200/300Tdi ADVANCED TUNING

mgreenspan

Founding Member
But if the electric pump is supplying more fuel then the return line banjo (with its somewhat small orifice) can bleed and injectors can spray, pressure in the lines is going to build. With the addition of electric pump I am seeing leaking on my spill rail fittings. This is a FP with a 14psi max pressure. What is max lift pump pressure? 11psi? https://www.summitracing.com/parts/atx-e8153

I don't know much of anything regarding this topic; however, a lot of folks with 200 and 300s have an inline 12 volt electric fuel pump and aren't having the same problem you have. I'd think something else is going on.
 

AdamSanta85

Well-known member
I don't know much of anything regarding this topic; however, a lot of folks with 200 and 300s have an inline 12 volt electric fuel pump and aren't having the same problem you have. I'd think something else is going on.

It is very possible my old spill rail is just worn out and leaky, and or my return line is clogged. The truck itself is running strong.

However it is still worth wondering if the extra fuel pressure, at least at low RPM, has required any fueling changes as the electric pump delivers static fuel pressure at idle vs the variable of the lift pump which is probably only 11psi (?) at max rpm. On fuel injected cars the tune will be affected with a change of base fuel pressure.
 

Viton

Well-known member
But if the electric pump is supplying more fuel then the return line banjo (with its somewhat small orifice) can bleed and injectors can spray, pressure in the lines is going to build. With the addition of electric pump I am seeing leaking on my spill rail fittings. This is a FP with a 14psi max pressure. What is max lift pump pressure? 11psi? https://www.summitracing.com/parts/atx-e8153

You also run the risk then of a line popping off a fitting or bursting a line and fuel being sprayed all over the engine compartment. I had the spill rail come off the #4 injector and fuel went everywhere at highway speeds. The fuel gauge started dropping fast & I was wondering why I was smelling weed killer. Pulled over quickly, and you would not believe the amount of fuel that was shooting out of that line even at idle, it was spraying a solid stream all the way to the bulkhead.

Guys that use an electric pump use then mainly (from what I read) for pushing air though the line after a filter change & for locating leaks. You won't be able to increase the output pressure of the IP without doing some modifications to the internals of the IP.
 

AdamSanta85

Well-known member
Guys that use an electric pump use then mainly (from what I read) for pushing air though the line after a filter change & for locating leaks. You won't be able to increase the output pressure of the IP without doing some modifications to the internals of the IP.

So what you are saying is once the fuel enters the IP, the IP solely takes over raising the pressure? The electric pump won't increase the IP output pressure, just the input pressure? I have never messed with an IP before. Also anyone know what the pressure is between IP and injector? (In the metal lines). I would assume it is very high.
 

4wdtravel

Well-known member
We are straying from the original intent of this thread but thats fine.

Lift pump pressure is like 6psi with the OEM mechanical pump. The IP raises this to several thousand PSI (exact specs in the first post of the thread - look at injector pressure).

There are two advantages to an electric lift pump. One of them is effortless bleeding of the fuel system. The other, *under high power conditions* is the ability to maintain high flow to the IP under all conditions to ensure full filling of the delivery valves at all times.

The excess fuel that flows through the pump case, and is returned to the tank, is also the only source of cooling in the pump. High flow means more cooling.

Leaking from your spill ports might be expected with the push on hoses that LR uses. There is likely a way to upgrade this but I don't know off the top of my head.

If none of this is for you, then it might be wise to stick to the old hat "turn the star wheel two clicks, the smoke screw a half turn, up the boost by 2 psi" and be happy. There are a million threads on that :)
 

AdamSanta85

Well-known member
Lift pump pressure is like 6psi with the OEM mechanical pump. The IP raises this to several thousand PSI (exact specs in the first post of the thread - look at injector pressure).

Thanks. That was what I was getting at. An electric pump putting out 14psi feeding another pump that raises pressure to upwards of 4075 psi on second stage isn't going to have any affect on fueling. Thanks for clarifying.

I didn't intend to drag my personal issues into this thread, I already have one for that. Thanks.
 

4wdtravel

Well-known member
Well, knowledge discovered by people tuning the VE pump at an extremely high level indicates that it can affect fuel delivery. But in a stock application, its irrelevant.
 

LostChord

Well-known member
Thanks. That was what I was getting at. An electric pump putting out 14psi feeding another pump that raises pressure to upwards of 4075 psi on second stage isn't going to have any affect on fueling. Thanks for clarifying.

I didn't intend to drag my personal issues into this thread, I already have one for that. Thanks.

Glad you're here doode....leaned a lot following your projects.
 

Oilburner

Member
A couple things to remember. On a VE pump fuel system there are three pressures. One is inlet pressure (from lift pump). The second is internal timing pressure. The VE has a vane pump built into the front of it. It creates a varying internal pressure that works against the timing piston, which allows for the injection timing to vary depending on RPM. The third is the injection pressure.

Running a higher pressure electric lift pump can have negative consequences since it pre-charges the vane pump. This can mess with the timing pressure and alter the timing (advance it too soon/low in RPM range). If you use an electric pump, keep it low pressure.

On really high-horsepower applications (like, Cummins 6BT with 4000 RPM) keeping fuel pressure at 6-10 PSI at the inlet becomes a problem just due to the tremendous volume of fuel used (12MM pump, 6 cylinders, BIG injectors, lots of fuel) and people run large lift pumps. The only way to tell if this is an issue for 300TDIs would be to put a gauge on the inlet and see what happens. On my Cummins project I am running an updated mechanical lift pump that is regulated to 14 psi, and I don't think that pressure has any effect on internal function.

A lot of Volkswagens never even ran a lift pump, and relied on the vane pump to pull from the tank, but again, that would change the internal timing function since it would probably lower the case pressure.
 

Viton

Well-known member
I can attest to the 1981 VW diesel rabbit I owned from new. For still an unknown reason the air inlet to the steel fuel tank became plugged and caused the tank to partially collapse. It only held about 10-12 gallons, but would only take about 6 when empty, investigation found that the tank was crushed inward on the top side. This demonstrates how much "pull power" the VE has.

My 1985 BMW 524td had an in tank lift pump but would only pump when the glow circuit was in operation and often still did not function because of a bad ground wire.
 

4wdtravel

Well-known member
Check this out.

ranger-elec-mtr-2g.jpg
 

4wdtravel

Well-known member
That is the 3.0 that replaced the 2.8 we are all familiar with. Cross flow 16V head, overhead cam, common rail injection.

Its still all on a fairly traditional Tdi block.
 

ian4455

New member
12mm Head, 3.16 Cam Plate

Question - if i use a 12mm Pump head and 3.16mm Cam Plate what size injector nozzles would suit this set-up on a 300tdi ?
 
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