and will begin throwing codes if the replacement pump pulls too much power; it won't because it doesn't. Or that the electrical system can not handle more power through-put than it already has; it will handle it like a champ. Or that the fuel hoses can not handle any pressure; they will provided you have the correct EFI hose in god condition. Or that the pump will not have a check valve and thus hold line pressure for a period of time; ALL new pumps have anti-back-flow check valves (or at least ALL I have ever seen).

Believe me when I say that the folks who design these pumps (and these cars) take ALL THAT into consideration (well all except the fuel line, but that's where your own personal responsibility comes into play).

Go buy yourself a Walbor 255 external pump (or not) and see how simple the upgrade is from the crappy 3-port pumps. You'll find that you are making a whole lot out of nothing. . .

[jaywithtype3]

new response to jay greenwood above: since you mentioned (in general-engine-fuel inj forum) examining a 3 port pump, i did not say some things well above. I looked again into the valve assembly of a dissembeled formerly-working 3 port pump (stopped for unknown electric reason) & should have reported found double-cone structure where fuel from rollers attempts passage. To D port the cone is sprung shut tight (i judge spring force to be moderate & reasonable for its alleged job). To R port a different cone sits slightly open, allowing low flow. A push thru D port from outside will move valve open & shut R. When pump starts, fuel goes thru R, despite it supposed to be shut except in overload. I have pondered & tested these for 2 months, and now i dont see how this once-working pump ever made fuel come out D, altho it did for 35 yrs. Some odd balance of flows and pressures opened valve to D? My blowing into D port was irrelevant. From all outside structure and testing the two new pumps cited above seem built same. In running the 2 new pumps, i repeat that 28psi+ occured at R as fuel flowed out. This pressure never somehow forced valve to move to open D.
In regard to rebuilt pumps, i should have said the case looks perfectly crimped shut, with no traces of how it could have been opened before. Traces of yellow-gray sealant there. I tell all this, & other earlier accurate observations, for your consideration if you do go into one of those pumps. I also reconfirmed that original pumps as VW supplied on Type3s had quite different valve structure. Diagrams exist in old books. Nothing blocking between rollers with fuel and D outlet.
To Nate & all: sum total of responses on this mystery shows so far that it cannot be overthunk. I have written as carefully& briefly as i could, & have "listened" carefully to all, & have so shown. have solutions to other type 3 problems awaiting anyone still making these cars go.

[jaywithtype3]

new question & new notes on all above: have walbro gss342 pump, surprised inlet has no means of connecting to, nor are adapters shown clearly as such on walbro parts area on amazon. rigged adapter for testing, would like more secure suggestions. yes check valve in outlet. pump comes with no instructions. really seems like goes in bottom of tank, which vw owners cant do.
note to nate if still watching: left PM for you which is there under sent messages, 4 Feb.

[aircooledtechguy]

sigh. . .

I got your PM. . . but why respond when you never listen anyway. . . The following response is purely for my own enjoyment. . .

Again, the reason your new pump looks like it belongs inside the tank is because against all advice given on the above replies, you went and bought an IN-TANK PUMP. . . It bogles the mind how you did that when you, yourself seemed to already know that you needed an in-line pump. . . Several of us even posted the correct part number of Walbro pump you needed. . .

Some folks should not own tools. . .